Depression in Mature Male Rhesus Macaques (Macaca mulatta): Direct and Delayed Consequences of Deprivation

We studied the effect of 6-month deprivation (individual housing) on the manifestations of depression in mature male rhesus macaques (Macaca mulatta). It was found that two weeks after the cessation of deprivation and return to group housing conditions, all males showed a significantly higher level of depressive manifestations. In most males, increased level of depressive manifestations in comparison with baseline conditions persisted a year after the cessation of deprivation. The severity of depressive manifestations at all stages of the study largely depended on the individual characteristics of the monkeys.