Charlotte Oomen investigated the effects of stress on brain structure and function. In humans, stress is a major risk factor for the development of depression and depressed patients show a reduced hippocampal volume. The hippocampus is involved in learning and memory and is endowed with a unique form of structural plasticity: adult neurogenesis i.e. the birth of neurons during adult life. Charlotte describes the effects of two 'high-impact stressors' (chronic stress in adulthood and early life stress) affect adult neurogenesis and cell morphology in the rat. One of the main findings was that a single period of maternal absence reduces neurogenesis in male offspring and changes cell morphology.
This reduction in structural plasticity was paralleled by a better memory for stressful events. Female offspring showed a decrease in the number of hippocampal neurons and no improved stress-related memory. In conclusion, early stress can irreversibly alter brain structure but can also program animals to improve functioning in a stressful context later in life. Differences between male and female offspring are interesting with respect to the increased vulnerability of women to develop depression.