Association between frailty and depression: A bidirectional Mendelian randomization study.

Abstract

Frailty and depression were linked in observational studies, but the causality remains ambiguous. We intended to explore it using Mendelian randomization (MR). We obtained frailty genome-wide association study (GWAS) data from UK Biobank and TwinGen meta-analysis, and depression GWAS data from Psychiatric Genomics Consortium (PGC) and FinnGen (respectively recorded as PD and FD). We performed univariable and multivariable-adjusted MR with adjustments for body mass index (BMI) and physical activity (PA). Frailty was significantly associated with elevated risks of PD (OR, 1.860; 95% CI, 1.439 to 2.405; <i>P</i> < 0.001) and FD (OR, 1.745; 95% CI, 1.193 to 2.552; <i>P</i> = 0.004), and depression was meanwhile a susceptible factor for frailty (PD: β, 0.146; 95% CI, 0.086 to 0.201; <i>P</i> < 0.001; and FD: β, 0.112; 95% CI, 0.051 to 0.174; <i>P</i> < 0.001). This association was robust after adjustments for BMI or PA. Our study provides evidence of the bidirectional causal association between frailty and depression from genetic perspectives.