Strong marketing can’t make up for weak ideas

Well Dr Leaf, 10 out of 10 for persistence.

Dr Caroline Leaf is a communication pathologist and a self-titled cognitive neuroscientist. In the last month or so, Dr Leaf has been hammering home her foundational belief that the mind is in control of the brain, and indeed, that your thoughts are the key to everything in life, a bit like 42 in “The Hitchhikers Guide to the Galaxy”. According to Dr Leaf, your thoughts are the answer to life, the universe, and everything.

Dr Leaf has attempted to prove her point through quotes from neuroscientists, from her own teaching, and from some published research. All she’s ended up proving is that she’s so desperate to prop up the concept that she’ll stoop to cherry-picking articles and massaging quotes. Poor form for a woman who promotes herself as a scientist.

Today’s meme is the spiritual justification of her position, expressed as a lovely little graphic with a verse from Proverbs 4:23. It’s a real Pinterest special. Most people would look at the pretty picture and accept the quote without question. It’s good marketing for sure.

Screen Shot 2016-06-24 at 5.51.29 PM

But if you strip back all of the eye-candy, is the meme still worth posting? Is Dr Leaf’s meme an accurate depiction of what Proverbs 4:23 truly means.

First things first, is the meme an accurate quote? In this case, it is. The Good News Bible really does say, “Be careful how you think; your life is shaped by your thoughts.” (

So the next question is, is the Good News version an accurate translation of the scripture? It’s interesting that nearly every other translation doesn’t mention thoughts and thinking at all:

New International Version = Above all else, guard your heart, for everything you do flows from it.
New Living Translation = Guard your heart above all else, for it determines the course of your life.
English Standard Version = Keep your heart with all vigilance, for from it flow the springs of life.
New American Standard Bible = Watch over your heart with all diligence, For from it flow the springs of life.
King James Bible = Keep thy heart with all diligence; for out of it are the issues of life.
Holman Christian Standard Bible = Guard your heart above all else, for it is the source of life.
International Standard Version = Above everything else guard your heart, because from it flow the springs of life.
NET Bible = Guard your heart with all vigilance, for from it are the sources of life.
Aramaic Bible in Plain English = Keep your heart with all caution because from it is the outgoing of life.
GOD’S WORD® Translation = Guard your heart more than anything else, because the source of your life flows from it.
JPS Tanakh 1917 = Above all that thou guardest keep thy heart; For out of it are the issues of life.
New American Standard 1977 = Watch over your heart with all diligence, For from it flow the springs of life.
Jubilee Bible 2000 = Above all else, guard thy heart; for out of it flows the issues of life.
King James 2000 Bible = Keep your heart with all diligence; for out of it are the issues of life.
American King James Version = Keep your heart with all diligence; for out of it are the issues of life.
American Standard Version = Keep thy heart with all diligence; For out of it are the issues of life.
Douay-Rheims Bible = With all watchfulness keep thy heart, because life issueth out from it.
Darby Bible Translation = Keep thy heart more than anything that is guarded; for out of it are the issues of life.
English Revised Version = Keep thy heart with all diligence; for out of it are the issues of life.
Webster’s Bible Translation = Keep thy heart with all diligence; for out of it are the issues of life.
World English Bible = Keep your heart with all diligence, for out of it is the wellspring of life.
Young’s Literal Translation = Above every charge keep thy heart, For out of it are the outgoings of life.

Nearly every other English translation refers to “the heart”. Obviously not the literal “heart”, that muscular blood pump in the middle of our chests, but the metaphoric heart, the human soul. So even on majority rules, the Good News Bible translation is looking shaky. Is there any further corroborating evidence to help us understand which version is the most correct?

