25.1 SOCIAL INVOLVEMENT MODULATES THE RESPONSE TO NOVEL AND ADVERSE LIFE EVENTS IN MICE

Objectives Social involvement affects our perception of our surroundings, including, importantly, adverse events and the way we react to and remember them. This phenomenon is conserved across phylogeny. Previous work has shown that individuals with anxiety and/or depression are more likely to be socially isolated, display poor communication patterns, and report unsupportive relationships. In contrast, when social networks and current relationships grow, symptoms of anxiety and depression are reduced. We present new, previously unreported data on how increased social involvement is a mechanism associated with decreased fear, anxiety, and depression. Methods We begin this session with a mouse model of social involvement in which we examine how being in the presence of sibling cagemates affects the way mice respond to a novel situation, a highly anxiety-provoking scenario, and a fearful stimulus. We then seek to identify a neuronal circuit underlying social modulation of fear response in mice. In humans, we examine the directionality of the relationship between friendship quality and social anxiety. Lastly, we explore how social functioning is a mediator of treatment effect in interpersonal psychotherapy for adolescents with depression (IPT-A). Results We find that social involvement in mice increases exploration in a novel environment, decreases anxiety in an anxiety-provoking scenario, decreases the initial encoding of fear memory, and hastens its extinction. Furthermore, we mapped a population of neurons in the infralimbic prefrontal cortex that activates during the social modulation of innate and conditioned fear response. We then show in humans that poor relationship quality was predictive of higher levels of social anxiety unidirectionally, with no effect of social anxiety on relationship quality. Finally, the increase in social involvement, specifically with parents in IPT-A for the treatment of depression within a Latino population, leads to a decrease in suicidal ideation and greater relief of symptoms of depression. Conclusions In this Symposium, we present work that investigated the effects of social involvement both in mice and in humans. In each case, the presence of peers or quality of relationships predicts a decrease in basic fear responses and decreased symptoms of depression and suicidal ideation within the clinical context of IPT-A.