Association between stroke and Alzheimer's disease: systematic review and meta-analysis.

Alzheimer's disease (AD) and stroke are common disorders of aging, but the relationship between these two disorders remains uncertain. Recent evidence recognized that they frequently co-occur and are influenced by each other, while other studies have produced inconsistent results. We conducted this systematic review and meta-analysis of stroke on risk for AD and AD on risk for stroke subtypes to clarify the relation between these two disorders on the basis of the studies published from 1975 to November 2013 in the PubMed, EMBASE, and Cochrane Library databases. In total, 7 cohort studies and 2 nested case-control studies met the inclusion criteria for meta-analysis. For stroke, the pooled effect size for AD risk was 1.59 (95% CI 1.25-2.02; z = 3.76; p = 0.000). For AD dementia, it was not associated with risk of all strokes or ischemic stroke (IS), but the risk of intracerebral hemorrhage (ICH was higher among persons with AD. The pooled RR for AD in relation to incident IS did not indicate a significant association (RR: 1.13; 95% CI 0.75-1.70; z = 0.58; p = 0.565). The pooled effect size for AD and ICH risk was 1.41 (95% CI 1.21-1.66; z = 4.27; p < 0.001). Stroke significantly and independently increased risk for AD and in turn AD increased risk for ICH. These results confirm that AD and ICH may have common pathogenesis and share preventive treatment measures.