Dr Caroline Leaf and Testimonials – Good marketing, poor evidence

Dr Caroline Leaf is a communication pathologist and self-titled cognitive neuroscientist. She is a pseudoscientist of the highest order. She once wrote a PhD. Now she has episodes of her TV show titled “Surviving cancer by using the Mind”.

This weeks edition of her newsletter started off with some subtle boasting:

“We have received many E-mails over the past years asking for Testimonies with regards to Dr Leaf’s research and teachings. We have summarized eight pages of testimonies received at TESTIMONIES. Be encouraged and feel free to refer them to friends, family, acquaintances, and work colleagues struggling with Mind issues.”

Testimonials are an empty box wrapped in shiny paper and trimmed with a bow. They look really good but offer nothing of substance. They’re simply an old advertising trick.

According to the Market Science Institute, “Testimonial solicitations – in which firms solicit consumers’ personal endorsements of a product or service – represent a popular marketing practice. Testimonials are thought to offer several benefits to firms, among them that participating consumers may strengthen their positive attitudes toward a brand, through the act of writing testimonials.” [1]

Who can argue with a person who says that Dr Leaf helped turn their life around? Saying anything negative just makes you sound like a cynical old boot.

And that’s the real problem, because while publishing a whole bunch of positive stories is good for marketing, it makes it very hard for those who had a genuinely bad experience to say anything. No one wants to listen to those people whom Dr Leaf has confused or mislead – it makes for terrible PR. Those people feel devalued, and sometimes worse, because it seems like everyone else had a good result from Dr Leaf’s teaching, except them.

Testimonials also make for very poor scientific evidence. Indeed, testimonials are considered the lowest form of scientific evidence [2]. It’s all very well and good for a bunch of people to share their positive experiences, but as life changing as the experience may have been, they are not evidence of the effectiveness of Dr Leaf’s teaching. Without specific, well-designed research, no one can say if the testimonials Dr Leaf is publishing are the norm. Recent research demonstrates that self-help literature for depression may not have any benefit over a placebo treatment [3]. So it may be that any improvement attributed to Dr Leaf’s teaching was actually the placebo effect. Dr Leaf can list testimonials until she’s blue in the face, but that doesn’t prove that her work is scientific or therapeutic.

Indeed, selectively publishing testimonials is duplicitous, telling half-truths, positively spinning her own story. How many e-mails has Dr Leaf gotten from people who have found her teaching inaccurate, ineffective, unbiblical or harmful? Dr Leaf’s social media minions deliberately delete any negative comments and block anyone from her sites that disagree with her. And over the years, many people have shared with me how arrogant and dismissive her team has been to polite, genuine concern or criticism. I can personally attest to the same treatment. If Dr Leaf was honest with her followers, she would be openly publishing the brickbats as well as the bouquets.

For her readers and followers, the testimonials need to be seen for what they are: just individual stories. Sure, we should rejoice with those who are rejoicing (Romans 12:15), and so good for those who feel Dr Leaf has helped them. But they do not constitute evidence for the therapeutic efficacy or scientific integrity of the work of Dr Leaf.

For people genuinely struggling with “mind issues”, the last thing they need is testimonials collated by Dr Leaf’s marketing team.  They don’t need to be referred to Dr Leaf’s work, they need to be referred to psychologists and doctors.

And if Dr Leaf really wanted to prove her legitimacy, she would rely on independent peer-reviewed published research, not on the list of vacuous, self-serving cherry-picked testimonials that she is currently offering.


[1] Marketing Science Institute. Consumer Testimonials as Self-Generated Advertisements: Evaluative Reconstruction Following Product Usage. [cited 2014, Aug 3]; Available from: http://www.msi.org/reports/consumer-testimonials-as-self-generated-advertisements-evaluative-reconstru/.
[2] Fowler, G., Evidence-based practice: Tools and techniques. Systems, settings, people: Workforce development challenges for the alcohol and other drugs field, 2001: 93-107
[3] Moldovan, R., et al., Cognitive bibliotherapy for mild depressive symptomatology: randomized clinical trial of efficacy and mechanisms of change. Clinical psychology & psychotherapy, 2013. 20(6): 482-93

Caroline Leaf – Carrie Fisher killed by bipolar meds


No longer content with just wilful ignorance, Dr Caroline Leaf has stooped even further by using the death of a beloved actress as a sick segue against psychiatric medications.

Dr Caroline Leaf is a communication pathologist and self-titled cognitive neuroscientist.  She markets herself as an expert in neuroscience and mental health despite not knowing how genes work (https://cedwardpitt.com/2014/09/27/dr-caroline-leaf-and-the-genetic-fluctuations-falsehood/ and https://cedwardpitt.com/2017/01/07/dr-caroline-leaf-the-christian-churchs-anti-vaxxer/).

In her latest “Mental Health News – January 2017” e-mail newsletter, Dr Leaf makes some astounding and outlandish statements about mental health.

She starts by claiming that Carrie Fisher’s death was ultimately caused by the psychiatric medications she was taking.

“Few people, however, are talking about the possible link between her heart attack and her psychiatric medication. As mental health activist Corinna West shows, ‘new antipsychotics cause weight gain, diabetes, and a bunch of other risk factors associated with heart disease.’ We have to take these risk factors seriously. We are not merely talking about statistics—we are talking about real people, people like Carrie Fisher.”

Dr Leaf, no one’s talking about the possible link between her heart attack and her psychiatric medication because we respect the Carrie Fisher too much and would rather celebrate her life and achievements, not perform a hypothetical post-mortem motivated by prejudiced speculation.

No one’s talking about the possible link between her heart attack and her psychiatric medication because no one really knows what caused Carrie Fisher’s heart attack.  No one knows if she had any other risk factors for heart attacks, or what medications she was on.  There could be a dozen other reasons why she had a heart attack.  No one else is asking because it’s none of our business.

No one’s talking about the possible link between her heart attack and her psychiatric medication because we know that psychiatric medications do much more good than harm.

No one is talking about the possible link between her heart attack and her psychiatric medication because it’s highly disrespectful to use someone’s death to promote your political or ideological position.  Using Carrie Fisher’s death as a segue to your soapbox about psychiatric medications is like someone using Princess Diana’s death as an opportunity to talk about the dangers of speeding in tunnels.  It’s ungracious, unbecoming, and in poor taste.

What’s even more dishonouring to Carrie Fisher is that Dr Leaf’s claims about psychiatric medications are not accurate.

“Sadly, individuals suffering from mental health issues ‘die, on average, 25 years earlier that the general population.’ These medications are incredibly dangerous, and we have to start asking ourselves, as the investigative journalist and mental health campaigner Robert Whitaker notes, if the benefits of these drugs truly outweigh the risks.”

Notice the giant hole in her argument?  She assumes that the increased risk of death in those with mental illness is the medications they’re on, just like she’s assumed that Carrie Fisher died because she was taking psychiatric medications.

That’s confirmation bias, not science.

Real mental health experts – the ones with training, clinical experience and research acumen – directly contradict Dr Leaf.  Experts like Correll, who say that, “Although antipsychotics have the greatest potential to adversely affect physical health, it is important to note that several large, nationwide studies providing generalizable data have suggested that all-cause mortality is higher in patients with schizophrenia not receiving antipsychotics.” [1]

In other words, the life expectancy of people with schizophrenia is shorter than the rest of the population, but it’s much shorter in schizophrenics not on meds.  Psychiatric medications help people with schizophrenia live longer.

