In:
Alzheimer's & Dementia, Wiley, Vol. 16, No. S5 ( 2020-12)
Abstract:
Circadian rhythms are altered with ageing, mild cognitive impairment and dementia and may be aetiologically linked to neurodegeneration. The gold standard measure of the circadian system is melatonin. This can be measured using Dim‐Light Melatonin Onset (DLMO), which measures the initial rise of melatonin signalling preceding sleep. However, DLMO collection is resource intensive, expensive and not feasible within the clinical environment. In older adults and those ‘at risk’ for dementia, the current study aims to determine 1) the best clinical and actigraphic associations of DLMO and 2) misalignment between melatonin onset and habitual sleep onset (phase angle of entrainment). Method Individuals who were healthy or ‘at risk’ (diagnosed with depression and/or mild cognitive impairment) had 14‐days of actigraphy followed by in‐lab measurement of salivary melatonin, from which DLMO and phase angle were computed. Standard nonparametric analyses were computed from actigraphy. Result 21 healthy (age=66±9.6, MMSE =29.25±0.79) and 44 individuals ‘at risk’ (age=66±10.3, MMSE=28.34±1.73) completed the study. Across all participants, multiple linear regression showed BMI(β=0.20), age(β=‐0.02), sex(β=‐0.26) and sleep onset time(β=0.35) predicted DLMO(F(4,59) =4.70, p=0.002, R 2 =0.238), driven by the strong correlation between DLMO and sleep onset (r=0.41, p=0.001). An additional exploratory analysis revealed M10 onset, the start of the 10 hours with greatest activity, was significantly correlated with phase angle in individuals ‘at risk’ (r=0.36, p=0.02) and not controls (r=‐0.31, p=0.19), Fisher’s r‐to‐z p=0.02. No other variables differed between groups. Conclusion The current study demonstrates that earlier habitual sleep onset is associated with advanced circadian rhythms in older adults, and that aside from demographic factors, BMI is a factor affecting circadian timing. Of significance, this study also shows that ‘at risk’ individuals who begin activity later in the day exhibit greater misalignment between their biological clock and external cues. This work highlights the potential use of actigraphy‐derived sleep onset as a circadian marker in ageing. Moreover, for those at risk for dementia, the timing of daytime activity may play a vital role in circadian misalignment. With growing evidence that circadian misalignment is involved in the pathogenesis of neurodegeneration, BMI and actigraphy markers could yield viable targets focusing on chronotherapeutic interventions.
Type of Medium:
Online Resource
ISSN:
1552-5260
,
1552-5279
Language:
English
Publisher:
Wiley
Publication Date:
2020
detail.hit.zdb_id:
2201940-6
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