24-h Activity Rhythms and Health in Older Adults

The lifestyle of new middle-aged and older adults in Taiwan described by wearable device: age and gender differences

Studies of lifestyle through comprehensive objective and subjective measurements of health outcomes are lacking. An examination of lifestyle factors in middle-aged and older adults in terms of age, gender, and the interaction effect of age and gender from physiological and psychological perspectives are imperative. Recent advances in technology such as actigraphy have facilitated objective measurements. This exploratory study contributes to research on age and gender interactions on circadian rhythm, physical activity, sleep, and psychological variables by employing wrist accelerometers to measure behavioral circadian rhythm objectively and by using questionnaires to assess psychological status subjectively. The data were drawn from 218 participants aged 50 and older from the "Middle-aged and older adults Chinese Health and Actigraphy in Taiwan (MOCHA-T)". The results: (1) older adult group is associated with declined physical activity (MVPA time 79.9 min VS. 107.9 min, p = .002), worse sleep efficiency (78.1% VS. 81.9%, p = .008), and earlier lifestyle (Acrophase 14.19 h VS. 14.69 h, p = .01) comparing to middle-aged group. (2) Women have a more regular lifestyle (Interdaily stability 0.6 VS. 051, p < 0.001), higher physical activity (MVPA time 105.7 min VS. 79.3 min, p = .004), and better sleep efficiency (81.6% VS. 77.8%, p = .011) than men. (3) Significant age-by-gender interactions existed in life satisfaction (p = .025), relative amplitude (p = .016), and total wake time (p = .038). Furthermore, aging was associated with significant increases in life satisfaction among men as well as significant decreases in relative amplitude and reductions in the total wake time among women. In conclusion, aging exerted differential effects on life satisfaction in men as well as relative amplitude and the total wake time in women. This result highlights disparities in lifestyle arising from interconnected social and biological challenges.

Circadian rhythm analysis using wearable-based accelerometry as a digital biomarker of aging and healthspan

Recognizing the pivotal role of circadian rhythm in the human aging process and its scalability through wearables, we introduce CosinorAge, a digital biomarker of aging developed from wearable-derived circadian rhythmicity from 80,000 midlife and older adults in the UK and US. A one-year increase in CosinorAge corresponded to 8-12% higher all-cause and cause-specific mortality risks and 3-14% increased prospective incidences of age-related diseases. CosinorAge also captured a non-linear decline in resilience and physical functioning, evidenced by an 8-33% reduction in self-rated health and a 3-23% decline in health-related quality of life score, adjusting for covariates and multiple testing. The associations were robust in sensitivity analyses and external validation using an independent cohort from a disparate geographical region using a different wearable device. Moreover, we illustrated a heterogeneous impact of circadian parameters associated with biological aging, with young (<45 years) and fast agers experiencing a substantially delayed acrophase with a 25-minute difference in peak timing compared to slow agers, diminishing to a 7-minute difference in older adults (>65 years). We demonstrated a significant enhancement in the predictive performance when integrating circadian rhythmicity in the estimation of biological aging over physical activity. Our findings underscore CosinorAge's potential as a scalable, economic, and digital solution for promoting healthy longevity, elucidating the critical and multifaceted circadian rhythmicity in aging processes. Consequently, our research contributes to advancing preventive measures in digital medicine.

Sleep and 24-H Activity Rhythms and the Risk of Stroke: A Prospective Cohort Study

INTRODUCTION

Short and long self-reported sleep durations are associated with a higher risk of stroke, but the association between objective estimates of sleep and 24-h activity rhythms is less clear. We studied the association of actigraphy-estimated sleep and 24-h activity rhythms with the risk of stroke in a population-based cohort of middle-aged and elderly.

METHODS

We included 1,718 stroke-free participants (mean age 62.2 ± 9.3 years, 55.1% women) from the prospective, population-based Rotterdam Study. Actigraphy-estimated sleep (total sleep time, sleep efficiency, sleep onset latency, and wake after sleep onset) and 24-h activity rhythms (interdaily stability, intradaily variability, and onset of the least active 5 h) were measured during a median of 7 days (Q1-Q3: 6-7 days). The association of sleep and 24-h activity rhythms with risk of stroke was analyzed using Cox proportional hazards models.

