Sleep quality and 1-year incident cognitive impairment in community-dwelling older adults

Extraction of sleep information from clinical notes of Alzheimer's disease patients using natural language processing

OBJECTIVES

Alzheimer's disease (AD) is the most common form of dementia in the United States. Sleep is one of the lifestyle-related factors that has been shown critical for optimal cognitive function in old age. However, there is a lack of research studying the association between sleep and AD incidence. A major bottleneck for conducting such research is that the traditional way to acquire sleep information is time-consuming, inefficient, non-scalable, and limited to patients' subjective experience. We aim to automate the extraction of specific sleep-related patterns, such as snoring, napping, poor sleep quality, daytime sleepiness, night wakings, other sleep problems, and sleep duration, from clinical notes of AD patients. These sleep patterns are hypothesized to play a role in the incidence of AD, providing insight into the relationship between sleep and AD onset and progression.

MATERIALS AND METHODS

A gold standard dataset is created from manual annotation of 570 randomly sampled clinical note documents from the adSLEEP, a corpus of 192 000 de-identified clinical notes of 7266 AD patients retrieved from the University of Pittsburgh Medical Center (UPMC). We developed a rule-based natural language processing (NLP) algorithm, machine learning models, and large language model (LLM)-based NLP algorithms to automate the extraction of sleep-related concepts, including snoring, napping, sleep problem, bad sleep quality, daytime sleepiness, night wakings, and sleep duration, from the gold standard dataset.

RESULTS

The annotated dataset of 482 patients comprised a predominantly White (89.2%), older adult population with an average age of 84.7 years, where females represented 64.1%, and a vast majority were non-Hispanic or Latino (94.6%). Rule-based NLP algorithm achieved the best performance of F1 across all sleep-related concepts. In terms of positive predictive value (PPV), the rule-based NLP algorithm achieved the highest PPV scores for daytime sleepiness (1.00) and sleep duration (1.00), while the machine learning models had the highest PPV for napping (0.95) and bad sleep quality (0.86), and LLAMA2 with finetuning had the highest PPV for night wakings (0.93) and sleep problem (0.89).

DISCUSSION

Although sleep information is infrequently documented in the clinical notes, the proposed rule-based NLP algorithm and LLM-based NLP algorithms still achieved promising results. In comparison, the machine learning-based approaches did not achieve good results, which is due to the small size of sleep information in the training data.

CONCLUSION

The results show that the rule-based NLP algorithm consistently achieved the best performance for all sleep concepts. This study focused on the clinical notes of patients with AD but could be extended to general sleep information extraction for other diseases.

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.

Factors Affecting Resilience and Prevention of Alzheimer's Disease and Related Dementias

Alzheimer's disease (AD) is a devastating, age-associated neurodegenerative disorder and the most common cause of dementia. The clinical continuum of AD spans from preclinical disease to subjective cognitive decline, mild cognitive impairment, and dementia stages (mild, moderate, and severe). Neuropathologically, AD is defined by the accumulation of amyloid β (Aβ) into extracellular plaques in the brain parenchyma and in the cerebral vasculature, and by abnormally phosphorylated tau that accumulates intraneuronally forming neurofibrillary tangles (NFTs). Development of treatment approaches that prevent or even reduce the cognitive decline because of AD has been slow compared to other major causes of death. Recently, the United States Food and Drug Administration gave full approval to 2 different Aβ-targeting monoclonal antibodies. However, this breakthrough disease modifying approach only applies to a limited subset of patients in the AD continuum and there are stringent eligibility criteria. Furthermore, these approaches do not prevent progression of disease, because other AD-related pathologies, such as NFTs, are not directly targeted. A non-mutually exclusive alternative is to address lifestyle interventions that can help reduce the risk of AD and AD-related dementias (ADRD). It is estimated that addressing such modifiable risk factors could potentially delay up to 40% of AD/ADRD cases. In this review, we discuss some of the many modifiable risk factors that may be associated with prevention of AD/ADRD and/or increasing brain resilience, as well as other factors that may interact with these modifiable risk factors to influence AD/ADRD progression. ANN NEUROL 2024.

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.

Relationship Between Sleep Duration and Cognitive Function in Older Adults: Analysis of NHANES and UK Biobank GWAS Data

OBJECTIVES

To explore the relationship between sleep duration and cognitive functions in older adults using NHANES, a national US population study dataset, and to explore the causal association with Mendelian randomization (MR) using the UK Biobank.

METHODS

First, an observational study was conducted with the NHANES database with participants ≥60 years. Sleep duration was measured with accelerometers for 7 consecutive days. Participants were divided into habitual short sleep (<7 h) and long sleep (>9 h) groups. Cognitive functions were measured with the CERAD Word Learning sub-set, Animal Fluency, and Digit Symbol Substitution test (DSST). Multivariate regression models were used to explore relationships between sleep duration and cognitive functions. Second, bidirectional MR was conducted with data for self-reported sleep duration, which came from a genome-wide association study (GWAS) comprising 446,118 adults from the UK Biobank, and general cognitive performance, which was obtained from a recent GWAS study (N = 257,841). Inverse-variance weighted (IVW) was used as the primary estimation of the outcome.

RESULTS

In the observational study, 2687 participants were included. Sleep duration was associated with cognitive functions in a non-linear way. Habitual long sleep (>9°h) was associated with lower scores on DSST (OR = 0.01, p = .003) in the fully-adjusted model. The association between habitual short sleep and cognitive functions was insignificant. For the MR, genetically predicted lower general cognitive performance was causally associated with a higher prevalence of habitual short sleep (OR = 0.97, p = 5.1 × 10-7) and long sleep (OR = 0.97, p = 8.87 × 10-16).

DISCUSSION

Short and long sleep duration might be both causally associated with worse outcomes of cognitive functions in older adults, highlighting the importance of maintaining sleep health.

Poor sleep quality may trigger cognitive deficits after recovery from COVID-19

Objective

In the present study, we aimed to assess the cognition of post-COVID-19 condition (PCC) participants in relation to their subjective sleep quality (Pittsburgh Sleep Quality Index, PSQI) and to analyse possible moderators of this effect, such as quality of life (European Quality of Life-5 Dimensions, EQ-5D), fatigue (Chadler Fatigue Questionnaire, CFQ), cognitive reserve (Cognitive Reserve Questionnaire, CRC), and subjective cognitive complaints (Memory Failures of Everyday Questionnaire, MFE-30).

Methods

We included 373 individuals with PCC and 126 healthy controls (HCs) from the NAUTILUS Project (NCT05307549 and NCT05307575) who were assessed with a comprehensive neuropsychological battery and various questionnaires.

Results

We found that PCC participants with poor sleep quality had a 4.3% greater risk of immediate verbal memory deficits than those with good sleep quality, as indicated by the greater odds ratio (OR) of 1.043 and confidence interval (CI) of 1.023-1.063. Additionally, their risk of immediate verbal memory disorders was multiplied by 2.4 when their EQ-5D score was low (OR 0.33; CI 0.145-0.748), and they had a lower risk of delayed visual memory deficits with a greater CRC (OR 0.963; CI 0.929-0.999). With respect to processing speed, PCC participants with poor sleep quality had a 6.7% greater risk of deficits as the MFE increased (OR 1.059; CI 1.024-1.096), and the risk of slowed processing speed tripled with a lower EQ-5D (OR 0.021; CI 0.003-0.141).

Conclusion

These results indicate that poor subjective sleep quality is a potential trigger for cognitive deficits. Therapeutic strategies to maximize sleep quality could include reducing sleep disturbances and perhaps cognitive impairment in PCC individuals.

The relationship between sleeptime and depression among middle-aged and elderly Chinese participant during COVID-19 epidemic and non-epidemic phases

Background

The global impact of the COVID-19 pandemic had significantly altered the daily routines of people worldwide. This study aimed to compare how sleeptime and depression among Chinese residents had differed between periods during and outside the epidemic. Furthermore, it delved into the interactive effect of age in this relationship.

