Elevated cortisol levels, which characterize some
moderate-to-severe depressive states, may be associated
with a reduction in hippocampal volume,
which appears to be proportional to the duration
of untreated depression.
20
This process has been
likened to a loss of neurons similar to that mediated
by corticosteroids in animal models of stress
21
and as suggested by magnetic-resonance-imaging
studies that have reported lower levels of
N
-acetyl
aspartate, a neuronal marker, in depression