Lim, Andrew S. P.

Abstract Introduction Comparing sleep and rest-activity rhythms (RARs) across the spectrum of cognitive aging can reveal novel risk factors and potential mechanisms underlying dementia disorders. However, our current understanding is restricted by differences in sleep measurement, limited longitudinal data, and heterogeneous cognitive aging processes. We aimed to determine (1) which sleep/RAR features exhibit meaningful changes within three distinct cognitive pathways; and (2) which sleep/RAR features differ between cognitive aging pathways prior to and after the onset of mild cognitive impairment (MCI) and/or dementia. Methods Longitudinal self-reported sleep and actigraphy data were obtained from 1,449 participants in the Rush Memory and Aging Project (mean age= 81.2±7.1 years, 75.2% female, 5.2% Black, 94.8% White). We applied flexible cubic spline models to quantify differences in the levels and trajectories of sleep amount (self-reported duration; actigraphy rest interval length and alpha), regularity (actigraphy interdaily stability, intradaily variability, and midpoint standard deviation), and timing (self-reported midpoint; actigraphy midpoint and acrophase) within and between three cognitive aging pathways over 12 years: Normal Cognitive Aging (‘Normal’), Progression to MCI (‘Stable MCI’), and Progression to Dementia (‘Dementia’). Models were adjusted for key sociodemographic and health variables. Results Sleep amount was lowest in the Dementia pathway prior to MCI or dementia, but increased with age, most rapidly following dementia. The greatest effect was observed in self-reported duration (standardized mean change, d[95%CI]=0.912 [0.47, 1.36]. Regularity declined across all pathways, most rapidly after cognitive diagnoses, with the largest increases in intradaily variability occurring among the Stable MCI (d=0.97 [0.70, 1.23]) and Dementia paths (d=1.11 [0.84, 1.38). Shifts toward earlier sleep timing were observed in actigraphy measures across all three pathways (-0.54≤d≤-0.31). Conclusion Shorter sleep amount in cognitively healthy older adults may be a risk factor or prodromal indicator of dementia, while longer sleep amounts and decreasing regularity following dementia may reflect neurodegeneration. Advances in sleep timing may be less useful as a clinical indicator of future cognitive impairment or decline. Differences between self-reported and actigraphy-measured sleep/RAR outcomes may reflect distinct underlying mechanisms, warranting further research. Support (if any) NIH: T32HL082610, RF1AG056331, R01AG052488, R01AG071638, RF1AG070436, R01AG17917

AbstractINTRODUCTIONComparing sleep and rest–activity rhythms across different cognitive aging pathways can identify novel risk factors and potential mechanisms. However, our current understanding is restricted by differences in sleep measurement, limited longitudinal data, and heterogeneous cognitive aging processes.METHODSWe applied cubic splines to longitudinal self‐reported sleep and actigraphy data from 1449 participants in the Rush Memory and Aging Project and quantified differences in the levels and trajectories of sleep amount, regularity, and timing within and between three cognitive aging pathways: normal, stable mild cognitive impairment, dementia.RESULTSSleep amount was lowest in the dementia pathway prior to cognitive impairment but increased with age, most rapidly after dementia. Regularity declined across all pathways, most rapidly after cognitive diagnoses. Timing advanced across all pathways.DISCUSSIONShorter sleep amount in cognitively healthy older adults may be a risk factor or prodromal indicator of dementia, while longer sleep amounts and decreasing regularity may reflect neurodegeneration.Highlights We quantified longitudinal changes in sleep across three cognitive‐aging pathways. We incorporated both subjective and objective measures of sleep health. Self‐report duration increased noticeably from before to after cognitive diagnosis. Sleep irregularity increased most prominently after cognitive diagnosis. Advances in sleep timing occurred in both normal and pathological aging.

The Canadian Consortium on Neurodegeneration in Aging (CCNA) was created by the Canadian federal government through its health research funding agency, the Canadian Institutes for Health Research (CIHR), in 2014, as a response to the G7 initiative to fight dementia. Two five-year funding cycles (2014–2019; 2019–2024) have occurred following peer review, and a third cycle (Phase 3) has just begun. A unique construct was mandated, consisting of 20 national teams in Phase I and 19 teams in Phase II (with research topics spanning from basic to clinical science to health resource systems) along with cross-cutting programs to support them. Responding to the needs of researchers within the CCNA teams, a unique sample of 1173 deeply phenotyped patients with various forms of dementia was accrued and studied over eight years (COMPASS-ND). In the second phase of funding (2019–2024), a national dementia prevention program (CAN-THUMBS UP) was set up. In a short time, this prevention program became a member of the World Wide FINGERS prevention consortium. In this article, the challenges, successes, and impacts of CCNA in Canada and internationally are discussed. Short-term deliverables have occurred, along with considerable promise of impacts in the longer term. The creation of synergy, networking, capacity building, engagement of people with lived experience, and economies of scale have contributed to the considerable success of CCNA by all measures. CCNA is evidence that an organized “centrally-organized” approach to dementia research can catalyze important progress nationally and yield significant and measurable results.