Chronic Stress

Moving into adulthood, Lupien, McEwen, Gunnar, and Heim (2009) delineated the effects of acute stress versus chronic stress on the brain and behavior. Acute stressors depends on the level of glucocorticoid elevations. Small increases result in enhanced hippocampus-mediated learning and memory, where larger, prolonged elevations impair hippocampal function. Chronic stress causes dendritic atrophy in the rodent’s hippocampal CA 3 pyramidal neurons. Chronic stress can inhibit neurogenesis in the dentate gyrus as well as cause hippocampal volume loss. This loss of volume is not associated with neuronal loss nor is it limited to the dentate gyrus, which could suggest that reduced neurogenesis may not be the only contributing factor. There is a relation …show more content…
This gives rise to the glucocorticoid cascade hypothesis (recently renamed neurotoxicity atrophy), suggesting that there is a relationship between cumulative exposure to high glucocorticoid levels and hippocampal atrophy. Stress can cause an increase in glutamate levels, as well as other neurotoxic insults, which may increase the vulnerability of the aging brain to neuronal damage. Aging humans typically exhibit higher levels of cortisol than younger individuals. Some studies have also shown elevated glucocorticoid levels negatively correlates with hippocampal volume and memory. It has been suggested that increased glucocorticoid levels could worsen cognition in people with Alzheimer’s disease. It also has been suggested that glucocorticoid could affect axonal transport in prefrontal neurons within the frontal lobe, with low concentrations causing a stimulating effect, while causing a depressing effect in high concentrations. Since axonal transport plays a critical role in neuronal survival and function, this suggests that glucocorticoids could potentially have negative effects on prefrontal cortex neurons’ survival and/or