Abstract WMP49: The Impact of Age vs. Age-Related Comorbidities on White Matter Hyperintensity Volume
Introduction: White matter hyperintensity (WMH) at MRIis a marker of cerebral microvascular disease and confers risk for cognitive impairment. The strongest determinant of WMH volume is age, but the extent to which this is explained by age related abnormalities comorbidities is unclear. Using data from the large, multi-ethnic Dallas Heart Study (DHS), we compared age related differences in WMH volume in the overall DHS cohort to a subset without obesity, diabetes, or hypertension.
Methods: Automated WMH volumes for 2,011 DHS participants were acquired from 3T MRI. The impact of aging on WMH volume independent of comorbidities was quantified in a subset of 218 DHS participants without obesity, diabetes, or hypertension. The impact of comorbidities in the overall cohort was then quantified by subtracting the mean age-specific WMH volumes of the healthy group from the overall cohort and evaluating the association of these normalized values with age using linear regression. To assess the possibility of a threshold effect, data were modeled using cubic splines.
Results: In the healthy cohort, WMH volume was correlated with age (p<0.001) with modest explanatory power (r2=0.12). The explanatory power of age in the overall cohort was higher (r2=0.22) and since a spline fit showed a threshold effect at age 55 (p<0.001), the analysis was stratified at that point. Using normalized data, there was no association between age and WMH volumes prior to age 55 (p=0.3), while WMH volume increased with age after that point (p<0.001), see attached figure.
Conclusions: In this large, multi-ethnic cohort, after accounting for the modest baseline association between age and WMH volume seen in healthy subjects, we characterize the relation between age and WMH volume that reflects the impact of comorbid obesity, hypertension, and diabetes. The observed threshold effect suggests that these comorbidites have little impact on WMH volume prior to age 55, but likely play a significant role above that age.
- © 2012 by American Heart Association, Inc.