Method

Utilizing data from the China Health and Retirement Longitudinal Study (CHARLS) study in 2015 and the recently released data from 2020, which covered the pandemic period. Depression was assessed using Center for Epidemiologic Studies Depression Scale (CESD-10), considering a score of 10 or higher as indicative of depression. Participants were categorized based on age, specifically those aged 60 years and older. multivariate logistic regression and interaction analyses were employed to assess the interplay of age, supported by subgroup and sensitivity analyses to reinforce our findings.

Results

The 2020 database comprised 19,331 participants, while the 2015 database had 10,507 participants. Our findings demonstrated a significant correlation between sleeptime and depression in both unadjusted models and models adjusted for all variables in both datasets (p<0.001). Upon stratifying by age and adjusting for relevant factors, we identified an interaction effect among age, sleeptime, and depression (p=0.004 for the interaction in the 2020 database, compared to 0.004 in 2015). The restricted cubic spline analysis in both datasets showcased a nonlinear relationship between sleeptime and depression.

Conclusions

During both epidemic and non-epidemic periods in China, there existed a correlation between sleep duration and depression, which interacts with age.

Sex-specific grey matter abnormalities in individuals with chronic insomnia

Previous studies have reported sex differences in altered brain function in patients with chronic insomnia (CI). However, sex-related alterations in brain morphology have rarely been investigated. This study aimed to investigate sex-specific grey matter (GM) alterations in patients with CI and to examine the relationship between GM alterations and neuropsychological assessments. Ninety-three (65 females and 28 males) patients and 78 healthy (50 females and 28 males) controls were recruited. Structural magnetic resonance imaging data were analysed using voxel-based morphometry to test for interactions between sex and diagnosis. Spearman's correlation was used to assess the associations among structure, disease duration, and sleep-, mood-, and cognition-related assessments. Males with CI showed reduced GM volume in the left inferior parietal lobe, left middle cingulate cortex, and right supramarginal gyrus. Females with CI showed increased GM volume in the right Rolandic operculum. Moreover, mood-related assessments were negatively correlated with GM volumes in the right supramarginal gyrus and left inferior parietal lobe in the male patients, and cognitive-related assessments were positively correlated with GM volumes in the Rolandic operculum in the female patients. Our findings indicate sex-specific alterations in brain morphology in CI, thereby broadening our understanding of sex differences in CI and potentially providing complementary evidence for the development of more effective therapies and individual treatments.

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.

Joint associations of sleep duration and physical activity with cognitive impairment among rural elderly over 65 years old: a cross-sectional study

BACKGROUND

During the long preclinical phase of dementia, accelerated cognitive impairment is regarded as a cardinal marker. Thus, the identification of risk factors for cognitive impairment is of great significance for dementia prevention. This study aims to examine the joint associations of sleep duration and physical activity with cognitive impairment among rural elderly over 65 years old, and provide suggestions for improving the cognitive function in rural elderly over 65 years old.

METHODS

A cross-sectional study was conducted in rural Nanjing by recruiting 1147 individuals aged above 65 years. Cognitive function was assessed using the brief community screening instrument for dementia. Physical activity was assessed using the Global Physical Activity Questionnaire. Data were analyzed by multivariate logistic regression models, and a significant difference was set at P < 0.05.

RESULTS

Compared with participants with proper sleep duration and sufficient physical activity, participants with short sleep duration and insufficient physical activity (odds ratio (OR): 1.820; 95% CI: 1.265 ~ 2.618), long sleep duration and sufficient physical activity (OR: 2.428; 95% CI: 1.137 ~ 5.183) showed an increased likelihood of cognitive impairment.

CONCLUSIONS

Inappropriate sleep duration combined with insufficient physical activity was associated with a significantly higher likelihood of cognitive impairment in rural elderly over 65 years old.

Genetic and chemical disruption of amyloid precursor protein processing impairs zebrafish sleep maintenance

Amyloid precursor protein (APP) is a brain-rich, single pass transmembrane protein that is proteolytically processed into multiple products, including amyloid-beta (Aβ), a major driver of Alzheimer disease (AD). Although both overexpression of APP and exogenously delivered Aβ lead to changes in sleep, whether APP processing plays an endogenous role in regulating sleep is unknown. Here, we demonstrate that APP processing into Aβ40 and Aβ42 is conserved in zebrafish and then describe sleep/wake phenotypes in loss-of-function appa and appb mutants. Larvae with mutations in appa had reduced waking activity, whereas larvae that lacked appb had shortened sleep bout durations at night. Treatment with the γ-secretase inhibitor DAPT also shortened night sleep bouts, whereas the BACE-1 inhibitor lanabecestat lengthened sleep bouts. Intraventricular injection of P3 also shortened night sleep bouts, suggesting that the proper balance of Appb proteolytic processing is required for normal sleep maintenance in zebrafish.

Sleep Quality and Cognitive Abilities in the Greek Cohort of Epirus Health Study

Purpose

Sleep is essential to all human body functions as well as brain functions. Inadequate sleep quantity and poor sleep quality have been shown to directly affect cognitive functioning and especially memory. The primary aim of the present study was to investigate the association of sleep quality with cognitive abilities cross-sectionally in a middle-aged Greek population and secondarily to examine this association prospectively in a smaller group of these participants.

Patients and Methods

A total of 2112 healthy adults aged 25-70 years (mean: 46.7±11.5) from the Epirus Health Study cohort were included in the analysis and 312 of them participated in secondary prospective analysis. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI) scale and cognition was assessed in primary cross-sectional analyses with three neuropsychological tests, namely the Verbal Fluency test, the Logical Memory test and the Trail Making test, and in secondary prospective analyses with online versions of Posner cueing task, an emotional recognition task, the Corsi block-tapping task and the Stroop task. Statistical analysis was performed using multivariable linear regression models adjusted for age, sex, education, body mass index and alcohol consumption.

Results

Attention/processing speed was the only cognitive domain associated cross-sectionally with PSQI score. Specifically, participants with better self-reported sleep quality performed faster on the Trail Making Test - Part A (β= 0.272 seconds, 95% CI 0.052, 0.493).

Conclusion

Further studies are needed to clarify the association of sleep quality with cognition, especially in middle-aged people that are still in productive working years.

Sex as a moderator of the sleep and cognition relationship in middle-aged and older adults: A preliminary investigation

OBJECTIVES

Despite known sex differences in the prevalence of sleep disturbance and cognitive impairment, research investigating sex differences in sleep/cognition associations is limited. We examined sex as a moderator of associations between self-reported sleep and objective cognition in middle-aged/older adults.

METHODS

Adults aged 50+ (32 men/31 women, Mage = 63.6 ± 7.7) completed the Pittsburgh Sleep Quality Index (PSQI) and cognitive tasks: Stroop (processing speed, inhibition), Posner (spatial attentional orienting) and Sternberg (working memory). Multiple regressions examined whether PSQI metrics (global score, sleep quality ratings, sleep duration, sleep efficiency) were independently or interactively (with sex) associated with cognition, controlling for age and education.

RESULTS

Sex interacted with sleep quality ratings in its association with endogenous spatial attentional orienting (∆R2 = .10, p = .01). Worse ratings of sleep quality were associated with worse orienting in women (B = 22.73, SE = 9.53, p = .02), not men (p = .24). Sex interacted with sleep efficiency in its associations with processing speed (∆R2 = .06, p = .04). Lower sleep efficiency was associated with slower Stroop control trial performance in women (B = -15.91, SE = 7.57, p = .04), not men (p = .48).

CONCLUSIONS

Preliminary findings suggest middle-aged/older women are more vulnerable to associations between poor sleep quality and low sleep efficiency on spatial attentional orienting and processing speed, respectively. Future studies in larger samples investigating sex-specific prospective sleep and cognition associations are warranted.

