Cognitive decline in short and long sleepers: a prospective population-based study (NEDICES)

Factors associated with cognitive reserve according to education level

INTRODUCTION

We investigated distinctive factors associated with cognitive reserve (CR) based on education level.

METHODS

Among 1247 participants who underwent neuropsychological assessment, amyloid positron emission tomography, and brain magnetic resonance imaging, 336 participants with low education (≤6 years) and 697 with high education (≥12 years) were selected. CR was measured as the difference between the predicted and observed value of cognitive function based on cortical thickness. Multiple linear regression was conducted in each group after controlling for age and sex.

RESULTS

In the low-education group, low literacy, long sleep duration(>8 h/day), and diabetes were negatively associated with CR, whereas cognitive and physical activity were positively associated with CR. In the high-education group, cognitive activity was positively related to CR, whereas low literacy, long sleep duration (> 8 h/day), and depression were negatively related to CR.

DISCUSSION

This study provides insights into different strategies for enhancing CR based on educational background.

HIGHLIGHTS

Factors associated with cognitive reserve (CR) varied according to the education level. Diabetes and physical activity were associated with CR in the low-education group. Depression was related to CR in the high-education group. Low literacy, sleep duration, and cognitive activity were associated with CR in both groups. Dementia-prevention strategies should be tailored according to educational level.

Prolonged sleep duration as a predictor of cognitive decline: A meta-analysis encompassing 49 cohort studies

Despite numerous studies have explored the association between sleep duration and cognition, the link between sleep duration trajectories and cognition remains underexplored. This systematic review aims to elucidate this correlation. We analyzed 55 studies from 14 countries, comprising 36 studies focusing on sleep duration, 20 on insomnia, and 13 on hypersomnia. A total of 10,767,085 participants were included in 49 cohort studies with a mean follow-up duration of 9.1 years. A non-linear association between sleep duration and cognitive decline was identified. Both long (risk ratio (RR):1.35, 95 % confidence intervals (CIs):1.23-1.48) and short sleep durations (RR: 1.12, 95 % CIs:1.03-1.22) were associated with an elevated risk of cognitive decline compared to moderate sleep duration. Additionally, hypersomnia (RR:1.26, 95 % CIs: 1.15-1.39) and insomnia (RR: 1.16, 95 % CIs: 1.002-1.34) were also linked to an increased risk. Moreover, prolonged sleep duration posed a higher risk of cognitive decline than stable sleep duration (RR:1.42, 95 % CIs:1.27-1.59). Importantly, transitioning from short or moderate to long sleep duration, as well as persistent long sleep duration, exhibited higher RRs for cognitive decline (RRs: 1.94, 1.40, and 1.28, respectively) compared to persistent moderate sleep duration. Our findings underscore the significance of prolonged sleep duration, alongside short and long sleep durations, with an elevated risk of cognitive decline. The association is tied to the degree of sleep duration changes. Our study highlights the importance of considering changes in sleep patterns over time, not just static sleep durations.

Biomarkers of sleep-wake disturbance as predictors of cognitive decline and accelerated disease progression

INTRODUCTION

In older adults, where sleep disturbances and cognitive impairment are common, mounting evidence suggests a potential connection between sleep and cognitive function, highlighting the significance of utilizing sleep as a biomarker for early detection of cognitive impairment to improve clinical outcomes in a noninvasive, cost-effective manner.

AREAS COVERED

This review describes the relationship between sleep and cognitive function in older adults, encompassing both subjective and objective measures of sleep quality, duration, architecture, and sleep-disordered breathing. The authors consider the directionality of the associations observed in prospective and cross-sectional studies, exploring whether sleep disturbances precede cognitive decline or vice versa. Furthermore, they discuss the potential bidirectional relationships between sleep and Alzheimer's disease (AD) risks in older adults while also examining the neurodegenerative pathways of this relationship.

EXPERT OPINION

Routine sleep monitoring in primary care settings has the potential to bolster early detection and treatment of sleep disturbance, and by extension, reduce the risk of dementia. Improving sleep assessment tools, such as wearables, provide scalable alternatives to traditional methods like polysomnography, potentially enabling widespread monitoring of sleep characteristics. Standardized measurement and inclusive participant recruitment are needed to enhance generalizability, while longitudinal studies are essential to understand the interaction between sleep and AD pathology.

Long sleep time and excessive need for sleep: State of the art and perspectives

The mechanisms underlying the individual need for sleep are unclear. Sleep duration is indeed influenced by multiple factors, such as genetic background, circadian and homeostatic processes, environmental factors, and sometimes transient disturbances such as infections. In some cases, the need for sleep dramatically and chronically increases, inducing a daily-life disability. This "excessive need for sleep" (ENS) was recently proposed and defined in a European Position Paper as a dimension of the hypersomnolence spectrum, "hypersomnia" being the objectified complaint of ENS. The most severe form of ENS has been described in Idiopathic Hypersomnia, a rare neurological disorder, but this disabling symptom can be also found in other hypersomnolence conditions. Because ENS has been defined recently, it remains a symptom poorly investigated and understood. However, protocols of long-term polysomnography recordings have been reported by expert centers in the last decades and open the way to a better understanding of ENS through a neurophysiological approach. In this narrative review, we will 1) present data related to the physiological and pathological variability of sleep duration and their mechanisms, 2) describe the published long-term polysomnography recording protocols, and 3) describe current neurophysiological tools to study sleep microstructure and discuss perspectives for a better understanding of ENS.

Sleep disturbances and change in multiple cognitive domains among older adults: a multicenter study of five Nordic cohorts

STUDY OBJECTIVES

We examined and compared cross-sectional and longitudinal associations between self-reported sleep disturbances and various cognitive domains in five separate Nordic European longitudinal aging studies (baseline N = 5631, mean age = 77.7, mean follow-up = 4.16 years).

METHODS

Comparable sleep parameters across studies included reduced sleep duration/quality, insomnia symptoms (sleep latency, waking up at night, and early awakenings), short and long sleep duration, and daytime napping. The cognitive domains were episodic memory, verbal fluency, perceptual speed, executive functioning, and global cognition (aggregated measure). A series of mixed linear models were run separately in each study and then compared to assess the level and rate of change in cognitive functioning across each sleep disturbance parameter. Models were adjusted for age, sex, education, hypnotic usage, depressive symptoms, lifestyle factors, cardiovascular, and metabolic conditions. By using a coordinated analytic approach, comparable construct-level measurements were generated, and results from identical statistical models were qualitatively compared across studies.

RESULTS

While the pattern of statistically significant results varied across studies, subjective sleep disturbances were consistently associated with worse cognition and steeper cognitive decline. Insomnia symptoms were associated with poorer episodic memory and participants sleeping less or more than 7-8 hours had a steeper decline in perceptual speed. In addition, daytime napping (>2 hours) was cross-sectionally and longitudinally associated with all examined cognitive domains. Most observed associations were study-specific (except for daytime napping), and a majority of association estimates remained significant after adjusting for covariates.

