Avoidance of premature closure on any one
scientific theory of the mechanism of depression
will best serve the search for new, more effective
treatments. It is likely that the pathogenesis of
acute depression is different from that of recurrent
or chronic depression, which is characterized by
long-term declines in function and cognition.
Mood can be elevated (by stimulants,by brain
stimulation,123 or by ketamine94) or depressed (by
monoamine depletion19 in recovered patients) for
short periods, but longer-term improvement may
require reduction of the abnormal glucocorticoid
function induced by stress or increases in brain
neurotrophic factors