Decreased brain responses during cognitive inhibition of food craving elicited by food stimulation in obese subjects

Objectives Obesity is associated with a higher risk for impaired executive cognitive function. Here we assessed changes in brain activity during cognitive inhibit (CI) in obese men (OB) during food stimulation (FS).

Methods Sixteen OB (32 ±8.7 yr/o) with BMI of 38.6±7.2 were compared with 10 age-matched non-obese men (NOB, 24.2±2.5) with PET and FDG. Brain metabolism was evaluated in food deprived (19 hrs) subjects during no stimulation (NS) and FS with CI and with no inhibition (NI) on 3 separate days. Absolute metabolic images were analyzed using SPM (p < 0.01) and ROI. Self-reports for hunger were recorded.

Results NOB and OB had lower scores in hunger (-37±29%, p<0.0001) during CI. FS produced greater activation in left caudate (CA) and left orbitofrontal cortex (OFC) in NOB than in OB and the activation for FS in left CA was negatively associated with BMI (p < 0.02). CI suppressed metabolism in right putamen, left amygdala, left OFC and left parahippocampus in NOB but not in OB. The differences between OB and NOB in the FS conditions were not significant. Suppression in OFC activity during FS with CI in NOB was associated with decreases in hunger (r = 0.73; p < 0.02) but not in OB.

Conclusions Compared to NOB, OB had lower activation in brain regions involved with motivation and reward during FS. They were also unable to suppress activation during FS in brain regions involved with emotional regulation, conditioning and motivation. These results suggest that this is the mechanism by which CI decreases the desire for food, which is consistent with the greater vulnerability of OB to uncontrolled eating when food is readily available.

Research Support NIH/GCRC/DOE