Summative effects of vascular risk factors on cortical thickness in mild cognitive impairment.

Vascular risk factors (VRFs) increase the risk of Alzheimer's disease (AD) and contribute to neurodegenerative processes. The purpose of this study was to investigate whether increasing number of VRFs contributes to within-cohort differences in cortical thickness (CThk) among adults with mild cognitive impairment (MCI) and cognitively intact older controls from the AD Neuroimaging Initiative 1, GO, and 2 data sets. Multivariate partial least squares analysis was used to investigate the effect of VRF index on regional CThk measurements, which produced a significant latent variable and identified patterns of cortical thinning in the MCI group but not controls. Subsequent analyses tested the interaction effects between VRF index and cognitive grouping and examined 1-year follow-up data. There was evidence of a VRF index by cognitive group interaction. Partial least squares results were replicated at 1-year follow-up among MCI cohort in a subset of baseline CThk regions. This study provides evidence that a summative VRF index accounts for some of the variance in brain tissue loss in regions implicated in AD among MCI adults.