Prevalence and Risk Factors of Acute Incidental Infarcts

The study of silent stroke has been limited to imaging of chronic infarcts; acute incidental infarcts (AII) detected on brain magnetic resonance imaging have been less investigated. This study aims to describe prevalence and risk factors of AII in a community and a clinic-based population.

Subjects were drawn from 2 ongoing studies: Epidemiology of Dementia in Singapore study, which is a subsample from a population-based study, and a clinic-based case-control study. Subjects from both studies underwent similar clinical and neuropsychological assessments and brain magnetic resonance imaging. Prevalence of AII from these studies was determined. Subsequently, risk factors of AII were examined using multivariable logistic regression models.

AII were seen in 7 of 623 (1.2%) subjects in Epidemiology of Dementia in Singapore (mean age, 70.9±6.8 years; 45% men) and in 12 of 389 (3.2%) subjects (mean age, 72.1±8.3 years; 46% men) in the clinic-based study. AII were present in 0.8% of subjects with no cognitive impairment, 1.9% of those with cognitive impairment not dementia, and 4.2% of subjects with dementia. Significant association of AII was found with cerebral microbleeds (≥5) in the Epidemiology of Dementia in Singapore (odds ratio, 6.76; 95% confidence interval, 1.28-35.65; P=0.02) and in the clinic-based cohort (odds ratio, 4.65; 95% confidence interval, 1.39-15.53; P=0.01). There was no association of AII with hypertension, diabetes mellitus, or hyperlipidemia.

AII are more likely to be present in those with cognitive impairment. Although a cause-effect relationship between the presence of AII and cognitive impairment is plausible, the association may be because of under-reporting of symptoms by individuals with cognitive impairment. The association between AII and cerebral microbleeds may indicate cerebral vasculopathy, independent of traditional vascular risk factors.