Working status and risk of Alzheimer's disease: A Mendelian randomization study.

BACKGROUND: Alzheimer's disease (AD) has become a common illness affecting the elderly, adding to society's social and financial burden. We used two-sample Mendelian randomization (MR) in this study to determine the association between working status and AD. METHODS: We performed a two-sample MR analysis. The genetic associations were derived from the UK Biobank (n = 263,615) and the International Genomics of Alzheimer's Project (n = 63,926). Inverse variance weighted (IVW), MR-Egger, and weighted median were used in the MR analysis. The funnel plot, Cochran's Q test, MR-Egger intercept test, and leave-one-out analysis were used in sensitivity analyses. Further risk factor analyses were carried out to look into the potential mediators. RESULTS: Jobs involve heavy manual or physical work (OR = 2.13, 95%CI 1.36-3.36; p = .0011), job involves mainly walking or standing (OR = 1.74, 95%CI 1.19-2.54; p = .004), and job involves shift work (OR = 2.78, 95%CI 1.14-6.80; p = .02) increased the risk of AD in the IVW analysis. There was no heterogeneity and no horizontal pleiotropy in the sensitivity analysis. Risk factor analysis suggested that each of the above association may be mediated by different risk factors. CONCLUSION: Our study adds to the evidence that the development of AD is associated with the working status (job involves heavy manual or physical work, job involves mainly walking or standing, and job involves shift work) by using extensive human genetic data.