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.