The answer would be in the original Hebrew. The word for ‘heart’ in Proverbs 4:23 is לֵב (leb), and more broadly is a word relating to the soul, ‘inner man, mind, will, heart, understanding’ ( In some verses, the word in used in reference to what would be considered thoughts, but in many others, the word is used to describe a person’s feelings or motivations, or attitudes, or even specific intelligence and manual skills. For example:

Genesis 17:17: “Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?”
Genesis 42:28: “And he said unto his brethren, My money is restored; and, lo, it is even in my sack: and their heart failed them, and they were afraid, saying one to another, What is this that God hath done unto us?”
Exodus 8:32: “And Pharaoh hardened his heart at this time also, neither would he let the people go.”
Exodus 35:35: “Them hath he filled with wisdom of heart, to work all manner of work, of the engraver, and of the cunning workman, and of the embroiderer, in blue, and in purple, in scarlet, and in fine linen, and of the weaver, even of them that do any work, and of those that devise cunning work.”

So it appears the Good News Bible is actually a poor translation. Again, this is an example of Dr Leaf cherry picking something that suits her theory out of a bulk of divergent views. No matter how she tries to sell the concept, the idea that the mind controls your brain and that your thoughts control your destiny is scientifically and scripturally weak. Persistence and good marketing isn’t going to change that.

Dr Caroline Leaf and Picking Cherries

Screen Shot 2014-09-20 at 11.58.36 am

When it comes to fruit, I’m a bit picky. Cherries are one of my least favourite. It makes things difficult at times. I’m no good with Black Forest cake or with traditional Christmas goodies like Christmas pudding or rumballs. I guess that’s a good thing, one less thing to be tempted by.

Some fruit can be picked a little unripe, because it will still ripen after it’s picked. Cherries are a bit more delicate. Apparently when it comes to picking cherries, the key is to pick only the ripest fruit and leave the rest on the tree.

In science, “cherry picking” is a colloquial expression for the practice of selectively picking or presenting only the information that agrees with your personal theory, ignoring the rest. Richard Somerville put it well: “Choosing to make selective choices among competing evidence, so as to emphasize those results that support a given position, while ignoring or dismissing any findings that do not support it, is a practice known as ‘cherry picking’ and is a hallmark of poor science or pseudo-science.” (Testimony before the US House of Representatives Committee on Energy and Commerce Subcommittee on Energy and Power, March 8, 2011).

You can see cherry picking everywhere if you know what to look for. It’s usually done by advertising and PR firms to make a product sound all sciencey or mediciney, something like, “Research shows that …”. Then deep in the fine print is a reference to a single scientific paper. When you actually look at the article in question, the “research” is weak or horribly biased.

Cherry picking is also common amongst organisations with a barrow to push, or websites like Natural Wellness Care (, which push a bunch of statistics to magnify a problem so they can sell or promote their “solution”.

Dr Caroline Leaf is a communication pathologist and a self-titled cognitive neuroscientist. Cherry picking is one of her favourite tricks. Her teaching from the pulpit is littered with the phrase, “Research says …”, without ever mentioning where the research came from. You just have to take her word for it.

Dr Leaf cherry picks extensively through her published work. There are too many examples to list them all, but her use of the quantum physics term, “quantum Zeno effect” is a prime example [1: p108, 2: ch13].

Another great example of cherry picking is Dr Leaf’s theory of the “Heart as a mini-brain” [2: ch11, 3: p40]. Dr Leaf exclusively relies on the information published by a group called HeartMath (, who themselves cherry pick extensively. HeartMath list reams of citations as evidence that the heart is a little brain, but even a basic understanding of routine clinical tests like an ECG shows that their ground breaking discoveries are little more than pseudoscience [see also Ref 2: ch11].

Dr Leaf then selectively uses certain studies from HeartMath to back up various claims she makes. A case in point is her claim that, “An ingenuous experiment set up by the HeartMath Foundation determined that genuine positive emotion, as reflected by a measure called ‘heart rate variability’, directed with intentionality towards someone actually changed the way the double helix DNA strand coils and uncoils. And this goes for both positive and negative emotions and intentions.” [1: p111]

This is cherry picking in its purest form. Despite the study being over 20 years old, and so badly designed that even alternative scientific journals wouldn’t publish it, Dr Leaf claimed it as proof that emotions and intentions can alter DNA [Chapter 13 of my book, Ref 2 outlines why the study is so poor].

