Restricting types of Eating Disorders and Brain Chemistry

The most recent evidence of the brain chemistry and mechanisms playing a role in the negative experiences associated with eating among those suffering with the restricting forms of eating disorders has explored the role of the neurotransmitter dopamine.

There are two divergent groups of brain imaging folks who believe dopamine [the "feel good" neurotransmitter] plays a role in disrupting the experience of hunger and appetite with those who restrict. Basically there are two theories on the table today.

The first suggests over eating types of eating disorders involve dopamine serving as the “reward” and "feel good" chemical released in the brain when overeating. However, with the restricting forms of eating disorders such as anorexia, the experience of increased dopamine concentrations when eating is unpleasant. Hence, the feelings associated with eating are negative for someone with anorexia and rewarding for someone with compulsive overeating or bulimia.

Another group of scientists are looking into the effects of fasting or restricting on dopamine levels for anorexics - the idea being a similar surge of “feel good” dopamine ensues - but this time stimulated by restricting to the point of starving. In other words, there may be a phenomenon for some people to “feel rewarded” by severely restricting their calorie intake. Accordingly, the more one restricts, at least in the early stages of anorexia, the more dopamine is released, the more rewarded they feel, and the more reinforced restricting behavior becomes. No one knows why some are prone to this end of the eating disorder spectrum as opposed to the other. In sum, this hypothesis suggests that dopamine “rushes” effect anorexics and over-eaters alike but for one group starving releases the chemical and for the other binge eating does the trick.

Here is an excerpt from Walter H. Kaye, M.D., one of the researchers at the University of California, San Diego who is looking into the above theories. His comments also touch upon a possible explanation for the body image distortions inherent with anorexia.

“The reason (anorexics) can go on a diet and lose all the weight is that their brain is not responding in a way that is driving eating.” Whether it’s not responding to the sensory aspect, it’s not the right signal about food, it’s not rewarding, we don’t really understand, but there’s something different about these homeostatic mechanisms.”

As someone who views eating disorders as part of the addictive disease continuum, I can't help but wonder if this phenomenon also exists within the chemically dependent population. Could it be possible some addicts and alcoholics experience some mood altering substances as pleasant while others experience the same substance as unpleasant. Perhaps this phenomenon of differences in the regulation of neurotransmitters among addicts will help us understand why some alcoholics become "cross addicted" while others remain alcohol dependent only.

For additional information or any questions regarding the above, email mlerner@MilestonesProgram.org or visit us at http:www.MilestonesProgram.Org