Depression and Memory Loss

Contributed by: Michael Rafii, M.D., Ph.D - Director of the Memory Disorders Clinic at the University of California, San Diego.

Studies show that prolonged stress leads to elevated levels of cortisol, a "stress" hormone produced by the adrenal glands. This in turn appears to shrink or atrophy the hippocampus, the sea-horse shaped part of the brain associated with many kinds of memory and learning. The hippocampus is a part of the brain that is particularly vulnerable to stress and stress hormones.

While cortisol levels normally fluctuate over the course of a day and night, they often soar when a person is faced with a stressful situation. Many studies have shown that this affects short term memory. For example, researchers have shown that people taking cortisone pills (which metabolize to cortisol in the body) were not as good at remembering a list of words as people taking placebo pills.

For many people, depression appears to cause similar damage; their cortisol levels remain slightly elevated as long as they are depressed. This moderate, but constant elevated cortisol appears to wear down the hippocampus--and lead to memory difficulties.

More studies are needed to fully understand the molecular connection between stress, depression and memory, and perhaps better treatments.

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