Introduction: Poor cardiovascular health has been linked to an increased likelihood of cognitive impairment in older adults. Cognitive impairment has also been identified as an emerging co-morbidity of obstructive sleep apnea, a highly prevalent sleep disorder, particularly in patients with neurological conditions. Whether other aspects of sleep, including sleep duration, sleep quality, sleep onset latency, and insomnia are associated with cognition is not established.
Objective: The aim of this study was to evaluate whether specific sleep patterns were associated with cognitive function in a diverse population of both younger and older, neurologically healthy women, and to determine whether this association is mediated by cardiovascular disease (CVD) risk factors.
Methods: This was a baseline analysis of 392 women (59% racial/ethnic minority, mean age=39±16.53y, range 20-76y) participating in the ongoing American Heart Association Go Red for Women Strategically Focused Research Network population-based study at Columbia University Medical Center (CUMC). Cognitive function was assessed by the validated Montreal Cognitive Assessment (MoCA) screening instrument. Sleep duration, sleep quality, and time to sleep onset were assessed using the Pittsburgh Sleep Quality Index; insomnia was assessed using the Insomnia Severity Index. Blood lipids and glucose were measured in the biomarker core laboratory at CUMC. Multivariable linear regression models were used to evaluate associations between sleep, CVD risk factors, and MoCA scores, adjusted for age, race/ethnicity, education, health insurance, and tested for interactions between age and sleep.
Results: The prevalence of abnormal MoCA (score <26) was 38%; mean scores were lower in adults ≥55y vs. <55y (p<0.0001), and racial/ethnic minorities vs. whites (p<0.0001). Average nightly sleep duration was 6.75±1.29 h, and 50% of women had poor sleep quality. In multivariable models testing for interactions, lower MoCA scores were associated with shorter sleep duration (p=0.007), worse quality sleep (p=0.0005), and higher insomnia level (p=0.04). In stratified analyses, associations between MoCA scores and sleep duration, sleep quality, and insomnia persisted among both younger (<55y) and older (≥55y) groups. Lower MoCA scores were also associated with higher triglycerides (p=0.0001) and lower HDL-cholesterol (p=0.0006); formal tests of mediation suggested that the relation between cognition and insomnia was mediated by triglyceride level.
Conclusions: Poor sleep patterns were highly prevalent and associated with lower cognitive function, even in younger women in this diverse population. Sleep patterns should be further investigated as a potential mechanism to identify individuals at risk of cognitive decline. Whether the relation is causal or mediated through traditional CVD risk factors deserves further study.