Actigraphic and melatonin alignment in older adults with varying dementia risk.

Circadian rhythms alter with ageing and may be aetiologically linked to neurodegeneration. This study explored the association between clinical markers and 1) dim light melatonin onset (DLMO) time and 2) phase angle derived from sleep midpoint, in older adults with varying dementia risks. Participants completed 14 days of actigraphy followed by in-lab measurement of salivary melatonin, from which DLMO time and phase angle were computed. Eighty participants (age = 65.5, SD = 9.6), 44 males (55%), MMSE (28.6, SD = 1.5) were included in the analysis. Sex (t = 2.15, p = .04), sleep onset (r = 0.49, p < .001) and midpoint (r = 0.44, p < .001) also correlated with DLMO time. Multiple linear regression showed chronotype, average actigraphy-derived light exposure during the DLMO window (window 2 h prior to DLMO to 2 h post), early biological day (6-10 h post DLMO time) and late biological day (10-14 h post DLMO time) were predictive of DLMO time (adjusted R2 = 0.75). Sleep offset, depression severity, average light exposure during the early biological night and early and late biological day were shown to be predictive variables in the estimation of phase angle (adjusted R2 = 0.78). The current study highlights the potential use of clinical variables, such as actigraphy-derived light, as circadian markers in ageing which could be easily implemented into existing clinical practice and could yield potential targets focusing on chronotherapeutic interventions.

Rest-activity rhythms and tract specific white matter lesions in older adults at risk for cognitive decline.

White matter lesions (WMLs) are common in older adults and represent an important predictor of negative long-term outcomes. Rest-activity rhythm disturbance is also common, however, few studies have investigated associations between these factors. We employed a novel AI-based automatic WML segmentation tool and diffusion-weighted tractography to investigate associations between tract specific WML volumes and non-parametric actigraphy measures in older adults at risk for cognitive decline. The primary non-parametric measures of interest were inter-daily stability (IS), intra-daily variability and relative amplitude, with the anterior thalamic radiation (ATR), superior longitudinal fasciculus (SLF) and inferior longitudinal fasciculus (ILF) selected as tracts of interest. One hundred and eight participants at risk for cognitive decline (classified as experiencing subjective or objective cognitive decline) were included (mean age = 68.85 years, SD = 8.91). Of the primary non-parametric measures of interest, results showed that lower IS was associated with a greater likelihood of higher WML burden in the ATR (OR = 1.82, 95% CI [1.12,3.15]). Analysis of secondary non-parametric measures revealed later onset of the least active period to be associated with greater likelihood of high WML burden in the SLF (OR = 1.55, 95% CI [1.00,2.53]) and increased activity during the least active 5-h period to be associated with a greater likelihood of high whole-brain WML burden (OR = 1.83, 95% CI [1.06,3.47]). This study shows integrity of the ATR and SLF, and overall WML burden is linked to altered rest-activity rhythms in older adults at risk for cognitive decline, with those demonstrating altered rest-activity rhythms showing 50%-80% higher odds of having high WML burden.

Rest-activity functioning is related to white matter microarchitecture and modifiable risk factors in older adults at-risk for dementia.

STUDY OBJECTIVES: Growing evidence demonstrates pronounced alterations in rest-activity functioning in older adults at-risk for dementia. White matter degeneration, poor cardiometabolic functioning, and depression have also been linked to a greater risk of decline; however, limited studies have examined the white matter in relation to rest-activity functioning in at-risk older adults. METHODS: We investigated associations between nonparametric actigraphy measures and white matter microarchitecture using whole-brain fixel-based analysis of diffusion-weighted imaging in older adults (aged 50 years or older) at-risk for cognitive decline and dementia. The fixel-based metrics assessed were fiber density, fiber cross-section, and combined fiber-density, and cross-section. Interactions between rest-activity functioning and known clinical risk factors, specifically body mass index (BMI), vascular risk factors, depressive symptoms and self-reported exercise, and their association with white matter properties were then investigated. RESULTS: Sixty-seven older adults were included (mean = 65.78 years, SD = 7.89). Lower relative amplitude, poorer 24-h synchronization and earlier onset of the least active 5-h period were associated with reductions in markers of white matter atrophy in widespread regions, including cortico-subcortical and cortical association pathways. Preliminary evidence was also found indicating more pronounced white matter alterations in those with lower amplitude and higher BMI (ß = 0.25, 95% CI [0.05, 0.46]), poorer 24-h synchronization and more vascular risk factors (ß = 0.17, 95% CI [-0.02, 0.36]) and earlier onset of inactivity and greater depressive symptoms (ß = 0.17, 95% CI [0.03, 0.30]). CONCLUSIONS: These findings highlight the complex interplay between rest-activity rhythms, white matter, and clinical risk factors in individuals at-risk for dementia that should be considered in future studies.

