Narrator: This is Science Today. High levels of a stress hormone
commonly thought to be a symptom of depression may actually turn
out to be the cause of depression. Dr. Owen Wolkowitz, a
professor of psychiatry at the University of California, San
Francisco, says at least some cases of depression may actually
be a disorder of the endocrine system, which affects the brain
rather than the body. Wolkowitz: What we think is happening is
that under conditions of stress, plus genetic susceptibility,
the adrenal gland puts out more cortisol, the cortisol feeds
back onto the brain and has effects in the brain - maybe in the
hippocampus - that then cause depression. Narrator: The story
gets even more interesting when you consider high levels of
cortisol may actually lower levels of neurotransmitters such as
serotonin. Low levels of serotonin are thought to underlie
depression. Wolkowitz: In fact, the two abnormalities may
feedback on each other. If that's the case, we could either
attack it biochemically by increasing