Diagnosing depression in Alzheimer disease with the National Institute of Mental Health provisional criteria

Objective: To compare the rates of depression in Alzheimer Disease (AD) determined using National Institute of Mental Health (NIMH) provisional criteria for depression in AD (NIMH-dAD) to those determined using other established depression assessment tools. Design: Descriptive longitudinal cohort study. Setting: The Alzheimer's Disease Research Centers of California. Participants: A cohort of 101 patients meeting NINDS-ADRDA criteria for possible/probable AD, intentionally selected to increase the frequency of depression at baseline. Measurements: Depression was diagnosed at baseline and after 3 months using NIMH-dAD criteria and the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) Axis I Disorders. Depressive symptoms also were assessed with the Cornell Scale for Depression in Dementia (CSDD), the Geriatric Depression Scale (GDS), and the Neuropsychiatric Inventory Questionnaire. Results: The baseline frequency of depression using NIMH-dAD criteria (44%) was higher than that obtained using DSM-IV criteria for major depression (14%; Z = -5.50, df = 101, p < 0.001) and major or minor depression (36%; Z = -2.86, df = 101, p = 0.021) or using established cut-offs for the CSDD (30%; Z = -2.86, df = 101, p = 0.004) or GDS (33%; Z = -2.04, df = 101, p = 0.041). The NIMH-dAD criteria correctly identified all patients meeting DSM-IV criteria for major depression, and correlated well with DSM-IV criteria for major or minor depression (kappa = 0.753, p < 0.001), exhibiting 94% sensitivity and 85% specificity. The higher rates of depression found with NIMH-dAD criteria derived primarily from its less stringent requirements for the frequency and duration of symptoms. Remission rates at 3 months were similar across instruments. Conclusions: The NIMH-dAD criteria identify a greater proportion of AD patients as depressed than several other established tools.