1. Association between daily sleep duration and the risk of incident dementia according to the presence or absence of diseases among older Japanese individuals in the New Integrated Suburban Seniority Investigation (NISSIN) project
- Author
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Shigekazu Ukawa, Wenjing Zhao, Satoe Okabayashi, Takashi Kimura, Masahiko Ando, Kenji Wakai, Kazuyo Tsushita, Takashi Kawamura, and Akiko Tamakoshi
- Subjects
Male ,Japan ,Risk Factors ,Humans ,Female ,Dementia ,Prospective Studies ,General Medicine ,Sleep ,Aged ,Proportional Hazards Models - Abstract
This study aimed to investigate the association between daily sleep duration and incident dementia among physically and socially independent older people with/without diseases (hypertension, diabetes mellitus, cardiovascular diseases) in a Japanese age-specific cohort.We carried out a prospective cohort study including 1954 (1006 men and 948 women) Japanese individuals aged 64/65 years. Information on daily sleep duration, medical status, demographics, and lifestyle characteristics was collected by a baseline questionnaire survey and health checkup (2000-2005). Dates of incident dementia were confirmed using the nationally standardized dementia scale proposed by the Ministry of Health, Labor, and Welfare. A competing risk model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for incident dementia. We treated censored cases due to death as competing events.During a median of 15.6 years of follow-up, 260 participants reported incident dementia. Compared with participants without diseases and who slept 6-7.9 h/day, those with a shorter daily sleep duration of6 h/day, presence of disease and shorter, moderate, or longer daily sleep duration ≥8 h/day had an increased risk of incident dementia (HR 1.73; 95% CI 1.04-2.88, HR 1.98; 95% CI 1.14-3.44, HR 1.44; 95% CI 1.03-2.00, and HR 2.09; 95% CI 1.41-3.09, respectively) with a significant interaction between the presence of diseases and sleep duration (p 0.001).The present findings suggest that habitual sleep duration predicts future risk of dementia.
- Published
- 2022