Antidepressant efficacy in the treatment of dysthymia.

Although the existence of chronic depression has been recognized for a long time, their definition was too inaccurate to enable reliable studies concerning their treatment. Among the numerous diagnostic classes that patients with chronic depression were assigned to, neurotic depression was the most common one, and was often considered to be unresponsive to antidepressant medication. Since DSM-III introduced 'Dysthymic Disorder', a new research was developed on the efficacy of tricyclic antidepressants, MAOIs or new antidepressants, whose results reversed previous opinion on its unresponsiveness. However the interpretation of those studies are hampered by methodological problems, yet unresolved, pertaining to the difficulty to differentiate dysthymia and major depression, to the frequency of 'double-depression', the usual mildness of symptoms in dysthymia, and the need of long-term trials.