Irregular sleep-wake patterns in older adults with current or remitted depression.

BACKGROUND: Disturbed sleep and irregular sleep-wake patterns have been associated with poor outcomes in older adults. Sleep regularity however has not been studied in a sample with current or remitted major depression. METHODS: 138 participants (63.8±8.6 years; n=27 current major depression, n=64 remitted, and n=47 healthy controls) were monitored using wrist-worn actigraphy. The Sleep Regularity Index (SRI), sleep-wake fragmentation and stability, sleep onset and offset timing, number of awakenings and measures from cosinor analysis were computed. RESULTS: Compared with controls, older adults with current depression had lower SRI (p < 0.01), lower relative amplitude (p < 0.05), and higher activity during sleeping and post-midnight hours (p < 0.05). Older adults with remitted depression displayed lower activity during the day (p < 0.05), showed reduced average activity and lower amplitude than controls. Total sleep time, sleep timing, and number of awakenings did not differ between groups. All groups differed significantly in self-reported sleep quality and depression severity. LIMITATIONS: Longitudinal studies which examine how sleep-wake patterns change based on depressive episode recency, severity and how medications may influence these patterns are needed. CONCLUSIONS: Older adults with current or remitted major depression do not differ from controls on traditional sleep metrics but do report poor quality sleep and show differences in sleep regularity and rest-activity patterns. Reducing the risk of poor outcomes in both groups may be aided by interventions that help promote sleep regularity and increased activity.

Actigraphy-recorded sleep efficiency and hippocampal volume are related to visual and verbal rate of forgetting in older adults.

This study aimed to determine if older adults "at-risk" for dementia (those with MCI or SMC) exhibit accelerated long-term forgetting (ALF) and whether rate of forgetting (RoF) is associated with sleep efficiency, hippocampal volume and demographic/clinical features. Forty-nine "at-risk" participants and eighteen controls underwent examination. Memory was assessed using the Scene Memory Task (SMT) and WMS-III Logical Memory (LM) subtest. Tests were administered at baseline, 24 hours and 2 weeks. While our study did not find ALF in those "at-risk" for dementia, on the SMT, RoF over 24 hours and 2 weeks was negatively correlated with sleep efficiency. For LM, RoF at 2 weeks was moderately associated with left hippocampal volume. Neither visual or verbal RoF was correlated with demographic or clinical variables (age, MMSE, IQ, GDS-15). While ALF was not observed in this sample, our results suggest that visual and verbal forgetting have differential predictors.

"Sleep Well, Think Well" Group Program for Mild Cognitive Impairment: A Randomized Controlled Pilot Study.

Objective/Background: Sleep-wake disturbance is associated with poor cognitive functioning and several other adverse outcomes that increase dementia risk in older adults. Targeting sleep-wake disturbance in individuals at risk for dementia may be an important treatment. This study evaluated the efficacy of a four-session multicomponent group intervention for participants with mild cognitive impairment (MCI). Participants: Thirty-five older adults with MCI (mean age = 69.7 years, SD = 9.1), were recruited. MCI was determined via consensus from neuropsychological, medical, and neurological review. Methods: Participants were randomized to the "Sleep Well, Think Well" (SWTW) group condition or a passive control group. The SWTW group received four fortnightly face-to-face sessions conducted by an experienced sleep psychologist and neuropsychologist. The control group received written material detailing strategies to improve sleep quality. Both groups received fortnightly coaching phone calls. The primary outcome was subjective sleep quality, measured by the Pittsburgh Sleep Quality Index (PSQI). Secondary outcomes included actigraphy sleep measures, daytime sleepiness, cognitive functioning, and depression severity. Results: The SWTW intervention was associated with a large and statistically significant improvement in subjective sleep quality (Cohen's d = 0.83, p < 0.02). A moderate nonsignificant effect was evident in reducing daytime sleepiness (Cohen's d = 0.70, p = .08). No significant effects were found on actigraphy markers, depressive symptoms, or tests of cognitive functioning. Conclusions: The eight-week SWTW group intervention for MCI significantly improved subjective sleep quality when compared with a passive control condition. The program also had a moderate (nonsignificant) effect on reducing daytime sleepiness.

