Depression, dementia, and reversible dementia.

This article reviews the syndromic concepts of depression and dementia and the concurrence of these common entities. In DAT, depression appears to be a reversible source of excess disability, amenable to pharmacologic as well as environmental interventions. In the vascular dementias, depression appears to be a specific complicating feature, in which localization of the lesion plays a significant role. The abulic state should not be mistaken for a depressive syndrome, although its presence should alert the clinician to evaluate for dementia and depression. Depression is especially prevalent in the subcortical dementias. Future studies using dynamic neuroimaging will help define the limits of this important concept. Reversible forms of dementia are much less common than previously suspected. The clinician's task is to identify causes of excess disability due to superimposed illnesses while avoiding diagnostic or therapeutic nihilism. The appropriate use of medication and the ongoing surveillance for adverse drug reactions are the foremost tasks of today's clinician treating the elderly patient.