RESULTS

During a mean follow-up of 12.2 years (SD: 3.2), 105 participants developed a stroke, of whom 81 had an ischemic event. Although there was no clear association between actigraphy-estimated sleep and the risk of stroke, a more fragmented 24-h activity rhythm was associated with a higher risk of stroke (hazard ratio [HR] per SD increase 1.28, 95% confidence interval [CI] 1.07-1.53). A less stable (HR per SD increase in stability 0.78, 95% CI: 0.63-0.97) and more fragmented (HR 1.28, 95% CI: 1.04-1.58) 24-h activity rhythm was also associated with a higher risk of ischemic stroke.

CONCLUSIONS

Disturbed 24-h activity rhythms, but not sleep, are associated with a higher risk of stroke in middle-aged and elderly persons. This suggests that unstable and fragmented activity rhythms may play a more prominent role in the risk of stroke than sleep per se.

Senescence-induced alteration of circadian phagocytic activity of retinal pigment epithelium cell line ARPE-19

Renewal of retinal photoreceptor outer segments is conducted through daily shedding of distal photoreceptor outer segment tips and subsequent their phagocytosis by the adjacent retinal pigment epithelium (RPE) monolayer. Dysregulation of the diurnal clearance of photoreceptor outer segment tips has been implicated in age-related retinal degeneration, but it remains to be clarified how the circadian phagocytic activity of RPE cells is modulated by senescence. In this study, we used the human RPE cell line ARPE-19 to investigate whether hydrogen peroxide (H2O2)-induced senescence in ARPE-19 cells alters the circadian rhythm of their phagocytic activity. After synchronization of the cellular circadian clock by dexamethasone treatment, the phagocytic activity of normal ARPE-19 cells exhibited significant 24-h oscillation, but this oscillation was modulated by senescence. The phagocytic activity of senescent ARPE-19 cells increased constantly throughout the 24-h period, which still exhibited blunted circadian oscillation, accompanied by an alteration in the rhythmic expression of circadian clock genes and clock-controlled phagocytosis-related genes. The expression levels of REV-ERBα, a molecular component of the circadian clock, were constitutively increased in senescent ARPE-19 cells. Furthermore, pharmacological activation of REV-ERBα by its agonist SR9009 enhanced the phagocytic activity of normal ARPE-19 cells and increased the expression of clock-controlled phagocytosis-related genes. Our present findings extend to understand the role of circadian clock in the alteration of phagocytic activity in RPE during aging. Constitutive enhancement of phagocytic activity of senescent RPE may contribute to age-related retinal degeneration.

The bidirectional association of 24-h activity rhythms and sleep with depressive symptoms in middle-aged and elderly persons

BACKGROUND

In older populations disturbed 24-h activity rhythms, poor sleep, and depressive symptoms are often lingering and co-morbid, making treatment difficult. To improve insights into these commonly co-occurring problems, we assessed the bidirectional association of sleep and 24-h activity rhythms with depressive symptoms in middle-aged and elderly persons.

METHODS

In 1734 participants (mean age: 62.3 ± 9.3 years, 55% women) from the prospective Rotterdam Study, 24-h activity rhythms and sleep were estimated with actigraphy (mean duration: 146 ± 19.6 h), sleep quality with the Pittsburgh Sleep Quality Index, and depressive symptoms with the Center for Epidemiological Studies Depression scale. Repeated measures were available for 947 participants (54%) over a median follow-up of 6 years (interquartile range = 5.6-6.3). Linear-mixed models were used to assess temporal associations of 24-h activity rhythms and sleep with depressive symptoms in both directions.

RESULTS

High 24-h activity rhythm fragmentation (IV) (B = 1.002, 95% confidence interval (CI) = 0.641-1.363), long time in bed (TIB) (B = 0.111, 95% CI = 0.053-0.169), low sleep efficiency (SE) (B = -0.015, 95% CI = -0.020 to -0.009), long sleep onset latency (SOL) (B = 0.009, 95% CI = 0.006-0.012), and low self-rated sleep quality (B = 0.112, 95% CI = 0.0992-0.124) at baseline were associated with increasing depressive symptoms over time. Conversely, more depressive symptoms at baseline were associated with an increasing 24-h activity rhythm fragmentation (B = 0.002, 95% CI = 0.001-0.003) and TIB (B = 0.009, 95% CI = 0.004-0.015), and a decreasing SE (B = -0.140, 95% CI = -0.196 to -0.084), SOL (B = 0.013, 95% CI = 0.008-0.018), and self-rated sleep quality (B = 0.193, 95% CI = 0.171-0.215) over time.

