Stress and the social brain: behavioural effects and neurobiological mechanisms

Key Points The effects of stress on social behaviour depend on the timing, the duration and the type of stress exposure. Social withdrawal and aggression are a typical consequence of experiencing, or having experienced, high and persistent stress levels. From a developmental perspective, early stressors impose an increasing pattern of dysfunctional social behaviour, progressing from asociality (elicited by prenatal stressors) to hostility (by postnatal stressors) and to antisociality (by stressors during juvenility). In humans, stress can also elicit prosocial behaviours, particularly towards ingroup members. Individual differences in the effect of stress in social behaviours are partly explained by certain gene polymorphisms (for example, the monoamine oxidase A ( MAOA ) gene). Glucocorticoids mediate, at least in part, the effects of stress on social behaviours. Monoamines, social neuropeptides, the corticotropin-releasing hormone (CRH) system, cell adhesion molecules and epigenetic mechanisms are implicated in the translation of stress effects in social behaviours. Positive social interactions can protect individuals from the adverse effects of stress. Early-life stress can contribute to predispositions to antisocial behaviour in adulthood. Similarly, acute or chronic stress during adulthood can alter our social behaviour. Sandi and Haller emphasize the importance of timing of stress for its effects on social behaviour and describe current understanding of the underlying mechanisms. Stress often affects our social lives. When undergoing high-level or persistent stress, individuals frequently retract from social interactions and become irritable and hostile. Predisposition to antisocial behaviours — including social detachment and violence — is also modulated by early life adversity; however, the effects of early life stress depend on the timing of exposure and genetic factors. Research in animals and humans has revealed some of the structural, functional and molecular changes in the brain that underlie the effects of stress on social behaviour. Findings in this emerging field will have implications both for the clinic and for society.