Behavior and physiology of social stress and depression in female cynomolgus monkeys

The hypothesis that social subordination is stressful, and results in a depressive response in some individuals, was examined in socially housed female cynomolgus monkeys. Social status was manipulated such that half of the previously subordinate females became dominant and half of the previously dominant females became subordinate. Current subordinates hypersecreted cortisol, were insensitive to negative feedback, and had suppressed reproductive function. Current subordinates received more aggression, engaged in less affiliation, and spent more time alone than dominants. Furthermore, they spent more time fearfully scanning the social environment and displayed more behavioral depression than dominants. Current subordinates with a history of social subordination were preferentially susceptible to a behavioral depression response. The results of this experiment suggest that the stress of social subordination causes hypothalamic-pituitary-adrenal and ovarian dysfunction, and support the hypothesis that chronic, low-intensity social stress may result in depression in susceptible individuals.