The role of cardiovascular health and vascular events in the relationship between excessive daytime sleepiness and dementia risk

Abstract

SummaryMany studies suggest a relationship between excessive daytime sleepiness (EDS) and dementia incidence, but the underlying mechanisms remain uncertain. The study aimed to investigate the role of cardiovascular burden in the relationship between EDS and dementia incidence over a 12‐year follow‐up in community‐dwelling older adults. We performed analyses on 6171 subjects (aged ≥65 years) free of dementia and vascular disease at baseline. Participants self‐reported EDS at baseline and an expert committee validated both prevalent and incident dementia. We defined cardiovascular burden by a low Cardiovascular Health score, constructed using the American Heart Association metrics, and incident vascular events. To explore the potential role of the cardiovascular burden in the relationship between EDS and dementia, we conducted mediation analyses with inverse odds ratio‐weighted estimation, using multivariable‐adjusted proportional hazard Cox and logistic regression models. Subjects with EDS had a higher risk of all‐cause dementia (hazard ratio [HR] 1.39, 95% confidence interval [CI] 1.13–1.69) and dementia with vascular component (DVC) (HR 2.14, 95% CI 1.30–3.51), but not Alzheimer's disease (HR 1.18, 95% CI 0.93–1.51). Cardiovascular burden explained 5% (95% CI 4.1–5.2) and 11% (95% CI 9.7–11.3) of the relationship between EDS and all‐cause dementia and DVC, respectively. These findings confirm that EDS may be implicated in the development of dementia and indicate a weaker than expected role of cardiovascular burden in the relationship between EDS and DVC.

Interrelationship of Sleep Disturbances and Cognitive Status on Mortality

“…Our findings demonstrate that the presence of sleep disturbances, defined in the NACC database as nighttime behaviors (insomnia, frequent awakening during the night, early awakening, and daytime sleepiness), were associated with a higher risk of mortality while controlling for other variables such as other neuropsychiatric symptoms, demographic factors, and a limited set of medical comorbidities. Sleep disturbances, as measured in various ways, in other disorders are associated with higher risks of earlier mortality; some examples are heightened cardiovascular deaths in older adults, 28 - 30 excessive mortality with untreated sleep apnea, 31 and shift work. 32 The current study demonstrates that a higher risk of early mortality occurs across the range of severity of cognitive impairment.…”