CONCLUSION

This study demonstrates a bidirectional association of 24-h activity rhythms, actigraphy-estimated sleep, and self-rated sleep quality with depressive symptoms over a time frame of multiple years in middle-aged and elderly persons.

The Cross-Sectional Association Between Tinnitus and Actigraphy-Estimated Sleep in a Population-Based Cohort of Middle-Aged and Elderly Persons

OBJECTIVES

Tinnitus is a common and burdensome disease, often accompanied by complaints of poor sleep. However, associations of tinnitus with objective estimates of sleep remain unclear, particularly in the general population. We assessed these associations in a population-based cohort of middle-aged and elderly persons.

DESIGN

This study included 1456 participants (mean age: 65.0 ± 7.1 years, 52% women) from the population-based Rotterdam Study. Tinnitus was self-reported and in those who reported tinnitus daily, symptom severity was assessed with the Tinnitus Handicap Inventory. We used actigraphy to estimate sleep and 24-hour activity rhythms objectively and sleep diaries to assess self-reported sleep. We estimated the difference in sleep and 24-hour activity rhythms first between those with and those without tinnitus and secondly with tinnitus severity.

RESULTS

Tinnitus, reported by 341 (23%) participants, and tinnitus severity, assessed in 194 participants with daily tinnitus, were not associated with actigraphy-estimated sleep or 24-hour activity rhythms, but were associated with a longer self-reported sleep onset latency (adjusted difference tinnitus = 2.36, 95% confidence interval [CI] = 0.95-3.78, adjusted difference tinnitus severity = 0.27, 95% CI = 0.013-0.54). After stratification for hearing loss, tinnitus was associated with longer self-reported sleep onset latency (adjusted difference = 2.26, 95% CI = 0.98-3.53) and less stable 24-hour activity rhythms (adjusted difference = -0.02, 95% CI = -0.04 to -0.00) in those with hearing loss. In those without hearing loss, tinnitus was associated with more stable rhythms (adjusted difference = 0.03, 95% CI = 0.01-0.05).

CONCLUSIONS

Having tinnitus is associated with a longer self-reported sleep onset latency, but not with objective estimates of sleep, suggesting that the subjective experience of sleep may be particularly disturbed in those with tinnitus. In addition, hearing loss may modify the association of tinnitus and 24-hour activity rhythms.

Associations of circadian rest/activity rhythms with cognition in middle-aged and older adults: Demographic and genetic interactions

Objectives

Wrist actigraphs (accelerometers) can record motor activity over multiple days and nights. The resulting data can be used to quantify 24-h activity profiles, known as circadian rest-activity rhythms (CRARs). Actigraphic CRARs have been tied to cognitive performance and decline in older adults; however, little is known about links between CRARs and performance or change in specific cognitive domains, or how individual differences may influence these associations. We investigated associations of actigraphic CRARs with cognitive performance and change in middle-aged and older adults, and explored whether age, sex/gender, race, and apolipoprotein E (APOE) e4 carrier status moderated these associations.

Materials and methods

Participants (N = 422; 47% male) were cognitively healthy adults (i.e., without mild cognitive impairment or dementia) at baseline aged ≥ 50 years from the Baltimore Longitudinal Study of Aging who completed 5.6 ± 0.89 nights of wrist actigraphy and tests of memory, executive function, attention, language, and visuospatial ability at the same visit the actigraph was issued; 292 participants had repeat cognitive testing 3.12 (1.58) years later. Predictors included indices of rhythm strength [i.e., amplitude; relative amplitude (RA); interdaily stability (IS); mesor], delayed timing of the rhythm peak [i.e., later acrophase; midpoint of an individual's least active 5 h (L5 time); midpoint of an individual's most active 10 h (M10 time)], and fragmentation [i.e., intradaily variability (IV)].

Results

In main effects, later L5 time was cross sectionally associated with poorer memory, and greater IS predicted slower longitudinal memory decline. Associations of CRARs with cognition differed as a function of age, sex/gender, race, and APOE e4 carrier status.

Conclusion

Among middle-aged and older adults, delayed circadian phase is associated with poorer memory performance, and greater day-to-day rhythm stability is associated with slower declines in memory. Significant interactions suggest that CRARs are generally more strongly associated with cognitive performance and rate of cognitive decline among women, Black adults, older individuals, and APOE e4 carriers. Replication in independent samples is needed.

