Association of Prior Stroke With Cognitive Function and Cognitive Impairment A Population-Based Study

Background: Defining the nature of the contribution of stroke to cognitive impairment remains challenging. Objective: To describe associations between stroke history, APOE genotype, and subtypes of mild cognitive impairment (MCI). Methods: We randomly selected residents from Olmsted County, Minnesota, aged 70 to 89 years on October 1, 2004, and invited eligible subjects without documented dementia to participate. Participants (n=2050) were evaluated through an informant interview, a neurological evaluation, and neuropsychological testing. Neuropsychological testing included 9 tests to assess memory, attention, executive function, visuospatial cognition, and language. Subjects were diagnosed by consensus as cognitively normal or as having MCI (either amnestic or non-amnestic) or dementia. A history of stroke was obtained from the subjects and confirmed in their medical records. We computed the odds ratios (ORs) for a clinical diagnosis of MCI or for scoring in the lowest quartile on each cognitive domain. Results: There were 1640 cognitively normal subjects and 329 subjects with MCI: 241 with amnestic MCI and 88 with nonamnestic MCI. In fully adjusted models with only subjects without dementia, a history of stroke was associated with a higher OR of nonamnestic MCI (OR, 2.85; 95% confidence interval [CI], 1.61-5.04) than amnestic MCI (OR, 1.77; 95% CI, 1.14-2.74). A history of stroke was also associated with impaired function in each cognitive domain except memory. The association was strongest for attention and executive function (OR, 2.48; 95% CI, 1.73-3.53). APOE epsilon 4 genotype was associated only with amnestic MCI and with impaired memory function. Conclusions: In this population-based sample of persons without dementia, a history of stroke was particularly associated with nonamnestic MCI and impairment in nonmemory cognition. The APOE e4 genotype was associated with memory impairment and amnestic MCI.