Syndromic validity of apathy in Alzheimer's disease.

OBJECTIVE: The study examined the usefulness and clinical correlates of specific diagnostic criteria for apathy in Alzheimer's disease. Whereas apathy is a frequent behavioral change in patients with Alzheimer's disease, the lack of standardized diagnostic criteria may explain the wide discrepancies in estimates of the frequency and demographic and clinical correlates of apathy.
METHOD: A consecutive series of 319 patients who met the criteria for probable Alzheimer's disease established by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association, 117 patients who met the DSM-IV criteria for depression without dementia, and 36 healthy individuals were assessed with a structured psychiatric interview. On the basis of modified Marin's criteria for apathy, they were classified into groups with or without apathy.
RESULTS: Apathy was diagnosed in 37% of the 319 Alzheimer's disease patients, compared to none of the healthy comparison subjects. In 24% of the Alzheimer's disease sample, apathy coexisted with either dysthymic disorder or major depressive disorder, whereas 13% had apathy without depression. Apathy was diagnosed in 32% of the depressed nondemented patients, mostly in those with major depressive disorder. Apathy in Alzheimer's disease was significantly associated with severe impairments in activities of daily living and cognitive functions, older age, and poor awareness of behavioral and cognitive changes.
CONCLUSIONS: This study provides partial validation of specific clinical criteria for apathy in Alzheimer's disease.