Richard G. Petty, MD

Blondes Make Us Dumb??

No, this isn’t just a cheap excuse to display a picture of Pamela Anderson.

I just received this from a regular reader:

“Dear Dr Petty,

Have you seen this article Times Online?

“WHEN men meet fair-haired women they really do have a “blonde moment”. Scientists have found that their mental performance drops, apparently because they believe they are dealing with someone less intelligent.

Researchers discovered what might be called the “bimbo delusion” by studying men’s ability to complete general knowledge tests after exposure to different women. The academics found that men’s scores fell after they were shown pictures of blondes.

Further analysis convinced the team that, rather than simply being distracted by the flaxen hair, those who performed poorly had been unconsciously driven by social stereotypes to “think blonde”.

“This proves that people confronted with stereotypes generally behave in line with them,” said Thierry Meyer, joint author of the study and professor of social psychology at the University of Paris X-Nanterre. “In this case blondes have the potential to make people act in a dumber way, because they mimic the unconscious stereotype of the dumb blonde.”

Do you have any comment to make about the research??”

The answer is that I have seen this article all over the Internet, with all kinds of sage comments.

The trouble is that I have not yet been able to read and critique the research. As far as I know, neither the hard copy nor electronic versions are available yet, so I cannot evaluate the report.

This highlights one of the problems of the Internet: news travels across it like the wind, yet a lot of material is passed on without analysis. So the story is fun to read, but until we can see and analyze the data, we cannot comment.

As soon as I get a copy I shall see if I have anything to add to the firestorm of commentary!

Anti-inflammatories and Colon Cancer

I just had a very good question after I published my list of Twelve Tips to Reduce Your Risk of Colorectal Cancer.

Dear Dr. Petty,

“That’s a great list, but I am wondering why you haven’t included aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs)? I thought that they had been shown to reduce the risk of colon cancer.”

This is an excellent question, and I deliberately omitted mention of anti-inflammatories because the research suggests that they may cause more harm than good.

There is a report in today’s edition of the Annals of Internal Medicine from the United States Preventive Services Task Force, a highly regarded and independent panel of experts in primary care and prevention, that confirms that screening for colorectal cancer is still important and everyone over 50 should have it. But they urge caution on taking preventive drugs, saying that on balance the health risks of aspirin outweigh the benefits when it comes to preventing colon cancer. This advice holds even for those people with a family history of the disease, as long as they have only an average risk of colon cancer. (20 per cent of people who get colorectal cancer also have a close relative with the disease, with proportionally more cases among African Americans than other races.)

They found good evidence that high doses of aspirin (i.e. 300 mg a day or more) and possibly ibuprofen protect against colorectal cancer but this comes with increased risk of intestinal bleeding, stroke and kidney failure.

In low doses – under 100 mg a day – the Task Force says that good evidence supports the notion that aspirin protects against heart disease. However, at this dosage it will have no preventive effect on colorectal cancer.

The US Preventive Services Task Force regularly reviews the available research evidence and issues advice based on what they regard the strength of the evidence to be. They use a grades to help guide practice. For example a grade A recommendation is equal to "strongly recommends", while a B is just "recommends", and C is "no recommendation for or against".

In this case the Task Force has issued a grade D "recommends against" to the routine use of aspirin and NSAIDs to prevent colorectal cancer.

So for now I recommend following the Twelve Tips that I published yesterday.

Posttraumatic Stress Disorder and Brain Laterality

I’ve just received an intriguing article from an individual who’s really been through the mill with an array of psychiatric problems going back to childhood.

The last diagnosis that he attracted was posttraumatic stress disorder (PTSD), and he seems to have cured himself by a combination of omega-3 fatty acids and learning to play the banjo left-handed.

This may sound like a bit of an odd claim, but although the writer did not realize it, there is actually some solid science behind his observation.

For years now we have known that if someone is paralyzed down one side after a stroke, binding the good arm or leg leads to rapid reorganization in the cerebral cortex, as a result of which the paralyzed arm or leg may begin to regain function.

One of the most potent ways to improve the functioning of regions of the brain is to try doing things with the opposite hand: if your are right-handed, brushing your teeth or writing with your left hand or using your knife and fork the other way round can all be very illuminating, and can help train your brain. A common tactic in couple’s therapy is to get people to change some habits, like switching the sides of the bed on which a couple sleeps.

