Neuropsychological tests accurately predict incident Alzheimer disease after 5 and 10 years

Objective: To determine whether neuropsychological tests accurately predict incident Alzheimer disease (AD) after 5 and 10 years in participants of the Canadian Study of Health and Aging (CSHA) who were initially nondemented. Methods: The CSHA was conducted in three waves: CSHA-1 (1991 to 1992), CSHA-2 ( 1996 to 1997), and CSHA- 3 ( 2001 to 2002). The 10-year prediction study included those who completed neuropsychological testing at CSHA- 1 and received a diagnostic assessment at CSHA- 3 (n = 263). The 5-year prediction study included those who completed neuropsychological testing at CSHA-2 and received a diagnostic assessment at CSHA- 3 ( n = 551). The diagnostic workup for dementia at CSHA- 3 was formulated without knowledge of neuropsychological test performance at CSHA-1 or CSHA-2. The authors excluded cases with a baseline diagnosis of dementia or a prior history of any condition likely to affect the brain. Age and education were included in all analyses as covariates. Results: In the 10-year follow- up study, only one test ( short delayed verbal recall) emerged from the forward regression analyses. The model with this test and two covariates was significant, chi(2) 2 ( 3) = 31.61, p < 0.0001 (sensitivity = 73 %, specificity = 70 %). In the 5-year follow- up study, three tests (short delayed verbal recall, animal fluency, and information) emerged from the forward logistic regression analyses. The model was significant, chi(2) (5) = 91.34, p < 0.0001 (sensitivity = 74 %, specificity = 83 %). Both models were supported with bootstrapping estimates. Conclusions: In a large epidemiologic sample of nondemented participants, neuropsychological tests accurately predicted conversion to Alzheimer disease after 5 and 10 years.