Cognitive dispersion is associated with white matter hyperintensities in amyloid positive older adults.

Objective

White matter hyperintensities (WMH), imaging markers of small vessel cerebrovascular disease, are associated with risk of dementia, including Alzheimer's disease (AD). Cognitive intraindividual variability (IIV) has emerged as a sensitive measure of future decline. We examined associations between IIV-dispersion, beta-amyloid (Aß) positivity, and WMH in older adults. Method: We included 819 participants (mean age = 72.01) without dementia from the Alzheimer's Disease Neuroimaging Initiative. IIV-dispersion was calculated as the intraindividual standard deviation across 6 neuropsychological scores. WMH volume was quantified on T2-weighted fluid attenuated inversion recovery images. Regression models examined interactions between IIV-dispersion and Aß status on WMH, adjusting for age, sex, and education.

Results

Amyloid status moderated associations between IIV-dispersion and WMH, such that higher IIV-dispersion was associated with greater WMH in Aß+ individuals whether WMH was examined as a continuous (B = 0.30, ß = 0.13, p = .006) or a dichotomous variable based on quartiles (odds ratio [OR] = 2.41, p < .001). Sensitivity analyses to adjust for the effects of individual mean cognition in the models modified findings such that greater IIV-dispersion was again associated with greater WMH in Aß+ individuals when WMH was examined dichotomously (OR = 2.13, p = .018) but the effect was attenuated for continuous WMH.

Conclusions

Greater IIV-dispersion was associated with greater WMH among Aß+ individuals. IIV-dispersion may be an early marker of cerebrovascular changes in AD although future research is needed to further establish its incremental utility.