CONCLUSION

This rigorous multicenter investigation further supports the importance of sleep disturbance, including insomnia, long and short sleep duration, and daytime napping on baseline cognitive functioning and rate of change among older adults. These sleep factors may be targeted in future lifestyle interventions to reduce cognitive decline.

Risk factors of cognitive frailty in elderly chronic obstructive pulmonary disease patients and its implication for death: a cohort study

BACKGROUNDS

Cognitive frailty, a clinical syndrome with physical frailty and cognitive impairment, leads to mortality and other adverse health outcomes in older adults. This study aimed to investigate the prevalence of cognitive frailty, and its influencing factors, and follow its impact on short-term mortality in elderly chronic obstructive pulmonary disease patients, to provide a theoretical scientific reference basis for clinical intervention and management of cognitive frailty.

METHODS

A sample of 243 elderly chronic obstructive pulmonary disease patients in the respiratory department of a tertiary care hospital was conveniently sampled from November 2021 to February 2023, and the prevalence of cognitive frailty was investigated using the General Information Survey Scale, the Fried Phenotype Scale, the Mini-Mental State Examination, the Anxiety Self-Rating Scale, the Brief Geriatric Depression Scale, and the Mortality Record. The mortality was recorded by telephone follow-up after 6 months. A database was created and statistical analysis such as one-way analysis of variance, logistic regression analysis, Kaplan-Meier, and Cox survival analysis were used to analyze the data.

RESULTS

A total of 47 patients (19.3%) had cognitive frailty; there were statistical differences in the prevalence of cognitive frailty by medical payment type, physical exercise, and sleeping time (P < 0.05). During a 6-month follow-up, 38 patients (15.6%) died. Cox survival analysis showed that the risk of death in elderly chronic obstructive pulmonary disease patients in the cognitive frailty group was 3.212 times higher than that in the normal cognitive function and non-frailty group (95% CI 1.646-6.270, P = 0.001), and 5.266 times higher than that in the normal cognitive function and frailty group (95% CI 3.159-8.778, P < 0.001).

CONCLUSIONS

The prevalence of cognitive frailty in elderly chronic obstructive pulmonary disease patients is high, and clinical staff should pay attention to patients' medical burden and financial ability, and reduce the incidence of cognitive frailty by instructing patients to perform physical exercise and arrange sleep time. Cognitive frailty is an important risk factor for mortality within 6 months in elderly chronic obstructive pulmonary disease patients, and early intervention should be emphasised to reduce or delay cognitive frailty and mortality.

Objectively measured prolonged sleep is associated with plasma cytokines in older adults with mild cognitive impairment

This study aimed to determine whether objective sleep time is associated with the concentrations of various plasma cytokines in older adults with mild cognitive impairment (MCI). In total, 118 adults with MCI (66 women; mean age: 75.7 years) participated in this prospective cohort study. All participants were required to wear a wristband sensor for 7.8 days, on average, every 3 months for 1 year and undergo measurement of 27 plasma cytokines using multiplex immunoassays. After adjusting for potential confounders, the associations of total sleep time with cytokine concentrations were assessed by multiple linear regression analysis. The total sleep time was significantly correlated with plasma interleukin (IL)-9 and macrophage inflammatory protein (MIP)-1β levels (r = 0.239, p = 0.009, and r = 0.242, p = 0.008, respectively). Moreover, these associations remained significant after adjusting for covariates, including demographic characteristics, lifestyle-related diseases, and apolipoprotein E status (β = 0.272, 95% confidence interval: 0.095-0.448, p = 0.003, and β = 0.27, 95% confidence interval: 0.092-0.449, p = 0.003, respectively). Thus, this study is the first to demonstrate the association between objective prolonged sleep and higher plasma IL-9 and MIP-1β levels in older adults with MCI.

Sleep Duration and Executive Function in Adults

PURPOSE OF REVIEW

To review the literature examining the relationship between sleep and cognition, specifically examining the sub-domain of executive function. We explore the impact of sleep deprivation and the important question of how much sleep is required for optimal cognitive performance. We consider how other sleep metrics, such as sleep quality, may be a more meaningful measure of sleep. We then discuss the putative mechanisms between sleep and cognition followed by their contribution to developing dementia.

RECENT FINDINGS

Sleep duration and executive function display a quadratic relationship. This suggests an optimal amount of sleep is required for daily cognitive processes. Poor sleep efficiency and sleep fragmentation are linked with poorer executive function and increased risk of dementia during follow-up. Sleep quality may therefore be more important than absolute duration. Biological mechanisms which may underpin the relationship between sleep and cognition include brain structural and functional changes as well as disruption of the glymphatic system. Sleep is an important modifiable lifestyle factor to improve daily cognition and, possibly, reduce the risk of developing dementia. The impact of optimal sleep duration and sleep quality may have important implications for every ageing individual.

Association between cumulative smoking exposure and cognitive decline in non-demented older adults: NEDICES study

Whether cumulative smoking exposure is associated with cognitive decline among older adults remains unresolved. To address this question, we used data from the Neurological Disorders in Central Spain (NEDICES) cohort study, in which 2624 older adults were evaluated at two-time points separated by three years. A 37-item version of the Mini-Mental State Examination (MMSE-37) was administered at two visits to assess cognitive change. Regarding smoking exposure, we calculated an individual baseline score based on pack-years (i.e., packs of cigarettes smoked per day multiplied by years of smoking) in current and former smokers. Thus, smoking exposure was categorized into tertiles (low: < 19.0, medium: 19.0-47.0, and high: > 47.0). We used multivariable generalized estimating equation models to assess associations between pack-years and smoking status with 37-MMSE total score change from baseline to follow-up. The MMSE-37 total score had a decline of 1.05 points (confidence interval [CI] 95% 0.62 to 1.48) in the lower tertile of pack-years, 1.16 (CI 95% 0.70 to 1.62) in the middle tertile and 1.17 (CI 95% 0.70 to 1.65) in the higher tertile compared to never smokers, after adjusting for several demographic and clinical variables. The same occurred with smoking status, i.e., a decline of 1.33 (CI 95% 0.87 to 1.79) in current smokers and 1.01 (CI 95% 0.63 to 1.40) in former smokers. Our study provides evidence of the cumulative effect of smoking on cognition in older adults. Using a prospective population-based design, we demonstrated that cumulative smoking exposure was associated with cognitive decline in non-demented older adults. More population-based evidence is required to elucidate this association in older adults without dementia.

Reported sleep duration reveals segmentation of the adult life-course into three phases

Classically the human life-course is characterized by youth, middle age and old age. A wide range of biological, health and cognitive functions vary across this life-course. Here, using reported sleep duration from 730,187 participants across 63 countries, we find three distinct phases in the adult human life-course: early adulthood (19-33yrs), mid-adulthood (34-53yrs), and late adulthood (54+yrs). They appear stable across culture, gender, education and other demographics. During the third phase, where self-reported sleep duration increases with age, cognitive performance, as measured by spatial navigation, was found to have an inverted u-shape relationship with reported sleep duration: optimal performance peaks at 7 hours reported sleep. World-wide self-reported sleep duration patterns are geographically clustered, and are associated with economy, culture, and latitude.

