Abstract 42: Impact Of White Matter Hyperintensities Extension On Rate Of Cognitive Decline
Background: Characterizing the impact of cerebral white matter (WM) damage in age related cognitive decline is of growing interest. Recently, we used DTI to show that White Matter Hyperintensities (WMH) are surrounded by a penumbra of subtly-injured WM. Because this finding supported the view that WMH may result from a continuous WM degeneration process rather than a sudden event, longitudinal studies are needed to determine whether development of WMH may determine subsequent change in cognitive performances.
Methods: This study examined the strength of association between longitudinally measured WMH and longitudinally measured cognition in a sample of 153 individuals. The sample included AD, MCI, and cognitively normal (CN) who completed cognitive evaluation and MRI scans on two dates (mean delay: 4.0 years). Psychometrically matched measures of cognition were used to assess episodic memory and executive function at both dates. WMHs were repeatedly measured, and incident WMH dissociated into two categories: WMH Extension (extension of existing baseline WMH) and WMH Emergence (newly formed WMH). We used a stepwise approach to investigate the effects of Baseline WMH and rates of WMH Extension and Emergence on the rate of change in episodic memory and executive functions including gender, years of education, ethnicity, BV and the baseline corresponding cognitive score as covariates.
Results: Analyses revealed significant increases in total WMH burden over time. In addition, baseline WMH volume and rate of WMH Extension, but not Emergence, were significantly associated with rates of change in cognitive measures with larger baseline WMH and higher rate of WMH Extension being associated with steeper rate of decline in executive functions and episodic memory (see Figure1).
Discussion: This work provides evidence that the extension over time of WMH, but not newly formed WMH, is a predictor of the rate of cognitive decline. This result is of importance as the extension of WMH accounted for about 80% of the overall WMH.
- © 2012 by American Heart Association, Inc.