The hippocampus of the brain is involved in many functions, but key amongst them is the laying down of short-term memories. People with several stress-related psychiatric disorders, including PTSD, borderline personality disorder with early abuse, depression with early abuse, alcoholism and dissociative identity disorder all have smaller hippocampi, presumably because this part of the brain is exquisitely sensitive to cortisol: high levels can damage and destroy hippocampal cells. Antidepressant medications and some types of cognitive training are thought to lead to the growth of new cells in the hippocampus. It is also possible that having a small hippocampus may predispose someone to the development of PTSD. There is also some evidence that mixed lateral preferences and parental left-handedness may all predispose someone to the development of PTSD.

In PTSD, the left hippocampus and two other brain regions: the left anterior cingulate cortex and both sides of the insula are all smaller than normal. Regions of this small left hippocampus associated with episodic and autobiographical memory is activated by stimuli that wouldn’t have much effect in people without the problem. Some researchers have also found that if the right hippocampus is smaller and more active, it correlates with the severity of PTSD symptoms.

Adults with PTSD have a higher incidence of mixed laterality with respect to handedness than the rest of the population. This has recently also been found in children: there is a positive correlation between PTSD symptom severity and mixed laterality. This strongly suggests that neurological abnormalities may be related to the severity of symptoms in PTSD.

In PTSD, the right amygdala, a region involved in fear and rapid emotional learning and processing, is smaller than the left. In healthy volunteers it’s the same on both sides.

When people with PTSD recall the traumatic event, especially if it involved assault, they over-activate the right hemisphere of the brain. It is not just cerebral blood flow: recent experimental work has shown that PTSD may be associated with a functional asymmetry of the brain, which favors the right hemisphere.

There are actually a number of therapeutic techniques that involve trying to switch the way in which the hemispheres interact. EMDR (which the writer had tried) is one. It is also amongst the techniques developed by Paul Dennison to aid learning.

I also wonder whether the writer has accidentally happened upon a method for treating psychological reversal.

I do wish the writer well, and I also hope that some of my colleagues in research might be interested in exploring some of these training techniques in PTSD.

Links, Citations and References

Following my recent article about mystical experiences, I had a charming note which included this question:

"Could you kindly give a reference or link to the above quote from Ramana Maharshi?"

This was my response:

"I am traveling at the moment, so I don’t have access to my library.

Happily I remember exactly where the quote came from. It was from someone who taught me a great deal – the late Paul Brunton. I think that Paul probably did more to introduce Ramana Maharshi to the West than anyone else, and he was also a close friend of Aurobindo. He once commented that it was rather convenient that two of the greatest sages of the 20th century only lived 65 miles apart!

He also mentions Ramana’s comment in Chapter 9, paragraph 23 of Volume 16 of The Notebooks of Paul Brunton.

Here’s the exact quote:
"That these differences of view exist even among illumined mystics is a striking but rarely studied fact. Why did Ramana Maharshi poke gentle fun at Aurobindo’s doctrine of spiritual planes?"

I do not know off hand whether there are any websites that specifically discuss their – respectful – differences of opinion.

If that does not give you what you need, please do let me know: I shall be home in a couple of days and I’d be happy to do a bit more digging in my library: I have over 12,000 volumes, and there are quite a lot of lesser known titles in there. Since I raised it, I shall also have a look online when I get home.”

The reason for re-printing this correspondence is this. Regular readers will know that my blog entries are festooned with links, citations and references. That is very deliberate. This blog is a bit different from most of the other medical ones out there in that I try to ensure that you can check everything that I say.

The other day I had the privilege of speaking to the Rotary Club of New York and mentioned that I had written something about five strategies that can dramatically reduce your risk of developing Alzheimer’s disease as well as discussing some of the evidence concerning nutrition and neurogenesis: the production of new neurons. I was asked what they were, and I recommended that people asking the question should check out the article. The reason was simply this: I wanted them to see the evidence for themselves.

I think that we have all had enough of people simply expressing opinions.

Now is the time for people who are writing on line – or anywhere else for that matter – to provide data to support what they are saying.

If you need further reading material on any of the topics that I write about, just let me know: I have access to a great many sources that are not always easy to get at.

