Evaluation of racial and ethnic heterogeneity in the associations of sleep quality and sleep apnea risk with cognitive function and cognitive decline

INTRODUCTIONThe prevalence of poor sleep quality and sleep apnea differs by race and ethnicity and may contribute to racial disparities in cognitive aging. We investigated whether sleep quality and sleep apnea risk were associated with cognitive function and decline and whether the associations differed by race/ethnicity.METHODSParticipants from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE; N = 1690; mean age: 75.7 years) study, a cohort of Asian, Black, Latino, and White participants, completed a modified Pittsburgh Sleep Quality Index assessing subjective sleep quality, latency, duration, disturbances, sleep medication use, and daytime dysfunction. Sleep apnea risk was measured by questions about snoring, tiredness, and whether apnea was observed. Executive function and verbal episodic memory were assessed at three time points over an average of 2.7 years with the Spanish and English Neuropsychological Assessment Scale. We fit linear mixed-effect models and stratified analyses by race/ethnicity.RESULTSHigher sleep apnea risk was associated with faster declines in verbal episodic memory (beta$\hat \beta $sleep apnea = -0.02, 95% confidence interval [CI], -0.04, -0.001) but not in executive function. Poorer sleep quality was associated with lower levels of and faster decline in executive function but not in verbal episodic memory. Race/ethnicity modified these associations: compared to estimated effects among White participants, poorer global sleep quality (beta$\hat \beta $sleep*time = -0.02, 95% CI, -0.02, -0.01) was associated with larger effects on decline in executive function among Black participants. Estimated effects of some individual sleep quality components were also modified by race/ethnicity; for example, sleep medication use was associated with faster declines in executive function (beta$\hat \beta $sleep*time = -0.05, 95% CI, -0.07, -0.03) and verbal episodic memory beta$\hat \beta $sleep*time = -0.04, 95% CI, -0.07, -0.02) among Black participants compared to White participants.DISCUSSIONObservational evidence indicates sleep quality is a promising target for addressing racial/ethnic disparities in cognitive aging, especially among Black older adults.Highlights Sleep apnea risk was associated with faster declines in verbal episodic memory but not executive function among all participants. Global sleep quality was associated with lower levels of and faster decline in executive function but not verbal episodic memory among all participants. Black older adults were particularly susceptible to the estimated adverse cognitive impacts of global sleep quality, particularly the use of sleep medication.