Association between Aβ and tau accumulations and their influence on clinical features in aging and Alzheimer's disease spectrum brains: A [(11)C]PBB3-PET study

INTRODUCTION: Amyloid-β (Aβ) and tau accumulations may occur independently and concurrently as exemplified by primary age-related tauopathy and Alzheimer's disease (AD), respectively. Interactions between Aβ and tau accumulations and their influence on clinical features, however, are still unclear. METHODS: Associations among clinical symptoms, gray-matter volume, regional tau, and Aβ deposition assessed by positron emission tomography with [(11)C]pyridinyl-butadienyl-benzothiazole 3 (PBB3) and [(11)C]Pittsburgh compound-B (PiB), were evaluated in 17 AD, 9 mild cognitive impairment due to AD, and 28 PiB(−)-cognitive healthy controls (HCs). RESULTS: High tau burden was associated with aging and low-level education in PiB(−)-HC and AD-spectrum groups, and with high Aβ burden and low-level education in all subjects. It was not Aβ but tau accumulation that showed significant associations with cognitive performance even in PiB(−)-HC. DISCUSSION: The present study indicated aging and low-level education after Aβ would be enhancers for tau pathology, associated with neurodegeneration and cognitive impairment in healthy and diseased elderly individuals.