Longitudinal changes of amyloid (A) and tau (T) image‐based biomarker in Alzheimer’s disease spectrum

Abstract

AbstractBackgroundTo investigate long‐term changes in dichotomous profiles of amyloid (A) and tau (T) image‐based biomarker in Alzheimer’s disease (AD) spectrum.MethodDuring the initial visit (V1), a total of 275 participants [96 cognitively unimpaired (CU), 108 mild cognitive impairment (MCI), and 71 AD] who completed 18F‐florbetaben and 18F‐flortaucipir PET studies were followed up to three times. Two years later, 189 participants (74 CU, 77 MCI, and 38 AD) were enrolled in the second visit (V2), and 83 participants (34 CU, 39 MCI, and 10 AD) were enrolled in the third visit (V3) five years later (mean 4.8 years) to complete the same PET studies. The A and T biomarker profile was determined based on the cut‐off standardized uptake value ratio of the most vulnerable region in each pathology.ResultIn A‐ participants, 5.4% (6/111) of participants converted to A+ at V2 and 17.9% (7/39) converted to A+ at V3. Likewise, 2.9% (4/138) of participants in T‐ participants converted to T+ at V2, and 17.7% (11/62) converted from T‐ to T+ at V3. Compared to the low conversion rate from T‐ to T+ in A‐T‐ participants [0.9% (1 A‐T+ / 106 A‐T‐) at V2 and 5.1% (2 A+T+ / 39 A‐T‐)] at V3, A+T‐ participants showed higher conversion rates from T‐ to T+ [9.4% (3 A+T+ / 32 A+T‐) at V2 and 39.1% (9 A+T+ / 23 A+T‐) at V3].ConclusionThe conversion of the at biomarker profile was observed more prominently in the long term than in the short term, and the conversion of the T biomarker in A+ compared to A‐ was over seven times more frequent in five years follow‐up.