Cognitively Healthy Centenarians are genetically protected against Alzheimer’s disease

Abstract

AbstractBackgroundThe prevalence of Alzheimer’s Disease (AD) increases with age, yet a small fraction of the population reaches ages beyond 100 years maintaining cognitive abilities, so‐called cognitively‐healthy‐centenarians. We aimed to uncover the genetic factors associated with such protection against AD, and to highlight the effects of AD‐associated variants during advanced aging.MethodPrevious Genome‐Wide‐Association‐Studies (GWAS) identified 86 single‐nucleotide‐polymorphisms (SNPs) associated with AD‐risk. We investigated the frequency of each SNP in 346 cognitively‐healthy‐centenarians (mean age 101.05±2.51), compared to 2,281 AD cases (mean age 67.96±9.84), 3,165 middle‐aged healthy controls (mean age 62.57±8.66), and we combined the SNPs into Polygenic Risk Scores (PRS) for each individual. Finally, we characterized the functional properties of the SNPs enriched/depleted the most in the centenarians.ResultAt the SNP level, centenarians were depleted with risk‐increasing SNPs and enriched with protective SNPs. The AD‐related PRS (excluding APOE SNPs) was significantly lower in centenarians; not only compared to AD (OR = 1.96, p = 4.07×10−26), but also to middle‐aged controls (OR = 1.29, p = 2.61×10−5). When including APOE SNPs these effects were even stronger (OR = 5.07, p = 6.15×10−71, and OR = 1.87, p = 4.67×10−17, for comparisons with AD and normal controls, respectively). The most depleted/enriched SNPs in centenarians functionally mapped to activation/regulation of immune response and endocytosis/phagocytosis. These SNPs were located near ANKH, TMEM106B, CLNK, EPDR1, WDR12, PLCG2, RIN3, CD2AP, MS4A, TREM2, ABCA7 and MAF.ConclusionThe ability to reach advanced age without cognitive decline is influenced by AD‐associated genetic variants. An advantageous regulation of the brain’s immune system, intracellular protein trafficking, and endocytosis/phagocytosis may confer the strongest protection against AD and potentially other age‐related diseases.