Dr Caroline Leaf and the 98 Percent Myth

Dr Caroline Leaf believes that nearly all our diseases come from our thoughts.

Dr Caroline Leaf believes that nearly all our diseases come from our thoughts.

In the hustle and bustle of daily life, most people wouldn’t stop to consider what makes people sick.  In my profession, I get a front row seat.

In the average week, I get to see a number of different things.  Mostly “coughs, colds and sore holes” as the saying goes, although there are some rarer things too.  And sometimes, people present with problems that aren’t for the faint of heart (or stomach – beware of nail guns is all I can say).

Normally, the statistics of who comes in with what doesn’t make it beyond the desk of the academic or health bureaucrat.  The numbers aren’t as important as the people they represent.

But to Dr Caroline Leaf, Communication Pathologist and self-titled Cognitive Neuroscientist, the numbers are all important.  To support her theory of toxic thoughts, Dr Leaf has stated that “75 to 98% of mental and physical (and behavioural) illness comes from one’s thought life” [1: p37-38].  She has repeated that statement on her website, on Facebook, and at seminars.

As someone with a front row seat to the illnesses people have, I found such a statement perplexing.  In the average week, I don’t see anywhere near that number.  In general practices around Australia, the number of presentations for psychological illnesses is only about eight percent [2].

But Australian general practice is a small portion of medicine compared to the world’s total health burden.  Perhaps the global picture might be different?  The World Health Organization, the global authority on global health, published statistics in November 2013 on the global DALY statistics [3] (a DALY is a Disability Adjusted Life Year).  According to the WHO, all Mental and Behavioural Disorders accounted for only 7.2% of the global disease burden.

You don’t need a statistics degree to know that seven percent is a long way from seventy-five percent (and even further from 98%).

Perhaps a large portion of the other ninety-three percent of disease that was classified as physical disease was really caused by toxic thoughts?  Is that possible?  In short: No.

When considered in the global and historical context, the vast majority of illness is related to preventable diseases that are so rare in the modern western world because of generations of high quality public health and medical care.

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.” [4] 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.” [5] 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.” [6]

Diarrhoeal disease in the developing world – the second most common contributor to disease in these countries, afflicting half of their population – has nothing to do with thought.  It’s related to the provision of toilets and clean running water.

We live in a society that prevents half of our illnesses because of internal plumbing.  Thoughts seem to significantly contribute to disease because most of our potential illness is prevented by our clean water and sewerage systems.  Remove those factors and thought would no longer appear to be so significant.

In the same manner, modern medicine has become so good at preventing diseases that thought may seem to be a major contributor, when in actual fact, most of the work in keeping us all alive has nothing to do with our own thought processes.  Like sanitation and clean water, the population wide practices of vaccination, and health screening such as pap smears, have also significantly reduced the impact of preventable disease.

Around the world, “Recent estimates of the global incidence of disease suggest that communicable diseases account for approximately 19% of global deaths” and that “2.5 million deaths of children annually (are) from vaccine-preventable diseases.” [7] Again, that’s a lot of deaths that are not related to thought life.

Since 1932, vaccinations in Australia have reduced the death rate from vaccine-preventable diseases by 99% [8].  Epidemiological evidence shows that when vaccine rates increase, sickness from communicable diseases decrease [9: Fig 2, p52 & Fig 8, p67].

Population based screening has also lead to a reduction in disease and death, especially in the case of population screening by pap smears for cervical cancer.  Canadian public health has some of the best historical figures on pap smear screening and cervical cancer. In Canada, as the population rate of pap smear screening increased, the death rate of women from cervical cancer decreased.  Overall, pap smear screening decreased the death rate from cervical cancer by 83%, from a peak of 13.5/100,000 in 1952 to only 2.2/100,000 in 2006, despite an increase in the population and at-risk behaviours for HPV infection (the major risk factor for cervical cancer) [10].

And around the world, the other major cause of preventable death is death in childbirth.  The risk of a woman dying in childbirth is a staggering one in six for countries like Afghanistan [11] which is the same as your odds playing Russian Roulette.  That’s compared to a maternal death rate of one in 30,000 in countries like Sweden.  The marked disparity is not related to the thought life of Afghani women in labour.  Countries that have a low maternal death rate all have professional midwifery care at birth.  Further improvements occur because of better access to hospital care, use of antibiotics, better surgical techniques, and universal access to the health system [11].  Again, unless one’s thought life directly changes the odds of a midwife appearing to help you deliver your baby, toxic thoughts are irrelevant as a cause of illness and death.