Interrelationship of Sleep Disturbances and Cognitive Status on Mortality

Sleep disturbances may promote the development and advancement of Alzheimer's disease. Our purpose was to determine if sleep disturbances were associated with earlier mortality while accounting for cognition. The National Alzheimer's Coordinating Center database was used to evaluate mortality risk conferred by sleep, and the Montreal Cognitive Assessment score determined cognitive status. Demographics, sleep disturbances, cognitive status, and comorbid/other neuropsychiatric conditions were examined as predictors of survival time via Cox regression. The sample (N = 31,110) had a median age [interquartile range] of 72 [66, 79] years, MoCA score of 23 [16, 26], and survival time of 106.0 months [104.0,108.0]; 10,278 (33%) died during follow-up; 21% (n = 6461) experienced sleep disturbances. Sleep disturbances impacted survival time depending on cognition, with the greatest effect in transition from normal to cognitive impairment (P < .001). Findings support that sleep disturbances negatively impact survival time, and the impact of sleep disturbances on survival time is interrelated with cognition.

The effect of mindfulness-based intervention on cognitively unimpaired older adults' cognitive function and sleep quality: a systematic review and meta-analysis

Objective: This systematic review and meta-analysis aimed to investigate the effect of mindfulness-based intervention (MBI) on cognitively unimpaired older adults' cognitive function and sleep quality.Method: Studies published in English since 2010 were considered for inclusion. Databases searched were PubMed, Embase, Web of Science, and PsycInfo. We included randomized controlled trials (RCTs) with adults over 55 with no known cognitive impairment, that recorded cognitive outcomes and/or sleep quality pre- and post-intervention, and that implemented Mindfulness-Based Stress Reduction (MBSR), or an MBI closely based on MBSR protocol.Results: Seven RCTs fit the inclusion criteria, with 276 participants in MBI groups and 287 in controls. Four studies investigated mindfulness and cognitive function, two investigated mindfulness and sleep quality, and one investigated mindfulness, cognitive function, and sleep quality. Some studies were not reported in sufficient detail to be included in meta-analyses. Results of meta-analyses showed no significant differences between MBI groups vs controls on cognitive measures of executive function, free recall, and delayed recall. Meta-analysis revealed that MBI significantly improved sleep quality compared to controls.Conclusion: Given that poor sleep quality is strongly linked to increased risk of cognitive decline, further research investigating sleep quality's role in the mindfulness-cognitive function relationship in cognitively unimpaired older adults is recommended.

Sleep disturbances as risk factors for neurodegeneration later in life

The relationship between sleep disorders and neurodegeneration is complex and multi-faceted. Using over one million electronic health records (EHRs) from Wales, UK, and Finland, we mined biobank data to identify the relationships between sleep disorders and the subsequent manifestation of neurodegenerative diseases (NDDs) later in life. We then examined how these sleep disorders' severity impacts neurodegeneration risk. Additionally, we investigated how sleep attributed risk may compensate for the lack of genetic risk factors (i.e. a lower polygenic risk score) in NDD manifestation. We found that sleep disorders such as sleep apnea were associated with the risk of Alzheimer's disease (AD), amyotrophic lateral sclerosis, dementia, Parkinson's disease (PD), and vascular dementia in three national scale biobanks, with hazard ratios (HRs) ranging from 1.31 for PD to 5.11 for dementia. These sleep disorders imparted significant risk up to 15 years before the onset of an NDD. Cumulative number of sleep disorders in the EHRs were associated with a higher risk of neurodegeneration for dementia and vascular dementia. Sleep related risk factors were independent of genetic risk for Alzheimer's and Parkinson's, potentially compensating for low genetic risk in overall disease etiology. There is a significant multiplicative interaction regarding the combined risk of sleep disorders and Parkinson's disease. Poor sleep hygiene and sleep apnea are relatively modifiable risk factors with several treatment options, including CPAP and surgery, that could potentially reduce the risk of neurodegeneration. This is particularly interesting in how sleep related risk factors are significantly and independently enriched in manifesting NDD patients with low levels of genetic risk factors for these diseases.

Air pollution, glymphatic impairment, and Alzheimer's disease

Epidemiological evidence demonstrates a link between air pollution exposure and the onset and progression of cognitive impairment and Alzheimer's disease (AD). However, current understanding of the underlying pathophysiological mechanisms is limited. This opinion article examines the hypothesis that air pollution-induced impairment of glymphatic clearance represents a crucial etiological event in the development of AD. Exposure to airborne particulate matter (PM) leads to systemic inflammation and neuroinflammation, increased metal load, respiratory and cardiovascular dysfunction, and sleep abnormalities. All these factors are known to reduce the efficiency of glymphatic clearance. Rescuing glymphatic function by restricting the impact of causative agents, and improving sleep and cardiovascular system health, may increase the efficiency of waste metabolite clearance and subsequently slow the progression of AD. In sum, we introduce air pollution-mediated glymphatic impairment as an important mechanistic factor to be considered when interpreting the etiology and progression of AD as well as its responsiveness to therapeutic interventions.

Sleep dysfunction mediates the relationship between hypothalamic-insula connectivity and anxiety-depression symptom severity bidirectionally in young adults

BACKGROUND

The hypothalamus plays a crucial role in regulating sleep-wake cycle and motivated behavior. Sleep disturbance is associated with impairment in cognitive and affective functions. However, how hypothalamic dysfunction may contribute to inter-related sleep, cognitive, and emotional deficits remain unclear.

METHODS

We curated the Human Connectome Project dataset and investigated how hypothalamic resting state functional connectivities (rsFC) were associated with sleep dysfunction, as evaluated by the Pittsburgh Sleep Quality Index (PSQI), cognitive performance, and subjective mood states in 687 young adults (342 women). Imaging data were processed with published routines and evaluated with a corrected threshold. We examined the inter-relationship amongst hypothalamic rsFC, PSQI score, and clinical measures with mediation analyses.

RESULTS

In whole-brain regressions with age and drinking severity as covariates, men showed higher hypothalamic rsFC with the right insula in correlation with PSQI score. No clusters were identified in women at the same threshold. Both hypothalamic-insula rsFC and PSQI score were significantly correlated with anxiety and depression scores in men. Further, mediation analyses showed that PSQI score mediated the relationship between hypothalamic-insula rsFC and anxiety/depression symptom severity bidirectionally in men.

CONCLUSIONS

Sleep dysfunction is associated with negative emotions and hypothalamic rsFC with the right insula, a core structure of the interoceptive circuits. Notably, anxiety-depression symptom severity and altered hypothalamic-insula rsFC are related bidirectionally by poor sleep quality. These findings are specific to men, suggesting potential sex differences in the neural circuits regulating sleep and emotional states that need to be further investigated.

Serum Vitamin D3 Concentration, Sleep, and Cognitive Impairment among Older Adults in China

BACKGROUND

Cognitive decline in older adults has become one of the critical challenges to global health. This study aims to examine both cross-sectional and longitudinal associations of levels of serum 25-hydroxyvitamin D3 (25(OH)D3) (briefed as VD3) concentration and sleep quality/duration, especially their interactions, with risk of cognitive impairment among older adults in China.

METHODS

We utilized a special subsample of adults aged 65-105 years (individuals = 3412, observations = 4816) from eight provinces in China derived from the 2011/2012 and 2014 waves of the Chinese Longitudinal Healthy Longevity Survey. Cognitive impairment was measured by the Mini-Mental State Examination scale. Sleep quality was classified as good versus fair/poor, and sleep duration was classified into short (<7 h), normal (≥7 but <9 h), and long (≥9 h). The VD3 concentration was divided into three levels: deficiency (VD3 < 25 nmol/L), insufficiency (25 nmol/L ≤ VD3 < 50 nmol/L), and sufficiency (VD3 ≥ 50 nmol/L). A wide set of covariates that include demographics, socioeconomic status, family support, health practice, and health conditions was adjusted for robust findings. Multilevel random intercept logit regression models were used to examine the cross-sectional associations between VD3, sleep, and cognitive impairment, whereas logit regression models were applied to investigate the longitudinal associations.

