Specific regions of brain implicated in anorexia nervosa, U of Pitt. study

[HuckleB]

Specific regions of brain implicated in anorexia nervosa, Univ. of Pittsburgh study

http://www.medicalnewstoday.com/medicalnews.php?newsid=27094

"Just why those with anorexia nervosa are driven to be excessively thin and seem unaware of the seriousness of their condition could be due to over-activity of a chemical system found in a region deep inside the brain, a University of Pittsburgh study suggests. Reporting in the journal Biological Psychiatry, researchers found an over-activity of dopamine receptors in the brain's basal ganglia, an area known to play a role in how people learn from experience and make choices.

Results of the study, led by Walter Kaye, M.D., of the University of Pittsburgh School of Medicine, and Guido Frank, M.D., now of the University of California at San Diego, contribute to the understanding of what may cause anorexia. The disorder affects about 1 percent of American women, some of whom die from complications of the disease. The research may point to a molecular target for development of more effective treatments than those currently available.

The study is the first to use positron emission tomography (PET) imaging to assess the activity of brain dopamine receptors, a neurotransmitter system that is best known for its role in controlling movement. These receptors also are associated with weight and feeding behaviors and responses to reinforcement and reward. Researchers used a harmless molecule designed to bind to the dopamine D2 and D3 receptors that lie on the membrane surface of neurons. Ten women who had recovered from anorexia nervosa for more than a year were studied, as were 12 normal female subjects. Because malnourishment affects brain chemistry, the researchers did not include acutely ill women in their study.

Since other studies have found reduced binding of these dopamine receptors in both people who are obese and those who have substance use problems, Drs. Kaye and Frank hypothesized that they would find just the opposite in women with anorexia.

..."

[seleff]

1. This report has scientific flaws.

Without seeing the j Biol Psych article, it is hard to evaluate this article. Increased binding of a PET ligand should indicate increased density of receptors. However, increased receptor levels for a neurotransmitter is often a result of an undreactive system, not overactive. If transmitter activity is decreased, post synaptic cells generally respond by increasing receptor numbers in order to increase sensitivity where transmission is underactive. If the authors used an agonist as ligand, the results would also be confusing because agonists bind with increased affinity if coupling proteins are up-regulated. Hopefully these results were also compared to a cohort of depressed but non-anorexic patients, because a decrease in DA transmission in this part of the brain may be indicative af anhedonia (inability to be happy, receive positive reward), a trait common in depressed individuals.

[HuckleB]

2. Hmm.

This was posted last July, and you only responded now. Interesting.

Are you are a researcher? If so, why don't you have access to the journal? UPItt's research in this area is quite well known, quite well critiqued by peers...