Neural correlates of happiness and its association with social avoidance and distress: Evidence from voxel-based morphometry and resting-state functional connectivity.

Happiness, a multifaceted construct including both affective and cognitive components of human experience, plays a vital role in individuals' mental and physical health, as well as their social development. Although numerous behavioral studies have demonstrated a negative association between social avoidance and distress (SAD) and happiness, the neural mechanisms underlying the relationship remain elusive. To address this gap, the present study employed voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) methods in a sample of 308 healthy young adults to examine the neural pathways linking SAD and happiness. The behavioral results showed that happiness was negatively correlated with SAD. The VBM results revealed that gray matter volumes (GMVs) in the left dorsolateral prefrontal cortex (lDLPFC), right dorsolateral prefrontal cortex (rDLPFC), and right inferior parietal lobule (rIPL) were negatively associated with happiness. Furthermore, the RSFC results showed that the functional connectivities between the lDLPFC and medial prefrontal cortex (MPFC), lDLPFC and left cerebellum posterior lobe (lCPL), and rDLPFC and left angular gyrus (lAG), were all positively correlated with happiness. Importantly, the mediation results demonstrated that the lDLPFC-MPFC and lDLPFC-lCPL functional couplings mediated the relationship between SAD and happiness. These findings not only deepen our understanding of the neurobiological substrates of happiness but also highlight the potential role of prefrontal functional connectivity as a target for psychophysiological interventions aimed at enhancing well-being in individuals experiencing high levels of SAD.