Alzheimer disease and risk of stroke: a population-based cohort study.

OBJECTIVE: To investigate the risk of stroke in patients clinically diagnosed with Alzheimer disease (AD) compared with non-AD patients with similar vascular risk factors.

METHODS: Using data obtained from Taiwan's National Health Insurance Research Database, we evaluated the risk of ischemic stroke (IS) and intracerebral hemorrhage (ICH) in patients with AD (n = 980) who had no history of stroke, vascular dementia, or other cerebral degenerative diseases. Our evaluation period spanned from 2000 to 2010. We performed a 1:5 case-control matched analysis, in which cases were matched to controls according to their estimated propensity scores, which were based on demographics and existing vascular risk factors. This approach reduced selection bias. Cox proportional hazards regression analysis was then used to estimate the risk of IS and ICH in AD, conditional for matched pairs.

RESULTS: Overall, patients with AD had a higher risk of IS and ICH than those without AD. The incidence of IS in AD cases and non-AD controls was 37.8 and 23.2 per 1,000 person-years, with an adjusted hazard ratio of 1.66 (95% confidence interval, 1.37-2.01, p < 0.001). The incidence of ICH in AD cases and non-AD controls was 5.2 and 3.0 per 1,000 person-years, with an adjusted hazard ratio of 1.70 (95% confidence interval, 1.03-2.79, p = 0.037).

CONCLUSION: Clinical diagnosis of AD is associated with considerably increased risk of stroke development.