In fact, the use of any anti-psychotic medication for a patient with schizophrenia decreased their risk of dying by nearly 20% [2] whereas the risk of dying for schizophrenics who didn’t take anti-psychotics was nearly ten times that of the healthy population [3].

This is the same for other psychiatric medications as well, “clozapine, antidepressants, and lithium, as well as anti-epileptics, are associated with reduced mortality from suicide.” [1]

Psychiatric drugs aren’t “incredibly dangerous”.  Like any tool, when used in the right way, they can bring radical transformation.  What IS incredibly dangerous is the disingenuous and ill-informed making libellous and inaccurate statements about medications they don’t understand.

Not content to just insult Carrie Fisher’s memory, Dr Leaf went on to claim that psychiatric labels are also as harmful as psychiatric drugs.  “These risks are not limited to taking medication. Psychiatric labels can also harm the individual involved. Child psychiatrist Sami Timimi recently discussed the adverse effect the autism label can have on children and adults alike. Labels can lock people in, taking away their hope for recovery, affecting their ability to perform everyday tasks and crippling their determination to live above their circumstances. Words can harm people as much as “sticks and stones” do, as psychologist Paula Caplan notes in her talk on psychiatric survivors and diagnoses.”

It’s witless to suggest that labels harm people or that they somehow lock people in and take away their hope.  The right label, which doctors call a diagnosis, doesn’t lock people in at all, it does the exact opposite:
* The right diagnosis gives hope – hope that comes from receiving the right treatment and not wasting time, money and energy pursuing the wrong treatment.
* The right diagnosis gives power – it empowers people by giving them the ability to make accurate decisions about what’s best for themselves and their loved ones.
* The right diagnosis gives certainty – in many situations, knowing what the diagnosis is reduces unnecessary anxiety and fear.

Imagine that you had a freckle on your arm, and it started growing suddenly.  You go to the doctor, and the doctor says that the freckle is actually a skin cancer.  Does that label lock you in and take away your hope?  Of course not.  It gives you the certainty of knowing that treatment is needed, and the power to decide if you want that treatment.  And it gives you hope that with the right treatment, you can continue to live a healthy life.

In the same way, a psychiatric diagnosis doesn’t lock people in and remove their hope.  A child who understands that they have autism can stop beating themselves up for being ‘odd’ and instead, they can understand that their different wiring gives them special powers that other kids don’t have.

Psychiatric labels do not harm an individual, it’s the backwards opinions of so-called mental health experts that harm individuals with psychiatric illness.  The stigma of a diagnosis is related to the way in which society treats individuals with that diagnosis, not the diagnosis itself.  Perpetuating the myth that that ‘depression and autism aren’t really diseases’ reduces the acceptance of society for those who suffer from those conditions.  That’s what causes harm.

Dr Leaf should apologise to her followers for showing such disrespect for Carrie Fisher, and to all those who take psychiatric medications.  Carrie Fisher spent her life supporting people with mental illness, trying to break down the stigma of psychiatric illness and treatment.  Her life’s work should be celebrated, not defaced by Dr Leaf and her unscientific opinion.


[1]        Correll CU, Detraux J, De Lepeleire J, De Hert M. Effects of antipsychotics, antidepressants and mood stabilizers on risk for physical diseases in people with schizophrenia, depression and bipolar disorder. World psychiatry : official journal of the World Psychiatric Association 2015 Jun;14(2):119-36.
[2]        Tiihonen J, Lonnqvist J, Wahlbeck K, et al. 11-year follow-up of mortality in patients with schizophrenia: a population-based cohort study (FIN11 study). Lancet 2009 Aug 22;374(9690):620-7.
[3]        Torniainen M, Mittendorfer-Rutz E, Tanskanen A, et al. Antipsychotic treatment and mortality in schizophrenia. Schizophrenia bulletin 2015 May;41(3):656-63.


Is sunshine healthy again?

  • New study claims avoiding the sun is as dangerous as smoking
  • Study found women in Sweden who had greatest sun exposure had lowest risk of dying from heart disease/stroke and death overall
  • But study failed to consider exercise as possible cause of improved health in cohort
  • UV exposure clearly linked to cancer risk
  • Safe sun exposure for most people still a few minutes of sunlight to face, arms and hands in the morning and evening

I live in Queensland.  Queensland is the Sunshine State, so named because we boast about having the most hours of sunshine than any other state in Australia (we actually don’t have the most sunshine in Australia, but we like to remain pleasantly deluded).

We’re blessed with temperatures that vary from pleasantly warm to oppressive and humid, but with an outdoor climate and a coastline that boasts some of the world’s most beautiful beaches, traditionally, Queenslanders have enjoyed lots of time in the sun.

In the 1960’s and 70’s, it was fashionable, and even considered healthy, to have a deep brown tan, even if that meant burning yourself to a lobster-red colour in order to achieve it.  Then in the 1980’s, we had a rethink because of the large number of skin cancers that were appearing.  I remember being at school in the 1980’s and being indoctrinated with the “Slip Slop Slap” mantra, “Slip on a shirt, slop on some sunscreen, and slap on a hat”.

Now, in the mid twenty-teens, the trend in sun avoidance behaviour has almost led us back to the Victorian era of full body swimsuits, enormous hats and constant shade seeking.  Tan’s are considered unhealthy, and if you get burnt enough to peel, everyone tells you that you’re going to die of melanoma.

If the trend continues, the next generation will be anaemic zombies whose only light exposure will be from LED devices.  Actually, come to think of it, that IS the current generation …

Given our carcinophobic sun-avoidance, I was surprised to see an article come across my social media feed entitled, “Avoiding sun as dangerous as smoking”.

Oh my goodness, was this another thing we’ve been get wrong all these years?  Should I start promoting tans again?  Should I be in my backyard in my underwear trying to get one myself?

As it turns out, I can keep my clothes on, much to the relief of my neighbours.

The study in question is a 20 year follow up of nearly 30,000 women in Sweden [1].  They measured their sun exposure habits at entry to the study, and throughout the two decades of follow up, and they found a nice linear relationship between their sun exposure and their overall mortality.

Screen Shot 2016-03-26 at 4.19.27 PM

The authors stated that, “Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking.”

This is sometimes where reading medical literature can be confusing.  I can imagine some people thinking, “Well, that means if I want to spend all day on the beach, I can protect myself by taking up smoking.”  So let’s take a step back here before we swap our sunblock for a packet of ciggies.  We have to be careful in how we apply this information from this study.

For a start, this research was done on women living in Sweden, where the climate is slightly different from living in the tropics.  There isn’t much sun in Sweden, and when it does come out, it’s not very intense.  That’s a big different from living in climates like Queensland where standing in the sun for an hour does to us what my microwave does to my leftovers.

We know that UV radiation is bad for us.  Tanning beds increase the risk of melanoma [2] and sunscreen decreases it [3].  When the current study broke down their numbers, the all-cause mortality related to sun-exposure was lower, but the cancer risk was higher.

Despite the risk of cancer increasing with sun-exposure, the cardiovascular causes of death were much lower, but this may be nothing to do with sun-exposure at all, but may be all to do with exercise, something the study failed to account for as an independent variable.  Time outside is usually going to be active time – exercising, gardening, walking, etc., and it may simply have been that those women who had the most sun exposure also did the most exercise or were the most active, which is common sense.

