Friday, January 16, 2009

Two Thoughts on Depression: Dexamethasone Suppression Tests and Cortisol

by Tara Deliberto

Cortisol and Depression:

1) The research on depression shows us that when dexamethasone is administered to people w/ depression and controls, people with depression do not show a decrease in their cortisol levels unlike their non-depressed counter-parts. In addition, we know that increased glucocorticoids such as cortisol increases the susceptibility of the brain (Gubba et al 2000; Sapolsky, 1985). Judging from these facts, it seems to me that people with a predisposition to non-suppression of cortisol who are on long term steroid treatment (i.e. people w/rheumatoid arthritis taking prednisone), could end up with depression because of prolonged exposure to cortisol as a side effect from the drug.

2) We also know that people with depression have higher levels of early morning cortisol. Although people w/ depression may have trouble suppressing cortisol in general, perhaps the early morning elevations of cortisol could, in part, simply have to do with having bad dreams. Chronically high level of cortisol produced during sleep could possibly lead to a dysfunctional HPA axis (hypothalamic-pituitary-adrenal axis - part of the neuroendocrine system that helps regulate stress). If this could be the case, perhaps treating people with prodromal depression/ depression with both drugs that have been shown to decrease production of nocturnal cortisol (probably through the decreased occurrence of nightmares) and perhaps even training in lucid dreaming or relaxation may be useful. Because high levels of anxiety can lead to prolonged problems, unlike many of my Acceptance and Commitment Therapy counterparts, I would argue that stress reduction training can be a very useful long term benefit.

In other words, since we know that prolonged anxiety leads to prolonged cortisol exposure, which could lead to dysfunction of the HPA axis, which leads to depression... maybe we shouldn't discount trying to decrease anxiety!
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