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Study shows differing neural mechanisms between individuals with, without anorexia

Individuals with anorexia nervosa who made maladaptive food choices resulting in starvation engaged the dorsal striatum more than healthy individuals when making choices about what to eat, according to study findings in Nature Neuroscience.

“In anorexia nervosa, repeated, maladaptive food choices result in starvation accompanied by substantial morbidity and mortality… Clinically, this pattern of behavior has often been understood as the manifestation of a remarkable, but misguided, ability to override primary drives; that is, as an expression of single-minded, goal-directed self-control,” Karin Foerde, PhD, of New York University, and colleagues wrote. “However, when goals change, as when individuals elect to enter treatment to gain weight, their ability to alter their pattern of food choice is exceedingly poor and, given the opportunity, they continue to choose low-fat and low-calorie foods. Thus, anorexia nervosa provides a unique and compelling model of persistent maladaptive behavior.”

To assess neurobiological mechanisms associated with persistent maladaptive food choices in anorexia nervosa, researchers used functional MRI to compare blood oxygen level-dependent activity among women recently hospitalized for anorexia nervosa (n = 21) and healthy female controls (n = 21). Study participants completed a three-part food choice task that detected the salient behavior of restrictive caloric intake.

In part one of the food choice task, study participants rate the healthiness and tastiness of 76 food items. After making ratings, a reference item was selected for each participant based on items they had rated as neutral in taste and health. In part three of the task, women made a number of choices between the reference item and the other foods.

Individuals with anorexia nervosa were significantly less likely to choose high-fat foods over the reference item compared with controls, though the tendency to choose low-fat foods over the reference item did not differ between groups.

Researchers found that food choices among individuals with anorexia nervosa during the food choice task related to their choices during a buffet lunch meal the following day. Specifically, caloric intake during lunch the following day was significantly correlated with the frequency with which individuals with anorexia nervosa chose high-fat foods during the task (P = .01).

Food choices among individuals with anorexia nervosa were more significantly associated with neural activity in the dorsal striatum compared with controls (P < .05). However, there were no group differences in blood oxygen level-dependent activity in the ventral striatum, according to researchers.

“Given that restrictive food intake is a persistent and clinically challenging problem in anorexia nervosa, these findings provide new insight into the neural mechanisms underlying this enigmatic illness. Furthermore, as human and animal data have documented that the dorsal striatum has a critical role in the establishment and expression of action control and learned automatic behaviors, our 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,” Foerde and colleagues wrote. “More broadly, our findings add to the growing evidence that disturbances in fronto-striatal circuits have a central role in persistent maladaptive human behaviors.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.