O4‐02‐04: Alzheimer's disease patients with microbleeds and additional white matter hyperintensities: Does it matter?

Abstract

Microbleeds (MBs) are generally considered an expression of cerebral small vessel disease (CSVD), and associations with white matter hyperintensities (WMH) have repeatedly been shown. MBs may also be observed in the absence of WMH, however. We studied how patients with Alzheimer's disease (AD) with both MBs and WMH differ from patients with exclusively MBs and hypothesized that MBs in isolation might indicate underlying cerebral amyloid angiopathy (CAA), while MBs in the company of WMH might reflect hypertensive vasculopathy. A total of 371 AD patients with available T2 and FLAIR MRI scans were included. MBs were counted and WMH were rated with the Fazekas scale. Patients were categorized depending on MB presence (MB-:0; MB+:>1) and WMH presence (WMH-:Fazekas 0-1; WMH+:Fazekas 2-3), into four groups: MB-WMH-; MB-WMH+; MB+WMH- and MB+WMH+. One-way analysis of variance with post-hoc LSD and Chi-squared tests were performed to compare groups. Of all AD patients (age 69+9, 55% female), 158 (43%) presented with MBs and/or WMH. Within this group, 47 (30%) patients presented with MB+WMH+, 51 (32%) patients had MB+WMH- and 60 (38%) patients had MB-WMH+. ANOVA's showed group differences for age, sex, systolic blood pressure, hypertension, MTA and lacunes (Table 1). APOE-ε4 status did not differ significantly. Cerebrospinal fluid (CSF) levels of Aß42 differed only for MB-WMH- versus MB+WMH+ (488+169 vs. 420+103, P<0.05). When directly comparing MB patients with and without WMH, patients with MB+WMH+ were older (74+10 vs. 68+9, P<0.05), presented more often with lacunes (24% vs. 5%, P<0.05) and showed a trend towards presenting more frequently with multiple MBs (62% vs. 43%, P = 0.07). In this fairly young sample, a substantial number of AD patients presented with MBs and/or WMH. Furthermore, we found that MBs regularly occur in the absence of WMH. We were not able to show a relationship with characteristics indicating a specific underlying substrate. The group with isolated MBs was younger, presented less often with lacunes and tended towards having fewer MBs than the group with both MBs and WMH, suggesting a less advanced disease stage. We are currently rating MB location to further elucidate this matter.