Understanding and approaching excessive daytime sleepiness

Excessive daytime sleepiness (EDS) is a public health issue. However, it remains largely undervalued, scarcely diagnosed, and poorly supported. Variations in the definition of EDS and limitations in clinical assessment lead to difficulties in its epidemiological study, but the relevance of this symptom from a socioeconomic perspective is inarguable. EDS might be a consequence of several behavioural issues leading to insufficient or disrupted sleep, as well as a consequence of sleep disorders including sleep apnoea syndrome, circadian disorders, central hypersomnolence disorders (narcolepsy and idiopathic hypersomnia), other medical or psychiatric conditions, or medications. Furthermore, EDS can have implications for health as it is thought to act as a risk factor for other conditions, such as cardiovascular and neurodegenerative disorders. Because of the heterogeneous causes of EDS and the complexity of its pathophysiology, management will largely depend on the cause, with the final aim of making treatment specific to the individual using precision medicine and personalised medicine.

Longitudinal associations between sleep duration and cognitive function in the elderly population in China: A 10-year follow-up study from 2005 to 2014

OBJECTIVE

Sleep duration is increasingly recognized as an important determinant of cognitive function among elderly. However, longitudinal studies on the relationship between sleep duration and cognitive function in Chinese elderly are rare. We sought to investigate the longitudinal association between sleep duration and cognitive function in Chinese elderly during a 10-year follow-up.

METHOD

This longitudinal study analyzed 2148 elderly (the baseline including 43.16% aged 70%-79%, 23.79% aged 80 and over) who had participated in four waves of the Chinese Longitudinal Healthy Longevity Survey during 2005-2014. Cognitive function (including global functioning and cognitive domains) was assessed using the Chinese version of the Mini-Mental State Examination. Sleep duration was assessed via self-reports. Mixed model analysis was used to evaluate the association between sleep duration and cognitive function, adjusting for sociodemographic variables and risk factors for cognitive function.

RESULTS

There is an inverted U-shaped relationship between sleep duration and global cognition and cognitive domains, with the highest cognitive scores observed for sleep durations between 6 and 9 h and the curve shifting from smooth to steeper from 2005 to 2014. The regression model showed that long sleep duration (>9 h) is significantly associated with global cognition and four cognitive domains: orientation, attention and calculation, immediate recall and visual construction. Both long and short sleep durations are significantly associated with delayed recall and not significantly associated with category fluency, language or the ability to follow a three-stage command. The five cognitive domains related to sleep duration are the domains that exhibited a rapid rate of decline.

CONCLUSIONS

Sleep duration can be identified as a modifiable risk factor for cognitive decline, as long or short sleep duration is associated with the five cognitive domains that exhibit cognitive decline. These findings suggest the need for intervention measures to maintain healthy sleep durations among Chinese elderly people.

Association of Short and Long Sleep Duration With Amyloid-β Burden and Cognition in Aging

Importance

Disrupted sleep is common in aging and is associated with cognition. Age-related changes to sleep are associated with multiple causes, including early Alzheimer disease pathology (amyloid β [Aβ]), depression, and cardiovascular disease.

Objective

To investigate the associations between self-reported sleep duration and brain Aβ burden as well as the demographic, cognitive, and lifestyle variables in adults with normal cognition.

Design, Setting, and Participants

This cross-sectional study obtained data from participants in the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) study, which is being conducted in 67 sites in the United States, Canada, Australia, and Japan. The sample for this analysis consisted of individuals aged 65 to 85 years who underwent an Aβ positron emission tomography (PET) scan, had complete apolipoprotein E (APOE) genotype data, and were identified as clinically normal (per a Clinical Dementia Rating score of 0) and cognitively unimpaired (per a Mini-Mental State Examination score of 25 to 30 and Logical Memory Delayed Recall test score of 6 to 18). Data were analyzed from April 3, 2020, to June 20, 2021.

Main Outcomes and Measures

The outcome was self-reported nightly sleep duration (grouped by short sleep duration: ≤6 hours, normal sleep duration: 7-8 hours, and long sleep duration: ≥9 hours) compared with demographic characteristics, Aβ burden (as measured with a fluorine 18-labeled-florbetapir PET scan), objective and subjective cognitive function measures, and lifestyle variables.

Results

The 4417 participants in the study included 2618 women (59%) and had a mean (SD) age of 71.3 (4.7) years. Self-reported shorter sleep duration was linearly associated with higher Aβ burden (β [SE] = -0.01 [0.00]; P = .005), and short sleep duration was associated with reduced cognition that was mostly in memory domains. No difference in Aβ was found between long and normal sleep duration groups (β [SE] = 0.00 [0.01]; P = .99). However, compared with normal sleep duration, both short and long sleep durations were associated with higher body mass index (short vs normal sleep duration: β [SE] = 0.48 [0.17], P = .01; long vs normal sleep duration: β [SE] = 0.97 [0.31], P = .002), depressive symptoms (short vs normal sleep duration: β [SE] = 0.31 [0.05], P < .001; long vs normal sleep duration: β [SE] = 0.39 [0.09], P < .001), and daytime napping (short vs normal sleep duration: β [SE] = 2.66 [0.77], P = .001; long vs normal sleep duration: β [SE] = 3.62 [1.38], P = .01). Long sleep duration was associated with worse performance across multiple cognitive domains.

Conclusions and Relevance

In this cross-sectional study, both short and long sleep durations were associated with worse outcomes for older adults, such as greater Aβ burden, greater depressive symptoms, higher body mass index, and cognitive decline, emphasizing the importance of maintaining adequate sleep.

Social capital and cognitive decline: Does sleep duration mediate the association?

Background

Studies have found that social capital (SC) is associated with the risk of cognitive decline; however, the mechanism explaining how SC leads to cognitive decline is unclear. The current study examines the mediation effect of sleep duration on the relationship between SC and cognitive decline in Chinese older adults.

Methods

A cross-sectional study of 955 community-dwelling aged 60 or over was conducted. The mini-mental state examination (MMSE), self-report sleep duration questionnaire, and social capital scales were administered during the face-to-face survey. The Bootstrap methods PROCESS program is employed to test the mediation model.

Results

After controlling for covariates, both social cohesion and social interaction were positively correlated with the MMSE score (p<0.001), and social cohesion was negatively correlated with sleep duration (p = 0.009); On the contrary, sleep duration was negatively correlated with MMSE score (p<0.001). Linear regression analysis showed social cohesion was positively associated with the MMSE score (β = 0.16, p = 0.005), while sleep duration was associated with an increased risk of cognitive decline (β = -0.72, p<0.001). Sleep duration has mediated the relationship between social cohesion and cognitive decline (explaining 21.7% of the total variance).