In her social media feed today, Dr Leaf quoted Peace Pilgrim, a silver haired mystic who walked across America for 28 years, owning nothing but the clothes on her back, all in the name of peace. The quote Dr Leaf republished was, “If you realized how powerful your thoughts are, you would never think a negative thought.” This was taken from a radio talk that Peace Pilgrim gave in 1964 ( Peace Pilgrim’s quote is interesting, even inspirational, but not scientific. Inspiring quotes from half a century ago are fine, but only if you’re a motivational speaker or a B-grade life coach.

Dr Leaf says she’s a cognitive neuroscientist. Real cognitive neuroscientists don’t cherry pick whichever quotes or studies fit with their prevailing theory. They look for the truth by synthesising all the evidence into an accurate theory.

Dr Leaf may be trying to inspire people, but if she claims to be a scientist of any form, she has to adhere to a higher standard. She has to make sure that the words she uses are not just inspiring, but accurate as well, because facts and fruit are not the same. If you want a good Black Forest cake, then cherry pick all you want, but if you want the truth, consider all the facts first.

Like to read more about Dr Leaf’s teaching and how it compares to current science? Download the free eBook HOLD THAT THOUGHT, Reappraising The Work Of Dr Caroline Leaf


  1. Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan:
  2. Pitt, C.E., Hold That Thought: Reappraising the work of Dr Caroline Leaf, 2014 Pitt Medical Trust, Brisbane, Australia, URL
  3. Leaf, C., Who Switched Off My Brain? Controlling toxic thoughts and emotions. 2nd ed. 2009, Inprov, Ltd, Southlake, TX, USA:

Dr Caroline Leaf – Contradicted by the latest research

This is my most popular post by far.  I truly appreciate the support and interest in this post, but I’ve discovered and documented a lot more about Dr Leaf’s ministry in the last two years.  I welcome you to read this post, but if you’d like a more current review of the ministry of Dr Caroline Leaf, a new and improved version is here:
Dr Caroline Leaf – Still Contradicted by the Latest Evidence, Scripture & Herself

* * * * *

Mr Mac Leaf, the husband of Dr Caroline Leaf, kindly took the time to respond to my series of posts on the teachings of Dr Leaf at Kings Christian Centre, on the Gold Coast, Australia, earlier this month. As I had intended, and as Mr Leaf requested, I published his  reply, complete and unabridged (here).

This blog is my reply.  It is heavily researched and thoroughly referenced.  I think it’s fair to say that while Dr Leaf draws her conclusions from some scientific documents, there is more than enough research that contradicts her statements and opinions.  I have only listed a small fraction, and only on some of the points she raised.

In fairness, the fields of neurology and neuroscience are vast and rapidly expanding, and it is impossible for one person to cover all of the literature on every subject.  This applies to myself and Dr Leaf.  However, I believe that the information I have read, and referenced from the latest peer-reviewed scholarly works, do not support Dr Leaf’s fundamental premises.  If I am correct, then the strength and validity of Dr Leaf’s published works should be called into question.

As before, I welcome any reply or rebuttal that Dr Leaf wishes to make, which I will publish in full if she requests.  In the interests of healthy public debate, and encouraging people to make their own informed decisions on the teachings of Dr Leaf, any comments regarding the response of Mr Leaf, Dr Leaf or myself, are welcome provided they are constructive.

This is a bit of a lengthy read, but I hope it is worthwhile.

Dear Mr Leaf,

Thank you very much for taking the time out to reply to some of the points raised in my blog.  I am more than happy to publish your response, and to publish any response you wish to make public.


I published my blog posts to open up discussion on the statements made by Dr Leaf at the two meetings that I attended at Kings Christian Centre on the Gold Coast.  As you rightly point out, people should be able to make informed decisions.  A robust discussion provides the information required for people to make an informed choice.  Any contributions to this discussion from either yourself or Dr Leaf would be most welcome.

