DYSTHYMIA AS A TEMPERAMENTAL VARIANT OF AFFECTIVE-DISORDER

Dysthymia is estimated to afflict at least 3% of the population worldw ide. Because it is a chronic disorder, its prevalence is high in psych iatric and general medical settings. The mystery of this incapacitatin g depressive subtype - long recognized but only recently sanctioned in the DSM-IV and ICD-10 - is that in their habitual condition, those su ffering from dysthymia lack the classical 'objective' or 'major' signs of acute clinical depression, such as profound changes in psychomotor and vegetative functions. Instead, patients consult their doctors for more fluctuating complaints consisting of gloominess, lethargy, self- doubt, malaise, and lack of joie de vivre. They typically work hard, b ut do not enjoy their work. if married, they are deadlocked in bitter and unhappy marriages which lead neither to reconciliation nor separat ion. For them, their existence is a burden: they are satisfied with no thing, complain of everything, and brood about the uselessness of exis tence. As a result, in the past they were labeled 'existential depress ives' or 'depressive characters' and condemned to the couch, often on a chronic basis. Several lines of research over the past fifteen years have shed new light on the biological origins of this disorder. Sleep neurophysiologic findings have shown that many parameters of paradoxi cal sleep in dysthymia (such as REM percentage, REM latency, and circa dian distribution of REM) are similar to those observed in major affec tive illness. Furthermore, family studies of dysthymia have demonstrat ed a significant excess of mood disorders. Indeed, dysthymia has been identified in childhood, and prospective follow-up has demonstrated ma jor affective breakdowns including bipolar switches in up to 20%. Coup led with sleep findings, these family and follow-up data suggest that dysthymia is best considered as 'trait depression', a constitutional v ariant of major affective illness. As expected from the early onset ch ronic nature of the disturbance, in both clinical and epidemiological studies, the social and health burden of dysthymia has been found to b e considerable and comparable to that of major medical disorders. The foregoing clinical and biological data. have provided the impetus for well-designed pharmacological trials in dysthymia, and a new therapeut ic optimism.