Late Midlife Subclinical Infarct Burden and Risk of Dementia: The Atherosclerosis Risk in Communities Neurocognitive Study.

At visit 3 (1993-1995) of the ARIC Study, 1.5T brain MRI was completed in 1,881 stroke-free participants (Mean age = 62.9±4.9, 50% Black). Cox regression examined associations between infarct group [infarct-free (referent; n = 1,611), smaller only (<3 mm; n = 50), larger only (≥3 mm but <20 mm; n = 185), both (n = 35)] and up to 25-year incident dementia (n = 539). Participants with both infarcts were over 2.5 times more likely to develop dementia [HR = 2.61; 95% CI = 1.44, 4.72]. Smaller only (HR = 1.22; 95% CI = 0.70, 2.13) and larger only (HR = 1.27; 95% CI = 0.92, 1.74) groups showed associations with wide confidence intervals, unsupported statistically. A late midlife infarct profile including smaller and larger infarcts may represent particular vulnerability to dementia risk.