Sensitivity shift theory: A developmental model of positive affect and motivational deficits in social anxiety disorder.

Social anxiety disorder (SAD) is a common and impairing condition that emerges in early adolescence, confers significant interpersonal disability and often persists into adulthood. Prevailing interventions for socially anxious youth are largely based on cognitive-behavioral models originally developed in adult samples, but produce only modest rates of remission in adolescents. The purposes of this review are to examine plausible explanations for these modest rates of treatment response and to critically evaluate the relevance of developmental mechanisms related to reward circuitry function. In doing so, we propose Sensitivity Shift Theory (SST), an integrated theoretical model addressing the development of social anhedonia in a meaningful subset of adolescents and adults with SAD. The central prediction of SST involves a shift, or developmental transition from social sensitivity during the late childhood/early adolescent period into later-emerging social anhedonia that includes reductions in positive affect, infrequent social approach behaviors and social skills deficits. We further provide a complementary mechanistic account by which these newly identified processes may be addressed using available evidence-based treatments that influence positive affect, including mindfulness-based interventions (MBIs). Collectively, SST provides a mechanisms-focused framework for explaining relatively modest rates of response to current front-line treatments in socially anxious youth, as well as discrepant observations in SAD samples of both high- and low- levels of social motivation depending on developmental factors and learning history.