The interaction between lifetime depression severity and BMI is related to altered activation pattern in the right inferior frontal gyrus during food anticipation

BackgroundDepression and obesity often co-occur but the underlying neural mechanisms for this bidirectional link are not well understood. Using fMRI, we examined how the relationship between Body Mass Index (BMI) and dimensional lifetime depression severity was associated with brain activation during food anticipation and pleasant/unpleasant rating. Methods90 participants (48 healthy controls, 42 with unipolar depression (UD), 69 female, age=28.5{+/-}6.6) were fMRI-scanned while performing the Food and Object Cued Encoding task consisting of food/object anticipation and food/object pleasant/unpleasant rating phases. ResultsThe analysis across all participants revealed a significant BMI-by-lifetime depression severity interaction on RIFG activation during food anticipation (p<0.0125). Most symptomatic and overweight/obese individuals with UD showed decreased right inferior frontal gyrus (RIFG) activation during food anticipation, while less symptomatic and/or normal-weight individuals with UD showed increased RIFG activation during food anticipation. RIFG activation during food anticipation was negatively correlated with RIFG activation during pleasant/unpleasant rating (r= -0.63, p<0.001). Individuals with UD who showed higher RIFG activation for food items during pleasant/unpleasant rating reported liking or wanting those food items less than those with lower RIFG activation (p<0.05). ConclusionsThe IFG is involved in emotion regulation and response inhibition necessary to control appetitive behavior. Greater RIFG activation during pleasant/unpleasant rating of food coupled with low ratings of food liking and wanting could be associated with inhibition of cognitive and emotional response to food in UD. This process may be cognitively challenging and stressful thus putting affected individuals with UD at risk for weight gain and worsening of depression.