Beginning in the early 1980s, various researchers, including myself, showed that this "glucocorticoid neurotoxicity" was not just a pharmacological effect, but was relevant to normal brain aging in the rat. Collectively, the studies showed that lots of glucocorticoid exposure {in the range seen during stress} or lots of stress itself would accelerate the degeneration of the aging hippocampus. Conversely, diminishing glucocorticoid levels {by removing the adrenals of the rat} would delay hippocampal aging. And as one might expect by now, the extent of glucocorticoid exposure over the rat's lifetime not only determined how much hippocampal degeneration there would be in old age, but how much memory loss as well.
( Robert M. Sapolsky )
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