IC‐P‐113: Microbleeds in logopenic progressive aphasia

Abstract

Microbleeds (MBs) have been associated with Alzheimer's disease (AD). They occur in 12-33% of patients with typical Alzheimer's dementia, although it is unknown whether they also occur in subjects with logopenic progressive aphasia (LPA); an atypical presentation of AD. We aimed to determine whether MBs occur in subjects with LPA, and to investigate associations between MBs and cognition, white matter hyperintensities (WMH) and β-amyloid deposition. We prospectively recruited nine subjects that met recent clinical criteria for LPA. All subjects underwent a speech and language assessment, neurological assessment, a standardized MRI protocol at 3T, including gradient-recalled echo T2*-weighted and fluid-attenuated inversion recovery (FLAIR) MRI, and Pittsburgh Compound B (PiB)-PET imaging. All MBs were identified on manual review by an experienced neuroradiologist (CRJ) and assigned a regional location using an atlas. Total and regional WMH burden was measured using an automated intensity based algorithm and a white matter parcellation atlas. PiB uptake was normalized to the cerebellum, and global and regional PiB uptake ratios were calculated. Three of the LPA subjects (33%) had MBs (Figure); two subjects had multiple MBs and one subject had just one MB. Microbleeds most commonly occurred in the frontal lobes, but were also present in temporal, parietal, and occipital lobes. Compared to the six subjects without MBs, the subjects with MBs were relatively older at onset (71 versus 65 years), more functionally impaired and had a greater total burden of WMH. All nine LPA subjects were PiB-positive, yet the global cortical PiB ratios were the highest in the three subjects with MBs. The regional distribution of MBs did not match the regional distribution of WMH or β-amyloid deposition. Gradient-recalled echo (GRE) T2∗-weighted MRI showing microbleeds in each three LPA subjects with microbleeds.