So the article isn’t able to prove that the health benefits which they ascribe to sunlight aren’t from something else.  Their cohort of subjects also doesn’t allow for a broad application of the results given their lack of UV intensity in their climate compared to other parts of the world.

I don’t think this study is enough to reverse the current wisdom about sun exposure.  It’s ok to have a few minutes of exposure to sunlight on your face, arms and hands most of the year, although some people in areas of higher latitudes (closer to the poles than the Equator) may need some more sun exposure in winter.  Look at information from a cancer council in your area for locally appropriate information.

So, keep your pants on, and the rest of your clothes for that matter.  We don’t need to expose ourselves and get a tan to live a longer life.


[1]        Lindqvist PG, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson H. Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort. Journal of internal medicine 2016 Mar 16.
[2]        Boniol M, Autier P, Boyle P, Gandini S. Cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis. Bmj 2012;345:e4757.
[3]        Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2011 Jan 20;29(3):257-63.

Dr Caroline Leaf and the Myth of the Chemical Imbalance Myth

Screen Shot 2015-10-27 at 2.49.38 am

There are lots of medical myths that people believe.

“I have acne because I eat too much chocolate, or my face isn’t clean enough”

“Stomach ulcers are because of stress”

“I coughed up some yellow phlegm, so I must need antibiotics right?”

“My baby’s fevers are because of teething.”

Is the “chemical imbalance” theory one of them?

Dr Leaf is a communication pathologist and self-titled cognitive neuroscientist. A couple of weeks ago she opened a proverbial can of worms by quoting the out-spoken Peter Gøtzsche, claiming that psychiatric drugs are the third leading cause of death after heart disease and cancer. This did not go down well, and Dr Leaf had to issue three separate statements on social media to try and justify herself and attempt to rescue her rapidly deteriorating credibility.

Not that she issued an apology, mind you, or retracted her statement.

Today, Dr Leaf published a blog on psychiatric medications … but again, not to apologise but to further justify why she’s right, and nearly every other doctor and scientist in the world is not. Worse than that, she went so far as to accuse doctors of deliberately prescribing “clearly dangerous” drugs, which she claims have no therapeutic effects, just because of some overcooked drug-company sponsored dinner and a few pens. More on that later.

Her post is a defiant deflection, a logically flawed and factually inaccurate criticism of modern psychiatry and psychopharmacology – not fueled by research, but largely based on the books of disgruntled fringe psychiatrists and researchers with an axe to grind.

Dr Leaf doesn’t discuss the actual science of the medications that she’s so against, but simply tries to create a smokescreen of distrust.

A good example of all that is wrong with this post is contained in the opening paragraph.

Today, it has become commonplace to say that people have chemical imbalances in their brain, most notably a disruption in the proper production of dopamine (for “diseases” like ADHD) and serotonin (for “diseases” like depression). These people, it is supposed, need drugs to “cure” these chemical imbalances, hence the terms “antipsychotics” or “antidepressants”.

The first thing to note is how Dr Leaf uses the term “cure”. No doctor ever uses the word “cure”, especially when talking about complex diseases. This is a pejorative term implying that modern medicine is only interested in permanently fixing things. But it’s a straw man fallacy, a false premise that Dr Leaf then uses to cast the medical model as impotent and futile. Nice try, but no one in medicine ever promises cure, and no doctor in their right mind would ever be so narrow-minded as to suggest that drugs are the only treatment for every condition. That doesn’t mean that drugs aren’t useful, nor that the medical model is broken. As we’ll discuss soon, medications are extremely helpful for certain conditions, when used carefully, as are non-drug treatments like CBT.

Dr Leaf also puts inverted commas around the word “diseases” as if to suggest that ADHD and depression aren’t diseases, an act which smacks of petulance and willful ignorance, and is insulting to those who have or who have ever suffered from ADHD and depression.   Last week, Dr Leaf was happy to share that her eldest daughter suffered from bulimia and depression, but now she’s suggesting that depression isn’t really a disease. So what is it then? Malingering? Personal weakness? Bad parenting?

It’s really surprising that someone claiming to be a cognitive neuroscientist would ignore strong scientific evidence.  For example, ADHD is associated with dopamine dysfunction as well as the dysfunction a number of other neurotransmitters [1-3]. And depression is associated with a decrease in the growth factor BDNF, (known as the neurotrophic hypothesis of depression) [4-6]. Schizophrenia, which Dr Leaf conveniently failed to mention, is clearly related to dopamine dysfunction in nerve cells of the pre-frontal cortex and the striatum, two parts of the brain that are incredibly important for how your brain processes incoming and outgoing signals [7-9].

There’s nothing to suppose here .. there’s ample evidence that psychiatric diseases are related to dysfunction within the brain, commonly with the function of neurotransmitters among other things. Call it whatever you like, the truth doesn’t change. “Chemical imbalance” is just an easy phrase for the general public to remember.

Dr Leaf then tries to suggest that psychiatric drugs don’t fix chemical imbalances but create them, citing the 1950’s observations of French researchers Deniker and Delay who noted that the first anti-psychotic, chlorpromazine, caused symptoms of Parkinson’s Disease. And indeed it did, but this wasn’t a new disease, just evidence that it worked.

Psychosis, a pathological state involving hallucinations and delusions, is because of an excess of the neurotransmitter called dopamine. Dopamine is the neurotransmitter that’s used by the nerve cells deep in the brain in a part called the basal ganglia, which acts like a central mail delivery centre for incoming and outgoing signals from other parts of the brain. The function of the nerves in one part of the basal ganglia are responsible for sending sensory signals to the frontal lobes of the brain. In another part, the signals are important for smooth movements of our muscles. Proper function depends on just the right amount of dopamine – too much and you get psychosis. Not enough and you get Parkinson’s disease symptoms.

The French researchers were simply noting the side-effects of too much medication blocking the action of dopamine in the basal ganglia – the psychosis had improved, but the blockade of dopamine was just too much in some patients, who had the opposite symptoms.

Again, Dr Leaf’s position is diametrically opposed to the published science [10, 11], and if anything, her claim contradicts her fundamental argument. After all, if chemical imbalances are myths, then how can chlorpromazine create a “new neurological syndrome” because of a chemical imbalance?

Dr Leaf then launches into a discussion on the history of the DSM and psychiatric medications. This is just the first in her ad hominem attacks on the medical profession –  playing the man, not the ball if you will. If she can discredit the doctors that prescribe the medication, then she indirectly discredits the medications.  This appears desperate and ultimately serves to weaken her case.

“It was just assumed that since these drugs affected brain chemistry in a certain way, the opposite reaction must be the result of the disease, notwithstanding the fact that this has never been adequately proven.”

The history of medicine is littered with cures being found without the disease being fully understood. Take Edward Jenner, for example, who is the founder of the modern technique of vaccination. He didn’t know why his smallpox vaccine worked, only that it did. Electron microscopes and a modern understanding of the immune system were centuries away, but Jenner saved billions of lives through his observation that prior vaccination with a small sample of cowpox virus would protect against smallpox [12].

When amphetamines, known to increase dopamine concentrations in the brain, caused psychotic symptoms and reserpine, a dopamine blocker, improved psychosis, it stood to reason that dopamine was a good candidate as a cause of psychosis and schizophrenia. Decades of research have gone on to further confirm and delineate the link [7]. Again, this is not “an overly simplistic explanation of chemical imbalances”. It is well proven, and rather complex.

