Abstract
BACKGROUND: To establish a polysocial risk score (PsRS) incorporating various social factors for capturing the dementia risk and investigate the benefits of favorable social conditions across different genetic backgrounds.
METHODS: This prospective cohort study comprised 345 439 participants initially free of dementia from the UK Biobank. A total of 10 social factors were summed to create a PsRS. A polygenic risk score (PRS) was constructed based on genome-wide significant variants.
RESULTS: During a median follow-up of 12.5 years, we documented 4 595 incident all-cause dementia events including 2 067 Alzheimer’s disease (AD) events and 1 028 vascular dementia (VD) events. Each additional PsRS was associated with a 19% increased risk of all-cause dementia (hazard ratio [HR], 1.19; 95% confidence interval [CI], 1.17 to 1.21), a 13% increased risk of AD (1.13; 1.10 to 1.16), and a 24% increased risk of VD (1.24; 1.19 to 1.29). 29% (24% to 33%) of dementia cases, 22% (14% to 29%) of AD cases, and 39% (28% to 48%) of VD cases were associated with a disadvantageous social environment. In addition, among participants at a high genetic risk, the low social risk was linked to a lower incidence rate of all-cause dementia, AD, and VD compared to those who had a high social risk, with reductions of 67.8%, 64.5%, and 84.2%, respectively.
CONCLUSIONS: The PsRS could be effectively used in discriminating individuals at high risk of dementia. Around a quarter of dementia events could have a connection with a disadvantageous social environment, especially for those genetically susceptible to dementia.