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OBJECTIVES: To assess the longitudinal association between sleep disturbances (insomnia and daytime sleepiness) and incidence of dementia and cognitive decline in older men. DESIGN: Community‐based longitudinal cohort study. SETTING: The Honolulu‐Asia Aging Study of dementia that is linked to the Honolulu Heart Program's fourth examination, conducted 1991–1993, and the 3‐year follow‐up fifth examination, conducted 1994–1996. PARTICIPANTS: Two thousand three hundred forty‐six Japanese‐American men age 71 to 93 years who screened negative for prevalent dementia at baseline and were screened again for dementia incidence in a 3‐year follow‐up examination. MEASUREMENTS: Baseline self‐reports of trouble falling asleep or early morning awakening (insomnia) and being sleepy during the day (daytime sleepiness); Cognitive Abilities Screening Instrument (CASI) scores from baseline and followup; clinical diagnosis of incident dementia; and other baseline measures including age, years of education, body mass index, depressive symptoms, and history of hypertension, heart disease, diabetes mellitus, asthma, and use of benzodiazepines. RESULTS: After adjusting for age and other factors, persons reporting excessive daytime sleepiness at baseline (8%) were twice as likely to be diagnosed with incident dementia than were those not reporting daytime sleepiness (odds ratio (OR) = 2.19, 95% confidence interval (CI) = 1.37–3.50) and about 40% more likely to have ≥9 point drop in their CASI score between examinations (OR = 1.44, 95% CI = 1.01–2.08). In contrast, insomnia was not associated with cognitive decline or incidence of dementia. CONCLUSIONS: Daytime sleepiness in older adults may be an early indicator of decline in cognitive functioning and onset of dementia.
Foley et al. (Sat,) studied this question.