Survival following dementia onset: Vascular dementia versus Alzheimer's disease

Survival following the onset of dementia has been reported to vary from 3 to over 9 years. We examined mortality in 3602 participants of the Cardiovascular Health Cognition Study in four U.S. communities evaluated for dementia incidence between 1992-1999 and followed for 6.5 years. By June 2000, 33 of 62 (53.2%) participants who had developed VaD had died compared to 79 of 245 (32.2%) with AD, 66 of 151 (43.7%) with both AD and VaD, and 429 of 2318 (18.5%) with normal cognition. Using Cox proportional hazards regression with a time-dependent covariate for dementia status adjusted for age, gender and race, individuals with VaD were more than four times as likely to die during follow-up than those with normal cognition (HR: 4.4, 95% CI: 3.1-6.3). The hazard ratios were 2.1. (95% CI: 1.6-2.7) for AD and 2.5 (95% CI: 1.9-3.3) for both types. Adjusted accelerated life models estimated median survival from dementia onset to death as 3.9 years for those with VaD, 7.1 years for AD, and 5.4 years for those with both types of dementia.