New approaches to the treatment of depression.

This review considers the various modes of action and possible advantages of the different types of second generation antidepressants. The biochemical changes that may be causally related to depression and the mechanisms whereby these changes may be attenuated by antidepressant treatment are briefly considered. Whereas the monoamine theory of depression and the receptor adaptation hypothesis of antidepressant action have been influential in helping to unify the mechanisms of action of antidepressants with the possible pathologic basis of depression, the introduction of novel antidepressants and the development of treatment strategies suggestive of a rapid onset of antidepressant response may initiate a revision of these concepts. The review ends with a consideration of the nonaminergic changes that may be of fundamental importance not only in the pathologic basis of depression but also to the means whereby antidepressants bring about their clinical effects.