Using subjective cognitive decline to identify high global amyloid in community-based samples: A cross-cohort study

Introduction: We aimed to examine the contribution of subjective cognitive decline (SCD) to reduce the number of beta-amyloid (A beta) positron emission tomography scans required for recruiting A beta+ clinically normal individuals in clinical trials. Methods: Three independent cohorts (890 clinically normal: 72 yrs 6.7; Female: 43.4%; SCD+: 24%; apolipoprotein E [APOE] epsilon 4+: 28.5%; A beta+: 32%) were used. SCD was dichotomized from one question. Using logistic regression, we classified A beta+ using the SCD dichotomy, APOE epsilon 4, sex, and age. Results: SCD increased odds of A beta+ by 1.58 relative to non-SCD. Female APOE epsilon 4 carriers with SCD exhibited higher odds of A beta+ (OR = 3.34), whereas male carriers with SCD showed a weaker, opposing effect (OR = 0.37). SCD endorsement reduces the number of A beta positron emission tomography scans to recruit A beta+ individuals by 13% and by 9% if APOE epsilon 4 status is known. Conclusion: SCD helps to classify those with high A beta, even beyond the substantial effect of APOE genotype. Collecting SCD is a feasible method for targeting recruitment for those likely on the AD trajectory. (C) 2019 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association.