Neuroticism as a predictor of frailty in old age: a genetically informative approach

Abstract

Objective: Neuroticism is associated with poor health outcomes, but its contribution to the accumulation of health deficits in old age, i.e. frailty, is largely unknown. We aimed to explore associations between neuroticism and frailty cross-sectionally and over up to 29 years, and to investigate the contribution of shared genetic influences.Method: Data were derived from the UK Biobank (UKB, n=502,631), the Australian Over 50's Study (AO50, n=3,011) and the Swedish Twin Registry (SALT n=23,744, SATSA n=1,637).Associations between neuroticism and the Frailty Index were investigated using regression analysis cross-sectionally in UKB, AO50 and SATSA, and longitudinally in SALT (25-29y follow-up) and SATSA (6 and 23y follow-up). The co-twin control method was applied to explore the contribution of underlying shared familial factors (SALT, SATSA, AO50). Genome-wide polygenic risk scores for neuroticism in all samples were used to further assess whether common genetic variants associated with neuroticism predict frailty. Results: High neuroticism was consistently associated with greater frailty cross-sectionally (adjusted β, 95% confidence intervals in UKB= 0.32, 0.32-0.33; AO50= 0.35, 0.31-0.39; SATSA= 0.33, 0.27-0.39) and longitudinally up to 29 years (SALT= 0.24; 0.22-0.25; SATSA 6y= 0.31, 0.24-0.38; SATSA 23y= 0.16, 0.07-0.25). When controlling for underlying shared genetic and environmental factors the neuroticism-frailty association remained significant, although decreased.Polygenic risk scores for neuroticism significantly predicted frailty in the two larger samples (metaanalyzed total β= 0.06, 0.05-0.06). Conclusion:High neuroticism is associated with the development and course of frailty. Both environmental and genetic influences, including neuroticism-associated genetic variants, contribute to this relationship.