MR signal abnormalities were assessed in 87 symptom-free volunteers (31-83 years of age) and correlated with cerebrovascular risk factors, cerebral blood flow and glucose metabolism. Lesions in the subcortical and deep white matter increased from 11% in the 4th decade to 83% in subjects over 70 years of age, and were detected significantly more often in individuals with cerebrovascular risk factors (p less than 0.01). They were associated with lower slow-compartmental flow (p less than 0.05) but did not affect adjacent cortical glucose metabolism. Periventricular signal changes also increased with age but were unrelated to risk factors or functional data.