RESULTS

In the cross-sectional analyses, when all covariates were adjusted, VD3 sufficiency was significantly associated with a 33% lower risk of cognitive impairment compared with VD3 deficiency; good sleep quality was associated with 34% lower odds of cognitive impairment compared with fair/poor sleep quality; sleep hours were not associated with cognitive impairment, although a long sleep duration (≥9 h) was associated with 30% higher odds of being cognitively impaired when baseline health was not controlled. Interaction analyses reveal that VD3 sufficiency could help to additionally reduce the risk of cognitive impairment for good sleep quality and normal sleep hours. In the longitudinal analyses, the association of VD3 sufficiency remains significant, whereas sleep quality and sleep duration were not significant associates.

CONCLUSIONS

Good sleep quality, normal sleep hours, and VD3 sufficiency are positively associated with good cognitive function. VD3 sufficiency could enhance the associations between sleep and cognitive impairment.

Self-reported sleep in relation to risk of dementia a quarter of a century later at age 90+: The 90+ Study

OBJECTIVE

To examine sex-specific associations of sleep duration and napping self-reported at mean age of 69 years (range: 53-81) with risk of incident dementia 24 years later at age 90 +.

METHOD

Analytic sample included individuals from a population-based study who reported sleep and napping once in the 1980s and 24 years later (range: 16-38) joined The 90+ Study and were evaluated in-person. Those without dementia at baseline of The 90+ Study were prospectively followed. Hazard ratios [HR] and 95% confidence intervals [CI] of dementia risk were estimated by Cox regression.

RESULTS

Of 574 participants 71% were women, mean age at start of dementia follow-up with The 90+ Study was 93 years (range: 90-102). After 3.3 years (range: 0.4-13.8) of follow-up 47% developed dementia. Higher risk of dementia at age 90+ was seen in women with <6 hours of self-reported sleep per night (adjusted HR = 2.00; 95% CI = 1.15-3.50; p = .01) compared with 8 hours. Lower risk of dementia at 90+ was seen in men with short-to-moderate (<60 minutes) self-reported naps compared with no naps (HR = 0.33; 95% CI = 0.18-0.63; p < .01).

CONCLUSIONS

Sleep and nap 24 years earlier are important risk factors for dementia after age 90.

Relationship between self-reported sleep and cognitive function: a specification curve analysis

The relationship between self-reported sleep and cognitive function is complex; it is unclear whether self-reported sleep is a robust correlate of people's cognitive function. We address this gap by using a comprehensive large-scale dataset (N = 1054) coupled with a novel modeling approach, specification curve analysis (SCA), to test the association between self-reported sleep and cognitive function. The results of the SCA showed robust correlations between self-reported sleep and cognitive function, with poorer sleep associated with worse cognitive function. Furthermore, the correlations between sleep components and cognitive function were heterogeneous, with differences emerging across cognitive measures and domains. Specifically, daytime dysfunction was associated with the strongest effect on subjective cognitive function, whereas sleep duration and sleep efficiency had the strongest effect on objective cognitive function. Therefore, the relationship between self-reported sleep and cognition depends largely on what and how cognitive function is measured. Our findings guide measurement and domain selection for future research on the role of sleep in cognitive function.

Sleep quality mediates the relationship between systemic inflammation and neurocognitive performance

Background

Systemic inflammation is a significant mechanism underpinning adverse cognitive changes. Sleep quality is a crucial factor associated with systemic inflammation and neurocognitive health. Elevated levels of pro-inflammatory cytokines in the periphery help mark inflammation. With this background, we examined the relationship between systemic inflammation, subjective sleep quality, and neurocognitive performance in adults.

Method & Results

In 252 healthy adults, we measured the systemic inflammation reflected by serum levels of IL-6, IL-12, IL-18, TNF-α and IFN-γ, subjective sleep quality reflected by the global scores of the Pittsburgh Sleep Quality Index, and their neurocognitive performance measured by the Hong Kong Montreal Cognitive Assessment. We observed that neurocognitive performance was negatively related to IL-18 (p = 0.046) and positively related to sleep quality (p = 0.006). We did not observe significant associations between other cytokines and neurocognitive performance. Furthermore, we found that sleep quality as a mediator explained the relationship between IL-18 and neurocognitive performance depending on the levels of IL-12 (index of moderated mediation: 95% CI = [0.0047, 0.0664]). Better subjective sleep quality buffered the negative effect of IL-18 on neurocognitive performance when IL-12 was low (bootstrapping 95% CI: [- 0.0824, - 0.0018]). On the contrary, poor subjective sleep quality mediated the association between higher IL-18 and poorer neurocognitive performance when IL-12 was elevated (bootstrapping 95% CI: [0.0004, 0.0608]).

Conclusion & Implications

Our findings indicate that systemic inflammation was negatively associated with neurocognitive performance. Sleep quality regulated by IL-18/IL-12 axis activation could be a potential mechanism underpinning neurocognitive changes. Our results illustrate the intricate relationships between immune functioning, sleep quality and neurocognitive performance. These insights are essential to understand the potential mechanisms underpinning neurocognitive changes, paving the way for the development of preventive interventions for the risk of cognitive impairment.

The Relationship Between Cognitive Impairments and Sleep Quality Measures in Persistent Insomnia Disorder

Study Objectives

Persistent insomnia disorder (pID) is linked to neurocognitive decline and increased risk of Alzheimer's Disease (AD) in later life. However, research in this field often utilizes self-reported sleep quality data - which may be biased by sleep misperception - or uses extensive neurocognitive test batteries - which are often not feasible in clinical settings. This study therefore aims to assess whether a simple screening tool could uncover a specific pattern of cognitive changes in pID patients, and whether these relate to objective aspect(s) of sleep quality.

Methods

Neurocognitive performance (Montreal Cognitive Assessment; MoCA), anxiety/depression severity, and subjective sleep quality (Pittsburgh Sleep Quality Index: PSQI; Insomnia Severity Index: ISI) data were collected from 22 middle-aged pID patients and 22 good-sleepers. Patients underwent overnight polysomnography.

Results

Compared to good-sleepers, patients had lower overall cognitive performance (average: 24.6 versus 26.3 points, Mann-Whitney U = 136.5, p = <0.006), with deficits in clock drawing and verbal abstraction. In patients, poorer overall cognitive performance correlated with reduced subjective sleep quality (PSQI: r(42) = -0.47, p = 0.001; and ISI: r(42) = -0.43, p = 0.004), reduced objective sleep quality (lower sleep efficiency: r(20) = 0.59, p = 0.004 and less REM-sleep: r(20) = 0.52, p = 0.013; and increased sleep latency: r(20) = -0.57, p = 0.005 and time awake: r(20) = -0.59, p = 0.004). Cognitive performance was not related to anxiety/depression scores.

Conclusion

Using a simple neurocognitive screening tool, we found that pID patients showed cognitive deficiencies that related to both subjective/self-reported and objective/polysomnographic measures of sleep quality. Furthermore, these cognitive changes resembled those seen in preclinical non-amnestic AD, and thus could indicate incumbent neurodegenerative processes in pID. Interestingly, increased REM-sleep was correlated with better cognitive performance. However, whether REM-sleep is protective against neurodegeneration requires further investigation.

