Incidence and risk factors of silent brain infarcts in the population-based Rotterdam Scan Study

The prevalence of silent brain infarcts in healthy elderly people is high, and these lesions are associated with an increased risk of stroke. The incidence of silent brain infarcts is unknown. We investigated the incidence and cardiovascular risk factors for silent brain infarcts.

The Rotterdam Scan Study is a prospective, population-based cohort study of 1077 participants 60 to 90 years of age. All participants underwent cranial MRI in 1995 to 1996, and 668 participants had a second MRI in 1999 to 2000 (response rate, 70%) with a mean interval of 3.4 years. We assessed cardiovascular risk factors by interview and physical examination at baseline. Associations between risk factors and incident silent infarcts were analyzed by multiple logistic regression.

Ninety-three participants (14%) had > or =1 new infarcts on the second MRI; of these, 81 had only silent and 12 had symptomatic infarcts. The incidence of silent brain infarcts strongly increased with age and was 5 times higher than that of symptomatic stroke. A prevalent silent brain infarct strongly predicted a new silent infarct on the second MRI (age- and sex-adjusted odds ratio, 2.9; 95% confidence interval, 1.7 to 5.0). Age, blood pressure, diabetes mellitus, cholesterol and homocysteine levels, intima-media thickness, carotid plaques, and smoking were associated with new silent brain infarcts in participants without prevalent infarcts.

The incidence of silent brain infarcts on MRI in the general elderly population strongly increases with age. The cardiovascular risk factors for silent brain infarcts are similar to those for stroke.