I apologise if you interpreted my blogs as judgemental, or if you believe there are any misunderstandings.  You may or may not have read my final two paragraphs from the third post, in which I acknowledged that I may have misunderstood where she was coming from, but that I would welcome her response.  If there were any misunderstandings, it is likely because Dr Leaf did not make any attempt to reference any of the statements she made on the day.  You may argue that she was speaking to a lay audience, and referencing is therefore not necessary.  However, I have been to many workshops for the lay public by university professors, who have extensively referenced their information during their presentations.  A lay audience does not preclude providing references.  Rather, it augments the speakers authority and demonstrates the depth of their knowledge on the subject at hand.


It’s interesting that you feel the need to resort to defence by association, and Ad Hominem dismissal as your primary counter to the points I raised.

Can you clarify how attending the same university as Dr Christaan Barnard, or a Nobel laureate, endorses her arguments or precludes her from criticism?  I attended the University of Queensland where Professor Ian Frazer was based.  He developed the Human Papilloma Virus vaccine and was the 2006 Australian of the Year.  Does that association enhance my argument?

Can you also clarify why a reference from a colleague was preferred to letting Dr Leaf’s statements and conclusions speak for themselves?  Dr Amua-Quarshie’s CV is certainly very impressive, no doubt about that, although he doesn’t list the papers he’s published.  (I’m assuming that to hold the title of Adjunct Professor, he’s published peer-reviewed articles.  Is he willing to list them, for the record?)

Whatever his credentials, his endorsement means very little, since both Dr Leaf and Dr Amua-Quarshie would know from their experience in research that expert opinion is one of the lowest forms of evidence, second worst only to testimonials [1].  Further, both he and Dr Leaf are obviously close friends which introduces possible bias.  His endorsement is noteworthy, but it can not validate every statement made by Dr Leaf.  Her statements should stand up on their own through the rigors of critical analysis.

On the subject of evidence, disparaging your critics is not a substitute for answering their criticism.  Your statement, “By your comments it is obvious that you have not kept up to date with the latest Scientific research” is an assumption that is somewhat arrogant, and ironic since Dr Leaf is content to use superseded references dating back to 1979 to justify her current hypotheses.


In the blog to which you referred, Dr Leaf makes a number of statements that are intended to support her case.  These include the following.

“A study by the American Medical Association found that stress is a factor in 75% of all illnesses and diseases that people suffer from today.”  She fails to reference this study.

“The association between stress and disease is a colossal 85% (Dr Brian Luke Seaward).”   But again, she fails to reference the quote.

“The International Agency for Research on Cancer and the World Health Organization has concluded that 80% of cancers are due to lifestyles and are not genetic, and they say this is a conservative number (Cancer statistics and views of causes Science News Vol.115, No 2 (Jan.13 1979), p.23).”  It’s good that she provides a reference to her statement.  However, referencing a journal on genetics from 1979 is the equivalent of attempting to use the land-speed record from 1979 to justify your current preference of car.  The technology has advanced significantly, and genetic discoveries are lightyears ahead of where they were more than three decades ago.

“According to Dr Bruce Lipton (The Biology of Belief, 2008), gene disorders like Huntington’s chorea, beta thalassemia, cystic fibrosis, to name just a few, affect less than 2% of the population. This means the vast majority of the worlds population come into this world with genes that should enable the to live a happy and healthy life. He says a staggering 98% of diseases are lifestyle choices and therefore, thinking.”  Even if it’s true that Huntingtons, CF etc account for 2% of all illnesses, they account for only a tiny fraction of genetic disease.  And concluding that the remaining 98% must therefore be lifestyle related is overly simplistic.  It ignores the genetic influence on all other diseases, other congenital, and environmental causes of disease.  I will fully outline this point soon.

Similarly, “According to W.C Willett (balancing lifestyle and genomics research for disease prevention Science (296) p 695-698, 2002) only 5% of cancer and cardiovascular patients can attribute their disease to hereditary factors.”  Science is clear that genes play a significant role in the development of cardiovascular disease and most cancers, certainly greater than 5%.  Again, I will discuss this further soon.

“According to the American Institute of health, it has been estimated that 75 – 90% of all visits to primary care physicians are for stress related problems ( Some of the latest stress statistics causing illness as a result of toxic thinking can be found at:”  These websites not peer-reviewed, and both suffer from a blatant pro-stress bias.

