Chronic depression: A concept to be revised

Although the current DSM-IV classification does not distinguish between chronic depression subtypes, clinical evidences suggest that such psychiatric condition differs for numerous aspects such as illness overall duration and psychiatric symptoms intensity and is associated with greater comorbidity, functional impairment and suicide risk compared to non-chronic depressive episodes. Different factors characterize chronic depression, for example older age, family history of depressive disorders, concurrent general medical illnesses and psychiatric comorbidity. An early and accurate diagnosis is essential for a good prognosis and the presence of certain somatic symptoms lacking medical explanation is a good predictor for the development of depressive disorders and suicidal behaviors. Current guidelines and systematic reviews suggest combined psychotherapeutic and pharmacological interventions as the best treatment of chronic depressive disorders, even though recent findings question these indications. Moreover, after an apparently successful antidepressant treatment it is not uncommon for the patients to manifest residual symptoms that can determinate functioning impairment, subjective suffering and tend to lead to an increase in depressive episode relapses. Correct diagnosis and treatment of these residual symptoms should play an important role in depression management and allow an achievement of better outcomes. The persisting difficulties in the treatment of chronic depression can be partially explained by the incomplete knowledge of its underlining pathological mechanisms. The discovery that depression is a neurodegenerative disorder with important brain inflammatory dysregulation could potentially lead to new pharmacological targets and a more personalized antidepressant care.