Unfortunately for Dr Leaf, her statement that “75 to 98 percent of mental, physical and behavioural illnesses come from toxic thoughts” is a myth, a gross exaggeration of the association of stress and illness.

In the global and historical context of human health, the majority of illness is caused by infectious disease, driven by a lack of infrastructure, public health programs and nursing and medical care.  To us in the wealthy, resource-rich western world, it may seem that our thought life has a significant effect on our health.  That’s only because we have midwives, hospitals, public health programs and internal plumbing, which stop the majority of death and disease before they have a chance to start.

Don’t worry about toxic thoughts.  Just be grateful for midwives and toilets.


1.         Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan:

2.         FMRC. Public BEACH data. 2010  [cited 16JUL13]; Available from: <http://sydney.edu.au/medicine/fmrc/beach/data-reports/public%3E.

3.         World Health Organization, GLOBAL HEALTH ESTIMATES SUMMARY TABLES: DALYs by cause, age and sex, GHE_DALY_Global_2000_2011.xls, Editor 2013, World Health Organization,: Geneva, Switzerland.

4.         Mara, D., et al., Sanitation and health. PLoS Med, 2010. 7(11): e1000363 doi: 10.1371/journal.pmed.1000363

5.         Bartram, J. and Cairncross, S., Hygiene, sanitation, and water: forgotten foundations of health. PLoS Med, 2010. 7(11): e1000367 doi: 10.1371/journal.pmed.1000367

6.         Hunter, P.R., et al., Water supply and health. PLoS Med, 2010. 7(11): e1000361 doi: 10.1371/journal.pmed.1000361

7.         De Cock, K.M., et al., The new global health. Emerg Infect Dis, 2013. 19(8): 1192-7 doi: 10.3201/eid1908.130121

8.         Burgess, M., Immunisation: A public health success. NSW Public Health Bulletin, 2003. 14(1-2): 1-5

9.         Immunise Australia, Myths and Realities. Responding to arguments against vaccination, A guide for providers. 5th ed. 2013, Commonwealth of Australia, Department of Health and Ageing, Canberra:

10.       Dickinson, J.A., et al., Reduced cervical cancer incidence and mortality in Canada: national data from 1932 to 2006. BMC Public Health, 2012. 12: 992 doi: 10.1186/1471-2458-12-992

11.       Ronsmans, C., et al., Maternal mortality: who, when, where, and why. Lancet, 2006. 368(9542): 1189-200 doi: 10.1016/S0140-6736(06)69380-X

Bad choices cause brain damage?

“To err is human; to forgive, divine.”  Alexander Pope.

I’m not perfect.  At least, not the last time I checked.  And we’re all the same, aren’t we.  We all know through experience that we all stuff things up on a fairly regular basis.  We make bad choices.  We’re human!

Dr Caroline Leaf, Communication Pathologist and self-titled Cognitive Neuroscientist, believes that these bad choices literally cause brain damage.  Her fundamental assumption is that our thoughts control our brain [1: p33].  These thoughts can be healthy or they can be toxic.  Toxic thoughts “are thoughts that trigger negative and anxious emotions, which produce biochemicals that cause the body stress.” [2: p19]

Dr Leaf’s assumption is that thoughts and bad choices cause our brain cells to shrivel or die. “Once your body is truly in stress mode and the cortisol is flowing, dendrites start shrinking and even ‘falling off’” [2: p32].  She also says that, “We have two choices, we can let our thoughts become toxic and poisonous or we can detox our negative thoughts which will improve our emotional wholeness and even recover our physical health.” [2: p21]

It sounds a little extreme.  We all make bad choices, and we all experience stress.  When we’re stressed, do our memories really go missing, or the dendrites of nerve cells shake and fall like tree branches in a storm?  If we make a bad choice, do we really get brain damage?  Lets see what the scientific literature has to say.

Imagine walking along a path in a forest and you see a snake, only inches in front of you on the path.  What do you do? When faced with a high level of acute stress, the brain switches into a binary mode – fight/flight or freeze. Self-preservation has to kick in.  The only decision you have to make then and there is whether to run, to try and kill the snake before it kills you, or stop dead still and hope that the snake ignores you and slithers away.

