Although most people find pleasure in eating and even have a difficult time refraining from foods they love, individuals suffering from anorexia nervosa often say that eating makes them feel more anxious. Instead, refusing to eat — something called food refusal — is what brings more pleasure.
New research, published online in the journal International Journal of Eating Disorders, helps explain why these symptoms occur in anorexia.
For the study, scientists administered a one-time dose of the drug amphetamine which releases dopamine in the brain; positron emission tomography (PET) was then used to visualize the subsequent dopamine activity.
In healthy subjects without an eating disorder, the amphetamine-induced release of dopamine was associated with feelings of extreme pleasure in the brain’s “reward center.” However, in people with anorexia, amphetamine made them feel anxious and activated the part of the brain that worries about consequences.
“This is the first study to demonstrate a biological reason why individuals with anorexia nervosa have a paradoxical response to food,” said Walter Kaye, M.D., professor of psychiatry and director of the Eating Disorder Treatment and Research Program at the University of California-San Diego School of Medicine.
“It’s possible that when people with anorexia nervosa eat, the related release of the neurotransmitter dopamine makes them anxious, rather than experiencing a normal feeling of reward. It is understandable why it is so difficult to get people with anorexia to eat and gain weight, because food generates intensely uncomfortable feelings of anxiety.”
Significantly, the study included individuals who had recovered from anorexia for at least a year, suggesting that the feeling provoked was possibly due to pre-existing traits, rather than a response to being extremely underweight.
Currently, there are few treatments proven to reduce core symptoms in anorexia, including eating-induced anxiety. Finding ways to help anorexic individuals eat and gain weight is necessary for treatment, even when food is still accompanied by severe anxiety.
The study was supported in part by the National Institute of Mental Health and the Prince Foundation.
Source: University of California