Early life stress- and sex-dependent effects on hippocampal neurogenesis

Neurogenesis refers to the birth of new neurons in an adult brain, a form of structural plasticity that has been implicated in cognition, mood, and anxiety, and is well regulated by environmental and hormonal factors. Exposure to stress (hormones) generally inhibits neurogenesis. Here, we discuss (sex-dependent) effects of stress on adult hippocampal neurogenesis, and focus on stress during the sensitive period of early life. While the effects of acute, mild stress are generally short-lasting and recover quickly, chronic or severe forms of stress can induce longer-lasting reductions in adult neurogenesis, especially when encountered during early life. Some of these inhibitory effects of early stress can normalize after appropriate recovery periods, exercise, drugs targeting the stress system, and some antidepressants. Early life stress may (re-)program hippocampal plasticity, thereby altering the overall composition of the hippocampal circuit. This may modify stress responsivity, hippocampal function, later cognition, and the risk for psychopathology.