At that point, most memory is redundant, as is a high-level analysis of snake species, or any other cognitive pursuit.  The brain doesn’t need them at that precise moment.  If they did engage, they would just get in the way.  Switching the thinking parts of your brain off focuses your attention on the immediate danger.  It’s an adaptive survival response.  Meantime, your memories and your theoretical knowledge about snakes don’t disappear.  They are still there, unchanged.  It is false to suggest that the memories “shrink”.

We’ve all experienced “mental block”.  Sometimes when we get into a situation, like an exam or a business meeting, our stress levels are high, and binary mode kicks in again, although this time it can be a hindrance.  This phenomenon of mental block under high stress was first proposed in 1908 and is currently known as the Yerkes-Dodson Law, a fundamental principle of the behavioural sciences [3].  Similar to the stress-productivity curve, Yerkes and Dodson proposed a U-shaped curve to represent the relationship between arousal (which could be either level of consciousness or stress) and behavioural performance.  At low arousal, there is poor performance.  At the mid-point of arousal, there is peak performance, and at high arousal, performance diminishes.

But again, our memories don’t shrink, and our nerve cell branches don’t fall off.  Once we reduce our level of arousal, we move away from the fight/flight/freeze mode, and everything is still there (and we perform better, according to Yerkes-Dodson).

Dr Leaf has a favourite analogy of “neurons as trees”.  And if neurons are trees, then the branches can “fall off”.  But neurons are not trees and dendrites are not tree branches.  The dendrites do not ‘fall off’ the neuron.  The neurons in the brain have mechanisms for ongoing brain plasticity – the ability of the brain to adapt to the challenges and changes in its internal and external environment that are constantly occurring.  If the brain needs to build a new circuit to encode a new piece of information, then it grows new dendrites and creates new synapses.  But the brain is limited by the amount of energy it can consume, and therefore the number of synapses it can maintain.  So the brain trims unnecessary dendrites, a process called “synaptic pruning”.

Synaptic pruning is a normal process. Chechik and Meilijson confirm that, “Human and animal studies show that mammalian brains undergoes massive synaptic pruning during childhood, removing about half of the synapses until puberty.” [4]

Synaptic pruning is not deleterious, but beneficial.  Chechik and Meilijson also note that, “synaptic overgrowth followed by judicial pruning along development improves the performance of an associative memory network with limited synaptic resources.” [4] So synaptic pruning is a normal physiological process, and occurs in all of us for many reasons, predominantly to improve the efficiency of our neural networks.  Perhaps synaptic pruning associated with the stress response is also an adaptive process?

Synaptic pruning also occurs in other physiological states that have nothing to do with stress or thought, such as the effects of oestrogen during the menstrual cycle and at menopause [5, 6].

A link between stress and dendrite loss has been discovered, but it is not consistent.  Some authors like Kopp and Rethelyi suggest that “severe stress for a prolonged period causes damage in hippocampal pyramidal neurons, especially in the CA3 and CA4 region and reductions in the length and arborization of their dendrites.” [7] However, Chen et al writes, “Whereas hippocampus-mediated memory deficits commonly were associated with—and perhaps result from—loss of synapse-bearing dendrites and dendritic spines, this association has not been universal so that the structure–function relationship underlying the effects of stress on hippocampal neurons has not been resolved.” [8]

It’s more accurate to think that chronic stress causes dendritic remodeling in animals [9], in which some nerve cells prune their synapses, which others grow them, and energy is diverted away from new nerve cell formation to the new synapses that are needed to cope with the stress.

A number of scientists have pointed out that patients with depression or anxiety, who normally have high levels of stress, have a smaller hippocampus and larger amygdala, so stress and depression must cause the smaller brain regions [9].  There may be some reduction in the number of synapses within the hippocampus and the frontal lobes of the brain, which may account for the change in size observed by a number of researchers.  But the modern thinking on these changes is that they are associated with depression, not caused by depression [10] (Correlation does not equal causation).

So, stress is associated with depression, but this is because genetic defects in one or multiple genes reduce the ability for the brain cells to produce synaptic branches.  It’s this decrease in the number of synapses that contributes to the typical changes in the brain seen at autopsy of patients who suffered from depression or anxiety [11].  The reduced ability of the nerve cells to grow synapses means that new branches can’t grow fast enough to process the stress signals properly [11, 12].  The poor signal transmission leads to a predisposition towards mood disorders like anxiety and depression [10, 11, 13-15], and less synaptic branches means both a smaller volume of the hippocampus, and an inability to process stress signals leads to a larger, overactive amygdala.

