Prenatal and maternal psychosocial stress in primates: Adaptive plasticity or vulnerability to pathology?

Abstract

In many species of vertebrates, prenatal and early postnatal stress can have long-lasting consequences for neuroanatomical, neuroendocrine, or behavioral development. In primates including humans, prenatal psychosocial stress and postnatal psychosocial stress induced by the mother's behavior represent important sources of nongenetic maternal effects through which mothers can modify their offspring's phenotype. Prenatal and maternal psychosocial stress are probably mediated by similar physiological mechanisms and primarily including the HPA axis. The biomedical/clinical view, the stress-inoculation model, and the adaptive calibration model make different assumptions and predictions concerning the adaptive or maladaptive developmental consequences of prenatal and maternal psychosocial stress. Studies of experimentally induced prenatal psychosocial stress in primates indicate that fetal programming occurs with characteristics similar to those observed in laboratory rodents and in humans. Studies of naturally occurring maternal psychosocial stress in primates have focused on maternal abuse and rejection of offspring. Although the developmental consequences of exposure to maternal abuse or high rates of maternal rejection are unlikely to be adaptive, exposure to moderate levels of rejection appears to result in physiological and behavioral changes that enhance resilience later in life. It is possible that some aspects of normal parenting in nonhuman primates and humans are designed to be stress inducing to prepare offspring to deal with the psychosocial stress that is an inevitable part of life in complex and competitive social environments.