Reduced neural circuitry recruitment may facilitate food avoidance in anorexia nervosa
Recruitment of neural circuitry, which translates taste stimulation to motivated eating behaviour when a person is hungry, appears to facilitate food avoidance and extended episodes of extremely restricted food intake when reduced in individuals with anorexia nervosa, according to a study.
Two scanning sessions were conducted, scheduled 24 hours apart: one after a 16-hour fast and another following a standardized meal. Twenty-six women in remission from anorexia nervosa (to avoid the confounding effects of malnutrition) and 22 matched controls received tastes of sucrose solution or ionic water while functional magnetic resonance imaging data were obtained.
Comparisons were made between the two groups across conditions on blood-oxygen-level-dependent (BOLD) signal and task-based functional connectivity within a network of interest responsible for food valuation and transforming taste signals into motivation to eat.
Women in both groups showed comparable BOLD responses to sucrose and water tastants. In group-by-condition interaction in the ventral caudal putamen, hunger appeared to have opposite effects on tastant response in controls and in those with remitted anorexia nervosa, showing an increase and a decrease in BOLD responses when hungry, respectively.
The effect of hunger on insula-to-ventral caudal putamen functional connectivity was also opposite in the control and remitted anorexia nervosa groups.
In exploratory analyses, reduced caudate response to tastants when hungry correlated with higher scores on harm avoidance among women with remitted anorexia nervosa.
“Anorexia nervosa has the highest mortality rate of any psychiatric condition, yet the pathophysiology of this disorder and its primary symptom, extreme dietary restriction, remains poorly understood,” the authors said. “In states of hunger relative to satiety, the rewarding value of food stimuli normally increases to promote eating, yet individuals with anorexia nervosa avoid food despite emaciation.”