Dissecting the genetic and proteomic risk factors for delirium.

Delirium is an acute change in cognition, common in hospitalized older adults, and associated with high healthcare and human cost; however, delirium's genetic and proteomic background remains poorly understood. Here we conducted a genetic meta-analysis on delirium using multi-ancestry data from the UK Biobank, FinnGen, All of Us Research Program and Michigan Genomics Initiative cohorts (n = 1,059,130; 11,931 cases), yielding the Apolipoprotein E (APOE) gene as a strong delirium risk factor independently of dementia. A multi-trait analysis of delirium with Alzheimer disease identified five delirium genetic risk loci. Plasma proteins associated with up to 16-year incident delirium in UK Biobank (n = 32,652; 541 cases) revealed protein biomarkers implicating brain vulnerability, inflammation and immune response processes. Incorporating proteomic and genetic evidence via Mendelian randomization, colocalization and druggability analyses, we indicate potentially useful drug target proteins for delirium. Combining proteins, APOE-ε4 status and demographics significantly improved incident delirium prediction compared to demographics alone. Our results provide insight into delirium's etiology and may guide further research on clinically relevant biomarkers.