O2‐10‐06: Frequency and distribution of cerebral microbleeds in dementia with lewy bodies

Microbleeds (MBs) and superficial siderosis (SS) identified on T2* gradient recalled echo (GRE) and susceptibility weighted MRI are recognized as markers of cerebral microangiopathy in older adults. The frequency and topography of cerebral MBs have not been extensively investigated in dementia with Lewy bodies (DLB). The purpose of this study was to determine the frequency and location of MBs in DLB in comparison with MBs in Alzheimer disease (AD) and cognitively normal controls (CN). Patients with probable DLB (n=20) with median (IQR) age of 68 (64-73) years, who were consecutively recruited to the Mayo Clinic Alzheimer's Disease Research Center (ADRC) and underwent 3T MRI examination with a T2* GRE scan were included. Age and sex matched patients with AD dementia (n=38) from the ADRC and cognitively normal controls (CN; n=83) from the population-based Mayo Clinic Study on Aging were included as referent groups. T2* GRE scans were assessed for the presence of MBs and SS. Frequency of MBs were compared among groups using Fisher's exact tests. A total of 7 DLB (35%), 19 CN (23%) and 8 AD (21%) subjects had at least one MB. A majority of the MBs were located in the frontal lobes in patients with probable DLB (57%), which was not different (p=0.81) from the CN (42%) and AD groups (38%). No MBs were identified in the deep gray nuclei, capsular white matter and infratentorial regions in patients with probable DLB when compared to AD (p=0.03) and CN (p=0.14). SS was present in five (4%) of all the subjects (2 CN and 3 AD). MBs occur at a similar frequency in patients with probable DLB compared to AD dementia and CN. The distribution of MBs showed a characteristic regional pattern in patients with probable DLB, predominantly involving the frontal lobes. The deep gray nuclei, capsular white matter and infratentorial regions, which are thought to be more susceptible to the arteriolosclerosis-related MBs than cerebral amyloid angiopathy were not affected in probable DLB.