Food tastes more bland and boring to anorexics than it does to people without eating disorders, finds a new study.
Furthermore, the inability to enjoy food might last even after people recover from the disease.
Outwardly, anorexia nervosa manifests as a relentless pursuit of thinness and emaciation to a weight that's at least 15 percent below normal. In extreme cases, it can lead to death. But whether the disorder is also linked with inner changes, such as alterations to portions of the brain that regulate appetite, has been a mystery.
Now, brain-scanning research, recently published online in advance of publication in the journal Neuropsychopharmacology, reveals that compared with individuals without an eating disorder, women with anorexia have distinct differences in the insula, a brain region important for recognizing taste.
Angela Wagner of the University of Pittsburgh School of Medicine and Walter Kaye, also of Pitt, and the University of California, San Diego School of Medicine, scanned the brains of 16 women who had recovered from anorexia nervosa and of 16 women without an eating disorder.
They measured brain activity in response to sucrose (considered a "pleasant" taste) and distilled water (considered "neutral").
In response to both water and sugars, women who had recovered from anorexia showed significantly less activity in the insula and related brain regions compared with the control group of women. These brain regions recognize taste and judge how rewarding that taste is to the person.
Kaye says the results suggest individuals with anorexia might have trouble recognizing tastes or responding to the pleasure associated with food.
In addition, the insula contributes to a type of emotional regulation, referred to as interoception. This raises the possibility that anorexics might find food aversive rather than rewarding, the researchers suggest.
“We know that the insula and the connected regions are thought to play an important role in interoceptive information, which determines how the individual senses the physiological condition of the entire body,” Kaye said. “Interoception has long been thought to be critical for self-awareness because it provides the link between thinking and mood, and the current body state.”
The results could shed light on why anorexics steer clear of “pleasurable” foods, and why they don't eat even when hungry, leading to the life-threatening plunge in weight. Other symptoms of anorexia nervosa, such as distorted body image and lack of desire to get better, could also be associated with these brain regions, they say.
The research was funded by the National Institute of Mental Health and the Price Foundation.