Clinicians' Corner / Research Updates

Eating Disorders Research Matters, Part 3

I recently had the privilege to sit down with B. Timothy Walsh, MD, the founding director of the Columbia Center for Eating Disorders (then called the Eating Disorders Research Unit) at the New York State Psychiatric Institute. A research psychiatrist who’s currently in charge of the Division of Clinical Therapeutics in Columbia University’s Department of Psychiatry, Dr. Walsh has been studying eating disorders and related conditions for over three decades.

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B. Timothy Walsh, MD. Founding Director of the Columbia Center for Eating Disorders.

His perspective on the field of feeding and eating disorders (past, present, and future) is invaluable as we – clinicians, researchers, patients, and families – seek to raise awareness about these conditions, and strive for answers to questions that remain unanswered.

Part 1 of the interview broadly addressed the topics of eating disorders research and treatment.

Part 2 provided an overview, in historical context, of research on anorexia nervosa, including a description of our latest studies.

Part 3 covers research on bulimia nervosa, binge eating disorder, and obesity. In this segment, Dr. Walsh weighs in on DSM-5 (the most recent version of the diagnostic manual for mental disorders used by clinicians nationally) and makes some predictions for DSM-6.


ON BULIMIA NERVOSA

Preliminary descriptions of the illness that came to be known as bulimia nervosa coincided with Dr. Walsh’s arrival at Columbia in 1979. In the early phases of a diagnosis being established, descriptive research detailing typical characteristics of the condition is essential. Because eating disorders involve a disturbance in behavior, this is an especially important aspect of the problem to understand.

According to Dr. Walsh, initially there was a brain-based theory of bulimia nervosa suggesting that people with the disorder experienced carbohydrate cravings, and binged on carbohydrates in particular, because eating these types of food would affect a brain chemical called serotonin in way that would make them feel better. The problem, however, was “nobody had actually studied what these folks would eat during a binge; it was just assumed to be carbohydrates.”

Getting to the bottom of binge eating behavior was the impetus for the beginning of eating laboratory studies. This research method has since become the gold-standard objective measure of eating behavior.

What has been learned by studying eating behavior in people with bulimia? Dr. Walsh explains:

This turns out to be a very valuable type of research. Our eating laboratory study proved that they [adults with bulimia nervosa] don’t binge purely on carbohydrates. They binge on dessert food—sweets, but sweet fat foods, which is what all humans like to eat. So, it isn’t what they eat that’s abnormal, it’s the amount that’s unusual. And, we’ve later learned, the psychological distress they have during the experience of eating.

 Results from this and other related studies helped to slow researchers down from pursuing the carbohydrate and serotonin mechanism, and underscored for Dr. Walsh just how critical it is to “know what the behavior is before looking for a mechanism to explain it.”

The observation that individuals who struggled with binge eating and purging behaviors tended to also experience many anxiety and depression symptoms led clinical researchers to study treatments that were useful for those problems for people with bulimia nervosa.

“We were one of two groups – the McLean Hospital/Harvard group being the other – to begin to examine whether antidepressants might be useful for adults with bulimia nervosa,” explains Dr. Walsh. “Generally, when researchers began to apply treatments for anxiety and depression, it directly led to the knowledge we now have that cognitive behavioral therapy is a good treatment, interpersonal psychotherapy is not a bad treatment, and antidepressants can be very helpful medications.”


ON BINGE EATING DISORDER AND OBESITY

With the publication of DSM-5 in May 2013, binge eating disorder was officially recognized as an eating disorder. Still, there is much to learn about this condition.

The definition of a binge has two parts – that there is a sense of loss of control while eating and that a clearly large amount of food is eaten. But Dr. Walsh wonders, “In the real world, how much of the problem is the amount eaten, and how much of it is this sense of loss of control over eating? Is this a problem people have with their actual eating behavior or how they feel about the eating behavior?”

The answer to this question becomes critical for better defining and treating the disorder. Binge eating disorder treatment studies — studies of specific psychotherapies (like cognitive behavioral therapy and interpersonal psychotherapy) and/or medications — tend to show that binge eating can be eliminated or greatly reduced, but that weight does not significantly change. The treatments in which weight changes are those that are focused on weight, not binge eating behavior.

Dr. Walsh thinks there are two possible explanations, and offers his hunch:

One is that people redistribute their eating, their calories. The other is that they redefine the behavior. They learn to think about it differently. And those are profoundly different. One’s a change in behavior disturbance and one’s not. We did some behavioral research in overweight binge eaters and found that, even when these people are not binge eating, they eat more than similarly overweight people. And when they are binge eating, they eat more than similarly obese people. So if I had to bet, I’d guess that binge eating disorder is more psychologically determined than behaviorally determined and that treatments should target the psychological aspects of the symptoms.

Eating behavior has also been especially important to study in obesity, and in kids who are and are not at risk to become overweight.

What are other important research questions about obesity?

Dr. Walsh is especially interested in learning about the group of people who were once obese who have successfully lost weight and kept it off. He wonders, “Are they successful because they engage in the same behaviors as people with anorexia nervosa? If so, is it the same brain mechanism? Have they successfully developed a new habit?  Then, they have likely rearranged the wiring in their brains to make changes to the default choice of what to eat, and doing anything else feels really strange, like it would to someone with anorexia nervosa.” This hypothesis is exciting because, if proven, it would indicate that the same brain mechanism underlies a serious disorder and a serious success.


ON DSM-5…AND DSM-6

DSM-5 further clarifies existing eating disorder diagnoses, and includes distinct feeding problems that previously lacked adequate recognition. One example of this is avoidant-restrictive food intake disorder, or ARFID, a diagnosis meant to capture individuals who go far beyond ‘picky eating.’ A child or adult with ARFID is seemingly disinterested in eating or food, worried about negative consequences of eating unrelated to body shape or weight, or avoidant of food because of how it looks, tastes, or feels. The restrictions placed on eating get in the way of meeting nutritional needs.

While the definition is clear, Dr. Walsh cautions: “It’s way early. What’s important now is descriptive research. ARFID was consciously constructed as a bigger tent to capture people who are having significant clinical problems, who came in for help, but who didn’t have a label. It is certainly a heterogeneous group, so we’re in the very early stage of asking, who are these people? And are there subgroups?”

Dr. Walsh hopes that by the time DSM-6 is in the works, the field will know more about ARFID and more about the conditions currently listed as ‘other’ specified feeding and eating disorders, such as purging disorder and atypical anorexia nervosa.

To learn more about existing diagnoses and their treatment, and to properly classify and develop treatments for more newly established diagnostic categories, feeding and eating disorder research – simply put – matters.


For more information on current eating disorders research at our program, please read about our latest studies, call us at 646-774-8066, or email us at edru@nyspi.columbia.edu.

Photo Credit (front): Creative Commons by mikemccaffrey.

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