In summary, synaptic pruning is not due to toxic thinking or bad choices, unless every one of us engages in nothing but toxic thinking from early childhood to puberty, and menopause causes bad choices and toxic thoughts.  Stress doesn’t cause dendrites to fall off, but causes a reorganization of the dendrites to adapt to the new signals. The reduced capacity to form new dendrites makes those prone to mood disorders more vulnerable to stress, and depression or anxiety is the end result.

We are all bound to make bad choices and to have stress.  They don’t cause brain damage.  Which if you’re not perfect like me, is good news.


1.         Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan

2.         Leaf, C., Who Switched Off My Brain? Controlling toxic thoughts and emotions. 2nd ed. 2009, Inprov, Ltd, Southlake, TX, USA:

3.         Cohen, R.A., Yerkes–Dodson Law, in Encyclopedia of Clinical Neuropsychology, Kreutzer, J.S., et al., Editors. 2011, Springer Science+Business Media LLC: New York ; London. p. 2737-8.

4.         Chechik, G., et al., Neuronal regulation: A mechanism for synaptic pruning during brain maturation. Neural Comput, 1999. 11(8): 2061-80  http://www.ncbi.nlm.nih.gov/pubmed/10578044

5.         Chen, J.R., et al., Gonadal hormones modulate the dendritic spine densities of primary cortical pyramidal neurons in adult female rat. Cereb Cortex, 2009. 19(11): 2719-27 doi: 10.1093/cercor/bhp048

6.         Dumitriu, D., et al., Estrogen and the aging brain: an elixir for the weary cortical network. Ann N Y Acad Sci, 2010. 1204: 104-12 doi: 10.1111/j.1749-6632.2010.05529.x

7.         Kopp, M.S. and Rethelyi, J., Where psychology meets physiology: chronic stress and premature mortality–the Central-Eastern European health paradox. Brain Res Bull, 2004. 62(5): 351-67 doi: 10.1016/j.brainresbull.2003.12.001

8.         Chen, Y., et al., Correlated memory defects and hippocampal dendritic spine loss after acute stress involve corticotropin-releasing hormone signaling. Proc Natl Acad Sci U S A, 2010. 107(29): 13123-8 doi: 10.1073/pnas.1003825107

9.         Karatsoreos, I.N. and McEwen, B.S., Psychobiological allostasis: resistance, resilience and vulnerability. Trends Cogn Sci, 2011. 15(12): 576-84 doi: 10.1016/j.tics.2011.10.005

10.       Palazidou, E., The neurobiology of depression. Br Med Bull, 2012. 101: 127-45 doi: 10.1093/bmb/lds004

11.       Karatsoreos, I.N. and McEwen, B.S., Resilience and vulnerability: a neurobiological perspective. F1000Prime Rep, 2013. 5: 13 doi: 10.12703/P5-13

12.       Russo, S.J., et al., Neurobiology of resilience. Nature neuroscience, 2012. 15(11): 1475-84

13.       Felten, A., et al., Genetically determined dopamine availability predicts disposition for depression. Brain Behav, 2011. 1(2): 109-18 doi: 10.1002/brb3.20

14.       Bradley, R.G., et al., Influence of child abuse on adult depression: moderation by the corticotropin-releasing hormone receptor gene. Arch Gen Psychiatry, 2008. 65(2): 190-200 doi: 10.1001/archgenpsychiatry.2007.26

15.       Hauger, R.L., et al., Role of CRF receptor signaling in stress vulnerability, anxiety, and depression. Ann N Y Acad Sci, 2009. 1179: 120-43 doi: 10.1111/j.1749-6632.2009.05011.x

Borderline Narcissism and Organic Food

Every time I go to the supermarket, I’m always amazed at the every-growing supply of “organic” products.  In fact, not just the supermarket, but everywhere I go, one of the first things out of the mouth of the sales assistant is, “and it’s organic.”

Organic food has gone gang-busters in the last decade.  It is currently worth around $200–$250 million per year domestically and a further $50–$80 million per year in exports, with an expected annual growth of up to 60 per cent. In 2010, the retail value of the organic market was estimated to be at least $1 billion.

Consumer demand for organic food is growing at a rate of 20–30 per cent per year, with retail sales increasing 670 per cent between 1990 and 2001–02. It is estimated that more than six out of every ten Australian households now buy organic foods on occasion (Better Health Channel, 2013).

