Patients with anorexia nervosa demonstrate higher-order cognitive mechanisms that may promote avoidance of food ingestion under homeostatic hunger conditions (independent of the cephalic phase of consumption) when tasked with food distraction stimuli, according to study results published in the Psychological Medicine.
Investigators of this single-blinded study (ClinicalTrials.gov Identifier: NCT03075371) sought to understand the effect of short-term homeostatic signaling, including satiety or hunger, on the neural regulation of cue-induced food cravings in anorexia nervosa. An important part of the study design required eliminating influences associated with the cephalic phase of food consumption, such as sight, smell, and taste, and awareness of caloric intake.
The study included 25 women with anorexia nervosa and 25 women at normal weight matched by age and education. All participants underwent 2 examinations in which they received an intragastric infusion of either glucose (to represent the condition of homeostatic satiety) or water (to represent the condition of homeostatic hunger). After the infusion, the investigators obtained event-related functional magnetic resonance imaging (fMRI) scans to assess the effect of intestinal glucose load on neural processing during either simple viewing or distraction from food stimuli (images of high-calorie food that elicited cravings). Before and after each fMRI session, the participants reported hunger using a visual analogue scale (0-100), severity of disturbed eating patterns and concern over weight using the Eating Disorder Examination Questionnaire, and severity of depressive symptoms. Analysis of variation was performed to compare differences in satiety both before and after the glucose/water infusions between the groups.
For both groups, self-reported measures on hunger revealed no significant differences before or after the fMRIs were obtained during either water or glucose conditions. Differences in neural processing between anorexia nervosa and the control groups were significant during the distraction condition but not during simple viewing. In patients with anorexia nervosa, fMRI after water infusion revealed stronger activation in higher-order cognitive control regions (left precuneus, left inferior parietal lobules, fusiform gyrus, middle occipital areas) in response to distraction stimuli; fMRIs obtained after glucose infusion showed decreased activation in the fronto-cingular brain regions (posterior cingulate gyrus, ventral prefrontal regions, perigenual anterior cingulate cortex) in response to food distraction.
Study limitations included using glucose to evoke homeostatic satiety instead of a nutritious meal, which may have a different satiating effect, and only examining distraction from food stimuli, where avoidance and cognitive reappraisal may also have roles in restraining eating behaviors.
Among patients with anorexia nervosa, disorder-specific reactions were influenced by homeostatic conditions and not just by the cephalic phase of digestion or awareness of caloric intake. In anorexia nervosa, excessive higher-order cognitive control observed during physiologic hunger was associated with food distraction, whereas decreased internally directed attention was linked to physiological satiety. The investigators suggested that the psychopathology of anorexia nervosa may facilitate a resistance to food cravings during food distraction tasks.
Stopyra MA, Friederich H-C, Mönning E, et al. The influence of homeostatic mechanisms on neural regulation of food craving in anorexia nervosa [published online January 14, 2020]. Psychol Med. doi:10.1017/S0033291719003970