An Investigation of White Matter Hyperintensities in Probable Dementia with Lewy Bodies (P6.235)

Objective: To investigate the pattern of distribution and clinical relevance of white matter hyperintensities (WMH) in patients with probable dementia Lewy Bodies (DLB). Background: WMH on MRI are thought to be associated with ischemic small vessel disease in the aging brain; however, little is known about their clinical impact in DLB. Methods: Probable DLB (n=81; mean age=72 years) and Alzheimer’s disease dementia (ADD) (n=240; mean age=75 years) patients were consecutively recruited to the Mayo Clinic AD Research Center and underwent 3T-MRI. Two groups of cognitively normal subjects (CN), age and sex matched to DLB (n=81) and ADD (n=240) with 3T-MRIs were included from the population-based Mayo Clinic Study of Aging. WMH were quantified on FLAIR scans. Regional distribution of WMH was compared with voxel-based analysis (VBA). Results: WMH volumes were higher in both DLB and ADD compared to the matched CN groups (p<0.001). Higher WMH in the occipital lobes were observed in DLB compared to ADD on VBA after adjusting for age (p<0.05; FDR-corrected). DLB patients with cardiovascular disease (p=0.05) and diabetes (p=0.04) had more WMH, and those with REM-sleep behavior disorder (RBD) had less WMH (p=0.04) than those without these features. WMH was not associated with other clinical features of DLB, nor with dementia severity and UPDRS. Conclusions: Greater occipital WMH in patients with DLB compared to ADD is consistent with previous observations of occipital hypo-metabolism on PET and occipital microstructural WM disruption on diffusion MRI in DLB. However, WMH volume does not appear to have a significant impact on the clinical features of DLB. In fact, DLB patients with RBD tend to have less WMH, but those with cardiovascular disease and diabetes tend to have more WMH than those without, suggesting that vascular disease is an important contributor to WMH in DLB.