It’s not cheap either.  I did a single price point comparison to see what the difference was between similar organic and conventional foods.  A 411g can of “Muir Glen” brand diced organic tomatoes on Organics Australia Online (http://www.organicsaustraliaonline.com.au/category173_1.htm) cost $4.28.  An equivalent product, “Annalisa” brand 400g can of diced tomatoes cost $1.00 at Woolworths Online (http://www2.woolworthsonline.com.au/#url=/Shop/SearchProducts%3Fsearch%3Ddiced%2Btomato%2Bcanned).

Allowing for the slight difference in size, that’s still a 400% premium, just because something is tagged as organic.

Given the massive price premiums and it’s overwhelming popularity, you’d assume there is something miraculous about organic food.  Like, it possessed some magical healing properties, or that it was the elixir of life.

Yet in the hard light of day, the aura of organic food turns out to be a shimmering mirage.  When critically examined by the power of science, organic food is found to be lacking.  It’s all hype, and no substance.

So why do people buy and consume organic produce?  Usually because they believe that organic foods are healthier (that is, they have more nutrients) or safer (or they believe that there are less pesticides or chemicals), that organic foods taste better, and that organic farming is better for the environment (Hughner, McDonagh, Prothero, Shultz, & Stanton, 2007).

But as it turns out, organic foods have essentially the same nutritional content as their conventionally farmed equivalents (Dangour et al., 2009).  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 (Smith-Spangler et al., 2012).  So organic foods can’t be claimed to be significantly safer than conventional foods either.

The other positive attribute pushed by organic proponents is that organic farming is much better for the environment than conventional farming.  But far from the stereotype, organic foods aren’t saving the planet from the evil greed of the multi-national corporations and their earth-raping large scale conventional farming techniques.

Tuomisto, Hodge, Riordan, and Macdonald (2012) concluded their meta-analysis of research into European farming by saying, “This meta-analysis has showed that organic farming in Europe has generally lower environmental impacts per unit of area than conventional farming, but due to lower yields and the requirement to build the fertility of land, not always per product unit. The results also showed a wide variation between the impacts within both farming systems. There is not a single organic or conventional farming system, but a range of different systems, and thus, the level of many environmental impacts depend more on farmers’ management choices than on the general farming systems.”

In other words, the impact on the planet has nothing to do with the food that’s grown, but the farmers who grow it.

That’s three strikes for organic food.  It isn’t healthier, safer, or better for the planet.  There’s nothing to organic food that justifies the enormous premium that is charged for them, except the egocentric inflation that comes from believing that “being organic” is superior.

Like going to the Opera or driving a Prius, “being organic” is just another outlet for borderline narcissism.

The take home message: If you care for your health or the environment, buy conventionally farmed food.  There’s no difference to organic food, except the price.


Better Health Channel. (2013, Oct 17). Organic Food.   Retrieved Jan 24, 2014, from http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/organic_food

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

Hughner, R. S., McDonagh, P., Prothero, A., Shultz, C. J., & Stanton, J. (2007). Who are organic food consumers? A compilation and review of why people purchase organic food. Journal of consumer behaviour, 6(2‐3), 94-110.

Smith-Spangler, C., Brandeau, M. L., Hunter, G. E., Bavinger, J. C., Pearson, M., Eschbach, P. J., . . . Stave, C. (2012). Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med, 157(5), 348-366.

Tuomisto, H. L., Hodge, I. D., Riordan, P., & Macdonald, D. W. (2012). Does organic farming reduce environmental impacts?–A meta-analysis of European research. Journal of environmental management, 112, 309-320.

Gardasil and the Deadly Scam

Making the rounds of Facebook is an article published on The Daily Sheeple (“Lead Developer Of HPV Vaccines Comes Clean, Warns Parents & Young Girls It’s All A Giant Deadly Scam,” 2014) about Gardasil, the Human Pappilloma Virus vaccine.

If what Sheeple are saying is correct, then Gardasil is a deadly scam!  We’ve all been conned into believing that Gardasil and other HPV vaccines were safe, and useful in protecting our children from cervical cancer, when really it doesn’t do anything but make money for Merck, that multi-billion dollar global tyrant, while our children wither and die.

True to the form of paranoid extremists everywhere, Sheeple uses hysterical accusations and mistruths in a breathless promotion of fear and ignorance.  The only deadly scam going on here is Sheeple’s.

Lets break down the article by Sheeple a little, then lets look at the facts from the peer-reviewed literature, not misquotes from misquotes.

