Archive for February, 2007

Feb 09 2007

Placebo Effect Not So Harmless

In response to my chiropractic entry there was a response essentially commenting that if it provides a placebo effect and people feel better, what’s the big deal. My prior entry on the placebo effect is a good place to start, but I will add a few more observations.

Although a placebo effect is of limited use, and not sufficient to justify anti-scientific treatments, let alone deception and fraud, it can also have negative consequences, and should not be viewed as benign. The primary malignant effect is that a placebo effect can seem very compelling evidence that a treatment works – meaning that it has a physiological effect. This can lead to the false conclusion that the theory behind a modality is valid, and therefore all of the claims for that modality are valid, or at least should be taken seriously.
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Feb 08 2007

Debate with a Chiropractor

Below is a response by a chiropractor to some statements I made in response to their entry on another forum. I include here their statements (in italics) and then my rebuttal. It is, in my experience, fairly representative of the kinds of arguments made by the proponents of unscientific medicine.

If MDs knew much about nutrition, then why would they prescribe drugs for every little symptom? If they knew much about nutrition, then they’d be prescribing diets rich in fruits, vegetables, EFAs, etc. instead of drugs.

This question, like most of the questions here, is loaded with false assumptions. The first question is also a false dichotomy – as if one can either offer nutritional advice or prescribe drugs. How about doing either or both when dictated by the evidence. It also assumes that doctors do not recommend dietary changes. This is patently false.
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Feb 07 2007

Hear This.

Published by under Neuroscience

A member of the SGU forums who goes by the name of Queequeg asked me the following question:

“My question is: is it true that what you hear with only one ear is transmitted to only one hemisphere of the brain? If true what effects on perception and cognition are there compared to when you hear things with both ears/hemispheres? Does the communication allowed across the hemispheres by the corpus callosum completely offset the effects of the information initially being received only by one ear/hemisphere?”

Hearing, actually, is the most bilateral of the special senses. Each ear registers sound in the inner ear. The eardrum translates air vibrations into movement, vibrating the basilar membrane of the cochlea, which in turn triggers so-called hair cells by causing the hair-like appendages of the cell to bend from shearing forces. The bending creates an electrical potential which conducts through the auditory nerve (the VIIIth cranial nerve) to the brainstem. This is the mechanism by which the vibrations of sound are translated into neuro-electrical signals.
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Feb 06 2007

Take Two Placebos and Call Me in the Morning

I often get questions about the placebo effect – what exactly is it, how can we exploit it, and what does it all mean. In my experience the placebo effect, briefly defined as a measurable response to an inert treatment, is almost completely misunderstood by the public – a fact that is exploited by purveyors of dubious treatments.

In order to demystify the placebo effect, I will try to first describe exactly what it is. The operational definition of a placebo effect is any health effect measured after an intervention that is something other than a physiological response to a biologically active treatment. In practical terms this is measured by comparing two groups in a clinical study, one group receives only a placebo (an inactive treatment) and the other received an active treatment (such as a pharmacologically active substance – a drug), and the outcome of the two groups is compared. If the placebo group has a 30% response (in whatever is being measured) and the treatment group has a 60% response, then it is concluded that the placebo was responsible for the 30% response and the active treatment for an additional 30% (it is assumed that the active treatment group also gets the placebo effect plus the treatment effect).
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Feb 05 2007

Iran’s AIDS “Cure”

Science requires transparency. That is why it can only truly thrive in open societies. Societies that are repressive, fascist, or totalitarian cannot help but subvert the scientific process and inhibit the free expression and exchange of ideas that drives scientific progress. There are many examples of this throughout history, my favorite always being Lysenkoism in the former Soviet Union. Iran has now given us a fresh example.

Iran’s Health Minister Kamran Baqeri Lankarani announced that Iranian scientists have developed an herbal cure (called IMOD) for HIV/AIDS. The story has all the earmarks of propaganda. First, the claim is too good to be true. They have discovered a treatment that is more effective than any treatment Western scientists have come up with, in fact they are claiming it is not just a treatment but strongly implying it is a cure. And the treatment has no discernable side effects. Second, the treatment is patriotic, for it is comprised completely of “Iranian native plants.”

The “breakthrough” was revealed with much ceremony and celebration, as part of a larger showcase of Iranian achievements. Iran’s president, Ahmadinejad, declared, “The world should know today that the capable Iranian nation, relying on its own youths and scientists, has now conquered the peaks of knowledge and science.”
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Feb 02 2007

Brain Size and Intelligence

Published by under Neuroscience

One aspect of the Hobbit brain debate I did not discuss, but will now in response to Nathan’s question from yesterday’s post, is the relationship between brain size and intelligence. There are actually some complexities to this question, and I’ll try to break it down.

How do you measure “size?”
The two basic ways to measure brain size is volume and weight. Weight is a better measure than volume, because it better accounts for the density of neurons, but there is a fairly linear relationship between volume and weight, at least within a class of animals. (It is always more meaningful to compare brain size with other closely related animals) For fossil species we cannot directly measure weight, but we can measure volume, which is the reason brain “size” for fossil species is always given in volume (cubic centimeters or ml). For living species it is common to designate brain weight.
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Feb 01 2007

The Return of the Hobbit

I reported earlier on the fascinating controversy over the status of Homo floresiensis – dubbed by the media as the Hobbit. Paleontologists are falling into two camps: the first maintains that the fossil (the specimen, which consists of a fairly intact skull about 18,000 years old, was discovered in 2003 on the island of Flores in Indonesia, and is designated Liang Bua 1 or LB1 after the site of its discovery) represents a new hominin species. The second maintains that LB1 represents a pygmy Homo sapiens (fully modern human) who also suffered from a developmental disorder called microcephaly (literally – small head).

The controversy remains without definitive resolution. I had commented that I really enjoy a good scientific controversy – it really showcases the scientific process at its best, but also reveals the messy human side of science. Good stuff. And the Hobbit story is shaping up to be a real epic battle.

In July of 2006 proponents of the microcephaly hypothesis published a fairly devastating paper outlining all the reasons to infer that LB1 is a deformed pygmy human. Some of the major points include the significant facial asymmetry and dental anomalies of LB1 – signs of a developmental disorder. Also, they note that while the average cranial capacity of the modern day Homo sapiens living on Flores is 1,270ml, LB1 has a cranial capacity of about 470ml. This is very small, even when accounting for the overall small stature of LB1. The authors argue that this small brain size is more in line with microcephaly than a hominin species closely related to humans.
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