Qigong Therapy at a Distance

I just had a very nice question from someone who had seen my article in which I commented on the way in which I had seen qigong masters treat patients without touching them.

Dear Dr. Petty,
That’s really interesting, and if it’s true, it would be very important for the future of therapy. Is that actually any scientific evidence to support what you said?

Good question, and yes, there is. But not very much of it.

A recent study from South Korea examined the effects of Qi therapy, also known as external qigong. During the study they looked at the effects – if any – of touching the patient. The researchers examined the impact of treatment on anxiety, mood, several hormones and cellular immune function. Whether or not they were touched, the patients showed improvements in anxiety, alertness, depression, fatigue, tension and cortisol levels. Treatment at a distance was just as good as hands-on treatment with one interesting exception: treatment at a distance caused the white blood count to rise slightly, while the effect wasn’t seen in people who were touched.

There is also another type of research in which qigong practitioners have tried to influence either animals or cells in culture. In one recent study practitioners directed their intention toward cultured brain cells for 20 minutes from a minimum distance of 10 centimeters. The first study seemed to show an effect on the proliferation of the cultured cells, but the second did not, showing the difficulty of doing experiments like these.

More experiments like these are underway in centers throughout the world, and I shall continue to report on both the positive and negative studies.

More on Brain Laterality and Attention Deficit Disorder

I recently wrote about the connections between attention deficit disorder and disturbances of the normal lateralization of the brain.

I had a very interesting question from a correspondent:
"Is there any CHANGE in handedness related to the use of stimulant medication?

I have been taking dexadrine (RP: That’s methamphetamine) at 60 mg/day for several months now to address ADD after diagnosis as an adult. I have found that I now use my left hand for some tasks that I would have solely used my right hand previously. For example, I am painting trim with a brush at home currently and have found myself, without forethought, switching hands and cutting in against the walls and other paint colours with my left hand at a skill level that matches my right hand. Is it possible that this is the result of increased "cross-talk" between the hemispheres? My father was not classically ambidextrous but he did play hockey and golf as a "lefty" while writing using his right hand.”

This is a fascinating question. There is evidence of shifts of functional lateralization in a number of situations, including severe changes in mood.

There is also some experimental data to support what the writer’s observations, though most of it comes from research in children.

  1. A study from the Netherlands showed that in children treated with methylphenidate, their manual dexterity and handwriting improved and became more accurate.
  2. Research from Germany using high density magnetoencephalography (MEG), showed that treatment improved activity in the frontal lobes of the brain.
  3. Investigators in New Mexico found that unmedicated children with ADHD had slower reaction time in their legs, which got better, particularly in the right leg, when they were given treatment.
  4. Another study, this time from Israel, also showed that children with ADHD had a lateralized attentional deficit that got better when they were treated.
  5. Children off treatment seem to have lower activity in the right hemisphere of the brain, which normalizes with treatment.
  6. Stimulant medications do not themselves seem to have an impact on inter-hemispheric transfer. But what it may do is to improve the imbalance between the hemispheres.

So I would suspect that the writer’s brain is becoming generally more efficient.

And his letter has also suggested a small research project.

I sense a grant proposal in our near future.

Recognizing Restless Legs

I’ve recently written a couple of articles about restless legs syndrome (RLS), following which I got this question:

"Dear Dr. Petty, I’ve thought that I’ve got RLS, and so did my doctor, but I’ve just heard about something called akathisia, and another doctor has told me that I might have that instead. Is there any way to tell them apart? The doctor seemed to think that they were the same thing. Have you heard of akathisia, and are there any tips for working out what I’ve really got?"

Yes, I do indeed know what akathisia is, and this is a good question. I’ve seen  many experts who have mixed up the two conditions. Both may be present in the same person, and there may be some small degree of overlap, but an experienced neurologist should be able to tell them apart without too much trouble.

Akathisia is most commonly seen in people taking certain types of medication that act on the brain. However something indistinguishable from akathisia was described three hundred years before we had any of these medicines. So medications are most certainly not the only cause.

I’d like to direct you to a new article by our friends over at Psychiatric Resource Forum, where you will find an article that goes through the clinical features and causes of akathisia and the nine classical features that distinguish akathisia from RLS.

Let me know if that does not give you the answer that you need, and I’ll happily write a more detailed account of how to distinguish the two.

Good luck, and let me know if I can help you further.