You’ll also have to forgive my confusion, but Dr Leaf also wrote, “Dr H.F. Nijhout (Metaphors and the Role of Genes and Development, 1990) genes control biology and not the other way around.”  So is she saying that genes DO control development?


Influence Of Thought On Health

Dr Leaf has categorically stated that “75 to 98% of all illnesses are the result of our thought life” on a number of occasions.  She repeated the same statement in her most recent book so it is something she is confident in.  However, in order to be true, this fact must be consistent across the whole of humanity.

And yet, in a recent peer-reviewed publication, Mara et al state, “At any given time close to half of the urban populations of Africa, Asia, and Latin America have a disease associated with poor sanitation, hygiene, and water.” [2]  Bartram and Cairncross write that “While rarely discussed alongside the ‘big three’ attention-seekers of the international public health community—HIV/AIDS, tuberculosis, and malaria—one disease alone kills more young children each year than all three combined. It is diarrhoea, and the key to its control is hygiene, sanitation, and water.” [3]  Hunter et al state that, “diarrhoeal disease is the second most common contributor to the disease burden in developing countries (as measured by disability-adjusted life years [DALYs]), and poor-quality drinking water is an important risk factor for diarrhoea.” [4]

Toilets and clean running water have nothing to do with stress or thought.  We live in a society that essentially prevents more than half of our illnesses because of internal plumbing, with additional benefits from vaccination and population screening.  If thoughts have any effect on our health, they are artificially magnified by our clean water and sewerage systems.  Remove those factors and any effects of thought on our health disappear from significance.  Dr Leaf’s assertion that 75 to 98% of human illness is thought-related is a clear exaggeration.

Let me be clear – I understand the significance of stress on health and the economy, but it is not the cause of 75-98% of all illnesses.  I’m not sure if there is a similar study in the US, but the latest Australian data suggests that all psychological illness only counts for 8% of visits to Australian primary care physicians [5].

In terms of cancer, I don’t have time to exhaustively list every cancer but of the top four listed in the review “Cancer Statistics 2013” [6] , here are the articles that list the gene x environment interactions:

  1. PROSTATE – There are only two risk factors for prostate cancer, familial aggregation and ethnic origin. No dietary or environmental cause has yet been identified [7].  It is most likely caused by multiple genes at various loci [8].
  2. BREAST – Genes make up 25% of the risk factors for breast cancer, and significantly interacted with parity (number of children born) [9].
  3. LUNG/BRONCHUS – Lung cancer is almost exclusively linked to smoking, but nicotine addiction has a strong hereditary link (50-75% genetic susceptibility) [10].
  4. COLORECTUM – Approximately one third of colorectal cancer is genetically linked [11].

So the most common cancer is not linked to any environmental factors at all, and the others have genetic influences of 25% to more than 50%.  This is far from being 2% or 5% as Dr Leaf’s sources state.

Also in terms of heart disease, the INTERHEART trial [12] lists the following as significant risk factors, and I have listed the available gene x environment interaction studies that have been done on these too:

  1. HIGH CHOLESTEROL – Genetic susceptibility accounts for 40-60% of the risk for high cholesterol [13].
  2. DIABETES – Genetic factors account for 88% of the risk for type 1 diabetes [14].  There is a strong genetic component of the risk of type 2 diabetes with 62-70% being attributable to genetics [15, 16].
  3. SMOKING – nicotine addiction has a strong hereditary link (50-75% genetic susceptibility) [10].
  4. HYPERTENSION – While part of a much greater mix of variables, genetics are still thought to contribute between 30% and 50% to the risk of developing high blood pressure [17].

So again, while genes are a part of a complex system, it is clear from the most recent evidence that genetics account for about 50% of the risk for cardiovascular disease, which again is a marked difference between the figures that Dr Leaf is using to base her assertions on.