Sex differences in the effects of sleep disorders on cognitive dysfunction

Sleep is an essential physiological function that sustains human life. Sleep disorders involve problems with the quality, duration, and abnormal behaviour of sleep. Insomnia is the most common sleep disorder, followed by sleep-disordered breathing (SDB). Sleep disorders often occur along with medical conditions or other mental health conditions. Of particular interest to researchers is the role of sleep disorders in cognitive dysfunction. Sleep disorder is a risk factor for cognitive dysfunction, yet the exact pathogenesis is still far from agreement. Little is known about how sex differences influence the changes in cognitive functions caused by sleep disorders. This narrative review examines how sleep disorders might affect cognitive impairment, and then explores the sex-specific consequences of sleep disorders as a risk factor for dementia and the potential underlying mechanisms. Some insights on the direction of further research are also presented.

The relationship between sleep duration and activities of daily living (ADL) disability in the Chinese oldest-old: A cross-sectional study

Objective

To investigate the relationship between sleep duration and activities of daily living (ADL) disability, and to explore the optimal sleep duration among oldest-old Chinese individuals.

Methods

In this cross-sectional study, 1,798 participants (73.2% female) were recruited from Dongxing and Shanglin in Guangxi Zhuang Autonomous Region, China in 2019. The restricted cubic spline function was used to assess the dose-response relationship between sleep duration and ADL disability, and the odds ratios (ORs) of the associations were estimated by logistic regression models.

Results

The overall prevalence of ADL disability was 63% (64% in females and 58% in males). The prevalence was 71% in the Han population (72% in females and 68% in males), 60% in the Zhuang population (62% in females and 54% in males) and 53% in other ethnic population (53% in females and 53% in males). A nonlinear relationship between sleep duration and ADL disability was observed. Sleep duration of 8-10 hours was associated with the lowest risk of ADL disability. Sleep duration (≥12 hours) was associated with the risk of ADL disability among the oldest-old individuals after adjusting for confounding factors (OR = 1.47, 95% CI [1.02, 2.10], p < 0.05).

Conclusion

Sleep duration more than 12 hours may be associated with an increased risk of ADL disability in the oldest-old individuals, and the optimal sleep duration among this population could be 8-10 h.

Metabotropic glutamate receptor function and regulation of sleep-wake cycles

Metabotropic glutamate (mGlu) receptors are the most abundant family of G-protein coupled receptors and are widely expressed throughout the central nervous system (CNS). Alterations in glutamate homeostasis, including dysregulations in mGlu receptor function, have been indicated as key contributors to multiple CNS disorders. Fluctuations in mGlu receptor expression and function also occur across diurnal sleep-wake cycles. Sleep disturbances including insomnia are frequently comorbid with neuropsychiatric, neurodevelopmental, and neurodegenerative conditions. These often precede behavioral symptoms and/or correlate with symptom severity and relapse. Chronic sleep disturbances may also be a consequence of primary symptom progression and can exacerbate neurodegeneration in disorders including Alzheimer's disease (AD). Thus, there is a bidirectional relationship between sleep disturbances and CNS disorders; disrupted sleep may serve as both a cause and a consequence of the disorder. Importantly, comorbid sleep disturbances are rarely a direct target of primary pharmacological treatments for neuropsychiatric disorders even though improving sleep can positively impact other symptom clusters. This chapter details known roles of mGlu receptor subtypes in both sleep-wake regulation and CNS disorders focusing on schizophrenia, major depressive disorder, post-traumatic stress disorder, AD, and substance use disorder (cocaine and opioid). In this chapter, preclinical electrophysiological, genetic, and pharmacological studies are described, and, when possible, human genetic, imaging, and post-mortem studies are also discussed. In addition to reviewing the important relationships between sleep, mGlu receptors, and CNS disorders, this chapter highlights the development of selective mGlu receptor ligands that hold promise for improving both primary symptoms and sleep disturbances.

Association of sleep with cognitive function during retirement transition: the Whitehall II study

STUDY OBJECTIVES

Sleep duration and difficulties have been shown to associate with cognitive function. This study examined how changes in sleep and in cognitive function are associated during retirement transition.

METHODS

The study population consisted of 2980 Whitehall II study participants, who retired during the follow-up, whose sleep was queried, and cognitive function measured (inductive reasoning and verbal memory) before and after retirement (follow-up 16 years). Using the last information on sleep before and the first after retirement, participants were categorized into constantly without (59%), increasing (13%), decreasing (11%), and constantly with (18%) sleep difficulties; and constantly short (26%), increasing (19%), decreasing (8.5%), and constantly mid-range (47%) sleep duration. Change in cognitive function during retirement transition was examined by sleep change groups using linear regression analyses with generalized estimating equations.

RESULTS

More pronounced decline in inductive reasoning during retirement transition was observed among participants with increasing sleep difficulties (-1.96, 95% CI -2.52 to -1.41) compared to those constantly without sleep difficulties (-1.25, 95% CI -1.52 to -0.98) and constantly with sleep difficulties (-1.26, 95% CI -1.75 to -0.92). Decreasing sleep difficulties (-0.64, 95% CI -0.86 to -0.43) were associated with a more pronounced decline in verbal memory when compared to constantly without sleep difficulties (-0.42, 95% CI -0.52 to -0.32) in post-retirement period. No statistically significant differences across sleep duration groups in cognitive function were observed.

CONCLUSIONS

Increasing and decreasing sleep difficulties may be associated with accelerated decline in cognitive function during retirement transition and post-retirement.

Sleep Disturbances Predict Cognitive Decline in Cognitively Healthy Adults

BACKGROUND

The effect of nighttime behaviors on cognition has not been studied independently from other neuropsychiatric symptoms.

OBJECTIVE

We evaluate the following hypotheses that sleep disturbances bring increased risk of earlier cognitive impairment, and more importantly that the effect of sleep disturbances is independent from other neuropsychiatric symptoms that may herald dementia.

METHODS

We used the National Alzheimer's Coordinating Center database to evaluate the relationship between Neuropsychiatric Inventory Questionnaire (NPI-Q) determined nighttime behaviors which served as surrogate for sleep disturbances and cognitive impairment. Montreal Cognitive Assessment scores defined two groups: conversion from 1) normal to mild cognitive impairment (MCI) and 2) MCI to dementia. The effect of nighttime behaviors at initial visit and covariates of age, sex, education, race, and other neuropsychiatric symptoms (NPI-Q), on conversion risk were analyzed using Cox regression.

RESULTS

Nighttime behaviors predicted earlier conversion time from normal cognition to MCI (hazard ratio (HR): 1.09; 95% CI: [1.00, 1.48], p = 0.048) but were not associated with MCI to dementia conversion (HR: 1.01; [0.92, 1.10], p = 0.856). In both groups, older age, female sex, lower education, and neuropsychiatric burden increased conversion risk.

CONCLUSION

Our findings suggest that sleep disturbances predict earlier cognitive decline independently from other neuropsychiatric symptoms that may herald dementia.

Patterns of sleep disturbances across stages of cognitive decline

OBJECTIVES

The purpose of this study was to investigate insomnia symptoms and excessive sleep/sluggishness across stages of cognitive decline (cognitively normal [CN], Cognitively Impairment, Not Demented [CIND], dementia) in a large, racially/ethnically diverse sample of older adults (70+) in the US. We also examined whether sleep disturbances at baseline predicted conversion to CIND or dementia at follow-up.

METHODS

In this secondary analysis of the Aging, Demographics, and Memory Study (ADAMS) supplement of the Health Retirement Study, we analyzed patterns of informant-reported insomnia and excessive sleep symptoms among three groups of older adults (n = 846): CN, CIND, and dementia.

RESULTS

CIND adults were significantly more likely to have informant-reported insomnia symptoms than those in the CN group (p = 0.013). This was driven by a significant race/ethnicity-by-insomnia interaction with diagnostic status (p = 0.029), such that CIND Black and Hispanic older adults had increased insomnia symptom rates compared to CN, whereas White adults had similar insomnia symptoms across diagnostic status. Across all racial/ethnic groups, the prevalence of excessive sleep symptoms increased stepwise from CN to CIND to dementia (p < 0.001). Overall, insomnia symptoms at baseline predicted conversion from CN to CIND (p < 0.001, OR = 0.288; 95% CI: 0.143-0.580) at 4-year (approximate) follow-up; there was no relationship between baseline insomnia or excessive sleep/sluggishness symptoms and conversion from CIND to dementia.