Measuring Insulin Resistance

After doing so much research, lecturing and writing about insulin resistance, I have constant requests for more information on how to measure it in clinical practice. This is not an academic exercise: it is estimated that a person on the road to developing type 2 diabetes may have been insulin resistant for as long as twelve years before the disease is diagnosed.

In high-risk populations, there is a lot of value in regularly checking plasma glucose, but the problem is that once glucose begins to rise, it implies that the pancreas can no longer keep up with the demand for insulin and that we may be passing the point of no return.

These are the most common questions that I get::

  1. Should you be having your insulin level measured?
  2. Should you have your insulin resistance measured?
  3. What’s normal?

First, measuring insulin levels themselves is not of much value: they bounce around a good deal in the course of a day, and many things can alter your circulating insulin levels.

Second, accurate measurement of insulin resistance is an expensive and cumbersome procedure involving intravenous sampling of blood and in some cases also giving intravenous insulin.

Third, there is no such thing as “normal.” Results derived from any kind of test are a “reference range.” This means that they show how a result related to a large group of apparently healthy people. This is an important concept. I often have students say, “What’s normal?” There is no such thing. Blood tests help and guide us but can only be understood in the context of the whole person.

We never treat a laboratory value: we treat people. You may be interested to have a look at an earlier article about this important issue.

But all is not lost: we do have a blood test that can be used to guide us. We don’t have evidence to suggest that we should be using it to screen the whole population for insulin resistance. Instead it is a test to help guide us in high-risk populations. The test is called the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR).

The original paper was published by a group of experts form the university of Oxford in 1985. The drawback of the HOMA-IR is that it is a mathematical model, and it’s only as good as the accuracy of an individual laboratory’s insulin assay.

Since then, the HOMA-IR has been used in epidemiological studies such as the famous Framingham study and there has been a lot of work on trying to correlate the HOMA-IR with other measures of insulin resistance. There are now over one thousand papers that reference it, and we have had a great deal of experience in using it in our studies of insulin resistance in people with mental illness.

Apart from research, we only use the HOMA-IR as a guide in high-risk individuals. A simultaneous fasting glucose and insulin are taken.

Insulin resistance (HOMA IR) =
Fasting insulin (µU/ml) X Fasting glucose (mmol/l) divided by 22.5.

Most studies now suggest that the cut-off for insulin resistance should be 1.7; although some have been slightly more forgiving, and suggested that up to 2.5 may be acceptable. But remember that the HOMA-IR is only giving us an estimate to help with the overall evaluation of a high-risk individual, and we do not treat a laboratory value.

If the value is above 2.5 many experts would suggest intervention if there are also features of the insulin resistance syndrome. The key interventions are diet and exercise, both of which have been proven to reduce insulin resistance. A very interesting approach adopted in two European studies has been to treat high risk people with a medication called metformin, and were able to show that within a year several cardiovascular risk factors improved.

A Special Offer

Today I’m attaching a first enhanced podcast to my blog.

We’ve been experimenting for months to get the music, sound and graphics just right. I’m planning to do a great many podcasts in the months to come so that you can listen at your leisure, and I can also share some specific tips and techniques that are tricky to explain using the written word alone.

Today’s podcast is a short introduction, some advice on motivation, and an offer.

To commemorate the launch of this new project, I’m also going to extend the offer here.

The Internet is full of people telling you what they think and sometimes even what you should think and do!

That’s not my way of doing things. I am here to serve you, and telling you what to do is scarcely an act of service!

Now that you have got a flavor for my areas of expertise, I am going to ask you what you would like to hear about or learn about or maybe even be amused about!

As you will see if you look at my list of "Categories," there are a few areas in which a great many people think of me as THE expert: the Go-To Guy.

So I get a huge number of questions every day, and I think that most of them merit a detailed response.

So the offer is this: I’m going to invite you to email me a question in any of these categories. Just send me a quick note to healingmeaningpurpose[at] The shorter the better!

Naturally I cannot diagnose or treat a person online. No responsible clinician would ever do such a thing without performing a full, detailed and personal evaluation.

I’m looking for questions that will be of interest and concern to many people.