Dr Leaf also makes the astounding accusation that psychiatrists inflicted suffering and caused “a public health disaster” by creating the DSM. The DSM, the ‘Diagnostic and Statistical Manual’ is an agreed-upon standard classification for psychiatric diagnoses. It is nothing more than a system of classification. It allows psychiatrists and researchers to speak a common language and attempt some coherence among their diagnoses.

Dr Leaf wrote, “… institutions like the American Psychiatric Association and the DSM would define what is normal, in turn telling us what it means to suffer and, essentially, what it means to be human. They medicalized misery, and today millions are suffering because of their actions, creating a public health disaster.”

That’s like saying that classifying the different types of cancer causes cancer. And that millions of people are suffering from cancer because doctors know to call it ‘cancer’. People have been suffering long before the DSM came along. The DSM doesn’t tell people they’re suffering, and it certainly doesn’t define what it is to be human. Such statements are disingenuous and melodramatic.

But wait, there’s more. “Today a psychiatrist can be praised for drugging a depressed person with mind-altering substances and, if these do not work, institutionalizing them and shocking their brain with ECT (electroconvulsive therapy). It is even an acceptable and commonplace practice to imprison mentally ill persons, drug them and lock them in solitary confinement, compelling them to live their days marinating in their own excrement.”

Dr Leaf is again playing to the fears of the public who have watched too many movies and only think of ‘One Flew Over the Cuckoo’s Nest’, ‘Shutter Island’ or scenes from ’12 Monkeys’. There are more oversight boards and lawyers than there are psychiatric patients, and the only people who are institutionalised are those who are clearly a danger to themselves or others. And while institutionalised, they are not subjected to random bouts of electrical shock as if some doctor is wandering around with a medical grade cattle prod, zapping people and laughing maniacally. Nor is anyone locked in solitary confinement and forced “to live their days marinating in their own excrement”.

The paranoid accusations continue some more. Dr Leaf accuses all psychiatrists of ignorance, and then accuses primary care physicians of negligence, by claiming that we prescribe medications that we do not understand because of the bribes and a pretty smile from a pharmaceutical rep.

Again, Dr Leaf contradicts her own argument:

Despite the recognition amongst many psychiatrists and medical health professionals that the chemical imbalance theory is not valid, drug companies like Eli Lilly still claim that ‘antipsychotic medicines are believed to work by balancing the chemical found naturally in the brain’.

Except that antipsychotic medications DO balance the naturally occurring chemical in the brain (dopamine) as we discussed earlier. What the … a drug company telling doctors how their drug works! How dare they tell the truth!

I find it disturbing that Dr Leaf would stoop so low as to insult the entire medical profession, especially every GP and family physician the world over.

Hey, I’m not above criticism. It’s important to have a good long look at ourselves from time to time, to review our practice, and make sure we’re treating our patients in the best possible way. The RACGP, the peak body of Australian GP’s, invited Prof Gøtzsche to present his opinions on anti-depressant medications so that GP’s could decide for themselves if they should adjust their prescribing.

But to suggest that primary care physicians are stupid, ignorant, incompetent and money hungry … that we would sell our soul for a drug company branded pen … is insulting. Though the irony of her statement, “we do not ask ourselves if these doctors really understand all the implications of using these substances. Not even the psychiatrists understand these drugs” is clearly lost on Dr Leaf.  It’s certainly clear from the rest of her essay that Dr Leaf has no idea how these medications work or what benefits they have for those who suffer from mental ill-health.

There’s a lot more to discuss in response to Dr Leaf’s diatribe, but for the sake of brevity, I’ll try and discuss just a couple of other important themes.

Dr Leaf continues to try to make the medications sound useless and poisonous. She has several paragraphs on the placebo effect, making the false argument that the effect of the medications is just because someone tells you it will work. Of course, the placebo effect is part of the therapeutic effect, but that’s the same for all treatments, even Dr Leaf’s programs … “So, if the pastor or cell-group leader says that these programs are safe and will fix your toxic thinking, even though they get most of their information from the author, we believe wholeheartedly in what he or she may say and are more inclined to believe the program will work for us. These beliefs, which ignore actual scientific results, are buttressed by a flood of distorted and biased news reports, press releases and scientific journal articles on supposed toxic thoughts, and have transformed the theory into church dogma. So, obviously, if we experience negative side effects and do not feel the program is working, it must be something wrong with us, not the program.” Is that a fair statement?

Dr Leaf then plays the fear card again by listing all of the potential side effects from psychiatric medications. Dr Leaf is right in saying that psychiatric medications have serious proven long term side effects, and we should be careful.

For instance, if you knew that thrombocytopenia, anaphylaxis, cutaneous hypersensitivity reactions including skin rashes, angioedema and Stevens Johnson syndrome, bronchospasm and hepatic dysfunction were the potential side effects for a medication, would you take it? Most people wouldn’t.  Reading the list makes that drug sound really dangerous.  We should be up in arms about such a potentially harmful drug being put up for sale … except that this list of side effects isn’t a psychiatric drug at all, but’s actually the side effect profile of paracetamol (acetaminophen in the US). People take paracetamol all the time without even thinking about it.

Saying that we shouldn’t take medications because of potential side effects is a scarecrow argument, a scary sounding straw man fallacy. All drugs have serious proven long term side effects. Licencing and prescribing a medication depends on the overall balance of the good and the harm that a medication does. And no one has ever hidden these side effects from the public as if there is a giant conspiracy from the doctors and the pharmaceutical companies. They’re right there in the product information (here is the product information for fluoxetine. See for yourself).

Whilst it’s true that these side effects do happen, we know that they happen infrequently, just like we know that people win lotteries infrequently. Even so, the medications are not just doled out like sweets at a candy store. You require a minimum of ten years of university level education to be able to prescribe them.

Patients ALWAYS have a right to ask questions about possible benefits and side effects, and in my practice, I tell my patients the pros and the cons before prescribing, and I give them the choice of whether they want them or not. No one is ever forced into taking them.

Finally, Dr Leaf makes a number of irrational statements and flawed arguments in her final page of ranting. Let me quickly go through some of the honourable mentions:

* “Most people recover from depression without antidepressants” – true, because most cases of depression are mild. That doesn’t mean to say that antidepressants shouldn’t be used for severe depression, just like most people recover from upper respiratory infections without antibiotics, but that doesn’t mean that we shouldn’t use antibiotics for severe tonsillitis or pneumonia.
* “Antidepressants are no better than placebos” – It’s a controversial topic right now. There are many pushing the barrow that SSRI medications are no better than a sugar pill. But Dr Leaf has conveniently ignored several Cochrane reviews (the best of medical evidence) that shows anti-depressants work for a variety of disorders [13-15], but that psychological therapy might not [16].
* Equating antidepressants and antipsychotics with illicit drugs, and claiming that “more people die from overdoses of psychiatric drugs than illicit drugs” – This is Reductio ad absurdum – the logical conclusion from this argument is that illicit drugs are safer than psychiatric drugs. And therefore we should not give people psychiatric drugs since we don’t give people the ‘safer’ illicit drugs. But that conclusion is absurd, and when you think about it, the whole thing is based on hidden false premises – people rarely die of illicit drug overdoses because they’re illegal and are hard to come by. And also, people who use illicit drugs are not usually suicidal, whereas those given psychiatric medications sometimes are suicidal, and sometimes use them to try and commit suicide. But modern psychiatric drugs are much less dangerous in overdose than their old counterparts.  It should also be noted here that more overdose suicide attempts are with paracetamol or ibuprofen than with psychiatric medications [19], but I don’t see paracetamol or ibuprofen being demonised.
* Psychiatric medications are part of a neo-liberal capitalist plot to keep the rich, richer and the poor, poorer – To me, this looks like Dr Leaf clutching at straws. Her statement, “By emphasizing that the problem lies within an individual’s biology, we are less inclined to look at their experiences and the social context of why they are feeling the way they feel. We look at the mythical chemical imbalance instead of economic exploitation, violence and inept political structures” is false.   Schizophrenia is often seriously discussed in terms of neurodevelopment and not just ‘chemical imbalances’ [17, 18]. So it’s just plain wrong to suggest that researchers don’t look at the “economic exploitation, violence and inept political structures”. Oh, and Dr Leaf suggests that foster children are abused because they’re all forced to take psychiatric medication, and implies that ADHD children are abused by being force-fed Ritalin because they “move a lot in class”. Again, these are emotional over-generalisations that have no basis in reality.

