Amyloid and tau PET imaging studies as a clinical prognostic marker in Alzheimer’s disease

Abstract

AbstractBackgroundTo investigate prognostic value of amyloid (A) and tau (T) imaging biomarkers in a long term follow up cohort study.MethodWe included 273 AD spectrum participants [96 cognitive unimpaired (CU), 106 mild cognitive impairment (MCI) and 71 AD dementia (DEM)] who completed 18F‐florbetaben, 18F‐flortaucipir PET and T1‐weighted MRI. Global cortical standardized uptake value ratios (SUVR) of 18F‐florbetaben, temporal meta‐region‐of‐interest SUVR of 18F‐flortaucipir and hippocampal atrophy of T1‐weighted MRI were used to define AT(N) classification. Longitudinal cognitive change was evaluated by repeated Mini‐Mental State Examination (MMSE) and Clinical Dementia Rating Sum of Boxes (CDR‐SB). Participants were categorized according to their A/T imaging biomarker, 18F‐florbetaben PET positive/negative (A+/A‐) and 18F‐flortaucipir PET positive/negative (T+/T‐) profiles. For measuring prognosis, we investigated the nursing care facility admission rate for all participants and the AD conversion rate for CU and MCI over 60 months.ResultParticipants were included CU (77/96 A‐T‐, 1/96 A‐T+, 11/96 A+T‐ and 7/96 A+T+), MCI (59/106 A‐T‐, 2/106 A‐T+, 18/106 A+T‐ and 27/106 A+T+) and DEM (20/71 A‐T‐, 1/71 A‐T+, 16/71 A+T‐ and 34/71 A+T+). Annual cognitive function change of all participants was correlated with A+ (MMSE: B=‐0.5944, p <0.000; CDR‐SB: B=0.6288, p <0.000), T+ (MMSE: ‐0.8187, p <0.000; CDR‐SB: B=0.7524, p <0.000), hippocampal atrophy (MMSE: B=‐0.3940, p <0.000; CDR‐SB: B=0.5577, p <0.000) and A+T+ compared with A‐T‐ (MMSE: B=‐0.8917, p <0.000; CDR‐SB: 0.8680, p <0.000, Figure 1). Admission rate of nursing care facility of all participants was higher with A+ (HR=2.37, p =0.026), T+ (HR=2.65, p =0.006) and A+T+ (HR=3.06, p=0.006). AD conversion rate in CU and MCI (n=202) was higher with A+ (HR=2.98, p=0.003), T+ (HR=3.19, p<0.000) and A+T+ (HR=3.897, p <0.000, Figure 2).ConclusionA/T imaging biomarkers have prognostic value for annual cognitive decline rate, anticipating admission rates to nursing care facility, and AD conversion rate.