Atrial Natriuretic Peptide

I am aware of research that’s studied the anxiolytic properties of Atrial Natriuretic Peptide.  For example, Wiedemann et al [18] did a trial using ANP to truncate panic attacks.  However, these experiments were done on only nine subjects, and the panic attacks were induced by cholecystokinin.  As such, the numbers are too small to have any real meaning.  And the settling is completely artificial.  Just as CCK excretion does not cause us all to have panic attacks every time we eat, ANP does not provide anxiolysis in normal day to day situations.  Besides, if ANP were really effective at reducing anxiety, then why do people suffering from congestive cardiac failure, who have supraphysiological levels of circulating ANP [19] , also suffer from a higher rate of anxiety and panic disorders than the general population? [20]

The Heart As A Mini-Brain

As for Heartmath, they advance the notion of the heart being a mini-brain to give themselves credibility.  It’s really no different to an article that I read the other day from a group of gut researchers [21] – “‘The gut is really your second brain,’ Greenblatt said. ‘There are more neurons in the GI tract than anywhere else except the brain.’”  The heart as a mini-brain and the gut as a mini-brain are both figurative expressions.  Neither are meant to be taken literally.  I welcome Dr Leaf to tender any further evidence in support of her claim.

Hard-Wired For Optimism

As for being wired for optimism, the brain is likely pre-wired with a template for all actions and emotions, which is the theory of protoconsciousness [22].  Indeed, neonatal reflexes often reflect common motor patterns.  If this is true, then the brain is pre-wired for both optimism and love, but also fear.  This explains the broad role of the amygdala in emotional learning [23] including fear learning.  It also means that a neonate needs to develop both love and fear.

A recent paper showed that the corticosterone response required to learn fear is suppressed in the neonate to facilitate attachment, but with enough stress, the corticosterone levels build to the point where amygdala fear learning can commence [24].  The fear circuits are already present, only their development is suppressed.  Analysis of the cohort of children in the Bucharest Early Intervention Project showed that negative affect was the same for both groups.  However positive affect and emotional reactivity was significantly reduced in the institutionalised children [25].  If the brain is truly wired for optimism and only fear is learned, then positive emotional reactivity should be the same in both groups and the negative affect should be enhanced in the institutionalised cohort.  That the result is reversed confirms that neonates and infants require adequate stimulation of both fear and love pathways to grow into an emotionally robust child, because the brain is pre-wired for both but requires further stimulation for adequate development.

The Mind-Brain Link

If the mind controls the brain and not the other way around as Dr Leaf suggests, why do anti-depressant medications correct depression or anxiety disorders?  There is high-level evidence to show this to be true [26-28].  The same can be said for recent research to show that medications which enhance NDMA receptors have been shown to improve the extinction of fear in anxiety disorders such as panic disorder, OCD, Social Anxiety Disorder, and PTSD [29].

If the mind controls the brain and not the other way around as Dr Leaf suggests, why do some people with acquired brain injuries or brain tumours develop acute personality changes or thought disorders?  Dr Leaf has done PhD research on patients with closed head injuries and treated them in clinical settings according to her CV.  She must be familiar with this effect.

One can only conclude that there is a bi-directional effect between the brain and the stream of thought, which is at odds with Dr Leaf’s statement that the mind controls the brain and not the other way around.


One further thing.  Can you clarify which of Dr Leaf’s peer-reviewed articles have definitively shown the academic improvement in the cohort of 100,000 students, as you and your referee have stated?  And can you provide a list of articles which have cited Dr Leaf’s Geodesic Information Processing Model?  Google Scholar did not display any articles that had cited it, which must be an error on Google’s part.  If her theory is widely used as you say, it must have been extensively cited.

I understand that you are both busy, but I believe that I have documented a number of observations, backed by recent peer-reviewed scientific literature, which directly contradict Dr Leaf’s teaching.  I have not had a chance to touch on many, many other points of disagreement.

For the benefit of Dr Leaf’s followers, and for the scientific and Christian community at large, I would appreciate your response.

I would be grateful if you could respond to the points raised and the literature which supports it, rather than an Ad Hominem dismissal or further defense by association.

Dr C. Edward Pitt


1. Fowler, G., Evidence-based practice: Tools and techniques. Systems, settings, people: Workforce development challenges for the alcohol and other drugs field, 2001: 93-107.