Conclusions

Social capital negatively associated with the risk of cognitive decline in this Chinese population, and sleep duration may partly explain this relationship. It may be a suggestive clue to identify those at a higher risk of progressing to cognitive impairment. Further prospective study in need to confirm this finding due to the cross-sectional design.

Late-life sleep duration associated with amnestic mild cognitive impairment

OBJECTIVE

To examine the association between sleep duration in different stages of life and amnestic mild cognitive impairment (aMCI).

DESIGN, SETTING, AND PARTICIPANTS

A total of 2472 healthy elderly and 505 patients with aMCI in China were included in this study. The study analyzed the association between aMCI and sleep duration in different stages of life.

MEASUREMENTS

We compared sleep duration in different stages of life and analyzed the association between Montreal Cognitive Assessment scores and sleep duration by curve estimation. Logistic regression was used to evaluate the association between aMCI and sleep duration.

RESULTS

In the analysis, there were no results proving that sleep duration in youth (P = 0.719, sleep duration < 10 hours; P = 0.999, sleep duration ≥ 10 hours) or midlife (P = 0.898, sleep duration < 9 hours; P = 0.504, sleep duration ≥ 9 hours) had a significant association with aMCI. In the group sleeping less than 7 hours in late life, each hour more of sleep duration was associated with approximately 0.80 of the original risk of aMCI (P = 0.011, odds ratio = 0.80, 95% confidence interval = 0.68-0.95).

CONCLUSIONS

Among the elderly sleeping less than 7 hours, there is a decreased risk of aMCI for every additional hour of sleep.

CCCDTD5 recommendations on early non cognitive markers of dementia: A Canadian consensus

Introduction

Cognitive impairment is the hallmark of Alzheimer's disease (AD) and related dementias. However, motor decline has been recently described as a prodromal state that can help to detect at‐risk individuals. Similarly, sensory changes, sleep and behavior disturbances, and frailty have been associated with higher risk of developing dementia. These clinical findings, together with the recognition that AD pathology precedes the diagnosis by many years, raises the possibility that non‐cognitive changes may be early and non‐invasive markers for AD or, even more provocatively, that treating non‐cognitive aspects may help to prevent or treat AD and related dementias.

Methods

A subcommittee of the Canadian Consensus Conference on Diagnosis and Treatment of Dementia reviewed areas of emerging evidence for non‐cognitive markers of dementia. We examined the literature for five non‐cognitive domains associated with future dementia: motor, sensory (hearing, vision, olfaction), neuro‐behavioral, frailty, and sleep. The Grading of Recommendations Assessment, Development, and Evaluation system was used to assign the strength of the evidence and quality of the recommendations. We provide recommendations to primary care clinics and to specialized memory clinics, answering the following main questions: (1) What are the non‐cognitive and functional changes associated with risk of developing dementia? and (2) What is the evidence that sensory, motor, behavioral, sleep, and frailty markers can serve as potential predictors of dementia?

Results

Evidence supported that gait speed, dual‐task gait speed, grip strength, frailty, neuropsychiatric symptoms, sleep measures, and hearing loss are predictors of dementia. There was insufficient evidence for recommending assessing olfactory and vision impairments as a predictor of dementia.

Conclusions

Non‐cognitive markers can assist in identifying people at risk for cognitive decline or dementia. These non‐cognitive markers may represent prodromal symptoms and several of them are potentially amenable to treatment that might delay the onset of cognitive decline.

Sleep Disturbances in MCI and AD: Neuroinflammation as a Possible Mediating Pathway

Mild cognitive impairment (MCI) and Alzheimer's disease (AD) affect a high proportion of the elderly population with an increasing prevalence. Sleep disturbances are frequent in those with MCI and AD. This review summarizes existing research on sleep disturbances and neuroinflammation in MCI and AD. Although strong evidence supports various pathways linking sleep and AD pathology, the temporal direction of this central relationship is not yet known. Improved understanding of sleep disturbance and neuroinflammation in MCI and AD may aid in the identification of targets for their prevention.

Sleep problems and risk of all-cause cognitive decline or dementia: an updated systematic review and meta-analysis

OBJECTIVES

To conduct an updated systematic review and meta-analysis of association between sleep and all-cause cognitive disorders.

METHODS

PubMed and EMBASE were searched from inception to 18 February 2019. Cohort studies exploring longitudinal associations of sleep with cognitive decline or dementia were included. The multivariable-adjusted effect estimates were pooled by random-effects models, with credibility assessment. The robust error meta-regression model was used to conduct the dose-response meta-analysis for sleep duration.

RESULTS

11 155 reports were searched and 51 eligible cohorts with 15 sleep problems were included for our meta-analyses. Ten types of sleep conditions or parameters, including six (insomnia, fragmentation, daytime dysfunction, prolonged latency, rapid eye movement sleep behaviour disorder and excessive time in bed) with moderate-to-high levels of evidence, were linked to higher risk of all-cause cognitive disorders. Furthermore, a U-shaped relationship was revealed for the associations with sleep duration.

CONCLUSIONS

Sleep management might serve as a promising target for dementia prevention.

Sleep Duration and Cognition in a Nationally Representative Sample of U.S. Older Adults

OBJECTIVE

Excessive and insufficient sleep have been associated with cognitive dysfunction in older adults in U.S. and non-U.S.

STUDIES

However, the U.S. studies were not in nationally representative samples. The authors investigated the association between sleep duration and cognitive performance in a nationally representative sample of U.S. older adults.

PARTICIPANTS

The authors studied 1,496 survey participants aged 60 years or older from the National Health and Nutrition Examination Survey 2013-2014 dataset.

MEASUREMENTS

Our primary predictor was weekday (or workday) nighttime sleep duration, categorized as 2-4, 5, 6, 7 (reference), 8, 9, and 10 hours or more. The authors studied five cognitive outcomes: Consortium to Establish a Registry for Alzheimer's Disease Word Learning (CERAD-WL) immediate recall, CERAD-WL delayed recall, Animal Fluency Test (AFT), Digital Symbol Substitution Test (DSST), and subjective cognitive problems (SCP).

RESULTS

After adjusting for age, sex, race, education, depressive symptoms, and sedative-hypnotic use, sleep duration of 10 hours or more was significantly associated with lower scores on CERAD-WL immediate recall, CERAD-WL delayed recall, AFT, and DSST, and greater odds of SCP; sleep duration of 8 hours or more was associated with lower CERAD-WL delayed recall scores: 8, 9, and 10 hours or more. After adjustment, there were no significant associations of shorter sleep duration with cognition.

CONCLUSION

In U.S. adults aged 60 years or older, long nighttime weekday or workday sleep duration is associated with poorer verbal memory, semantic fluency, working memory, and processing speed in addition to greater odds of self-reported cognitive problems. Long sleep duration may be a marker of fragmented sleep or neurodegeneration in U.S. older adults.