DISCUSSION/CONCLUSION

This study provides evidence for the increased risk of insomnia symptoms among Hispanic and Black older adults with CIND, and indicates that insomnia symptoms may be associated with increased risk for development of cognitive impairment.

Prevalence and associated factors of poor sleep quality among Chinese retirees: A multicenter cross-sectional study

BACKGROUND

Sleep problems are common among older adults worldwide. The present study aims to determine the prevalence of poor sleep quality and its independent factors among retired people in health check-ups population in China.

METHOD

In this multicenter, cross-sectional survey in 2017, a group of retired people was invited to participate in an online survey of health status, and their data, including socio-demographic information, lifestyle, and medical characteristics, were recorded. Binary logistic regression was used to analyze the independent factors responsible for poor sleep quality.

RESULTS

Data from 17,408 responders who met the inclusion criteria were analyzed; among them, 53.04 % (95 % CI = 52 %-54 %) reported poor sleep quality. Binary logistic regression showed that poor sleep quality was associated with a number of factors, including being female (OR = 1.42, 95 % CI = 1.32-1.53), being single (OR = 1.35, 95 % CI = 1.18-1.54), non-smoker (OR = 1.12, 95 % CI = 1.03-1.22), physical inactivity (OR = 1.14, 95 % CI = 1.05-1.23), poor self-rated health status (OR = 1.69, 95 % CI = 1.43-2.00), long-term medication use (OR = 1.05, 95 % CI = 1.07-1.23), chronic pain (OR = 1.33, 95 % CI = 1.22-1.45), comorbidity (OR = 1.16, 95 % CI = 1.07-1.25), and depressive symptoms (mild depression: OR = 2.14, 95 % CI = 1.96-2.34; moderate depression: OR = 4.00, 95 % CI = 3.49-4.58, moderately severe depression: OR = 4.15, 95 % CI = 3.47-4.97, severe depression: OR = 4.27, 95 % CI = 2.93-6.22); while age (OR = 0.99, 95 % CI = 0.99-1.00) was negatively related to poor sleep quality.

CONCLUSION

The prevalence of poor sleep quality in the studied population is relatively high (53.04 %). Sleep problems are common among Chinese retirees, especially older females, and have a great impact on their quality of life. People living with depression, chronic diseases, and chronic pain were at a higher risk of developing sleep disorders. Therefore, it is critical to formulate effective management strategies for Chinese retirees with poor sleep quality in the context of healthy aging.

Insomnia disorder increases the risk of subjective memory decline in middle-aged and older adults: a longitudinal analysis of the Canadian Longitudinal Study on Aging

STUDY OBJECTIVES

To examine the longitudinal association between probable insomnia status and both subjective and objective memory decline in middle-aged and older adults.

METHODS

26 363 participants, ≥45 years, completed baseline and follow-up (3 years after baseline) self-reported evaluations of sleep and memory, and neuropsychological testing in the following cognitive domains: memory, executive functions, and psychomotor speed. Participants were categorized as having probable insomnia disorder (PID), insomnia symptoms only (ISO), or no insomnia symptoms (NIS), based on sleep questionnaires. Participants were further grouped based on their sleep change over time. Prospective odds of self-reported memory worsening were assessed using logistic regression, and associations between insomnia and cognitive performance were assessed via linear mixed-effects modeling, adjusted for demographic, lifestyle, and medical factors.

RESULTS

An increased odds (OR 1.70; 95% CI 1.29-2.26) of self-reported memory worsening was observed for NIS participants at baseline who developed PID at follow-up compared to those who developed ISO or remained NIS. Additionally, participants whose sleep worsened from baseline to follow-up (i.e. transitioned from NIS to ISO, ISO to PID, or NIS to PID) displayed increased odds (OR 1.22; 95% CI 1.10-1.34) of subjective memory worsening at follow-up compared to those who remained insomnia-free or improved their sleep. There were no significant associations between the development of PID or worsening sleep and performance on neuropsychological tests.

CONCLUSIONS

These findings of an increased odds for subjective memory decline in middle-aged and older adults with insomnia disorder suggest insomnia may be an important target for early interventions addressing age-related cognitive decline.

Excessive sleep increased the risk of incidence of cognitive impairment among older Chinese adults: a cohort study based on the Chinese Longitudinal Healthy Longevity Survey (CLHLS)

STUDY OBJECTIVES

Based on a cohort from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), we aimed to evaluate the relationship between sleep duration and the incidence of cognitive impairment among older Chinese adults.

METHODS

We conducted a prospective analysis based on 3692 participants from the CLHLS at baseline (in 2011), and as a 3-year follow-up (till 2014), 531 participants (14.4%) had cognitive impairment, which was defined as a Mini-Mental State Examination score <24. Sleep duration was classified into three groups: short (≤5 hours/day), normal (>5 but <10 hours), and long (≥10 hours/day). A logistic regression model was used to examine the association between baseline sleep duration and cognitive impairment after adjusting for sociodemographic data, living habits, and health conditions.

RESULTS

Five hundred sixty-two participants (15.2%) were in the short-duration group, and 608 participants (16.5%) were in the long-duration group. After adjusting for multiple potential confounders, compared with normal sleep duration, long sleep duration was associated with the incidence of cognitive impairment (OR = 1.309, 95% CI: 1.019-1.683), especially among men (OR = 1.527, 95% CI: 1.041-2.240) and those having a primary and above education level (OR = 1.559, 95% CI: 1.029-2.361). No significant association was observed between short sleep duration and cognitive impairment (OR = 0.860, 95% CI: 0.646-1.145).

CONCLUSIONS

Excessive sleep may increase the risk of cognitive impairment in older individuals. It may be a suggestive sign of early neurodegeneration and may be a useful clinical tool to identify those at a higher risk of progressing to cognitive impairment.

Association between the self-reported duration and quality of sleep and cognitive function among middle-aged and older adults in China

BACKGROUND

The World Alzheimer Report showed that 46.8 million people suffered from dementia in 2015. This study examined how the duration and quality of sleep are associated with cognition among older adults in China.

METHOD

Data were drawn from waves 2011, 2013, and 2015 of the China Health and Retirement Longitudinal Study (CHARLS), including noninstitutionalized adults aged 45 and older (n=10,768). Cognition was measured by interview-based assessments of mental status (TICS-10), episodic memory, and visuospatial abilities. Sleep duration was categorized as long, medium, or short and sleep quality was categorized as good, fair, or poor.

RESULTS

Sleep duration had an inverted U-shape relationship with cognitive scores (P <.001); and sleep quality had a positive linear relationship with cognitive scores (P <.001). Short and long sleep durations were associated with consistently lower cognition scores with increasing age (both P <.001); and fair and poor quality of sleep were associated with consistently lower levels of cognition (both P <.001). Tests of interactions between sleep duration and sleep quality showed that participants reporting long durations of sleep with poor quality of sleep had the lowest overall cognitive scores.

LIMITATIONS

Self-reported methods were used to measure sleep quality and duration and thus our findings underscore the need for more evidence-based research to improve prevention efforts and tailor interventions to reduce cognitive decline among Chinese older adults.

CONCLUSIONS

Suboptimal sleep duration and quality were associated with poor cognition. Cognitive scores were lowest among those who reported long durations of sleep that were of poor quality.

A New Perspective on the Treatment of Alzheimer's Disease and Sleep Deprivation-Related Consequences: Can Curcumin Help?