Light in the Senior Home: Effects of Dynamic and Individual Light Exposure on Sleep, Cognition, and Well-Being

Disrupted sleep is common among nursing home patients and is associated with cognitive decline and reduced well-being. Sleep disruptions may in part be a result of insufficient daytime light exposure. This pilot study examined the effects of dynamic “circadian” lighting and individual light exposure on sleep, cognitive performance, and well-being in a sample of 14 senior home residents. The study was conducted as a within-subject study design over five weeks of circadian lighting and five weeks of conventional lighting, in a counterbalanced order. Participants wore wrist accelerometers to track rest–activity and light profiles and completed cognitive batteries (National Institute of Health (NIH) toolbox) and questionnaires (depression, fatigue, sleep quality, lighting appraisal) in each condition. We found no significant differences in outcome variables between the two lighting conditions. Individual differences in overall (indoors and outdoors) light exposure levels varied greatly between participants but did not differ between lighting conditions, except at night (22:00–6:00), with maximum light exposure being greater in the conventional lighting condition. Pooled data from both conditions showed that participants with higher overall morning light exposure (6:00–12:00) had less fragmented and more stable rest–activity rhythms with higher relative amplitude. Rest–activity rhythm fragmentation and long sleep duration both uniquely predicted lower cognitive performance.

Circadian disturbances in Alzheimer's disease progression: a prospective observational cohort study of community-based older adults

BACKGROUND

Circadian disturbances are commonly seen in people with Alzheimer's disease and have been reported in individuals without symptoms of dementia but with Alzheimer's pathology. We aimed to assess the temporal relationship between circadian disturbances and Alzheimer's progression.

METHODS

We did a prospective cohort study of 1401 healthy older adults (aged >59 years) enrolled in the Rush Memory and Aging Project (Rush University Medical Center, Chicago, IL, USA) who had been followed up for up to 15 years. Participants underwent annual assessments of cognition (with a battery of 21 cognitive performance tests) and motor activities (with actigraphy). Four measures were extracted from actigraphy to quantify daily and circadian rhythmicity, which were amplitude of 24-h activity rhythm, acrophase (representing peak activity time), interdaily stability of 24-h activity rhythm, and intradaily variability for hourly fragmentation of activity rhythm. We used Cox proportional hazards models and logistic regressions to assess whether circadian disturbances predict an increased risk of incident Alzheimer's dementia and conversion of mild cognitive impairment to Alzheimer's dementia. We used linear mixed-effects models to investigate how circadian rhythms changed longitudinally and how the change integrated to Alzheimer's progression.

FINDINGS

Participants had a median age of 81·8 (IQR 76·3-85·7) years. Risk of developing Alzheimer's dementia was increased with lower amplitude (1 SD decrease, hazard ratio [HR] 1·39, 95% CI 1·19-1·62) and higher intradaily variability (1 SD increase, 1·22, 1·04-1·43). In participants with mild cognitive impairment, increased risk of Alzheimer's dementia was predicted by lower amplitude (1 SD decrease, HR 1·46, 95% CI 1·24-1·72), higher intradaily variability (1 SD increase, 1·36, 1·15-1·60), and lower interdaily stability (1 SD decrease, 1·21, 1·02-1·44). A faster transition to Alzheimer's dementia in participants with mild cognitive impairment was predicted by lower amplitude (1 SD decrease, odds ratio [OR] 2·08, 95% CI 1·53-2·93), increased intradaily variability (1 SD increase, 1·97, 1·43-2·79), and decreased interdaily stability (1 SD decrease, 1·35, 1·01-1·84). Circadian amplitude, acrophase, and interdaily stability progressively decreased over time, and intradaily variability progressively increased over time. Alzheimer's progression accelerated these aging effects by doubling or more than doubling the annual changes in these measures after the diagnosis of mild cognitive impairment, and further doubled them after the diagnosis of Alzheimer's dementia. The longitudinal change of global cognition positively correlated with the longitudinal changes in amplitude and interdaily stability and negatively correlated with the longitudinal change in intradaily variability.

INTERPRETATION

Our results indicate a link between circadian dysregulation and Alzheimer's progression, implying either a bidirectional relation or shared common underlying pathophysiological mechanisms.

FUNDING

National Institutes of Health, and the BrightFocus Foundation.