Sheeple quotes an article on a similarly extreme blog, which took the quotes from another extremist blog.  It alleges that Dr Harper believed that Gardasil was pointless, and harmful, even more harmful than cervical cancer which it was designed to prevent.  The article alleges that there were 15,037 adverse reactions and 44 deaths.  They quote Harper to CBS stating that, “‘The risks of serious adverse events including death reported after Gardasil use in (the JAMA article by CDC’s Dr. Barbara Slade) were 3.4/100,000 doses distributed,’ Harper tells CBS NEWS.  ‘The rate of serious adverse events on par with the death rate of cervical cancer.’”

The truth is that the rates of serious adverse reactions to the HPV vaccine are incredibly small.

The CDC Morbidity and Mortality Weekly report from the 26th July 2013 states that, “From June 2006 through March 2013, approximately 56 million doses of HPV4 were distributed in the United States … During June 2006–March 2013, the Vaccine Adverse Event Reporting System (VAERS) received a total of 21,194 adverse event reports occurring in females after receipt of HPV4” (Centers for Disease Control and Prevention, 2013).  That’s an adverse events rate of 0.04%.

The vast majority of vaccination side effects are a red, sore arm and fainting, which are not exclusive side effects to HPV vaccinations, but to all vaccinations in adolescents (Centers for Disease Control and Prevention, 2013; Harper & Vierthaler, 2011).  In large trials, the rate of vaccine side effects was comparable to the rate of side effects from the placebo (Centers for Disease Control and Prevention, 2013; Gee et al., 2011; Lu, Kumar, Castellsague, & Giuliano, 2011; Rambout, Hopkins, Hutton, & Fergusson, 2007).  So the vaccine is not the problem, it’s the histrionic teenagers.

In terms of deaths from the HPV vaccine, there aren’t any.  Rambout et al. (2007) wrote, “The meta-analysis demonstrated that, overall, the incidence of serious adverse events and death was balanced between the vaccine and control groups … Most deaths were reported as accidental, and none of the deaths was considered attributable to the vaccine.”  National Centre For Immunisation Research and Surveillance (2013) states that, “HPV vaccines are approved for use in over 100 countries, with more than 100 million doses distributed worldwide … No deaths reported in safety surveillance systems data in Australia or overseas, have been determined to be causally related to either of the HPV vaccines.”

Compare that to the current Australian road toll, which currently stands at 5.2/100,000 (Road Deaths Australia, December 2013).  It’s safer to have a HPV vaccination than it is to drive a car.

The Sheeple article also fails to correctly report the benefits of the HPV vaccine, which has already shown a dramatic drop in the rate of HPV infection (Lu et al., 2011) and the incidence of genital warts (Ali et al., 2013).

Given all of this, did Dr Harper really suggest that the HPV vaccine was useless and harmful?  I doubt she said anything of the sort, since in 2011 in a formal paper in a peer-reviewed journal, she said, “Should vaccination be an option that women choose for their cervical cancer protection, Cervarix is an excellent choice for both screened and unscreened populations due to its long-lasting protection, its broad protection for at least five oncogenic HPV types, the potential to use only one-dose for the same level of protection, and its safety.” (Harper & Vierthaler, 2011)

One final word about every woman’s favourite health check, the pap smear.  Australia does have a low death rate from cervical cancer, compared to the rest of the world, even before the introduction of the HPV vaccine.  The national co-ordinated approach to cervical screening with pap smears is the reason why.  “Vaccination is not an ‘alternative’ to Pap tests; together these two approaches provide optimal protection. The National Cervical Screening Program recommends routine screening with Pap tests every 2 years for all women between the ages of 18 (or 2 years after first sexual intercourse) and 69 years.” (National Centre For Immunisation Research and Surveillance, 2013)

Is there a giant deadly scam behind the Gardasil vaccine?  Only from those who oppose it.  The same people wouldn’t think twice about letting their teenagers in a car, which is far more dangerous.  When it’s their turn, I’ll have no hesitation in having my children vaccinated for HPV.  If you disagree, that’s ultimately your choice.  But examine all the facts first.  Don’t let your children’s health rest on a baseless Internet meme.


Ali, H., Donovan, B., Wand, H., Read, T. R., Regan, D. G., Grulich, A. E., . . . Guy, R. J. (2013). Genital warts in young Australians five years into national human papillomavirus vaccination programme: national surveillance data. BMJ, 346, f2032. doi: 10.1136/bmj.f2032

Centers for Disease Control and Prevention. (2013). Human papillomavirus vaccination coverage among adolescent girls, 2007-2012, and postlicensure vaccine safety monitoring, 2006-2013 – United States. MMWR Morb Mortal Wkly Rep, 62(29), 591-595.

