AV-1451 TAU-PET BINDING IN TYPICAL AND ATYPICAL SYNDROMIC VARIANTS OF ALZHEIMER’S DISEASE

Abstract

Patients with Alzheimer’s disease typically present with episodic memory loss (dementia of the Alzheimer’s type (DAT)). However, 25% can have an atypical presentation dominated by language difficulties (logopenic aphasia (lvPPA)), or visuo-spatial/perceptual deficits (posterior cortical atrophy (PCA)). Tau-PET imaging using AV-1451 demonstrates striking uptake in DAT. It remains unclear whether elevated uptake occurs in atypical AD and whether regional patterns of uptake differ from DAT. We aimed to investigate tau-PET imaging in atypical AD. Tau-PET imaging using AV-1451 was performed in three patients with PCA and three with lvPPA; all six had a positive beta-amyloid PiB-PET scan. These six patients were compared to an age-matched group of 101 controls and 19 patients with DAT. Regional tau-PET uptake was assessed within medial and lateral temporal, parietal, frontal and occipital grey matter regions using the automated anatomical labelling atlas. Compared to controls, elevated tau uptake was observed in all PCA and lvPPA subjects. The PCA subjects all showed greatest uptake in occipital lobe and asymmetric patterns of uptake, with greatest involvement of the right hemisphere. Two PCA subjects showed additional widespread involvement of frontal, temporal and parietal lobes, with more focal and mild patterns observed in the third. The lvPPA subjects all showed left-sided patterns of uptake with the lateral temporal lobes showing striking uptake in two subjects. The third lvPPA subject showed widespread uptake throughout the cortex. Regional patterns of uptake in PCA and lvPPA overlapped with those observed in DAT, although there was a tendency for the left hippocampus to be involved to a greater degree in DAT.