A large-scale genomic analysis partitioning Alzheimer's disease (AD) polygenic risk across 166 tissue annotations and 4.4 million single cells spanning 28 peripheral tissues and 100 brain regions found that AD genetic risk concentrates in peripheral—not solely central nervous system—biology. The strongest enrichments localized to circulating and tissue-resident myeloid cells, hepatocytes, cardiac muscle, and intestinal epithelium. Crucially, immune-cell enrichment was independent of the APOE locus, while metabolic enrichment was substantially APOE-driven. Mendelian randomization pointed to predominantly protective effects of peripheral immune genes.
This preprint, not yet peer-reviewed, challenges a decade of AD genetics research that centered almost exclusively on brain microglia and neuronal pathways as the primary mediators of genetic risk. The findings align with emerging clinical observations linking metabolic syndrome, gut dysbiosis, and systemic inflammation to AD incidence—but now ground those associations in formal genetic architecture rather than epidemiological correlation. For longevity-focused adults, the data suggest that interventions targeting liver metabolism, gut epithelial integrity, and systemic immune tone may have mechanistic, not merely symptomatic, relevance to AD prevention. Limitations include the analytical nature of the work—no new clinical cohort is enrolled, and causal direction from Mendelian randomization remains dependent on instrument validity. Translating tissue enrichment into druggable targets will require functional validation. Still, reframing AD as a systemic disease with peripheral genetic drivers is a potentially paradigm-shifting perspective warranting close follow-up once peer review is complete.
