woensdag 14 oktober 2015
Anorexia a habit?
This article (Anorexia May Be Habit, Not Willpower, Study Finds quotes a brain study that sees with anorexia activity in the brain regions that are related to habits. Neither psychiatric medications nor talk therapies that are used successfully for other eating disorders are much help in most cases. And research suggests that 50 percent or more of hospitalized anorexic patients who are discharged at a normal weight will relapse within a year. The researchers used a brain scanning technique to look at brain activity in 21 women with anorexia and 21 healthy women while they made decisions about what foods to eat. The anorexic women were more likely than the healthy women to choose low-fat, low-calorie foods, and they were less apt to rate high-fat, high-calorie foods as “tasty,” the study found. As expected, both the anorexic and the healthy women showed activation in an area known as the ventral striatum, part of the brain’s reward center. But the anorexic women showed more activity in the dorsal striatum, an area involved with habitual behavior, suggesting that rather than weighing the pros and cons of the foods in question, they were acting automatically based on past learning.  B. Timothy Walsh, the senior author of the report, said the study grew out of a theoretical paper he published in 2013. In that paper, he proposed that for women who are vulnerable to anorexia, weight loss initially serves as a reward, eliciting compliments, relieving anxiety and increasing self-esteem. Over time, though, the pairing of dieting with a reward — weight loss — may result in the act of dieting itself becoming rewarding. This theory, said Dr. Walsh, a professor of psychiatry at the psychiatric institute at Columbia, might shed light on why treatment is more successful the earlier it is offered and less successful the longer the illness has been established. He predicted in the paper that as an anorexic patient’s dieting became more habitual, the dorsal striatum would become more involved.  But he noted that activation in the dorsal striatum had been associated with other aspects of anorexia, like anxiety.