Dr Leaf seems lost.  She’s ignored solid published medical and scientific evidence in coming to an opinion based on the discontented rumblings of a few vocal but outspoken critics. In order to make her arguments, she has had to resort to borderline-slanderous ad hominem attacks on scientists and the medical profession, and purely emotional arguments based on fear and mistrust.

And this was only part one.  If Dr Leaf’s promised second part is anything like the first, we’re in for a real treat.

Though as if that wasn’t enough, by suggesting that psychiatric drugs cause changes in your brain, cause chemical imbalances, and cause that slew of negative side effects, Dr Leaf is admitting that it’s your brain that changes your thought life, which directly contradicts her most recent teachings. After all, if thought was the dominant force in your neurology and your mind controlled your brain, then the medications would have no effect since they’re physical and aren’t connected to our mind.

So which is it? Because if the brain controls our mind, then her best-seller needs to be pulped and refunds offered to the hundred of thousands of people who bought it. But on the other hand, if the mind really does control the brain, then her entire argument against psychiatric medications implodes.

Dr Leaf has painted herself into a corner and there’s still part two to come.


[1]        Prince J. Catecholamine dysfunction in attention-deficit/hyperactivity disorder: an update. J Clin Psychopharmacol 2008 Jun;28(3 Suppl 2):S39-45.
[2]        Del Campo N, Chamberlain SR, Sahakian BJ, Robbins TW. The roles of dopamine and noradrenaline in the pathophysiology and treatment of attention-deficit/hyperactivity disorder. Biological psychiatry 2011 Jun 15;69(12):e145-57.
[3]        Cortese S. The neurobiology and genetics of Attention-Deficit/Hyperactivity Disorder (ADHD): what every clinician should know. European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society 2012 Sep;16(5):422-33.
[4]        Haase J, Brown E. Integrating the monoamine, neurotrophin and cytokine hypotheses of depression–a central role for the serotonin transporter? Pharmacol Ther 2015 Mar;147:1-11.
[5]        Bus BA, Molendijk ML, Tendolkar I, et al. Chronic depression is associated with a pronounced decrease in serum brain-derived neurotrophic factor over time. Molecular psychiatry 2015 May;20(5):602-8.
[6]        Sousa CN, Meneses LN, Vasconcelos GS, et al. Reversal of corticosterone-induced BDNF alterations by the natural antioxidant alpha-lipoic acid alone and combined with desvenlafaxine: Emphasis on the neurotrophic hypothesis of depression. Psychiatry research 2015 Sep 1.
[7]        Howes OD, Fusar-Poli P, Bloomfield M, Selvaraj S, McGuire P. From the prodrome to chronic schizophrenia: the neurobiology underlying psychotic symptoms and cognitive impairments. Curr Pharm Des 2012;18(4):459-65.
[8]        Williams GV, Castner SA. Under the curve: critical issues for elucidating D1 receptor function in working memory. Neuroscience 2006 Apr 28;139(1):263-76.
[9]        Der-Avakian A, Markou A. The neurobiology of anhedonia and other reward-related deficits. Trends Neurosci 2012 Jan;35(1):68-77.
[10]      Leucht S, Tardy M, Komossa K, et al. Antipsychotic drugs versus placebo for relapse prevention in schizophrenia: a systematic review and meta-analysis. Lancet 2012 Jun 2;379(9831):2063-71.
[11]      Torniainen M, Mittendorfer-Rutz E, Tanskanen A, et al. Antipsychotic treatment and mortality in schizophrenia. Schizophrenia bulletin 2015 May;41(3):656-63.
[12]      Riedel S. Edward Jenner and the history of smallpox and vaccination. Proc (Bayl Univ Med Cent) 2005 Jan;18(1):21-5.
[13]      Arroll B, Elley CR, Fishman T, et al. Antidepressants versus placebo for depression in primary care. The Cochrane database of systematic reviews 2009(3):CD007954.
[14]      Soomro GM, Altman D, Rajagopal S, Oakley-Browne M. Selective serotonin re-uptake inhibitors (SSRIs) versus placebo for obsessive compulsive disorder (OCD). The Cochrane database of systematic reviews 2008(1):CD001765.
[15]      Kapczinski F, Lima MS, Souza JS, Schmitt R. Antidepressants for generalized anxiety disorder. The Cochrane database of systematic reviews 2003(2):CD003592.
[16]      Jakobsen JC, Lindschou Hansen J, Storebo OJ, Simonsen E, Gluud C. The effects of cognitive therapy versus ‘treatment as usual’ in patients with major depressive disorder. PloS one 2011;6(8):e22890.
[17]      van Os J, Linscott RJ, Myin-Germeys I, Delespaul P, Krabbendam L. A systematic review and meta-analysis of the psychosis continuum: evidence for a psychosis proneness-persistence-impairment model of psychotic disorder. Psychological medicine 2009 Feb;39(2):179-95.
[18]      Howes OD, Murray RM. Schizophrenia: an integrated sociodevelopmental-cognitive model. Lancet 2014 May 10;383(9929):1677-87.
[19]     Prescott K, Stratton R, Freyer A, Hall I, Le Jeune I. Detailed analyses of self-poisoning episodes presenting to a large regional teaching hospital in the UK. Br J Clin Pharmacol 2009 Aug;68(2):260-8.


  1. Do not abruptly stop any medications that you are taking. Talk to your licenced physician first. They’re not all money-hungry, imbecilic drug-company bitches. Most of them actually know what they’re talking about.
  2. For the record, I declare that I have no connection with any pharmaceutical company. I do not accept gratuities of any form from any sales representative. I don’t eat their food, I don’t take their pens, and I don’t listen to their sales pitches

Update – 8 August 2016.

Dr Leaf has since taken the offending post from her blog page, and re-gifted it as an answer on her “Scientific” FAQ page (“Chemical Imbalances and Mental Health” http://drleaf.com/about/scientific-faqs/).  It remains as unbalanced and inaccurate as it’s former iteration.  It’s unfortunate that Dr Leaf continues to make such preposterous claims in the face of overwhelming scientific evidence to the contrary.

“Touching the hem of her garment” – A Review of Dr Caroline Leaf at Nexus Church, Brisbane, 2nd August 2015

Dr Caroline Leaf is a communication pathologist and a self-titled cognitive neuroscientist. She’s currently on tour through Queensland and New South Wales in Australia. Her only stop in Brisbane, my home town, was at Nexus, my former home church. Dr Leaf presented a keynote address at Nexus’s annual Designing Women conference yesterday, and was the guest speaker at their two morning services today.

