Depressive symptoms in schizophrenia: comprehensive differential diagnosis.

Depression is a common complication of schizophrenia and is associated with increased morbidity and mortality. Contrary to traditional clinical wisdom, depressive symptoms occur during all phases of schizophrenia and are not restricted to the postpsychotic period. In this review, the authors summarize current empirical research and offer a practical approach to the identification of depressive subtypes in schizophrenia. The following subtypes are considered: (1) depressive symptoms occurring secondary to organic factors (caused by medications, substance abuse, or underlying medical problems); (2) nonorganic depressive symptoms occurring with acute psychotic symptoms (intrinsic to the acute psychotic episode or schizoaffective disorder); and (3) nonorganic depressive symptoms occurring without acute psychotic symptoms (prodromal symptoms, negative symptoms, acute dysphoria, secondary depressive syndrome, or chronic demoralization). The authors discuss each of these entities and offer guidelines for diagnosis.