Background

There is growing interest in the area of "wearable tech" and its relationship to health. A common element of many of these devices is a triaxial accelerometer that can yield continuous information on gross motor activity levels; how such data might predict changes in health is less clear.

Methods

We examined accelerometry data from 2,976 older men who were part of the Osteoporotic Fractures in Men (MrOS) study. Using a shape-naive technique, functional principal component analysis, we examined the patterns of motor activity over the course of 4-7 days and determined whether these patterns were associated with changes in polysomnographic-determined sleep and cognitive function (Trail Making Test-Part B [Trails B], Modified Mini-Mental State Examination [3MS]), as well as mortality over 6.5-8 years of follow-up.

Results

In comparing baseline to 6.5 years later, multivariate modeling indicated that low daytime activity at baseline was associated with worsening of sleep efficiency (p < .05), more wake after sleep onset (p < .05), and a decrease in cognition (Trails B; p < .001), as well as a 1.6-fold higher rate of all-cause mortality (hazard ratio = 1.64 [1.34-2.00]). Earlier wake and bed times were associated with a decrease in cognition (3MS; p < .05). Having a late afternoon peak in activity was associated with a 1.4-fold higher rate of all-cause mortality (hazard ratio = 1.46 [1.21-1.77]). Those having a longer duration of their daytime activity with a bimodal activity pattern also had over a 1.4-fold higher rate of cardiovascular-related mortality (hazard ratio = 1.42 [1.02-1.98]).

Conclusions

Patterns of daily activity may be useful as predictive biomarkers for changes in clinically relevant outcomes, including mortality and changes in sleep and cognition in older men.

Disruptions in activity are core features of mood states in bipolar disorder (BD). This study sought to identify activity patterns that discriminate between mood states in BD. Locomotor activity was collected using actigraphy for six weeks in participants with inter-episode BD type I (n=37) or participants with no lifetime mood disorders (n=39). The 24-hour activity pattern of each participant-day was characterized and within-person differences in activity patterns were examined across mood states. Results show that among participants with BD, depressive days are distinguished from other mood states by an overall lower activity level, and a pattern of later activity onset, a midday elevation of activity, and low evening activity. No distinct within-person activity patterns were found for hypomanic/manic days. Since activity can be monitored non-invasively for extended time periods, activity pattern identification may be leveraged to detect mood states in BD, thereby providing more immediate delivery of care.

Altered 24-hour rest-activity rhythms may be associated with cognitive impairment in older adults, but evidence from prospective studies is limited. Nonparametric methods were used to assess actigraphy-based activity patterns in 2 496 older men. Incident cognitive impairment was assessed 4 times over 12 years using the Modified Mini-Mental State Examination (3MS) and Trails B tests, self-reported medication use, and clinical diagnosis. The highest quartile (vs the lowest) of intradaily variability and the lowest quartiles (vs the highest) of interdaily stability and relative amplitude were associated with incident cognitive impairment (hazard ratio [95% confidence interval]: 1.82 [1.31-2.53], 1.36 [0.99-1.86], and 1.85 [1.33-2.56], respectively). A larger increase in intradaily variability over 7.5 years was associated with a greater subsequent decline in 3MS scores but not in Trails B performance. In conclusion, less stable and more variable rest-activity rhythms may represent early biomarkers of cognitive impairment in older men.

Study objectives

Disrupted daily rhythms are associated with mild cognitive impairment (MCI) and dementia. The specific nature of how rhythms and cognition are related, however, is unknown. We hypothesized characteristics from a nonparametric estimate of circadian rest-activity rhythm patterns would be associated to the development of MCI or dementia.

Methods

Wrist actigraphy from 1232 cognitively healthy, community-dwelling women (mean age 82.6 years) from the Study of Osteoporotic Fractures was used to estimate rest-activity patterns, including intradaily variability (IV), interdaily stability (IS), most active 10-hour period (M10), least active 5-hour period (L5), and relative amplitude (RA). Logistic regression examined associations of these predictors with 5-year incidence of MCI or dementia. Models were adjusted for potential confounders.

Results

Women with earlier sleep/wake times had higher risk of dementia, but not MCI, (early vs. average L5 midpoint: OR, 1.66; 95% CI, 1.08-2.55) as did women with smaller day/night activity differentials (low vs. high RA: OR, 1.96; 95% CI, 1.14-3.35). IV, IS, and M10 were not associated with MCI or dementia.

Conclusion

The timing and difference in day/night amplitude, but not variability of activity, may be useful as predictors of dementia.

Background

Older men with worse alignment of activity and light may have lower levels of cognition and increased rates of cognitive decline.

Methods

This cohort consisted of 1,036 older men (81.1 ± 4.6 years) from the MrOS Sleep Study (2009-2012). Light and activity levels were gathered by wrist actigraphy. Phasor analysis was used to quantify alignment of light-dark and rest-activity patterns (magnitude) and their temporal relationship (angle). Global cognitive function (Modified Mini-Mental State examination, 3MS) and executive function (Trails B test) were measured, then repeated 4.2 ± 0.8 years later. Linear regression models examined the associations of phasor magnitude and angle with cognition and cognitive decline. Models were adjusted for age, clinic, race, education and season.

Results

Smaller phasor magnitude (worse aligned light and activity patterns) was associated with lower initial level and increased decline in executive function. Compared to those with higher phasor magnitude, those with lower magnitude took an average of 11.1 seconds longer to complete the Trails B test (Quartile 1 vs. Quartile 4, p=.02). After follow-up, Trails B completion time increased an average of 5.5 seconds per standard deviation increase in phasor magnitude (95% CI 0.7-10.4, p=.03). There were no associations with phasor angle, and none with magnitude and global cognition (3MS).

Conclusions

Among older men, worse alignment of light and activity patterns was associated with worse initial performance and increased decline in executive function, but not related to global cognition. Interventions that improve alignment of light and activity may slow cognitive decline in older adults.

Purpose of the study

To compare the prevalence and cardiometabolic health impact of sleep disturbance among postmenopausal Veteran and non-Veteran participants in the Women's Health Initiative (WHI).

Design and methods

The prevalence of five categories of sleep disturbance--medication/alcohol use for sleep; risk for insomnia; risk for sleep disordered breathing [SDB]; risk for comorbid insomnia and SDB (insomnia + SDB); and aberrant sleep duration [SLD]--was compared in 3,707 Veterans and 141,354 non-Veterans using logistic or multinomial regression. Cox proportional hazards models were used to evaluate the association of sleep disturbance and incident cardiovascular disease (CVD) and Type 2 diabetes in Veterans and non-Veterans.

Results

Women Veterans were more likely to have high risk for insomnia + SDB relative to non-Veteran participants. However, prevalence of other forms of sleep disturbance was similar across groups. Baseline sleep disturbance was not differentially associated with cardiometabolic health outcomes in Veteran versus non-Veteran women. Risks for SDB and insomnia + SDB were both linked to heightened risk of CVD and diabetes; SLD was consistently linked with greater risk of CVD and diabetes in non-Veterans but less strongly and consistently in Veterans.

Implications

Efforts to identify and treat sleep disturbances in postmenopausal women are needed and may positively contribute to the attenuation of cardiometabolic morbidity risk. Increased awareness of women Veterans' vulnerability to postmenopausal insomnia + SDB may be particularly important for health care providers who treat this population.