Agreement between subjective and objective measures of sleep duration in a low-middle income country setting.

OBJECTIVES: Describe sleep duration in adult Sri Lankans and determine the bias and agreement of self-report and actigraphic assessments. DESIGN: Validation sub-study nested within the Colombo Twin and Singleton Study (2012-2015). SETTING: Colombo, Sri Lanka. PARTICIPANTS: 175 adults with actigraphy, randomly selected from 3497 participants with self-reported sleep assessed in a population-based cohort. MEASUREMENTS: Self-reported sleep duration, ascertained by the Pittsburgh Sleep Quality Index (PSQI), was compared to a minimum of four days of actigraphy. Bias and agreement were assessed using the Bland-Altman method and a novel application of criterion cut-point analysis. Objective measurements of wake after sleep onset (WASO) and sleep efficiency were evaluated. RESULTS: Sri Lankans have short sleep duration; averaging 6.4h (SD 1.5) self-reported and 6.0h (SD 0.9) actigraphically. Poor sleep quality was prevalent with an average WASO of 49 min., and sleep efficiency <85%. Bias was observed, with self-report consistently over-reporting sleep on average by 27.6 min (95% CI: -0.68, -0.24) compared to objective measures, but wide individual variation in disagreement, ranging from over-reporting by 3.34h to under-reporting by 2.42h. A criterion cut-point method also failed to define agreed definitions of short and long sleep duration. CONCLUSIONS: Sleep in Sri Lankan adults, whether measured subjectively or objectively, is of short duration and suboptimal objective quality by High Income Country consensus standards. Given the high cardiometabolic morbidity in Sri Lanka and poor measurement agreement observed, this warrants further investigation and supports the need for culturally appropriate, reliable, and valid assessment for analytic epidemiology in non-Western settings.

Is Obstructive Sleep Apnoea Related to Neuropsychological Function in Healthy Older Adults? A Systematic Review and Meta-Analysis.

Previous systematic reviews and meta-analyses have identified cognitive deficits in adults with obstructive sleep apnoea (OSA). However, quantitative analysis of the association between OSA and neuropsychological performance has not been conducted specifically in older adults, for whom there is a greater risk of cognitive decline. We searched Medline, Embase and PsycINFO through August 2016 for studies describing associations between OSA and neuropsychological outcomes in people aged>50 years. Meta-analyses were performed on these studies for overall cognition and within cognitive domains. Subgroup analyses were performed taking into account risk of bias and moderating differences in study design. 13 studies met eligibility criteria for analysis. A small negative association was found between OSA and all neuropsychological outcomes combined, g=0.18(95% CI 0.04-0.32), and in memory and processing speed domains. Small case-control studies from sleep clinic populations observed the greatest associations, while larger cohort studies from community samples illustrated no association. Analysis accounting for publication bias resulted in a null overall association, g=0.02 (95%CI -0.12 to 0.16). Associations between OSA and cognition in later life are highly variable and the findings differ based on the type and setting of study. It appears some older adults may be at risk of cognitive impairments attributable to OSA; however, the risk of bias renders the evidence inconclusive. High quality research is warranted in clinically diagnosed OSA patients as well as those already experiencing neuropsychological impairment and who may be regarded at higher risk of further cognitive decline.

The Effects of Precautionary Messages about Electromagnetic Fields from Mobile Phones and Base Stations Revisited: The Role of Recipient Characteristics.

Precautionary messages have been shown to increase recipients' threat perceptions about radio-frequency electromagnetic fields (RF-EMFs) emitted by mobile phones and mobile phone base stations. The current study explored the interplay of variables on the side of message recipients with this effect. The individual difference variables of interest were gender, trait anxiety, personal need for structure, and personal fear of invalidity. Furthermore, the study determined whether the increased threat perception is accompanied by emotional distress. A total of 298 university students answered a survey after reading either a basic text about RF-EMFs or a text including precautionary information. Linear multiple regression with interactions analyses showed that the effect of precautionary messages differed for people with different levels of trait anxiety. How trait anxiety was related to the effect of precautionary messages in turn depended on participants' gender. Personal need for structure and personal fear of invalidity were mostly unrelated to the effect of precautionary messages. Regarding participants' emotional distress, we found no difference in state anxiety scores between those participants who received precautionary information and those who did not. The findings show that the effects of precautionary messages on threat perception depend on individual difference variables such as recipients' trait anxiety and gender. Also, the fact that precautionary communication did not result in heightened state anxiety challenges the assumption that precautionary messages induce fear or anxiety.