The long-term impact of early adversities on psychiatric disorders : focus on neuronal plasticity

The impact of early physical and social environments on life-long pathological phenotypes is well known and there is now compelling evidence that stressful experiences during gestation or early in life can lead to enhanced susceptibility to mental illness. Here, we discuss the data from preclinical studies aimed at investigating the molecular consequences of the exposure to stressful events during prenatal or early postnatal life that might contribute to later psychopathology. Particularly, we will discuss the existence of age windows of vulnerability to environmental conditions during brain maturation using as examples several studies performed with different animal models. Specifically, major deviations from normative neurobehavioural trajectories have been reported in animal models obtained following exposure to severe stress (maternal separation) ea rly in infancy or with rodent models of difficult and/or stressful pregnancies, including obstetric complications (e.g. prenatal restrain stress) and gestational exposure to infection (e.g prenatal immune challenge). These models have been associated with profound long-lasting deficits in the offspring's emotional and social behaviour, and with molecular changes associated with neuroplasticity.