Alzheimer’s polygenic risk scores, APOE, Alzheimer’s disease risk, and dementia-related blood biomarker levels in a population-based cohort study followed over 17 years

Abstract

AbstractBackgroundIn order to utilize polygenic risk scores (PRSs) for Alzheimer’s disease (AD) in a meaningful way, influential factors (i.e. training set) and prediction across groups such asAPOE e4 (APOE4)genotype as well as associations to dementia-related biomarkers should be explored. Therefore, we examined the association ofAPOE4and various PRSs, based on training sets that utilized differing AD definitions, with incident AD and all-cause dementia (ACD) within 17 years, and with levels of phosphorylated tau181 (P-tau181), neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) in blood. Secondarily, effect modification byAPOE4status and sex was examined.MethodsIn this prospective, population-based cohort study and nested case–control study, 9,940 participants in Germany were enrolled between 2000 and 2002 by their general practitioners and followed for up to 17 years. Participants were included in this study if dementia status and genetic data were available. A subsample of participants additionally had measurements of P-tau181, NfL, and GFAP obtained from blood samples. Cox and logistic regression analyses were used to assess the association of genetic risk (APOEgenotype and PRSnoAPOE) with incident ACD/AD and log-transformed blood levels of P-tau181, NfL, and GFAP.ResultsFive thousand seven hundred sixty-five participants (54% female, aged 50-75years at baseline) were included in this study, of whom 464 received an all-cause dementia diagnosis within 17 years. The PRSs were not more predictive of dementia thanAPOE4. AnAPOE4specific relationship was apparent with PRSs only exhibiting associations to dementia amongAPOE4carriers. In the nested case–control study including biomarkers (n = 712),APOE4status and polygenic risk were significantly associated to levels of GFAP in blood.ConclusionsThe use of PRSs may be beneficial for increased precision in risk estimates amongAPOE4carriers. WhileAPOE4may play a crucial etiological role in initial disease processes such as Aβ deposition, the PRS may be an indicator of further disease drivers as well as astrocyte activation. Further research is necessary to confirm these findings, especially the association to GFAP.