Repeated sleep-medication reporting patterns and cognitive change in HRS and SHARE

Background: Self-reported sleep-medication use has been inconsistently linked to cognitive decline, largely because sleep disturbances, affective symptoms, and treatment transitions co-evolve over time. Moreover, whether repeated sleep-medication reports across consecutive survey waves follow a monotonic dose-response gradient with subsequent cognitive aging remains unclear. We evaluated baseline, two-wave, and three-wave longitudinal patterns of sleep-medication reporting in relation to cognitive trajectories across two large aging cohorts in the United States and Europe. Methods: We analyzed population-based data from adults aged >=50 years in the US Health and Retirement Study (HRS) and the Survey of Health, Ageing and Retirement in Europe (SHARE). First, we examined associations between baseline sleep-medication use and longitudinal changes in standardized global cognition and memory scores (Analysis 1: HRS n = 16,323; SHARE n = 41,453). Second, we conducted a prespecified two-wave landmark analysis classifying participants by reported sleep-medication use across two consecutive visits (HRS waves 11-12; SHARE waves 4-5) as 0, 1, or 2 use-positive visits, and by reporting sequence (00, 01, 10, and 11), with cognitive trajectories modeled from the second visit onward (Analysis 2: HRS n = 13,915; SHARE n = 29,214). Linear mixed-effects models with random intercepts and slopes adjusted for baseline sociodemographic, lifestyle, and clinical covariates and all covariate-by-time interactions. Third, we extended the landmark window to three consecutive visits (HRS waves 11-13, 2012-2016; SHARE waves 6-8, 2015-2020) to separate sustained from transient reporting, adjusting for interview mode and testing equivalence of sustained use to non-use (Analysis 3: HRS n = 12,310; SHARE n = 24,692). Results: In baseline analyses, sleep-medication use was associated with modestly faster decline in global cognition (HRS: beta = -0.0060 SD/year, 95% CI -0.0103 to -0.0017; SHARE: beta = -0.0034 SD/year, 95% CI -0.0070 to 0.0002) and memory (HRS: beta = -0.0062 SD/year, 95% CI -0.0115 to -0.0009; SHARE: beta = -0.0037 SD/year, 95% CI -0.0074 to 0.0001). In the two-wave landmark analysis, reporting sleep-medication use at both visits (2 vs 0 visits