Obesity and Insulin Resistance Moderate Neural Responses to Unpleasant, but not Pleasant, Stimuli

Obesity and insulin resistance (IR) increase the risk for mood disorders and may impair emotional experiences. This study investigated whether obesity/IR moderated the brain potentials–affective processing association during young adulthood. Thirty young adults completed a passive picture-viewing task utilizing the International Affective Picture System while real-time electroencephalography was recorded. Early posterior negativity (EPN) and late positive potential (LPP) were quantified. Affective processing parameters included mean valence ratings and stimulus-to-response-onset reaction times in response to unpleasant, pleasant, and neutral images. Body fat percentage and Homeostatic Model Assessment for Insulin Resistance values were measured. Hierarchical moderated regression analysis was utilized to test the interrelationships between brain potentials, adiposity, IR, and affective processing parameters. In the Negative–Neutral valence condition, lean and insulin-sensitive participants gave less negative valence ratings to unpleasant versus neutral images when late-window LPP amplitudes were larger, whereas respective counterparts showed no such relationship. Contrariwise, obesity/IR did not moderate LPP responses to affective processing parameters in the Positive–Neutral or Negative–Positive conditions. Lean and insulin-sensitive young adults showed attenuated negative affective processing of unpleasant stimuli through stronger neural responses, whereas neural responses to pleasant stimuli did not vary across levels of body fat or IR in young adults.