Neural processing of laughter in depression

Laughter can convey social intent ranging from acceptance (friendly inclusive laughter) to rejection (malign taunting laughter). We investigated perception of auditory and visual laughter in patients with major depressive disorder (MDD) versus healthy controls (HC). 48 MDD patients and 52 HC rated 60 laughter recordings presented auditorily or visually regarding the expressed social intent during an fMRI experiment at 3T. Depression severity was assessed based on questionnaires. MDD patients rated the perceived social intent of the laughter significantly more negative than HC across both modalities. The individual magnitude of this negativity bias of social intent attribution significantly correlated with both depression severity as well as activation in anteromedial prefrontal cortex (AMPFC) during perception of auditory laughter. MDD patients also exhibited a significantly reduced activation in AMPFC and depression severity partially mediated effects on rating of auditory laughter as evidenced by mediation analysis. Our results demonstrate altered perception of social intent expressed by laughter in MDD. Neuroimaging data point to the AMPFC for mediation of this effect as its activity was correlated with both depression severity and a negative attribution bias during perception of auditory laughter. Furthermore, at group level activity in this area was reduced in MDD patients.