2. Mara, D., et al., Sanitation and health. PLoS Med, 2010. 7(11): e1000363.

3. Bartram, J. and Cairncross, S., Hygiene, sanitation, and water: forgotten foundations of health. PLoS Med, 2010. 7(11): e1000367.

4. Hunter, P.R., et al., Water supply and health. PLoS Med, 2010. 7(11): e1000361.

5. FMRC. Public BEACH data. 2010  16JUL13]; Available from: <;.

6. Siegel, R., et al., Cancer statistics, 2013. CA Cancer J Clin, 2013. 63(1): 11-30.

7. Cussenot, O. and Valeri, A., Heterogeneity in genetic susceptibility to prostate cancer. Eur J Intern Med, 2001. 12(1): 11-6.

8. Alberti, C., Hereditary/familial versus sporadic prostate cancer: few indisputable genetic differences and many similar clinicopathological features. Eur Rev Med Pharmacol Sci, 2010. 14(1): 31-41.

9. Nickels, S., et al., Evidence of gene-environment interactions between common breast cancer susceptibility loci and established environmental risk factors. PLoS Genet, 2013. 9(3): e1003284.

10. Berrettini, W.H. and Doyle, G.A., The CHRNA5-A3-B4 gene cluster in nicotine addiction. Mol Psychiatry, 2012. 17(9): 856-66.

11. Hutter, C.M., et al., Characterization of gene-environment interactions for colorectal cancer susceptibility loci. Cancer Res, 2012. 72(8): 2036-44.

12. Yusuf, S., et al., Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet, 2004. 364(9438): 937-52.

13. Asselbergs, F.W., et al., Large-scale gene-centric meta-analysis across 32 studies identifies multiple lipid loci. Am J Hum Genet, 2012. 91(5): 823-38.

14. Wu, Y.L., et al., Risk factors and primary prevention trials for type 1 diabetes. Int J Biol Sci, 2013. 9(7): 666-79.

15. Ali, O., Genetics of type 2 diabetes. World J Diabetes, 2013. 4(4): 114-23.

16. Murea, M., et al., Genetic and environmental factors associated with type 2 diabetes and diabetic vascular complications. Rev Diabet Stud, 2012. 9(1): 6-22.

17. Kunes, J. and Zicha, J., The interaction of genetic and environmental factors in the etiology of hypertension. Physiol Res, 2009. 58 Suppl 2: S33-41.

18. Wiedemann, K., et al., Anxiolyticlike effects of atrial natriuretic peptide on cholecystokinin tetrapeptide-induced panic attacks: preliminary findings. Arch Gen Psychiatry, 2001. 58(4): 371-7.

19. Ronco, C., Fluid overload : diagnosis and management. Contributions to nephrology,. 2010, Basel Switzerland ; New York: Karger. viii, 243 p.

20. Riegel, B., et al., State of the science: promoting self-care in persons with heart failure: a scientific statement from the American Heart Association. Circulation, 2009. 120(12): 1141-63.

21. Arnold, C. Gut feelings: the future of psychiatry may be inside your stomach. 2013  [cited 2013 Aug 22]; Available from:

22. Hobson, J.A., REM sleep and dreaming: towards a theory of protoconsciousness. Nat Rev Neurosci, 2009. 10(11): 803-13.

23. Dalgleish, T., The emotional brain. Nat Rev Neurosci, 2004. 5(7): 583-9.

24. Landers, M.S. and Sullivan, R.M., The development and neurobiology of infant attachment and fear. Dev Neurosci, 2012. 34(2-3): 101-14.

25. Bos, K., et al., Psychiatric outcomes in young children with a history of institutionalization. Harv Rev Psychiatry, 2011. 19(1): 15-24.

26. Arroll, B., et al., Antidepressants versus placebo for depression in primary care. Cochrane Database Syst Rev, 2009(3): CD007954.

27. Soomro, G.M., et al., Selective serotonin re-uptake inhibitors (SSRIs) versus placebo for obsessive compulsive disorder (OCD). Cochrane Database Syst Rev, 2008(1): CD001765.

28. Kapczinski, F., et al., Antidepressants for generalized anxiety disorder. Cochrane Database Syst Rev, 2003(2): CD003592.

