NYU Child Study Center Grand Rounds Summary, June 23, 2000

Featured speaker

B. Timothy Walsh, M.D.
William Joy Ruane Professor of Pediatric Psychopharmacology
Department of Psychiatry
College of Physicians and Surgeons, Columbia University

What was the main issue or question being addressed?

Dr. Walsh reviewed the psychobiology of the eating disorder bulimia and the current research findings in the field. To date, approximately 95% of the research done on Bulimia have been with adults despite the fact that the disease usually develops in adolescence. Therefore, much of the thinking and treatment of teenagers is based on extrapolation of the data.

What are the main findings or conclusions?

Main findings with respect to physiology: One focus of the research has been to more thoroughly define a "binge." In one lab study done by Dr. Walsh in collaboration with St. Lukes Roosevelt Hospital in New York City, 25 subjects with Bulimia and 18 control subjects were asked to binge. The subjects with Bulimia consumed 3500 calories during the meal compared to 1500 for the controls. While eating a regular meal, subjects consumed approximately 500 calories compared to 900 consumed by controls. Interestingly, for both groups, 45% of the calories came from carbohydrates. Thus, the binge eaters may swing between eating both too much and too little, indicative of a more general regulation problem regarding the amount rather than the type of food eaten.

Other findings related to the physiological influence of regulation were reported in the New England Journal of Medicine. It was found that, individuals with Bulimia felt less full after a meal than controls and this was consistent with their having less of an enzyme (CCK) released by the intestine after eating. Dr. Walsh participated in a study that found those with Bulimia also had delayed gastric emptying. These results are suggestive of a physiological disturbance or abnormality in the upper gastrointestinal tract. Specifically, those with Bulimia have increased gastric capacity, decreased release of CCK, causing altered sense of satiety. Those with Bulimia, may diet because they can not trust their own physical self regulators, which sets a vicious cycle in motion leading to related emotional changes that perpetuate and result in abnormal eating behaviors. Yet to be determined, is whether the physiological changes are the result or cause of Bulimia.

Main findings with respect to treatment: Treatment studies have looked at the use of different verbal therapies and medications. A great deal of research has been conducted by a British group at Oxford lead by Fairburn. In one of their 1992 studies comparing Interpersonal Therapy (IPT), Cognitive Behavior Therapy (CBT), and Behavior Therapy (BT), they found that CBT was best at the end of treatment (cure rate of 50%) with BT and IPT both being effective. But at one year, the gains fell off for BT and were best for CBT and IPT. Interestingly, IPT didn't even address the eating disorder.

In a comparable study led by Walsh, they concluded that CBT was the treatment of choice. In evaluating the utility of psychopharmacological interventions, the majority of the work has been done using Selective Serotonin Reuptake Inhibitors (SSRIs) antidepressants. In assessing the use of medication with and without treatment, the results suggest that antidepressants are more effective than placebos. Which antidepressant is most successful has not been established. Luvox however has not been shown effective. Still to be determined is how long therapy should last, what type of follow up therapy is best, and given only a 25-50% success rate in some studies, how to tailor specific therapies to specific individuals to increase the rate of cure.

Are there any practical implications?

Currently CBT is the treatment of choice. Antidepressant medication may provide added benefit when used in conjunction with CBT or alone, for those who have not responded to other therapies.