Objective napping, cognitive decline, and risk of cognitive impairment in older men

INTRODUCTION

Little is known about the longitudinal association between napping and cognitive impairment in older adults.

METHODS

We used wrist actigraphy to measure naps in 2751 community-dwelling older men. Cognition was assessed repeatedly over 12 years, and clinically significant cognitive impairment was determined by physician diagnosis, Alzheimer's medication use or a significant cognitive decline.

RESULTS

After adjustment for all covariates, men with longer napping duration had greater cognitive decline and higher risk of cognitive impairment. Men who napped for ≥120 min/day (vs. <30 min/day) were 66% more likely to develop cognitive impairment (odds ratio = 1.66, 95% CI: 1.09-2.54) in 12 years. Further adjustment for nighttime sleep quality did not appreciably alter the results. The association between napping and cognitive impairment was more pronounced among those with higher sleep efficiency and average sleep duration.

DISCUSSION

Napping might be useful as an early marker of cognitive impairment in the elderly, and its cognitive effects may differ by nighttime sleep.

Subjective Cognitive Decline and Nighttime Sleep Alterations, a Longitudinal Analysis

Objective: The aim of this study was to analyze quantitative sleep changes and their implication on subjective cognitive decline (SCD). Objective sleep patterns were investigated by an actigraph and recorded at the baseline and 2-year after in order to examine specific sleep alterations in SCD.

Background: Sleep disorders are very common among average elderly adults and an altered sleep pattern is known to be a risk factor for future development of mild cognitive impairment (MCI) and dementia. Recent studies have shown how sleep is objectively altered in average senior adults with SCD, without any other significant change in cognition and behavior or brain structure. Considering that both SCD and disrupted sleep are risk factors for future MCI and dementia, with sleep only as a modifiable risk factor, further research is required to deeply investigate the interaction between sleep and SCD.

Methods: Among 70 community-dwelling elderly individuals who had been enrolled at baseline, 35 (64.6 ± 5.6 years, 15 M/20 F) underwent a complete neuropsychological battery and 1-week wrist actigraphy recording 2 years later during the follow-up stage. Individuals were divided into two groups according to their SCD Questionnaire (SCD-Q) score. Sleep hours, sleep efficiency and onset latency, napping and time awake after sleep onset (WASO) were collected. All individuals underwent structural magnetic resonance imaging (MRI) examination to exclude brain disorders. Data collection was performed at baseline and after 2 years at the follow-up phase.

Results: A significantly different night sleep time between the two groups was observed: SCD showed a lower total sleep time (TST) than non-SCD subjects. Moreover, a total time spent in bed (TIB) was significantly lower in SCD subjects over 2 years of observation.

Conclusions: Objective changes over time of the sleep pattern, specifically TIB and TST, are present in SCD individuals. The results of the study show that sleep alterations are common in SCD and underline the clinical importance of screening in order to assess sleep alterations as well as improve sleep in average adults with SCD complaints.

Association of postlunch napping duration and night-time sleep duration with cognitive impairment in Chinese elderly: a cross-sectional study

OBJECTIVE

To analyse the independent and combined associations of postlunch napping duration and night-time sleep duration with risk of cognitive impairment among Chinese elderly.

DESIGN

A cross-sectional study.

SETTING

We analysed the data from Zhejiang Ageing and Health Cohort, a population-based survey of seven counties located in Zhejiang province in eastern China.

PARTICIPANTS

10 740 participants aged 60 years or older were included in final analysis.

PRIMARY AND SECONDARY OUTCOME MEASURES

Cognitive impairment was assessed through Mini-Mental State Examination. Data on sleep-related characteristics was collected in the behavioural habits section within the questionnaire.

RESULTS

Relative to participants with 1-30 min of postlunch napping, those who did not nap and who napped longer had significantly higher risks for cognitive impairment. OR of cognitive impairment were 1.41 (95% CI 1.14 to 1.75) for participants with longer night-time sleep duration (≥9 hours), compared with those sleeping 7-8.9 hours. In addition, combined effects were further identified. Participants with both longer night-time sleep duration (≥9 hours) and longer postlunch napping duration (>60 min) (OR=2.01, 95% CI 1.30 to 3.13), as well as those with both longer night-time sleep duration (≥9 hours) and appropriate postlunch napping duration (1-30 min) (OR=2.01, 95% CI 1.20 to 3.38), showed significantly higher risk of cognitive impairment than those with sleeping 7-8 hours and napping 1-30 min. Meanwhile, a 34% increase in odds of cognitive impairment was observed in participants with both shorter night-time sleep duration (5-6.9 hours) and no napping.

CONCLUSION

Both postlunch napping duration and night-time sleep duration were independently and jointly associated with cognitive impairment, which needs verification in prospective studies.

Decision Tree for Early Detection of Cognitive Impairment by Community Pharmacists

Purpose: The early detection of Mild Cognitive Impairment (MCI) is essential in aging societies where dementia is becoming a common manifestation among the elderly. Thus our aim is to develop a decision tree to discriminate individuals at risk of MCI among non-institutionalized elderly users of community pharmacy. A more clinically and patient-oriented role of the community pharmacist in primary care makes the dispensation of medication an adequate situation for an effective, rapid, easy, and reproducible screening of MCI.

Methods: A cross-sectional study was conducted with 728 non-institutionalized participants older than 65. A total of 167 variables were collected such as age, gender, educational attainment, daily sleep duration, reading frequency, subjective memory complaint, and medication. Two screening tests were used to detect possible MCI: Short Portable Mental State Questionnaire (SPMSQ) and the Mini-Mental State Examination (MMSE). Participants classified as positive were referred to clinical diagnosis. A decision tree and predictive models are presented as a result of applying techniques of machine learning for a more efficient enrollment.

Results: One hundred and twenty-eight participants (17.4%) scored positive on MCI tests. A recursive partitioning algorithm with the most significant variables determined that the most relevant for the decision tree are: female sex, sleeping more than 9 h daily, age higher than 79 years as risk factors, and reading frequency. Moreover, psychoanaleptics, nootropics, and antidepressants, and anti-inflammatory drugs achieve a high score of importance according to the predictive algorithms. Furthermore, results obtained from these algorithms agree with the current research on MCI.

Conclusion: Lifestyle-related factors such as sleep duration and the lack of reading habits are associated with the presence of positive in MCI test. Moreover, we have depicted how machine learning provides a sound methodology to produce tools for early detection of MCI in community pharmacy.

Impact of findings on practice: The community of pharmacists provided with adequate tools could develop a crucial task in the early detection of MCI to redirect them immediately to the specialists in neurology or psychiatry. Pharmacists are one of the most accessible and regularly visited health care professionals and they can play a vital role in early detection of MCI.

The relationship between sleep and cognitive function in patients with prediabetes and type 2 diabetes

AIMS

Diabetes is linked to cognitive impairment. Sleep plays a role in memory consolidation. Sleep disturbances, commonly found in patients with diabetes, were shown to be related to cognitive dysfunction. This study explored the role of sleep in cognitive function of patients with abnormal glucose tolerance.