29. Davis, M., NMDA receptors and fear extinction: implications for cognitive behavioral therapy. Dialogues Clin Neurosci, 2011. 13(4): 463-74.

Dr Caroline Leaf – Serious questions, few answers (Part 1)

Caroline Leaf. The name is popping up more and more around Christian circles. I was curious to hear her speak, since as a Christian and a (family) physician, I like to know how people integrate science and spirituality. So I took the opportunity to drive down to Kings Christian Church on the Gold Coast to hear what she had to say.

I left with more questions than answers.  And some serious concerns.

The following blog posts are a discussion on some of the points that she raised. I simply don’t have the time to go through all of them, although I’m seriously considering whether to do a formal review and response to her teaching.

I had to divide up the original post into three parts to make it more manageable. Here’s part 1, in which I review her academic qualifications, her link of thoughts and illness, our innate wiring, and the myth of the mini-brain.

Part 2 of this post will look further at the pecking order of the mind and brain, some miscellaneous issues, and her ‘professional’ opinion on ADHD.

Part 3 will examine her claim that “Toxic thoughts are sin” and why such a statement is incongruent with the Christian faith.


For a start, she was introduced as a cognitive neuroscientist. Her CV lists her degrees as a Bachelor of Science, Masters in Speech Therapy and Audiology, and a PhD in Communication Pathology. She did not advise where she has tenure or does her research. Her CV lists guest lectures at a few Universities (Wits, University of Pretoria, University of Cape Town, University of Western Cape Annual Education Conference, SASHLA, Rotary Foundation), but no tenure.

Admittedly, the definition of a cognitive neuroscientist is somewhat vague ( but the term ‘cognitive neuroscientist’ confers the idea that one is actively involved in cognitive neuroscientific research, or at least in the recent past.

So the question remains: is she really a cognitive neuroscientist, or is she just a woman with a PhD that reads a lot?


The next thing to grab my attention was her statement: “75 to 98% of ALL illness is related to our thought life.” Somehow I doubt that. The influence of stress is high.  But I am a GP – I see sick people everyday, on the coal face, before they are collected in subspecialist clinics, or improve spontaneously. It’s a real stretch to ascribe stress to more than 30%. Looking at her book ‘Who Switched Off My Brain’ (Leaf 2009, p15), she says that 80% of all diseases are the result of our thought lives. So her own figures are conflicting. (The other thing is that, for a PhD recipient, she has poorly referenced her book!)

Besides, stress causes illness, but I’m not yet satisfied she’s proven that ‘negative’ thought and stress are the same thing.


She also claimed that the brain and the heart connect to every cell in your body. Again, it’s a bit of a stretch. Every cell needs to be bathed in nutrients from the blood which in turn is connected to the heart, and nerves are every where.  But there are many cells that are not innervated directly.

The only way that the brain or the heart are connected to every cell is simply because, technically, every cell is connected to every other cell. Like if everyone in a church stood up and held hands, the man in the front row would be “connected” to the woman in the back.

But she went further on her theory, by claiming that the heart has a mini-brain that directly influences the real brain – by making moral decisions on its own, and that it is part of our conscience. She justified her statement by saying that the heart has 40,000 interconnected nerve cells, and the heart is directly connected to the brain. But on that same logic, my rectum could be a mini-brain and be part of my conscience.

She alluded to the effect of ANF, atrial natriuretic factor. There are actually three natriuretic peptides. ANF, produced by the top two chambers of the heart, actually regulates blood pressure ( If it has an effect on thought, it is secondary, not primary.


She also states that we are wired for optimism, and that emotions like fear are learned. That doesn’t make sense since I have seen research that shows a newborn baby is wired for pleasure and emotions like disgust. These pathways are developed and refined during childhood, but we are born with built-in templates for basic emotion.

I will have more in the next 24 hours, including her statement on the pecking order of the mind and brain, some miscellaneous issues, and her ‘professional’ opinion on ADHD.


Leaf, C. (2009). Who Switched Off My Brain? Controlling toxic thoughts and emotions. Southlake, TX, USA, Inprov, Ltd.