Neurobiology of early life stress: nonhuman primate models

Numerous studies have shown that early life stress in nonhuman primates produces profound and long-lasting changes in behavior and biological function. We review several aspects of the neurobiology of early life stress, focusing on nonhuman primate experimental paradigms. There is experimental evidence that even prenatal stress can produce profound alterations in biological factors such as regulation of the hypothalamic-pituitary-adrenal (HPA) axis, biogenic amines, and immune function, as well as in behavioral measures of attention and sociability. An ongoing struggle in research studies is defining the relative contributions of nature and nurture in mediating the long-term effects of stress. Studies of social support contend that this has the capacity to buffer the deleterious effects of stressful early rearing environments, whereas social deprivations appear to have negative behavioral and medical outcomes, most notably deficits in immune function. From studies involving variable foraging demand (VFD)-reared nonhuman primates and other models, we suggest that many of the behavioral and biochemical changes produced resemble those seen in humans who suffer from depressive and anxiety conditions. Finally, there appears to be remarkable consistency of key neurobiological findings across species.