In vivo tau is associated with retrospective change in memory and processing speed, but not reasoning, in cognitively unimpaired older adults.

Abstract

AbstractBackgroundThe relationship between tau accumulation and cognitive decline in cognitively unimpaired older adults is still unclear. The tau PET tracer 18F‐MK‐6240 has shown favorable imaging carachteristics to identify early tau accumulation in older adults.MethodWe evaluated the relationship between in vivo tau levels (18F‐MK‐6240) and retrospective cognitive change over 5 years in episodic memory, processing speed, and reasoning. For tau quantification, we created a set of regions of Interest (ROIs), selected a priori based on previous literature: 1) Total‐ROIs comprising all 16 areas selected; 2) Medial Temporal Lobe‐ROI, 3) Lateral Temporal Lobe‐ROI and Cingulate/Parietal lobel‐ROI.Result41 cognitively unimpaired older adults was included in the study, 82% classified as amyloid‐b negative. Higher tau burden in most meta‐ROIs was associated with steeper decline in memory and speed. There were no associations between tau and reasoning change.ConclusionOur finding reforces the notion that early tau accumulation in areas related tio Alzheimer’s disease is associated with cognitive decline in cognitively unimpaired individuals, even in a sample characterized with low amyloid‐b pathology. The novel contributin of this work is the relevante of tau accumulation beyond memory, particularly in processing speed decline.