On the Inseparability of Mental and Physical Health in Aged Persons: Lessons From Depression and Medical Comorbidity.

Recent research findings demonstrate that general medical and mental health are inseparable in older individuals. The medical consequences of depression can be summarized with the unifying hypothesis that depression interacts with medical or neurological illness to modify the course of disease and to amplify its associated effects. The medical causes of depression can be divided into specific mechanisms of certain diseases or medications and general mechanisms that may integrate effects of a number of the common chronic disorders of late life. The authors discuss two general hypotheses: One suggests that depression may be associated with subclinical cerebrovascular disease in older patients with cerebrovascular risk factors; the other suggests that depression occurring in association with various conditions may be related to cytokine-mediated "sickness behavior." The research literature makes a compelling case for the need to address psychiatric-medical comorbidity in late life as a central issue in public policy and the design of health care systems.