This morning typified Brisbane winter – cloudless azure skies and a refreshingly cool breeze. In contrast to the air temperature, the hospitality at Nexus was warm and friendly. The worship, soulful and uplifting. I really enjoyed being there.

Then it was Dr Leaf’s turn. It’s amazing just how much misinformation one person can fit into a 30 minute sermon.

The main theme for her sermons was an exposition on the parable of the sower, linking the different ways people receive information, with the story of the woman with the issue of blood. Dr Leaf tried to prove that thought and faith are synonymous by linking verses at the beginning and of the story from the gospel of Mark (5:25-34) – “because she thought, ‘If I just touch his clothes, I will be healed.’” (v28) and “He said to her, ‘Daughter, your faith has healed you. Go in peace and be freed from your suffering.’” (v34).

The link is highly tenuous to start with. Faith is an action, whereas thought is not. We assume that action is always preceded by thought, but it is not. Action does not require thought. Many people act without thinking. This is explained in more detail in my discussion on the Cognitive Action Pathways model.

Though to try and make her explanation more plausible, Dr Leaf padded out the story by telling the Nexus crowds that it was only because the woman had spent 12 years in deep intellectual thinking, meditating on the scriptures, that Jesus could heal her. But that’s Dr Leaf’s conjecture. In truth, no one knows exactly what that woman was doing or thinking in the 12 years that preceded her healing. The Bible never says anything else about the woman, in either version of the story in Mark or Luke (8:43-48), other than “She had suffered a great deal under the care of many doctors and had spent all she had, yet instead of getting better she grew worse” (Mark 5:26). If you have to rely on pure speculation to make your sermon work, then that’s story-telling, not preaching.

The other part of her sermon was an attempt to link the parable of the sower to some neuroscience, specifically the role of hippocampal synaptogenesis in the formation of long term memory (or in English, the changes that take place to nerves in the brain when you hear information and try to remember it).

Dr Leaf interpreted the parable as describing four different types of listener – Listener 1, corresponding to the man who hears the word but the devil takes it away, Listener 2, who hears the word and receives it with joy, but it doesn’t take root, Listener 3 who hears the word but it gets choked out by worries, riches or pleasure, and Listener 4 who hears the word and retains it, and the word produces a harvest.

According to Dr Leaf, these types of listener correspond to different levels of nerve branch growth in the formation of long term memory – Listener 1 doesn’t get past 24 hours before the memory dissipates. Listener 2 only lasts about four to seven days but there isn’t enough emotional salience to continue the growth of the nerve branch. Listener 3 doesn’t get past fourteen days, while the 4th Listener makes it through to a full 21 days, Dr Leaf’s magic number for long term memory.

Sounds great … except that the encoding and consolidation of incoming information is much more complex, and doesn’t rely on just new nerve growth [1]. That, and her numbers are completely arbitrary – with some permanent long term memory encoded in a couple of days. In fact, some long-term memory doesn’t need new synaptic growth at all, just a state of high excitation of the nerve network, known as Long-Term Potentiation, which is reliant on a self-reinforcing chemical cascade (if you want more information on the neurobiology of memory, a good place to start is The Brain From Top To Bottom, maintained by McGill University in Canada).

So the bulk of her sermon was based on biblical conjecture and bad science. Dr Leaf also made a myriad of misleading or mistaken statements: we are wired for love not fear, we learn through the quantum zeno effect, every thought effects every one of our 75 trillion cells, your toxic thoughts poison other people in relationship with you because of quantum physics, and many, many others.

I’ve only really got room for a few extra-special mentions.

1. “The mind controls brain”, and “the non-conscious mind is not bound by time and space”

No actual cognitive neuroscientist would be caught dead making those sort of statements. Saying that the mind controls the brain is like saying that air controls your lungs. The mind is a function of the brain, because when the brain is changed in certain ways, structurally or chemically, the mind changes. This has been known about for over a century, at least as far back as Freud who experimented with cocaine and other “mind-altering” substances.

Therefore if the brain controls the mind, then the non-conscious mind must be bound by the physical universe, which includes space and time. To suggest anything otherwise is just science fiction.

Besides, Dr Leaf herself tells us in her book “The Gift In You” [2], that our brain controls our mind. Dr Leaf is simply contradicting her own teaching.

2. “75 to 98% of all physical, mental and emotional illness is caused by your thought life.”

This factoid has been thoroughly debunked. If you would like to read more, you can click here or see chapter 10 in my book [3].

Today, in the second service, Dr Leaf took her fiction a step further and categorically stated that “98% of cancer comes from your thought life”. What nonsense! There is no rational evidence for such a ridiculous statement, and I don’t think there is anything more insensitive to cancer victims and their families than to blame then for causing their own cancer.

3. Mental Health

(a) “Mental illness is worse in the last 50 years than ever before”

To try and prove this is true, Dr Leaf flashed up a slide of ‘horrifying statistics” on mental illness. She claims that,
“35-fold increase in mental illness in children”
“Our children are the first in human history to grow up under the shadow of ‘mental illness'”
“Dramatic increase in the number of mentally ill since 50’s … things are worse not better”
“Mental ill health worst its ever been in history of mankind”

Every one of these statements is patently false. Mental illness has been with humankind for ever. The ancient Egyptians were writing about hysteria in women some two thousand years before Christ [4]. It’s only been in the last century or so that mental illnesses have become seen for the biological entities that they are, and not some form of demon possession, criminal behaviour or sexual deviancy.

Dr Leaf was quick to malign the DSM (the Diagnostic and Statistical Manual of psychiatry), suggesting that it’s unscientific. The DSM isn’t perfect, true, but before the DSM, there was even less science to the diagnosis of mental illness. As Dr Leaf herself pointed out, mental illness was previously viewed philosophically or spiritually. There was no consistency in diagnosis and no collection of statistics.

The DSM, for all its faults, gave a framework for mental health diagnosis, but as the science has become more refined, and with increasing awareness and general acceptance of mental health conditions, more people have qualified and/or accepted a diagnosis.

Mental illness has always been there, but now we know what to look for, it’s no longer hidden or ignored.

(b) “Psychotropic medications cause damage to the brain”

While on the subject of mental health, Dr Leaf made the litigation-attracting statement that psychotropic medications (anti-depressants, anti-psychotics) cause damage to the brain. That’s a particularly bold statement to make without citations, or a medical degree, to back it up.

Rather than ‘causing’ damage to the brain, there is scientific evidence that psychotropic medications increase synaptogenesis (the growth of new nerve branches) [5-7], while the NICE guidelines in the UK reviewed the evidence for anti-depressants and found them to be an effective treatment for depression [8], not harmful as Dr Leaf suggests.

(c) Biological causes for psychiatric illnesses have not been proven.

Dr Leaf also made the preposterous claim that biological causes of psychiatric illness have never been proven, but again, changes to brain structure have been associated with psychiatric symptoms ever since a 13-pound, three-and-a-half foot iron rod went through Phineas Gage’s skull and frontal lobe in 1848, and his personality suddenly changed from pleasant and congenial to depressed and angry [9]. Personality changes represent early symptoms of brain tumours. Use of drugs such as crystal meth can cause paranoia and extreme aggression. You don’t even need to be a doctor to know that, you just need to watch ‘Breaking Bad‘. So examples of the biological basis of psychiatric symptoms are everywhere. There are no grounds for Dr Leaf’s assertion.

