Factors Attenuating the Validity of the Geriatric Depression Scale in a Dementia Population

OBJECTIVE: The validity of the Geriatric Depression Scale (GDS) in cognitively impaired patients has been questioned. We investigated possible factors (memory loss, dementia severity, unawareness of illness) attenuating the validity of the GDS in patients with dementia. PATIENTS: Eighty-three patients who met research diagnostic criteria for "probable Alzheimer's disease." Subjects with major depressive disorder were excluded. Dementia severity ranged from mild to moderate. SETTING: Outpatient clinics, including institutional settings and private research settings. MEASUREMENTS: Depression--GDS; Hamilton Depression Scale. Memory--Wechsler Memory Scale; Benton Visual Retention Test. Dementia severity--Mini-Mental State Examination. Self-awareness of cognitive deficits--Difference score between a self-report memory questionnaire and an informant-rated memory questionnaire. RESULTS: Multiple regression analysis revealed that Hamilton scores were the major predictor of GDS scores. Memory scores and self-awareness scores were also significant predictors. Dementia severity scores were not a significant predictor. CONCLUSIONS: The GDS is a valid measure of mild-to-moderate depressive symptoms in Alzheimer patients with mild-to-moderate dementia. However, Alzheimer patients who disavow cognitive deficits also tend to disavow depressive symptoms, and the GDS should be used with caution in such patients. Finally, the argument that memory impairment precludes accurate self-report of recent mood is negated by our finding that many patients accurately reported depressive symptoms and that worse memory was associated with more self-reported depressive symptoms.