METHODS

A total of 162 patients (81 type 2 diabetes and 81 prediabetes) participated. Sleep duration and sleep efficiency (an indicator of sleep quality) were obtained using 7-day actigraphy recordings. Obstructive sleep apnea (OSA) was screened using an overnight in-home monitor. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). Three sub-scores of MoCA, visuoexecutive function, attention and delayed recall, were also analyzed.

RESULTS

Mean age was 54.8 (10.2) years. OSA was diagnosed in 123 participants (76.9%). Mean sleep duration was 6.0 (1.0) h and sleep efficiency was 82.7 (8.1) %. Sleep duration and OSA severity were not related to MoCA scores. Higher sleep efficiency was associated with higher MoCA scores (p = 0.003), and having diabetes (vs. prediabetes) was associated with lower MoCA scores (p = 0.001). After adjusting covariates, both having diabetes (vs. prediabetes) (B = - 1.137, p = 0.002) and sleep efficiency (B = 0.085, p < 0.001) were independently associated with MoCA scores. In addition, diabetes (B = - 0.608, p < 0.001) and sleep efficiency (B = 0.038, p < 0.001) were associated with visuoexecutive function. Sleep parameters were not related to delayed recall or attention scores.

CONCLUSION

Lower sleep efficiency is independently associated with lower cognitive function in patients with abnormal glucose tolerance. Whether sleep optimization may improve cognitive function in these patients should be explored.

Sleep, Cognitive impairment, and Alzheimer's disease: A Systematic Review and Meta-Analysis

Study Objectives

Mounting evidence implicates disturbed sleep or lack of sleep as one of the risk factors for Alzheimer's disease (AD), but the extent of the risk is uncertain. We conducted a broad systematic review and meta-analysis to quantify the effect of sleep problems/disorders on cognitive impairment and AD.

Methods

Original published literature assessing any association of sleep problems or disorders with cognitive impairment or AD was identified by searching PubMed, Embase, Web of Science, and the Cochrane library. Effect estimates of individual studies were pooled and relative risks (RR) and 95% confidence intervals (CI) were calculated using random effects models. We also estimated the population attributable risk.

Results

Twenty-seven observational studies (n = 69216 participants) that provided 52 RR estimates were included in the meta-analysis. Individuals with sleep problems had a 1.55 (95% CI: 1.25-1.93), 1.65 (95% CI: 1.45-1.86), and 3.78 (95% CI: 2.27-6.30) times higher risk of AD, cognitive impairment, and preclinical AD than individuals without sleep problems, respectively. The overall meta-analysis revealed that individuals with sleep problems had a 1.68 (95% CI: 1.51-1.87) times higher risk for the combined outcome of cognitive impairment and/or AD. Approximately 15% of AD in the population may be attributed to sleep problems.

Conclusion

This meta-analysis confirmed the association between sleep and cognitive impairment or AD and, for the first time, consolidated the evidence to provide an "average" magnitude of effect. As sleep problems are of a growing concern in the population, these findings are of interest for potential prevention of AD.

Excessive Sleepiness and Longer Nighttime in Bed Increase the Risk of Cognitive Decline in Frail Elderly Subjects: The MAPT-Sleep Study

Objective: To identify self-reported sleep-wake disturbances that increase the risk of cognitive decline over 1-year follow-up in frail participants.

Background: Risk factors for cognitive impairment need to be better identified especially at earliest stages of the pathogenesis. Sleep-wake disturbances may be critical factors to consider and were thus being assessed in this at-risk population for cognitive decline.

Methods: Frail elderly participants aged ≥70 years were selected from a subsample of the Multi-domain Alzheimer Preventive Trial (MAPT) for a sleep assessment (MAPT-sleep study) at 18-month follow-up (M18). Sleep-wake disturbances were evaluated using a clinical interview (duration of daytime and nighttime sleep, time in bed, number of naps, and presence of clinically-defined sleep disorders) and numerous validated questionnaires [Epworth Sleepiness Scale for excessive daytime sleepiness (EDS), Insomnia Severity Scale and Berlin Questionnaire]. Cognitive decline was defined as a difference between the MMSE and cognitive composite scores at M24 and M36 that was ranked in the lowest decile. Multivariate logistic regression models adjusted for several potential confounding factors were performed.

Results: Among the 479 frail participants, 63 developed MMSE-cognitive decline and 50 cognitive composite score decrease between M24 and M36. Subjects with EDS had an increased risk of MMSE decline (OR = 2.46; 95% CI [1.28; 4.71], p = 0.007). A longer time spent in bed during night was associated with cognitive composite score decline (OR = 1.32 [1.03; 1.71], p = 0.03). These associations persisted when controlling for potential confounders. Patients with MMSE score decline and EDS had more naps, clinically-defined REM-sleep Behavior Disorder, fatigue and insomnia symptoms, while patients with cognitive composite score decline with longer time in bed had increased 24-h total sleep time duration but with higher wake time after onset.

Conclusions: The risk of cognitive decline is higher in frailty subjects with EDS and longer nighttime in bed. Early detection of sleep-wake disturbances might help identifying frail subjects at risk of cognitive decline to further propose sleep health strategies to prevent cognitive impairment.

http://www.clinicaltrials.gov NCT00672685; Date of registration May, 2nd 2008.

Sleep Disturbance, Cognitive Decline, and Dementia: A Review

Approximately half of older people report sleep disturbances, which are associated with various health conditions, including neurodegenerative disease and dementia. Indeed, 60 to 70% of people with cognitive impairment or dementia have sleep disturbances, which are linked to poorer disease prognosis. Sleep disturbances in people with dementia have long been recognized and studied; however, in the past 10 years, researchers have begun to study disturbed sleep, including sleep fragmentation, abnormal sleep duration, and sleep disorders, as risk factors for dementia. In this review the authors summarize evidence linking sleep disturbance and dementia. They describe how specific aspects of sleep (e.g., quality, duration) and the prevalence of clinical sleep disorders (e.g., sleep-disordered breathing, rapid eye movement sleep behavior disorder) change with age; how sleep parameters and sleep disorders are associated with the risk of dementia; how sleep can be disturbed in dementia; and how disturbed sleep affects dementia prognosis. These findings highlight the potential importance of identifying and treating sleep problems and disorders in middle-aged and older adults as a strategy to prevent cognitive decline and dementia. The authors also review recent evidence linking sleep disturbances to the pathophysiology underlying dementing conditions, and briefly summarize available treatments for sleep disorders in people with dementia.

Actigraphic Sleep Duration and Fragmentation in Older Women: Associations With Performance Across Cognitive Domains

Study Objectives

To determine the association of actigraphic sleep duration and fragmentation with cognition in community-dwelling older women.

