Nosological validity of dysthymia. Part II: familial, comorbidity, biological and psychological data

If some recent studies seem to reveal a more specific familial relationship for dysthymia in addition to a previously known familial relationship to mood disorders, and if results concerning the relationship between dysthymia and depressive personality as well as the search for possible biological and psychological correlates support the nosological validity of dysthymia, comorbidity studies raise difficult questions. Both comorbidity studies with Axis I and Axis II disorders challenge the validity of dysthymia, but as well they question the categorical model presently in use more than the validity of a definite category. However, there are now enough data confirming some of the hypotheses implied by the nosological construct of dysthymia inside this model for this category not to be discarded. For instance, dysthymia is definitely not a personality disorder, and appears also distinct from major depression. The problem of the complex nature of the relationship between dysthymia and major depression still remains unsolved.