4. Toxic thinking causes dementia

Dr Leaf claimed at the end of both sermons that toxic thinking results in the tubular backbone of the new nerve branches becoming contorted, which caused the accumulation of the tau protein in the nerve cells, which was responsible for dementia of every type. This, too, is a fallacy. The accumulation of the tau protein is found only in Alzheimers, not in Lewy Body dementia or in vascular dementia. The abnormal tau protein is likely related to the loss of a intracellular clean-up enzyme system [10], but Alzheimers is more complicated than just tau protein deposition, and has nothing to do with toxic thinking.

At the conclusion of the second service, I was outside the church when Dr Leaf and her entourage left the church auditorium before the rest of the crowd did, and I approached them to shake her hand and introduce myself. It was the mature thing to do after all. When I was about two metres from her presidential detail, a woman stepped out in front of me, blocking my way.

“You can’t follow them,” she said. “They’re going inside” (ie: hiding in the green room).
“Really?” I said, somewhat caught off guard. “I was simply going to introduce myself.”
“No”, was the firm reply. “You’re not allowed.”

By that time, the presidential detail had disappeared into their fortified sanctuary. The woman with the issue of blood may have got to Jesus, but there was no way I was even getting close to Dr Leaf.

This was a common pattern … Dr Leaf made herself deliberately scarce before and after each service, only coming into the church when the service was well underway, and leaving as soon as she preached, under heavy guard. One has to ask why? What’s she got to be afraid of? Is she so insecure about her teaching that she couldn’t possibly risk speaking to someone and being exposed as intellectually brittle? Or is it that she’s so arrogant as to insist on avoiding the rank-and-file church goer?

The pattern of avoidance of anyone other than her devotees, and her tendency to block anyone who disagrees with her from her social media accounts, would strongly suggest the former, although since she is so insistent on hiding from regular people, it’s really anyone’s guess.

Not that it matters. Dr Leaf could be the nicest person in the world.  Her ministry doesn’t rest on her sociability, but its own Biblical and scientific merits, and on that alone, it has been found seriously wanting.


[1]        Citri A, Malenka RC. Synaptic plasticity: multiple forms, functions, and mechanisms. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 2008 Jan;33(1):18-41.
[2]        Leaf CM. The gift in you – discover new life through gifts hidden in your mind. Texas, USA: Inprov, Inc, 2009.
[3]        Pitt CE. Hold That Thought: Reappraising the work of Dr Caroline Leaf. 1st ed. Brisbane, Australia: Pitt Medical Trust, 2014.
[4]        Tasca C, Rapetti M, Carta MG, Fadda B. Women and hysteria in the history of mental health. Clinical practice and epidemiology in mental health : CP & EMH 2012;8:110-9.
[5]        Karatsoreos IN, McEwen BS. Resilience and vulnerability: a neurobiological perspective. F1000prime reports 2013;5:13.
[6]        Duric V, Duman RS. Depression and treatment response: dynamic interplay of signaling pathways and altered neural processes. Cellular and molecular life sciences : CMLS 2013 Jan;70(1):39-53.
[7]        Karatsoreos IN, McEwen BS. Psychobiological allostasis: resistance, resilience and vulnerability. Trends in cognitive sciences 2011 Dec;15(12):576-84.
[8]        Anderson I. Depression. The Treatment and Management of Depression in Adults (Update). NICE clinical guideline 90.2009. London: The British Psychological Society and The Royal College of Psychiatrists, 2010.
[9]        Kihlstrom JF. Social neuroscience: The footprints of Phineas Gage. Social Cognition 2010;28:757-82.
[10]      Tai HC, Serrano-Pozo A, Hashimoto T, Frosch MP, Spires-Jones TL, Hyman BT. The synaptic accumulation of hyperphosphorylated tau oligomers in Alzheimer disease is associated with dysfunction of the ubiquitin-proteasome system. The American journal of pathology 2012 Oct;181(4):1426-35.

Aspartame. Is it more ‘Die’ than ‘Diet’?

A link came around tonight on my Facebook feed about aspartame: “Aspartame is linked to Leukemia and Lymphoma in new Landmark Study on Humans” (http://worldtruth.tv/aspartame-is-linked-to-leukemia-and-lymphoma-in-new-landmark-study-on-humans/)

I’ve seen these sorts of articles come around on social media before, usually in the form of an alternative health website hysterically exaggerating an irrelevant or pseudoscientific study, trying to prove some point about the evils of western medicine or society, or get more internet traffic through sensationalist click-bait.

And I’d heard the whole aspartame-causes-cancer thing before. I’d heard that there was maybe some evidence in animal studies, but that there was no definitive link in humans.

So just from the title, before I’d even read the article, my sceptical mind was primed to expect the opposite of the articles eye-catching headline.  I started searching the literature to see if there was any evidence to prove me right.

The first research article I came across that wasn’t on rats was from the American Journal of Clinical Nutrition in 2012, “Consumption of artificial sweetener – and sugar-containing soda and risk of lymphoma and leukemia in men and women” [1]. It was an impressive study in terms of its numbers and its quality. It was drawn from the data of the Nurses Health Study and the Health Professionals Follow-Up Study, which were both prospective studies (which follow a large number of subjects over a long time to see who gets the disease in question, rather than starting with who has the disease in question and trying to work backwards trying to ascertain causes, which is much less reliable). Both studies also had a large number of subjects which increased their statistical power, and made their findings more robust.

The results didn’t look very good for aspartame. There was a clear-cut increase in the risk of Non-Hodgkins Lymphoma for men who consumed two or more serves per day of diet drinks containing aspartame (Relative Risk: 1.69; 95% Confidence Interval: 1.17, 2.45; P-trend = 0.02) and Multiple Myeloma for men who consumed one or more serve per day of diet drinks containing aspartame (RR: 2.02; 95% CI: 1.20, 3.40). However, there was no change in the risks for women who consumed aspartame.

The results certainly caught me a little off guard. Perhaps there was some truth to the alternative website’s assertions after all. Interestingly enough, the study that the worldtruth.tv site reviewed was the same article I’d found. I was guilty of making a snap judgement, and I had to remind myself not to always jump to conclusions.

Still, even though the article wasn’t sensationalist click-bait, some unanswered questions remained. Why was the risk only found in men? Was there a real association, and if so, why the difference. Should we extrapolate this finding like worldtruth.tv did and justifiably ask “will future, high-quality studies uncover links to the other cancers in which aspartame has been implicated (brain, breast, prostate, etc.)?”

In terms of the gender difference, the authors of the original study did have a theory: “We hypothesized that the sex differences we observed may have been due to the recognized higher enzymatic activity of alcohol dehydrogenase type I (ADH) in men, which possibly induced higher conversion rates from methanol to the carcinogenic substrate formaldehyde.” In support of this theory, they looked at the risk of leukaemia and lymphoma in those aspartame users who were drinkers vs the aspartame users who weren’t. Ethanol stops the metabolic conversion of aspartame to formaldehyde, so if their theory was on the right track, those aspartame users who also drank alcohol would have a lower risk. As it turns out, their data was supportive, with aspartame non-drinkers having an increased risk for Non-Hodgkins Lymphoma (RR: 2.34; 95% CI: 1.46, 3.76; P-trend = 0.004) compared with aspartame users who also drank (RR: 0.96; 95% CI: 0.48, 1.90; P-trend = 0.99) [1].

