Relationships between excessive daytime sleepiness and arterial stiffness with cognitive function in a racially diverse high‐risk cohort

Abstract

AbstractBackgroundAs pathologic processes leading to Alzheimer’s disease (AD) begin many years before clinical diagnosis, assessment of pre‐clinical AD risk factors in high‐risk individuals is needed. Excessive daytime sleepiness (EDS) is associated with increased cardiovascular dysfunction, neuroinflammation, and neurodegeneration, leading to cognitive impairment. We tested the hypothesis that EDS and increased arterial stiffness are related to worse cognitive function in a cohort of Black or African American (B/AA) and non‐Hispanic White (NHW) participants.MethodA community‐based racially diverse sample of cognitively unimpaired adults (47‐83 years), most (87%) with a family history of AD, were enrolled. Cognitive testing took one hour and included domains of executive function, working memory, and verbal and visuospatial ability and language. Daytime sleepiness was measured with Epworth Sleepiness Scale (ESS); EDS was defined as ESS≥10. Arterial stiffness was measured using pulse wave velocity (PWV).ResultParticipants (N = 85) were 64±8 years of age, 75% female, 48% B/AA, and highly educated (81% ≥college). Mean central blood pressures were 126±18 mmHg (systolic) and 80±10 mmHg (diastolic), with no differences by race or sex. Scores were lower among B/AA versus NHW participants for Judgement of Line of Orientation (17.71±6.0 versus 23.53±6.0, p<.001, Cohen’s d = .083) and Multilingual Naming Test (28.25±2.7 versus 30.57±2.0, p = .005, d = .950). EDS was present among 15% of participants and associated with lower scores on Digit Symbol (p = .004, d = .917), and Multilingual Naming Test (p = .006, d = 1.455). Total time on Trails A was higher among those with EDS (36s versus 30s, p = .040, d = .575). Higher PWV values were associated with lower scores on Digit Symbol Substitution (r = ‐.259, p = .029), Buschke Selective Reminding Test (‐.298, p = .012), CERAD Word List (‐.306, p = .009), F‐A‐S (r = ‐.253, p = .033), and Animal Fluency (r = ‐.326, p = .006).ConclusionIn a racially diverse cohort at risk for AD, we found that excessive self‐reported daytime sleepiness and increased arterial stiffness were associated with worse scores across multiple cognitive domains. Poor sleep and vascular dysfunction are known contributors to AD pathology, providing potential modifiable targets of intervention to reduce or delay the development of AD in cognitively normal, but high‐risk individuals. Further work is needed for a better understanding of modifiable AD risk factors in diverse populations