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Eur J Epidemiol. 2018 Oct;33(10):977-987. doi: 10.1007/s10654-018-0430-8. Epub 2018 Aug 3.

Shift work and risk of incident dementia: a study of two population-based cohorts.

Author information

1
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177, Stockholm, Sweden. kathleen.bokenberger@ki.se.
2
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177, Stockholm, Sweden.
3
School of Health and Welfare, Institute of Gerontology, Jönköping University, 55111, Jönköping, Sweden.
4
Stress Research Institute, Stockholm University, 10691, Stockholm, Sweden.
5
Department of Clinical Neuroscience, Karolinska Institutet, 17177, Stockholm, Sweden.
6
Department of Psychology, University of Southern California, Los Angeles, CA, 90089-1061, USA.

Abstract

This study aimed to investigate the association between shift work and incident dementia in two population-based cohorts from the Swedish Twin Registry (STR). The STR-1973 sample included 13,283 participants born 1926-1943 who received a mailed questionnaire in 1973 that asked about status (ever/never) and duration (years) of shift work employment. The Screening Across the Lifespan Twin (SALT) sample included 41,199 participants born 1900-1958 who participated in a telephone interview in 1998-2002 that asked about night work status and duration. Dementia diagnoses came from Swedish patient registers. Cox proportional-hazards regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI). Potential confounders such as age, sex, education, diabetes, cardiovascular disease and stroke were included in adjusted models. In genotyped subsamples (n = 2977 in STR-1973; n = 10,366 in SALT), APOE ε4 status was considered in models. A total of 983 (7.4%) and 1979 (4.8%) dementia cases were identified after a median of 41.2 and 14.1 years follow-up in the STR-1973 and SALT sample, respectively. Ever shift work (HR 1.36, 95% CI 1.15-1.60) and night work (HR 1.12, 95% CI 1.01-1.23) were associated with higher dementia incidence. Modest dose-response associations were observed, where longer duration shift work and night work predicted increased dementia risk. Among APOE ε4 carriers, individuals exposed to ≥ 20 years of shift work and night work had increased dementia risk compared to day workers. Findings indicate that shift work, including night shift work, compared to non-shift jobs is associated with increased dementia incidence. Confirmation of findings is needed.

KEYWORDS:

Dementia incidence; Epidemiology; Night shift work; Prospective cohort; Shift work

PMID:
30076495
PMCID:
PMC6153510
DOI:
10.1007/s10654-018-0430-8
[Indexed for MEDLINE]
Free PMC Article

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