The association of magnetic resonance imaging measures with cognitive function in a biracial population sample.

BACKGROUND: White matter hyperintensity volume (WMHV), cerebral infarcts, and total brain volume (TBV) are associated with cognitive function, but few studies have examined these associations in the general population or whether they differ by race.

OBJECTIVE: To examine the association of WMHV, cerebral infarcts, and TBV with global cognition and cognition in 5 separate domains in a biracial population sample.

SETTING: A biracial community population of Chicago, Illinois.

DESIGN: Cross-sectional population study.

PARTICIPANTS: The study population comprised 575 participants from the Chicago Health and Aging Project (CHAP).

MAIN OUTCOME MEASURES: Volumetric magnetic resonance imaging (MRI) measures of WMHV, TBV, and cerebral infarcts and detailed neuropsychological testing assessments of global cognition and 5 cognitive domains.

RESULTS: Overall and among those without dementia, cognition was inversely associated with WMHV and number of infarcts but was positively associated with TBV. When all 3 measures were simultaneously added to the model, the association of global cognition with WMHV and TBV remained significant and unchanged but was no longer significant with infarcts. Among subjects without dementia, all 3 MRI measures were associated with performance in multiple cognitive domains, specifically perceptual speed. However, among subjects with dementia, only TBV was associated with cognition and performance in multiple cognitive systems. Race did not significantly modify any of these associations.

CONCLUSIONS: In this biracial general population sample, the associations of MRI measures with cognition differed according to clinical status of subjects (stronger among subjects without dementia) and were not modified by race. These associations did not affect all cognitive domains equally but were more consistent with impairments in perceptual speed.