Microbleeds, Mortality, and Stroke in Alzheimer Disease: The MISTRAL Study.

IMPORTANCE: Microbleeds are more prevalent in patients with Alzheimer disease (AD) compared with the general elderly population. In addition, microbleeds have been found to predict mortality in AD.

OBJECTIVE: To investigate whether microbleeds in AD increase the risk for mortality, stroke (including intracerebral hemorrhage), and cardiovascular events.

DESIGN, SETTING AND PARTICIPANTS: The MISTRAL (do MIcrobleeds predict STRoke in ALzheimer's disease) Study is a longitudinal cohort study within the memory clinic-based Amsterdam Dementia Cohort. We selected all patients with AD with a baseline visit between January 2, 2002, and December 16, 2009, and microbleeds (n = 111) and matched those (1:2) for age, sex, and magnetic resonance imaging scanner to 222 patients with AD without microbleeds. After a minimal follow-up of 3 years, information on all-cause mortality, stroke-related mortality, and cardiovascular mortality was obtained between November 1, 2012, and May 1, 2014. In addition, we obtained information on the occurrence of incident stroke or transient ischemic attack, cardiovascular events, and nursing home admittance.

MAIN OUTCOMES AND MEASURES: Stroke-related mortality, incident stroke, and intracerebral hemorrhage.

RESULTS: Patients had a mean (SD) age of 71.2 (7.8) years and 127 (42%) were female. Compared with having no microbleeds, microbleeds in lobar locations were associated with an increased risk for stroke-related mortality (hazard ratio [HR], 33.9; 95% CI, 2.5-461.7), whereas nonlobar microbleeds were associated with an increased risk for cardiovascular mortality (HR, 12.0; 95% CI, 3.2-44.7). In addition, lobar microbleeds were associated with an increased risk for incident stroke (HR, 3.8; 95% CI, 1.5-10.1) and nonlobar microbleeds with an increased risk for cardiovascular events (HR, 6.2; 95% CI, 1.5-25.0). Even higher risks for incident stroke and cardiovascular events were found in patients using antithrombotic medication. All 5 patients with an intracerebral hemorrhage had lobar microbleeds at baseline; 4 of them used antithrombotics.

CONCLUSIONS AND RELEVANCE: In patients with AD, the presence of nonlobar microbleeds was associated with an increased risk for cardiovascular events and cardiovascular mortality. Patients with lobar microbleeds had an increased risk for stroke and stroke-related mortality, indicating that these patients should be treated with the utmost care.