Sleep disturbances, as well as sleep-wake rhythm disorders, are characteristic symptoms of Alzheimer's disease (AD) that may head the other clinical signs of this neurodegenerative disease. Age-related structural and physiological changes in the brain lead to changes in sleep patterns. Conditions such as AD affect the cerebral cortex, basal forebrain, locus coeruleus, and the hypothalamus, thus changing the sleep-wake cycle. Sleep disorders likewise adversely affect the course of the disease. Since the sleep quality is important for the proper functioning of the memory, impaired sleep is associated with problems in the related areas of the brain that play a key role in learning and memory functions. In addition to synthetic drugs, utilization of medicinal plants has become popular in the treatment of neurological diseases. Curcuminoids, which are in a diarylheptanoid structure, are the main components of turmeric. Amongst them, curcumin has multiple applications in treatment regimens of various diseases such as cardiovascular diseases, obesity, cancer, inflammatory diseases, and aging. Besides, curcumin has been reported to be effective in different types of neurodegenerative diseases. Scientific studies exclusively showed that curcumin leads significant improvements in the pathological process of AD. Yet, its low solubility hence low bioavailability is the main therapeutic limitation of curcumin. Although previous studies have focused different types of advanced nanoformulations of curcumin, new approaches are needed to solve the solubility problem. This review summarizes the available scientific data, as reported by the most recent studies describing the utilization of curcumin in the treatment of AD and sleep deprivation-related consequences.

Neuropsychiatric Inventory-Questionnaire Assessed Nighttime Behaviors in Cognitively Asymptomatic Patients with Pathologically Confirmed Alzheimer's Disease Predict More Rapid Cognitive Deterioration

BACKGROUND

The temporal relationship between sleep, Alzheimer's disease (AD), and cognitive impairment remains to be further elucidated.

OBJECTIVE

First, we aim to determine whether the Neuropsychiatric Inventory-Questionnaire (NPI-Q) assessed nighttime behaviors prior to cognitive decline influence the rate of cognitive deterioration in pathologically confirmed AD, and second, to assess the possible interactions with APOE allele and cerebral amyloid angiopathy (CAA).

METHODS

The rate of cognitive decline between cognitively asymptomatic participants from the National Alzheimer Coordinating Center who eventually received a neuropathologic diagnosis of AD with (+NTB) or without (-NTB) nighttime behaviors were compared using independent samples t-test. Participants were stratified by APOE carrier and CAA status. Demographic and patient characteristics were assessed using descriptive statistics, and the independent samples t-test was used for continuous variables and chi-square test for categorical variables. The significance level was set at p≤0.05.

RESULTS

The rate of cognitive decline was greater in +NTB (n = 74; 3.30 points/year) than -NTB (n = 330; 2.45 points/year) (p = 0.016), even if there was no difference in cognitive status at onset. This difference was restricted to APOE ɛ4 carriers (p = 0.049) and positive CAA participants (p = 0.020). Significance was not reached in non-carriers (p = 0.186) and negative CAA (p = 0.364). APOE and CAA were not differentially distributed between the NTB groups.

CONCLUSION

NPI-Q assessed nighttime behaviors, a surrogate for sleep disturbances, are associated with more rapidly deteriorating cognition in patients with AD neuropathology who are also carriers of APOE ɛ4 or show CAA.

Sleep, Sirtuin 1 and Alzheimer's disease: A review

Sleep plays a major role in brain health, and cognition. Disrupted sleep is a well-described symptom of Alzheimer's disease (AD). However, accumulating evidence suggests suboptimal sleep also increases AD risk. The deacetylase Sirtuin 1 (Sirt 1), encoded by the SIRT1 gene, impacts sleep via its relationship to wake-sleep neurotransmitters and somnogens. Evidence from animal and human studies supports a significant and complex relationship between sleep, Sirt 1/ SIRT1 and AD. Numerous hypotheses attempt to explain the critical impact of Sirt 1/ SIRT1 on wake- and sleep- promoting neurons, their related mechanisms and neurotransmitters. However, there is a paucity of studies assessing the interaction between sleep and Sirt 1/ SIRT1, as a principal component of sleep regulation, on AD pathology. In this review, we explore the potential association between Sirt 1/ SIRT1, sleep, and AD aetiology. Given sleep is a likely modifiable risk factor for AD, and recent studies suggest Sirt 1/ SIRT1 activation can be modulated by lifestyle or dietary approaches, further research in this area is required to explore its potential as a target for AD prevention and treatment.

Interactive Associations of Neuropsychiatry Inventory-Questionnaire Assessed Sleep Disturbance and Vascular Risk on Alzheimer's Disease Stage Progression in Clinically Normal Older Adults

Background: To determine whether sleep disturbance (SD) and vascular-risk interact to promote Alzheimer's disease (AD) stage-progression in normal, community-dwelling older adults and evaluate their combined risk beyond that of established AD biomarkers. Methods: Longitudinal data from the National Alzheimer's Coordinating Center Uniform-Dataset. SD data (i.e., SD+ vs. SD-), as characterized by the Neuropsychiatric Inventory-Questionnaire, were derived from 10,600 participants at baseline, with at-least one follow-up visit. A subset (n = 361) had baseline cerebrospinal fluid (CSF) biomarkers and MRI data. The Framingham heart study general cardiovascular disease (FHS-CVD) risk-score was used to quantify vascular risk. Amnestic mild cognitive impairment (aMCI) diagnosis during follow-up characterized AD stage-progression. Logistic mixed-effects models with random intercept and slope examined the interaction of SD and vascular risk on prospective aMCI diagnosis. Results: Of the 10,600 participants, 1,017 (9.6%) reported SD and 6,572 (62%) were female. The overall mean (SD) age was 70.5 (6.5), and follow-up time was 5.1 (2.7) years. SD and the FHS-CVD risk-score were each associated with incident aMCI (aOR: 1.42 and aOR: 2.11, p < 0.01 for both). The interaction of SD and FHS-CVD risk-score with time was significant (aOR: 2.87, p < 0.01), suggesting a synergistic effect. SD and FHS-CVD risk-score estimates remained significantly associated with incident aMCI even after adjusting for CSF (Aβ, T-tau, P-tau) and hippocampal volume (n = 361) (aOR: 2.55, p < 0.01), and approximated risk-estimates of each biomarker in the sample where data was available. Conclusions: Clinical measures of sleep and vascular risk may complement current AD biomarkers in assessing risk of cognitive decline in older adults.

Relationship between Resting State Heart Rate Variability and Sleep Quality in Older Adults with Mild Cognitive Impairment

Sleep problems can be caused by psychological stress but are also related to cardiovascular and neurodegenerative diseases. Improving lifestyle behaviors, such as good sleep hygiene, can help to counteract the negative effects of neurodegenerative diseases and to improve quality of life. The purpose of this cross-sectional study was to investigate the relationship between subjectively reported measures of sleep quality (via Pittsburgh Sleep Quality Index (PSQI)) and objective measures of cardiac autonomic control (via resting state heart rate variability (HRV)) among individuals with mild cognitive impairment (MCI). The PSQI and resting state HRV data of 42 MCI participants (69.0 ± 5.5; 56-80 years) were analyzed. Nineteen of the participants reported poor sleep quality (PSQI score > 5). Good sleepers showed higher resting heart rate than bad sleepers (p = 0.037; ES = 0.670). Correlation analysis showed a significant correlation between the parameter HF nu and sleep efficiency, contrasting the expected positive association between reduced HRV and poor sleep quality in healthy and individuals with specific diseases. Otherwise, there were no significances, indicating that measures of subjective sleep quality and resting HRV were not related in the present sample of MCI participants. Further research is needed to better understand the complex relationship between HRV and lifestyle factors (e.g., sleep) in MCI.

