Progression of white matter hyperintensities in Alzheimer disease, dementia with lewy bodies, and Parkinson disease dementia: a comparison with normal aging.

OBJECTIVE: The objective of this study was to investigate cross-sectional and longitudinal white matter hyperintensity (WMH) changes in older subjects with clinically diagnosed dementia. METHODS: Fluid-attenuated inversion recovery images were acquired one year apart in subjects with dementia with Lewy bodies (DLB), Parkinson disease dementia (PDD), Alzheimer disease (AD), and also healthy elderly comparison subjects. WMH volume was quantified using an automated technique. RESULTS: Baseline WMH (as a percent of brain volume) was significantly greater compared with healthy subjects (N=33, geometric mean WMH: 0.4%) in subjects with AD (N=23 [1.3%], analysis of variance post hoc p <0.001) but not PDD (N=13 [0.6%]) or DLB (N=14 [0.4%]). Increase in WMH volume (as a percent of brain volume) was not significantly different (Kruskal-Wallis p=0.4) between groups (AD median change: 0.08%; DLB: 0.025%; PDD: 0.07%, healthy: 0.02%). Severity of baseline WMH, rather than diagnosis or severity of dementia, was a significant predictor of lesion progression. Rate of change of WMH had no association with change in global cognitive performance. CONCLUSIONS: Significant WMH progression occurs in degenerative dementias with rates influenced by severity of lesions at baseline rather than dementia type or cognitive decline.