1139 MIDLIFE SHIFT WORK AND RISK OF INCIDENT DEMENTIA

• Published in: Sleep (New York, N.Y.) N.Y.), 2017-04, Vol.40 (suppl_1), p.A425-A425
• Main Authors: Bokenberger, K, Sjölander, A, Dahl Aslan, AK, Karlsson, IK, Åkerstedt, T, Pedersen, NL
• Format: Article
• Language: English
• Subjects: Dementia; Shift work
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleepj/zsx050.1138

Abstract Introduction: Research examining the long-term effects of midlife shift work in relation to dementia risk is limited. The aim is to investigate the association between shift work and incident dementia in two population-based cohorts from the Swedish Twin Registry (STR). Methods: The STR-1973 sample included 13,283 participants who were born 1926–1943 and were at least 30 years old upon receiving a mailed questionnaire in 1973 that included information on status (ever/never) and duration (years) of shift work employment. The Screening Across the Lifespan Twin (SALT) sample included 41,610 participants who were born 1900–1958 and participated in a telephone interview in 1998–2002 that asked about status and duration of night work history. Dementia diagnoses were obtained from Swedish national health registers. Cox regression models were used to estimate hazard ratios (HR) with 95% confidence intervals (CI). Restricted cubic spline functions were incorporated into models for dose-response analyses. Potential confounding factors such as age, sex, education, cardiovascular disease and diabetes were included in adjusted models. Results: A total of 983 (7.4%) and 2,033 (5.0%) dementia cases were identified after a median of 41.2 and 14.1 years follow-up from the STR-1973 and SALT sample, respectively. History of any-type shift work (HR=1.40, 95% CI=1.19–1.65) and night work (HR=1.13, 95% CI=1.02–1.25) were associated with higher dementia incidence in separate multivariable-adjusted models. Sensitivity analysis on the SALT sample restricted to persons born 1926 or after yielded a slightly amplified HR of 1.17 (95% CI=1.03–1.32). Spline models indicated modest dose-response relationships, where longer duration of shift work and night work predicted greater dementia risk. Conclusion: Findings suggest that having any type of shift work or night shift work is associated with increased dementia risk in later life. The association persists after multivariable adjustment for potential confounders, which suggests that the association may be causal. Support (If Any): This work was supported by the National Institute on Aging and the Swedish Research Council for Health, Working Life and Welfare.