Models for the experimental analysis of depression.

Numerous models of depression have been proposed by investigators to assist in understanding this common and complex disorder. Some of these models have been specifically created to reflect certain philosophical or theoretical aspects of depression thought to be important. Other experimental paradigms evolved into models of depression when certain similarities with depressed patients were observed. The label depression undoubtedly refers to many separate and independent disorders that happen to share some similar behavioral symptoms. Although no one model can be appropriate for all types of depression, the evaluation in depressed patients of hypotheses developed in the models may provide diagnostic clues that would assist in selecting the therapeutic intervention that is most appropriate for a particular patient.