Methods

We studied 782 women (mean age = 87.4) of varied cognitive status from the Study of Osteoporotic Fractures who completed wrist actigraphy and the Modified Mini-Mental State Examination (3MS), California Verbal Learning Test-II-Short Form, digit span, verbal fluency tests, and the Trailmaking Test, Part B (Trails B). Total sleep time (TST) and wake after sleep onset (WASO) tertiles were our primary predictors.

Results

There were few significant associations in adjusted analyses. Compared to women with intermediate TST (mean = 430.1 minutes), those with the longest (508.7 minutes) had significantly poorer performance on the 3MS and phonemic and semantic fluency. Compared to women with the least WASO (31.5 minutes), those in the middle tertile (61.5 minutes) had significantly poorer delayed recall and those in the middle tertile and highest tertile (126.2 minutes) had poorer total recall and semantic fluency. We observed significant adjusted associations of TST with impaired 3MS performance and of WASO with impaired delayed recall, semantic fluency, and digit span. After excluding participants with adjudicated dementia diagnoses or indeterminate cognitive status, some adjusted associations remained but decreased in magnitude, others became nonsignificant, and a new association emerged.

Conclusions

In community-dwelling older women, longer objectively measured sleep duration and greater sleep fragmentation are associated with poorer performance and impairment in only a subset of cognitive domains. Some of these associations may be driven by women with dementia in whom disturbed sleep and cognitive performance share an underlying neuropathological basis.

Prevalence and correlates of sleep problems among elderly Singaporeans

BACKGROUND

The current study examined the prevalence and correlates of sleep problems among elderly Singaporeans.

METHODS

Data were taken from the Well-being of Singapore Elderly study, a cross-sectional, epidemiological survey conducted among Singapore residents aged 60 years and above (n = 2565). Respondents were screened for sleep problems through a series of questions in the Geriatric Mental State examination. Details on sociodemographic characteristics, physical activity, cognition, disability, chronic physical conditions, and depression were also collected. Logistic regression analysis was used to explore significant associations between sleep problems, sociodemographic characteristics, physical activity, cognition, disability, chronic physical conditions, and depression.

RESULTS

Overall, 13.7% (n = 341) of older adults reported at least one sleep problem. Of those who reported sleep problems, 69.4% experienced sleep interruption at night, 48.9% reported having difficulty falling asleep, 22.3% reported early morning awakening, and 11.4% had all three problems. Elderly with sleep problems were significantly more likely to have a range of chronic physical conditions and depression and were also significantly less likely to be physically active. Older adults with at least one sleep problem reported significantly greater disability compared to those with no sleep problems.

CONCLUSION

The high probability of comorbid chronic conditions as well as higher disability among those with sleep problems makes this an important area of research.

Sleep Duration and Subsequent Cortical Thinning in Cognitively Normal Older Adults

STUDY OBJECTIVES

To determine the association between self-reported sleep duration and cortical thinning among older adults.

METHODS

We studied 122 cognitively normal participants in the Baltimore Longitudinal Study of Aging with a mean age = 66.6 y (range, 51-84) at baseline sleep assessment and 69.5 y (range, 56-86) at initial magnetic resonance imaging (MRI) scan. Participants reported average sleep duration and completed a mean of 7.6 1.5-T MRI scans (range, 3-11), with mean follow-up from initial scan of 8.0 y (range, 2.0-11.8).

RESULTS

In analyses adjusted for age, sex, education, race, and interval between sleep assessment and initial MRI scan, participants reporting > 7 h sleep at baseline had thinner cortex in the inferior occipital gyrus and sulcus of the left hemisphere at initial MRI scan than those reporting 7 h (cluster P < 0.05). In adjusted longitudinal analyses, compared to those reporting 7 h of sleep, participants reporting < 7 h exhibited higher rates of subsequent thinning in the superior temporal sulcus and gyrus, inferior and middle frontal gyrus, and superior frontal sulcus of the left hemisphere, and in the superior frontal gyrus of the right hemisphere; those reporting > 7 h of sleep had higher rates of thinning in the superior frontal and middle frontal gyrus of the left hemisphere (cluster P < 0.05 for all). In sensitivity analyses, adjustment for apolipoprotein E (APOE) e4 genotype reduced or eliminated some effects but revealed others. When reports of < 7 h of sleep were compared to reports of 7 or 8 h combined, there were no significant associations with cortical thinning.

CONCLUSIONS

Among cognitively normal older adults, sleep durations of < 7 h and > 7 h may increase the rate of subsequent frontotemporal gray matter atrophy. Additional studies, including those that use objective sleep measures and investigate mechanisms linking sleep duration to gray matter loss, are needed.

Impaired Sleep Predicts Cognitive Decline in Old People: Findings from the Prospective KORA Age Study

STUDY OBJECTIVES

To investigate the association between sleep-related characteristics and cognitive change over 3 years of follow up in an aged population.

METHODS

Sleep characteristics and covariates were assessed at baseline in a standardized interview and clinical examination of the population-based KORA Age Study (n = 740, mean age = 75 years). Cognitive score (determined by telephone interview for cognitive status, TICS-m) was recorded at baseline and 3 years later.

RESULTS

At baseline, 82.83% (n = 613) of participants had normal cognitive status, 13.51% (n = 100) were classified with mild cognitive impairment (MCI), and 3.64% (n = 27) with probable dementia. The effect of three distinct patterns of poor sleep (difficulties initiating [DIS] or maintaining sleep [DMS], daytime sleepiness [DS] or sleep duration) were considered on a change in cognitive score with adjustments for potential confounders in generalized linear regression models. Cognitive decline was more pronounced in individuals with DMS compared to those with no DMS (β = 1.33, 95% CI = 0.41-2.24, P < 0.001). However, the predictive power of DMS was only significant in individuals with normal cognition and not impaired subjects at baseline. Prolonged sleep duration increased the risk for cognitive decline in cognitively impaired elderly (β = 1.86, 95% CI = 0.15-3.57, P = 0.03). Other sleep characteristics (DIS and DS) were not significantly associated with cognitive decline.

CONCLUSIONS

DMS and long sleep duration were associated with cognitive decline in normal and cognitively impaired elderly, respectively. The identification of impaired sleep quality may offer intervention strategies to deter cognitive decline in the elderly with normal cognitive function.

Sleep and Cognition in Community-Dwelling Older Adults: A Review of Literature

Changes in sleep and cognition occur with advancing age. While both may occur independently of each other, it is possible that alterations in sleep parameters may increase the risk of age-related cognitive changes. This review aimed to understand the relationship between sleep parameters (sleep latency, wake after sleep onset, sleep efficiency, sleep duration, general sleep complaints) and cognition in community-dwelling adults aged 60 years and older without sleep disorders. Systematic, computer-aided searches were conducted using multiple sleep and cognition-related search terms in PubMed, PsycINFO, and CINAHL. Twenty-nine manuscripts met the inclusion criteria. Results suggest an inconsistent relationship between sleep parameters and cognition in older adults and modifiers such as depressive symptoms, undiagnosed sleep apnea and other medical conditions may influence their association. Measures of sleep and cognition were heterogeneous. Future studies should aim to further clarify the association between sleep parameters and cognitive domains by simultaneously using both objective and subjective measures of sleep parameters. Identifying which sleep parameters to target may lead to the development of novel targets for interventions and reduce the risk of cognitive changes with aging.

Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion

The American Academy of Sleep Medicine and Sleep Research Society recently released a Consensus Statement regarding the recommended amount of sleep to promote optimal health in adults. This paper describes the methodology, background literature, voting process, and voting results for the consensus statement. In addition, we address important assumptions and challenges encountered during the consensus process. Finally, we outline future directions that will advance our understanding of sleep need and place sleep duration in the broader context of sleep health.

Symptomatic Atherosclerotic Disease and Decreased Risk of Cancer-Specific Mortality: A Prospective, Population-Based Study (NEDICES)

The few studies that have assessed the association between symptomatic atherosclerotic disease and risk of cancer have had conflicting results. In addition, these studies ascertained participants either from treatment settings (ie, service-based studies) or by using a records linkage system (ie, medical records of patients evaluated at clinics or hospitals) and, therefore, were prone to selection bias. Our purpose was to estimate the risk of cancer mortality in a large population-based sample of elderly people, comparing participants with symptomatic atherosclerotic disease (atherosclerotic stroke and coronary disease) to their counterparts without symptomatic atherosclerotic disease (ie, controls) in the same population.In this population-based, prospective study (Neurological Disorders of Central Spain, NEDICES), 5262 elderly community-dwelling participants with and without symptomatic atherosclerotic disease were identified and followed for a median of 12.1 years, after which the death certificates of those who died were reviewed.A total of 2701 (53.3%) of 5262 participants died, including 314 (68.6%) of 458 participants with symptomatic atherosclerotic disease and 2387 (49.7%) of 4804 controls. Cancer mortality was reported significantly less often in those with symptomatic atherosclerotic disease (15.6%) than in controls (25.6%) (P < 0.001). In an unadjusted Cox model, risk of cancer-specific mortality was decreased in participants with symptomatic atherosclerotic disease (HR = 0.74, 95% confidence interval [CI], 0.55-0.98, P = 0.04) vs. those without symptomatic atherosclerotic disease (reference group). In an adjusted Cox model, HR = 0.58; 95% CI, 0.38-0.89; P = 0.01.This population-based, prospective study suggests that there is an inverse association between symptomatic atherosclerotic disease and risk of cancer mortality.

Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion

The American Academy of Sleep Medicine and Sleep Research Society recently released a Consensus Statement regarding the recommended amount of sleep to promote optimal health in adults. This paper describes the methodology, background literature, voting process, and voting results for the consensus statement. In addition, we address important assumptions and challenges encountered during the consensus process. Finally, we outline future directions that will advance our understanding of sleep need and place sleep duration in the broader context of sleep health.

Sleep, cognition, and normal aging: integrating a half century of multidisciplinary research

Sleep is implicated in cognitive functioning in young adults. With increasing age, there are substantial changes to sleep quantity and quality, including changes to slow-wave sleep, spindle density, and sleep continuity/fragmentation. A provocative question for the field of cognitive aging is whether such changes in sleep physiology affect cognition (e.g., memory consolidation). We review nearly a half century of research across seven diverse correlational and experimental domains that historically have had little crosstalk. Broadly speaking, sleep and cognitive functions are often related in advancing age, though the prevalence of null effects in healthy older adults (including correlations in the unexpected, negative direction) indicates that age may be an effect modifier of these associations. We interpret the literature as suggesting that maintaining good sleep quality, at least in young adulthood and middle age, promotes better cognitive functioning and serves to protect against age-related cognitive declines.

Long sleep duration in elders without dementia increases risk of dementia mortality (NEDICES)

OBJECTIVE

To determine in a population-based study whether long sleep duration was associated with increased risk of dementia mortality.

METHODS

In this prospective, population-based study of 3,857 people without dementia aged 65 years and older (NEDICES [Neurological Disorders in Central Spain]), participants reported their daily sleep duration. The average daily total sleep duration was grouped into 3 categories: ≤5 hours (short sleepers), 6-8 hours (reference category), and ≥9 hours (long sleepers). Community-dwelling elders were followed for a median of 12.5 years, after which the death certificates of those who died were examined.

RESULTS

A total of 1,822 (47.2%) of 3,857 participants died, including 201 (11.0%) deaths among short sleepers, 832 (45.7%) among long sleepers, and 789 (43.3%) among those participants in the reference category. Of 1,822 deceased participants, 92 (5.1%) had a dementia condition reported on the death certificate (49 [53.3%] were long sleepers, 36 [39.1%] reported sleeping between 6 and 8 hours, and 7 [7.6%] were short sleepers). In an unadjusted Cox model, risk of dementia-specific mortality was increased in long sleepers (hazard ratio for dementia mortality in long sleepers = 1.58, p = 0.04) when compared with the reference group. In a Cox model that adjusted for numerous demographic factors and comorbidities, the hazard ratio for dementia mortality in long sleepers was 1.63 (p = 0.03).

CONCLUSIONS

Self-reported long sleep duration was associated with 58% increased risk of dementia-specific mortality in this cohort of elders without dementia. Future studies are required to confirm these findings.

Faster cognitive decline in elders without dementia and decreased risk of cancer mortality: NEDICES Study

OBJECTIVE

To assess whether faster cognitive decline in elders without dementia is associated with decreased risk of cancer mortality.

METHODS

In this population-based, prospective study of 2,627 people without dementia aged 65 years and older (Neurological Disorders in Central Spain), a 37-item version of the Mini-Mental State Examination (37-MMSE) was administered at 2 visits (baseline and follow-up, approximately 3 years later). We divided change in 37-MMSE into tertiles (lower tertile ≥ 2 point improvement in score, higher tertile ≥ 2 point decline in score). Community-dwelling elders were followed for a median of 12.9 years, after which the death certificates of those who died were examined.

RESULTS

A total of 1,003 (38.2%) died, including 339 (33.8%) deaths among participants who were in the higher tertile of 37-MMSE change and 664 (66.2%) deaths among those in the remaining tertiles. Cancer was reported significantly less often in those in the higher tertile of MMSE change (20.6%) than in those in the remaining tertiles (28.6%): in an unadjusted Cox model, hazard ratio for cancer mortality in participants within the higher tertile = 0.75 (p = 0.04) compared with the participants within the remaining tertiles. In a Cox model that adjusted for a variety of demographic factors and comorbidities, hazard ratio for cancer mortality in participants within the higher tertile = 0.70 (p = 0.01).

CONCLUSION

In this population-based, prospective study of community-dwelling elders without dementia, faster cognitive decline was associated with a decreased risk of cancer mortality. Further studies are required to elucidate this inverse association in elders without dementia.