ABSTRACT
The ability of stress and glucocorticoids (GCs) to affect learning and memory has been extensively documented, particularly in the hippocampus where GC receptors are highly expressed. One factor that may contribute to variable age-related changes in brain function is individual differences in the stress system. These differences in the stress system could arise through natural genetic variation or through dissimilar environmental exposure to stressors over the lifespan of the individual. The effects of aging on learning and memory are similar to those produced by GCs and stress in younger animals. Studies examining synaptic plasticity in animal models have demonstrated that putative cellular substrates for learning and memory are also regulated by stress and GCs. In rodents, chronic stress has been shown to cause neuronal atrophy in numerous brain regions, including the inferior colliculus, medial prefrontal cortex, and the hippocampus. Neurogenesis has been shown to be very sensitive to stress and GCs.
