Predicting accumulation and age at onset of amyloid-β from genetic risk and resilience for Alzheimer's disease

Background: Accumulation of brain amyloid beta (Aβ), a key pathological hallmark of Alzheimer's disease (AD), begins decades before cognitive symptoms. Being able to predict the risk of Aβ accumulation, or the age at which Aβ exceeds a critical threshold, may enable intervention to delay or prevent onset of AD. Methods: Using published genome-wide association studies (GWASs), we developed polygenic scores (PGS) for AD risk (PGS_risk) and resilience (PGS_resilience), and tested whether these predicted (i) if an individual is an Aβ accumulator (‘Accumulator Status’), and (ii) in accumulators, the age at which brain Aβ exceeds a 20 centiloid (CL) threshold (‘Age at onset of Aβ’; AAO-Aβ) in 2175 participants (1158 with AAO-Aβ) from the Alzheimer's Dementia Onset and Progression in International Cohorts (ADOPIC) study. We also performed GWASs on these traits to develop phenotype-specific PGSs. Findings: Higher genetic risk of AD predicted increased odds of Aβ accumulation (OR = 1.16; 95% CI = 1.05–1.29; p = 0.003) and younger AAO-Aβ (β = −1.32; SE = 0.31; p = 1.63 × 10−5). Higher genetic resilience to AD predicted later AAO-Aβ (β = 0.91; SE = 0.29; p = 0.002) but did not predict Aβ accumulation. These associations were independent of APOE ε4 status, the strongest genetic risk factor for AD. Phenotype-specific PGSs were not significantly associated with either trait. Interpretation: Polygenic scores, alongside other risk factors, may help identify individuals at risk of accumulating Aβ, and predict the age at which this exceeds a critical threshold. This could provide a window for administering disease-modifying treatment or lifestyle interventions to prevent or delay the onset of AD. Funding: National Institutes of Health (R01-AG058676-01A1) and Australian National Health and Medical Research Council (GNT1161706; GNT2001320).