Women remitted from anorexia nervosa maintained reduced neural response to the effects of hunger, according to neural imaging data published in the American Journal of Psychiatry.
Walter Kaye, MD, of the department of psychiatry at the University of California, San Diego (UCSD), and colleagues conducted a functional magnetic resonance imaging (fMRI) study of women with and without a history of anorexia nervosa. For 72 hours, participants were housed at UCSD and provided food. Women with remitted anorexia nervosa (n=26) were age- and weight-matched with healthy controls (n=22).
On day 1, participants completed baseline assessments and consumed standardized meals. On days 2 and 3, participants performed a taste task while undergoing fMRI scans. There were 2 fMRI conditions: “hungry”, where participants fasted for16 hours prior; and “fed”, where participants consumed standardized meals over the 16 hour period. During the taste task, women received 1.0 cc of 10% sucrose or ionic water for 80 separate replications. Participants reported hunger, thirst, and tastant pleasantness at scanning assessments.
Women with remitted anorexia reported higher levels of anxiety and harm avoidance. There was a significant group-by-condition effect detected in 2 clusters within the left ventral caudal putamen (voxel-wise P <.001). Specifically, in the control group, these clusters were more responsive to tastants when hungry compared with having been fed. By contrast, women in the remitted anorexia group were significantly less responsive to tastants in the hungry vs fed condition.
In task-based functional connectivity analyses, the researchers identified the right ventral caudal putamen and dorsal mid-insula as corresponding to peak coordinates based on the main effect of condition. Metabolic state modulated group differences. Post hoc analyses suggested that the control group displayed greater insula-to-ventral caudal putamen functional connectivity when hungry vs fed. However, in the remitted anorexia nervosa group, responses were greater when fed. In exploratory analyses, lower caudate response to tastants when hungry appeared to predict higher harm avoidance scores among women with a history of anorexia nervosa (P <.001).
Overall, reduced neural response to hunger and taste stimulation may underlie prolonged food avoidance and limited food intake in patients with anorexia nervosa. The investigators noted that the small study cohort may limit generalizability, and that the effects of specific foods were not assessed.
The underlying neural mechanisms of anorexia nervosa may be rooted in the “reduced recruitment of the neural circuitry implicated in translating reward signals to motivated behaviors when hungry,” which may in turn disrupt food approach and eating initiation. The investigators suggested that “pharmacological and psychotherapeutic strategies that directly target these processes may be beneficial.”
Kaye WH, Wierenga CE, Bischoff-Grethe A, et al. Neural insensitivity to the effects of hunger in women remitted from anorexia nervosa [published online March 12, 2020]. Am J Psychiatry. doi: 10.1176/appi.ajp.2019.19030261.