However, despite the findings of Schernhammer et al, a more recent large prospective trial published in the Journal of Nutrition last year found there was no association between soft-drinks of any variety and blood cancers, including those containing aspartame [2].

So the jury is still out on aspartame. Based on what we currently know, if you’re a woman, then there’s no risk of developing leukaemia or lymphoma from drinking diet drinks. If you’re a man, there’s also probably no risk, but a glass or two of alcohol a day would probably make sure of that. Although the best advice is probably to not bother drinking diet drinks at all. The best diet drink is still plain old water, which has virtually no associated risks, is much cheaper, and probably tastes a whole lot better.


  1. Schernhammer, E.S., et al., Consumption of artificial sweetener- and sugar-containing soda and risk of lymphoma and leukemia in men and women. Am J Clin Nutr, 2012. 96(6): 1419-28 doi: 10.3945/ajcn.111.030833
  2. McCullough, M.L., et al., Artificially and sugar-sweetened carbonated beverage consumption is not associated with risk of lymphoid neoplasms in older men and women. J Nutr, 2014. 144(12): 2041-9 doi: 10.3945/jn.114.197475

Dr Caroline Leaf: All scare and no science?

Screen Shot 2014-12-24 at 11.02.44 am

On her social media feed today, Dr Leaf posted a meme implying that conventionally farmed food was toxic.

Dr Caroline Leaf is a communication pathologist and self-titled cognitive neuroscientist. Anyone who’s been following Dr Leaf will know from her frequent food selfies that she is an organic convert.

Dr Leaf is welcome to eat whatever she chooses, though not content to simply push her personal belief in organic foods, Dr Leaf is now actively criticising conventional food, publishing memes on her social media posts which imply that conventional produce is poisonous.

As I’ve written before, despite Dr Leaf’s blinding passion and quasi-religious zeal for organic foods, there is no evidence that organic food is any more beneficial than conventional food (Dangour et al, 2009; Bradbury et al, 2014). Indeed, there’s no magic to a healthy food lifestyle. Eat more vegetables. Drink more water. Conventional veggies and conventional water do just fine. Sage advice, even if it doesn’t lend itself to food selfies.

While organic zealots believe they have the high ground on the topic of food safety, the published science cuts through the hype. As noted by Smith-Spangler et al (2012), there is some evidence that there may be less pesticide residue on organically grown foods, but there is no significant difference in the risk of each group exceeding the overcautious Maximum Residue Limit.

Two points on the Maximum Residue Limit that are particularly important:

  1. The Maximum Residue Limit is extremely cautious, and most food tested is well below this already overcautious limit. The Maximum Residue Limit is set to about 1% of the amount of the pesticide that has no effect on test animals.   According to a recent survey of grapes done by Choice Australia, the amount of residue was well below the Maximum Residue Limit (about 1% of the Maximum Residue Limit on average) (Choice Australia, 2014). So on the average bunch of grapes in Australia, the pesticide residue is about one ten thousandth of the level that is safe in animals, and this pattern is the same across all conventional produce. Thinking in more practical terms, “a 68 kg man would have to eat 3,000 heads of lettuce every day of his life to exceed the level of a residue that has been proven to have no effect on laboratory animals … an 18 kg boy would have to eat 534 apples every day of his life to exceed a residue level that is not dangerous to laboratory animals. And an 18 kg girl would have to eat 13,636 kg of carrots every day of her life to exceed such a level.” (ecpa.eu, 2014)

    2. Organic foods have pesticides too. Granted, this is at lower levels than their conventional counterparts, but it’s there all the same (Smith-Spangler et al, 2012). I once had a lively discussion with an organic food zealot about the pesticides in organic farming. Her argument was that organic pesticides are safe because they’re “natural” poisons. So are arsenic, cyanide, belladonna and digitalis (foxglove), but why let the truth get in the way of ones opinion. Poisons are poisons whether they’re “natural” or not. The Maximum Residue Limit applies to organic foods just the same as conventionally farmed produce for that reason.

Another interesting thing … in the Choice survey, the organic grapes had no detectable pesticides, but so did conventionally farmed grapes bought at a local green grocer. So organic food zealots can’t claim that they have a monopoly on low pesticides in their foods.

Not that having lower pesticide residues means that organic foods are necessarily safer. Organically farmed produce has a higher risk of contamination from E. coli and other potentially toxic bacteria, depending on the farming method used (Mukherjee et al, 2007; Sample, 2011).

So to bring it all together, conventional produce has levels of pesticide residues so low that it would take an extra-ordinary feat of vegetarian gluttony to exceed a level that was still found to be non-toxic in animals. The risk to human health from conventional farming with pesticides is nanoscopic. Organic foods may have less pesticide, but they have a higher risk from enterotoxigenic bacteria.

Since there is nothing to fear from conventional foods, it seems irresponsible for Dr Leaf to promote the unscientific idea that conventional foods are poisonous. One wonders why Dr Leaf would engage in a campaign of fear against healthy, nutritious foods? Personal bias perhaps, although that doesn’t bode well for her credibility as an objective scientist. Another plausible reason could be marketing. Fear sells things, that’s Marketing 101. Gardner (2008) wrote, “Fear sells. Fear makes money. The countless companies and consultants in the business of protecting the fearful from whatever they may fear know it only too well. The more fear, the better the sales.”

Posts like today’s make Dr Leaf seem like all scare and no science. Publishing images with the skull and cross bones and the word “POISON” is certainly not attempting to allay anyone’s anxiety, and that fact that it‘s directly tied to a reminder of her upcoming book on food only makes shameless promotion all the more likely. I’m sure that a Godly woman of Dr Leaf’s standing wouldn’t stoop so low as to use fear and mistruth just to make better sales, but posts like today’s open her up to legitimate questions from others regarding her credibility and her motivation.

For her sake, I hope that she tightens up her future posts, and reconsiders her stance on the science of organic and conventional foods.


Bradbury, K.E., et al., Organic food consumption and the incidence of cancer in a large prospective study of women in the United Kingdom. Br J Cancer, 2014. 110(9): 2321-6 doi: 10.1038/bjc.2014.148

Choice Australia, 2014. <http://www.choice.com.au/reviews-and-tests/food-and-health/food-and-drink/groceries/pesticide-residues-in-fruit-and-vegetables.aspx&gt;

Dangour, A. D., Dodhia, S. K., Hayter, A., Allen, E., Lock, K., & Uauy, R. (2009). Nutritional quality of organic foods: a systematic review. Am J Clin Nutr, 90(3), 680-685. doi: 10.3945/ajcn.2009.28041

European Crop Protection Agency, 2014, <http://www.ecpa.eu/faq/what-maximum-residue-level-mrl-and-how-are-they-set>

Gardner, D., The science of fear: Why we fear the things we shouldn’t – and put ourselves in greater danger; 2008, Dutton / The Penguin Group, New York

Mukherjee, A., et al., Association of farm management practices with risk of Escherichia coli contamination in pre-harvest produce grown in Minnesota and Wisconsin. Int J Food Microbiol, 2007. 120(3): 296-302 doi: 10.1016/j.ijfoodmicro.2007.09.007

Sample, I., E coli outbreak: German organic farm officially identified. The Guardian, London, UK, 11 June 2011 <http://www.theguardian.com/world/2011/jun/10/e-coli-bean-sprouts-blamed>

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