Associations between microinfarcts and other macroscopic vascular findings on neuropathologic examination in 2 databases.

Clinicians may undervalue brain microinfarcts because they are defined by neuropathology and not seen on magnetic resonance imaging (MRI). We sought to identify what neuropathologic vascular findings-likely to be evident on brain MRI during life-would predict the presence of microinfarcts. We sought associations between such findings and microinfarcts in neuropathology databases from the National Alzheimer's Coordinating Center (NACC) and the Adult Changes in Thought (ACT) study. Considering only subjects 65 years or older at death, microinfarcts were evaluated in 6189 from NACC and 219 from ACT. Despite different definitions being used, microinfarcts were common in both studies (19.7% in NACC and 16.0% in ACT), and their frequency increased significantly with age. In NACC specimens, after controlling for age and sex in multivariable models, microinfarcts were strongly associated with macroinfarcts [odds ratio (OR): 4.4, 95% confidence interval (CI): 3.8, 5.0], leukoencephalopathy (OR: 2.6, 95% CI: 2.1, 3.3), and hemorrhages (OR: 2.0, 95% CI: 1.6, 2.6). Similarly in the ACT specimens, microinfarcts were strongly associated with macroinfarcts (OR: 2.9, 95% CI: 1.4, 6.3). These neuropathologic associations suggest that people whose cranial MRI shows macroinfarcts, hemorrhages, or leukoencephalopathy are more likely also to have microinfarcts.