December 1st, 2015

Study boosts belief that anorexia is brain-based illness

A new study may help explain why anorexia nervosa is so hard to treat: those who struggle with it activate a different part of the brain when making food choices than those who don’t.

The study, “Neural mechanisms supporting maladaptive food choices in anorexia nervosa,” which was published in Nature Neuroscience, demonstrated that when making decisions on what to eat – women with anorexia nervosa showed increased activity in the dorsal striatum area of the brain compared to women without anorexia.

The dorsal striatum has a critical role in the establishment and expression of action control and learned automatic behaviors. The study authors say their results are consistent with the possibility that the persistent, maladaptive food choice in anorexia nervosa is subserved by fronto-striatal networks that are crucial for the development of habitual behavior.

“What is striking in this study is that it is the first demonstration of differences in neuro-activity related to actual choice,” said study co-author Joanna Steinglass, M.D., associate professor of clinical psychiatry, Columbia Center for Eating Disorders, New York State Psychiatric Institute, which conducted the study.

Scott E. Ewing, M.D., medical director, Cambridge Eating Disorder Center, said the findings are in agreement with what his center sees clinically with individuals who have anorexia nervosa. “They often have very rigid styles of thinking and as a result it is very difficult to try to help them break ingrained habits or practices.”

The study demonstrates that active selection of food choice in anorexic individuals activates certain specific neural circuitry. “There’s no question this adds to the already substantial evidence that anorexia nervosa is a brain-based illness,” Ewing said, adding that such data could help the public better understand that anorexia nervosa is not an illness of choice, but rather one that arises from abnormalities in the way information is processed in the brain.

The study recruited a group of women recently hospitalized for anorexia and a similar number of healthy controls. Participants rated a series of foods on healthfulness and tastiness. Then, the researchers took one of the items that were rated “neutral” on both qualities, and gave participants a choice between the neutral item and each of the other foods (some low-fat, some high-fat), with one of the foods chosen in the task randomly selected for participants to consume after scanning.

During this decision-making phase, individuals with anorexia nervosa were significantly less likely than healthy controls to choose high-fat foods over the reference item. With the use of functional magnetic resonance imaging, it was observed that individuals with anorexia engaged the dorsal striatum more than the healthy controls when making choices about what to eat.

Even the next day, for those with anorexia nervosa, activity in fronto-striatal circuits was correlated with their actual food consumption – the choices they made during the previous day’s task were significantly associated with how much they ate the next day.

James M. Greenblatt, M.D., chief medical officer and vice president of medical services at Walden Behavioral Care, said the study reinforces a shift in the field in the past 10-15 years, which recognizes the genetics and neurobiology of anorexia nervosa, demonstrating that it is not a matter of “will” or a struggle for control.

“We moved beyond that years ago, but there’s been so little research that this does provide a framework,” Greenblatt said of the study, which he said helps put anorexia more in a biological-based framework, demonstrating the need for more than just behavioral interventions.

“Hopefully, this sensitizes clinicians to the fact that patients who struggle with anorexia should be treated more like the way we treat someone with OCD. We appreciate this disorder is more brain-based,” he said.

“It’s refreshing for me to be able to see some neuroscience research being integrated into the eating disorder field because for too long I believe they’ve been stuck in pure psychological models that have not been effective,” Greenblatt added. “We now have some hard data … the functioning of an anorexic brain around food looks different than someone without anorexia.”

Steinglass said clinicians may need to start thinking differently about the behavior of those with anorexia nervosa. “Rather than focusing on the outcome of the behavior, maybe we need to be focusing on the onset of the behavior,” she said. She said clinicians can work with patients to help them become more aware of the cues and develop new sets of behavior to push them in an alternative direction.

Added Ewing, “The study would suggest therapeutic methods directed toward entrenched routines would possibly have applicability to anorexia nervosa. Most individuals who treat large numbers of anorexic patients already incorporate behavioral methods and psychotherapies that are effective in trying to change entrenched patterns of behavior.”

Ewing said such findings could lead to more effective pharmacologic treatments, as well.

By Pamela Berard

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