I am going to select the hundred and one questions that I can answer with something new: a new perspective, new information or new insight. Or perhaps a question that will be best answered by intuition or by an appeal to the classics or the spiritual Masters and Mistresses who have taught us over the centuries. I am then going to put these hundred and one questions and answers together into an electronic book. I can guarantee you that the book will contain an absolute treasure trove of life-changing information.

How do I know that?

Because of the quality of the questions that I’ve already received and the kindness of the responses to my answers. 

When it’s finished in late October, I’m going to offer the eBook for sale at $49.00.


Anyone who sends a question that I select and can use will receive a FREE copy of the eBook.

I’m totally serious about that, and there’s no catch: I really am going to give away almost five thousand dollar’s worth of books!

While also, I hope, offering guidance, help, support and inspiration to a great many people around the world.

Enjoy the podcast, and I look forward to hearing from you if you have a question with which you think I may be able to help!

Download podcast.August.18th.2006 1.mp3

Diet and Blood Types

One of my earlier posts entitled “What in Your Blood?” elicited a most interesting and important question from a reader:

“Does any of this have to do with the research that Dr. Peter D’Adamo has in his "Blood Type Diet" book? I have had clients tell me diseases and pains vanished when they followed his diet, while others had no effect. I would be interested in hearing your take on it all.”

This is a great question that gives me the opportunity to comment about this whole issue. I think that many of us have made similar observations to the reader who asked the question.

For people not familiar with this theory, D’Adamo’s notion is that our ancestors originally all had type O blood group, and that the appearance of agriculture was associated with the appearance of type A blood group, and then as recently as 10,000 B.C.E. – A.D. 1000, types B and AB started to evolve.

In this scheme, people with Type O blood group are the descendents of Hunters, the dominant, hunter-caveman types that require meat in their diet and should avoid wheat and beans. They are supposed to be most likely to suffer from asthma, hay fever, and other allergies. People with Type A blood are originally the Cultivators, and they should eat a vegetarian diet since they are predisposed to heart disease, cancer and diabetes; Type B blood group people were allegedly Nomads, and are dairy-eating omnivores who are susceptible to chronic fatigue and autoimmune disorders, such as systemic lupus erythematosus and multiple sclerosis. The rare individuals who have the AB blood group require a mixed diet, but should avoid chicken. They are supposed to be at risk of heart disease, cancer, and anemia, but tend to have the fewest problems with allergies. So D’Adamo decided that we should eat according to our blood types.

Like a lot of simple models, it is attractive and can be seductive. Yet the underlying concepts are deeply flawed. There are some weak associations between some blood groups and some physical ailments: to name just two, blood type A and coronary artery disease, and type O and gastric ulcers. That second one we now understand: people with blood group O are not able to mount a strong immune response to the usual causative organism: Helicobacter pylori. I did a literature review and dug up over 700 research papers on the subject of blood groups, disease and lectins (the adhesion molecules found, amongst other places, on red blood cells). There was nothing whatsoever to confirm D’Adamo’s claims. Indeed I think that some of his claims are potentially risky. Few people would agree with the idea of feeding some people high fat diets, and the theory takes no account of ethnic differences in food tolerability. For instance the high rates of insulin resistance amongst most people of Indian heritage, or the dairy intolerance common in much of the Asia-Pacific rim.

D’Adamo’s theory of blood group evolution is not correct. Far from having developed new blood groups with the arrival of agriculture, there is solid molecular evidence that the different blood groups were already present at least 5 million years ago. Gorillas and chimpanzees possess similar blood groups. One of the scientists quoted on the D’Adamo website is Winifred Watkins, who was one of the team that first described the structure of the molecules determining blood group types. She was only 29 at the time, and later she became a Fellow of the Royal Society and a mentor of mine. She passed away about three years ago. She was the person who first told me about the evolution of blood groups, and there’s now a fair bit written about it. The last great African Diaspora occurred long before the development of agriculture, and the migrants took their diverse blood groups with them. That is one of the ways in which migration patterns have been tracked. So there is no link between blood groups and “professions.” It is still possible that there is some other arcane link between optimum nutrition and blood groups, but it is now ten years since D’Adamo’s book came out, and we have to ask why there is no published research to support the claims. His website contains a lot of references to research papers on blood groups. Many are quite old, and there is no critical evaluation of the papers.

Yes, some people will benefit from any kind of diet or intervention, which is why some of your clients have benefited, but the predictive value of the four major blood group types is clearly very low.

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