Gee, J., Naleway, A., Shui, I., Baggs, J., Yin, R., Li, R., . . . Weintraub, E. S. (2011). Monitoring the safety of quadrivalent human papillomavirus vaccine: findings from the Vaccine Safety Datalink. Vaccine, 29(46), 8279-8284. doi: 10.1016/j.vaccine.2011.08.106

Harper, D. M., & Vierthaler, S. L. (2011). Next Generation Cancer Protection: The Bivalent HPV Vaccine for Females. ISRN Obstet Gynecol, 2011, 457204. doi: 10.5402/2011/457204

Lead Developer Of HPV Vaccines Comes Clean, Warns Parents & Young Girls It’s All A Giant Deadly Scam. (2014). The Daily Sheeple.  Retrieved Jan 17, 2014, from http://www.thedailysheeple.com/lead-developer-of-hpv-vaccines-comes-clean-warns-parents-young-girls-its-all-a-giant-deadly-scam_012014 – sthash.lDJcsFRt.dpuf

Lu, B., Kumar, A., Castellsague, X., & Giuliano, A. R. (2011). Efficacy and safety of prophylactic vaccines against cervical HPV infection and diseases among women: a systematic review & meta-analysis. BMC Infect Dis, 11, 13. doi: 10.1186/1471-2334-11-13

National Centre For Immunisation Research and Surveillance. (2013). Human papillomavirus (HPV) vaccines for Australians | NCIRS Fact sheet: March 2013.   Retrieved Jan 17, 2014, from http://www.ncirs.edu.au/immunisation/fact-sheets/hpv-human-papillomavirus-fact-sheet.pdf

Rambout, L., Hopkins, L., Hutton, B., & Fergusson, D. (2007). Prophylactic vaccination against human papillomavirus infection and disease in women: a systematic review of randomized controlled trials. CMAJ, 177(5), 469-479. doi: 10.1503/cmaj.070948

Road Deaths Australia, December 2013. (2014).  Canberra, Australia: Commonwealth of Australia. Retrieved from http://www.bitre.gov.au/publications/ongoing/rda/files/RDA_Dec13.pdf.

Dr Caroline Leaf and the myth of optimism bias

“What are little girls are made of?  Sugar and spice, and all things nice.”

It sounds sweet doesn’t it?  We like to connect with these rosy little memes that warm our cockles and make us feel good about the world and ourselves.  We think of all of the examples in our own experience, which seems to confirm the saying.  We may think of a few examples that don’t quite fit, but they’re just the exception that proves the rule.

It doesn’t seem to matter what the saying or proverb is, we usually just assume it’s true.  Think of some other examples:
“Blondes have more fun.”
“Women can’t read maps.”
“White guys can’t dance.”

In all of these things, we tend to experience what psychologists call confirmation bias (Princeton University, 2014), our own mini-delusion in which we fool ourselves into believing a half-truth.  It looks right on first glance, and we can easily think of a few confirming examples, so without deeper inspection, we assume it must be true.

When Dr Leaf proclaims that,

“Science shows we are wired for love with a natural optimism bias”

the same process kicks in.  But in truth, science doesn’t show anything of the sort.  What science shows is that we learn love and fear, and our genetics influences the way we see the world, our personality.

We are prewired to LEARN to love and fear.  It doesn’t come naturally.  We require exposure to both love and to fear for these emotions to develop.  The Bucharest Early Intervention Project is a study looking at the long-term psychological and physical health of children in Bucharest, one group who remained in an orphanage, and the other, a group of children that were eventually adopted.  Analysis of the cohort of the two groups of children showed that negative affect was the same for both groups.  However positive affect and emotional reactivity was significantly reduced in the institutionalised children (Bos et al., 2011).  This shows that children who lived in an institution all of their lives and given limited emotional stimulation had lower levels of positive affect (ie: love, happiness) compared to a child that was adopted.

The children in the institution did not have high positive affect because they were not shown love.  Those children who were adopted were higher on positive affect because they were shown love by their adopted parents.  Both groups were exposed to distress and fear during their time in the orphanage, so their negative affect was the same across both groups.  Thus, love and fear don’t come naturally.  They need to be learned.

