Incidence of stroke in people with Alzheimer disease: a national register-based approach.

OBJECTIVE: Stroke increases the risk of dementias, including Alzheimer disease (AD), but it is unknown whether persons with AD have a higher risk of strokes. We investigated whether noninstitutionalized persons with AD were more likely to experience incident stroke than persons without AD and whether there are differences in the incidence of ischemic or hemorrhagic strokes.

METHODS: We performed a register-based matched cohort study including all community-dwelling persons with verified clinical diagnosis of AD, residing in Finland on December 31, 2005, and a single age-, sex-, and region of residence-matched comparison person without AD for each individual with AD (n = 56,186, mean age 79.6 [SD 6.9] years). Persons with previous strokes and their matched participants were excluded, leaving 50,808 individuals with 2,947 incident strokes occurring between January 1, 2006, and December 31, 2009. Diagnosis of AD was based on prescription reimbursement register and diagnosis of stroke on hospital discharge register of Finland.

RESULTS: AD dementia was not associated with risk of all strokes or ischemic strokes, but the risk of hemorrhagic strokes was higher among persons with AD (adjusted hazard ratio [95% confidence interval] 1.34 [1.12-1.61]). When the associations were analyzed according to age groups, AD was associated with higher risk of all strokes, regardless of etiology, in the 2 youngest age groups, but not in the older groups. Similar associations were observed when the results were categorized according to age at diagnosis.

CONCLUSIONS: Our findings suggest that persons with AD dementia, especially younger patients, have higher risk of hemorrhagic strokes.