Personality is “the combination of characteristics or qualities that form an individuals distinctive character.” (“Oxford Dictionary of English – 3rd Edition,” 2010) As Professor Greg Henriques wrote in psychology today, “Personality traits are longstanding patterns of thoughts, feelings, and actions which tend to stabilize in adulthood and remain relatively fixed. There are five broad trait domains, one of which is labeled Neuroticism, and it generally corresponds to the sensitivity of the negative affect system, where a person high in Neuroticism is someone who is a worrier, easily upset, often down or irritable, and demonstrates high emotional reactivity to stress.” (Henriques, 2012) Personality is heavily influenced by genetics, with up to 60% of our personality pre-determined by our genes (Vinkhuyzen et al., 2012), expressed through the function of the serotonin and dopamine transporter systems in our brain (Caspi, Hariri, Holmes, Uher, & Moffitt, 2010; Chen et al., 2011; Felten, Montag, Markett, Walter, & Reuter, 2011).

So some people *ARE* natural optimists – their genetic heritage blessed them with a rosy outlook and their early life experiences cemented it in.  These naturally optimistic people, and the people who know them, are the ones who take Dr Leaf’s word as truth because they see it in themselves or their friends.  But the fact that some people are naturally wired for pessimism or a neurotic personality disproves Dr Leaf’s assertion.

Its important that Dr Leaf’s misleading meme is seen for what it is.  If we assume that we’re all pre-wired for love and optimism, then those who are pessimistic must be deficient or deviant, and the fact they can’t change must mean they are incompetent or lazy.  If we know the truth, those who are less optimistic won’t be unnecessarily judged or marginalised.

I should point out that what I’ve said isn’t a free licence to be cranky or sullen all the time.  The natural pessimist still needs to be able to negotiate their way through life, and being a misery-guts makes it hard to get what you need from other people in any business, social or interpersonal relationship.  We have the ability to learn, and the person with a neurotic personality can still learn ways of dealing with people in a positive way.

But if you naturally see the glass half-empty, don’t tell yourself that you’re abnormal, or that you aren’t good enough.  You are who you are.  Accept who you are, because while there are weaknesses inherent to having neurotic personality traits, there are also strengths, such as the enhanced awareness of deception, or protection from gullibility (Forgas & East, 2008).

A good thing to have when searching for the truth.


Bos, K., Zeanah, C. H., Fox, N. A., Drury, S. S., McLaughlin, K. A., & Nelson, C. A. (2011). Psychiatric outcomes in young children with a history of institutionalization. Harv Rev Psychiatry, 19(1), 15-24. doi: 10.3109/10673229.2011.549773

Caspi, A., Hariri, A. R., Holmes, A., Uher, R., & Moffitt, T. E. (2010). Genetic sensitivity to the environment: the case of the serotonin transporter gene and its implications for studying complex diseases and traits. Am J Psychiatry, 167(5), 509-527. doi: 10.1176/appi.ajp.2010.09101452

Chen, C., Chen, C., Moyzis, R., Stern, H., He, Q., Li, H., . . . Dong, Q. (2011). Contributions of dopamine-related genes and environmental factors to highly sensitive personality: a multi-step neuronal system-level approach. PLoS One, 6(7), e21636. doi: 10.1371/journal.pone.0021636

Felten, A., Montag, C., Markett, S., Walter, N. T., & Reuter, M. (2011). Genetically determined dopamine availability predicts disposition for depression. Brain Behav, 1(2), 109-118. doi: 10.1002/brb3.20

Forgas, J. P., & East, R. (2008). On being happy and gullible: Mood effects on skepticism and the detection of deception. Journal of Experimental Social Psychology, 44, 1362-1367.

Henriques, G. (2012). (When) Are You Neurotic?  Retrieved from http://www.psychologytoday.com/blog/theory-knowledge/201211/when-are-you-neurotic

Oxford Dictionary of English – 3rd Edition. (2010)   (3rd edition ed.). Oxford, UK: Oxford University Press.

Princeton University. (2014). Confirmation bias.   Retrieved January 10, 2014, from http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Confirmation_bias.html

Vinkhuyzen, A. A., Pedersen, N. L., Yang, J., Lee, S. H., Magnusson, P. K., Iacono, W. G., . . . Wray, N. R. (2012). Common SNPs explain some of the variation in the personality dimensions of neuroticism and extraversion. Transl Psychiatry, 2, e102. doi: 10.1038/tp.2012.27