Effect of a Recliner Chair with Rocking Motions on Sleep Efficiency

In this study, we analyze the effect of a recliner chair with rocking motions on sleep quality of naps using automated sleep scoring and spindle detection models. The quality of sleep corresponding to the two rocking motions was measured quantitatively and qualitatively. For the quantitative evaluation, we conducted a sleep parameter analysis based on the results of the estimated sleep stages obtained on the brainwave and spindle estimation, and a sleep survey assessment from the participants was analyzed for the qualitative evaluation. The analysis showed that sleep in the recliner chair with rocking motions positively increased the duration of the spindles and deep sleep stage, resulting in improved sleep quality.

Association Between Sleep and Motoric Cognitive Risk Syndrome Among Community-Dwelling Older Adults: Results From the China Health and Retirement Longitudinal Study

Background: Sleep is increasingly recognized as an important lifestyle contributor to health; however, its relationship with Motoric cognitive risk syndrome (MCR) is still unclear. The present study aimed to examine the associations between sleep duration, sleep quality, and MCR among community-dwelling Chinese older adults.

Methods: We recruited 5,387 participants aged ≥60 years from the China Health and Retirement Longitudinal Study (CHARLS). Sleep-related variables including night sleep duration and sleep quality were assessed via self-reported questionnaires. MCR syndrome was defined as cognitive complaints and slow gait speed without dementia or impaired mobility. Multivariate logistic regression analysis was performed to explore the associations between sleep-related variables and MCR after controlling for all potential confounders including demographic characteristics, lifestyle factors, and comorbidities.

Results: We found that sleep duration was significantly associated with MCR, and the multivariate-adjusted odds ratios (OR) were highest for those with the shortest (<6 h OR = 1.55, 95% CI = 1.18–2.04) and longest (≥10 h OR = 1.73, 95% CI = 1.03–2.91) sleep durations. Moreover, an increasing frequency of self-perceived poor sleep quality was significantly associated with MCR in the adjusted model (3–4 days OR = 1.58, 95% CI = 1.16–2.17; 5–7 days OR = 1.81, 95% CI = 1.37–2.40).

Conclusions: Our study indicated an inverted U-shaped association between night sleep duration and MCR. Poor sleep quality was also associated with higher odds of MCR in community-dwelling Chinese elders. Longitudinal studies with a larger population size are needed to establish causality in the future and further explore potential action mechanisms.

Sleep difficulties, incident dementia and all-cause mortality among older adults across 8 years: Findings from the National Health and Aging Trends Study

Sleep difficulties have been implicated in the development and progression of dementia and in all-cause mortality. This study examines the relationship between sleep difficulties, incident dementia and all-cause mortality over 8 years of follow-up among a nationally representative sample of older (≥65 years) adults in the United States. We used data collected from the National Health and Aging Trends Study (NHATS) from 2011 to 2018, a prospective cohort study of Medicare beneficiaries. At baseline, the NHATS sample comprised 6,376 older adults who were representative of 32 million older adults. Respondents reported routine difficulty initiating sleep or difficulty falling back asleep "most nights" or "every night" in each study year. In each year, dementia was determined by either self-reported diagnosis or performance on immediate and delayed recall word and clock drawing tests, whereas all-cause mortality was determined by proxy. We conducted Cox proportional hazards modelling, adjusting for age, sex, marital status and chronic conditions. In models predicting all-cause mortality, we also controlled for dementia. Among respondents at baseline, 19% were 65-75 years of age, 71% identified as non-Hispanic white and 59% were female. Difficulty initiating sleep (hazard ratio [HR], 1.49; 95% confidence interval [CI],1.25-1.77), difficulty falling back asleep (HR, = 1.39; 95% CI,1.14-1.70) and concurrent sleep difficulties (HR, 1.58; 95% CI, 1.25-1.99) were associated with greater risk of dementia. Difficulty initiating sleep (HR, 1.44; 95% CI,1.20-1.72), difficulty falling back asleep (HR, 1.56; 95% CI,1.29-1.89), and concurrent sleep difficulties (HR, 1.80; 95% CI, 1.44-2.24) were associated with greater risk of all-cause mortality. Our findings demonstrate that reported difficulties are prospectively associated with an increased risk of dementia and all-cause mortality among older people.

Self-reported sleep relates to microstructural hippocampal decline in ß-amyloid positive Adults beyond genetic risk

STUDY OBJECTIVES

A critical role linking sleep with memory decay and β-amyloid (Aβ) accumulation, two markers of Alzheimer's disease (AD) pathology, may be played by hippocampal integrity. We tested the hypotheses that worse self-reported sleep relates to decline in memory and intra-hippocampal microstructure, including in the presence of Aβ.

METHODS

Two-hundred and forty-three cognitively healthy participants, aged 19-81 years, completed the Pittsburgh Sleep Quality Index once, and two diffusion tensor imaging sessions, on average 3 years apart, allowing measures of decline in intra-hippocampal microstructure as indexed by increased mean diffusivity. We measured memory decay at each imaging session using verbal delayed recall. One session of positron emission tomography, in 108 participants above 44 years of age, yielded 23 Aβ positive. Genotyping enabled control for APOE ε4 status, and polygenic scores for sleep and AD, respectively.

RESULTS

Worse global sleep quality and sleep efficiency related to more rapid reduction of hippocampal microstructure over time. Focusing on efficiency (the percentage of time in bed at night spent asleep), the relation was stronger in presence of Aβ accumulation, and hippocampal integrity decline mediated the relation with memory decay. The results were not explained by genetic risk for sleep efficiency or AD.

CONCLUSIONS

Worse sleep efficiency related to decline in hippocampal microstructure, especially in the presence of Aβ accumulation, and Aβ might link poor sleep and memory decay. As genetic risk did not account for the associations, poor sleep efficiency might constitute a risk marker for AD, although the driving causal mechanisms remain unknown.

Cross-sectional and prospective associations between self-reported sleep characteristics and cognitive function in men and women: The Midlife in the United States study

Sleep behaviour is an important contributing factor in healthy human ageing and cognitive function. Previous studies have linked sleep deficiency with cognitive decline in older adults. However, there is need for more prospective investigations that focus on specific domains of cognitive function. The present study analysed cross-sectional and prospective associations between self-reported sleep and cognitive function in the Midlife in the United States (MIDUS) study. Weekday and weekend sleep duration and habitual sleep quality were obtained via questionnaire data. Brief Test of Adult Cognition by Telephone was conducted to assess overall cognitive function, as well as episodic memory and executive function. We found significant trend for both long weekday and weekend sleep (>8 hr) and lower episodic memory scores in the overall sample. Sex-specific cross-sectional analysis demonstrated men with longer weekend sleep duration have lower overall cognitive function scores, and a negative association between weekend sleep and episodic memory scores. Women demonstrated a positive association between weekend sleep duration and executive function scores. There was no prospective significance for overall or sex-specific analysis. Our present results suggest that sleep duration may contribute to cognitive function, and future studies should include objective sleep measurements and focus on the potential cognitive benefits of improving sleep to further elucidate this association.

Sleep and longitudinal cognitive performance in preclinical and early symptomatic Alzheimer's disease

Sleep monitoring may provide markers for future Alzheimer's disease; however, the relationship between sleep and cognitive function in preclinical and early symptomatic Alzheimer's disease is not well understood. Multiple studies have associated short and long sleep times with future cognitive impairment. Since sleep and the risk of Alzheimer's disease change with age, a greater understanding of how the relationship between sleep and cognition changes over time is needed. In this study, we hypothesized that longitudinal changes in cognitive function will have a non-linear relationship with total sleep time, time spent in non-REM and REM sleep, sleep efficiency and non-REM slow wave activity. To test this hypothesis, we monitored sleep-wake activity over 4-6 nights in 100 participants who underwent standardized cognitive testing longitudinally, APOE genotyping, and measurement of Alzheimer's disease biomarkers, total tau and amyloid-β42 in the CSF. To assess cognitive function, individuals completed a neuropsychological testing battery at each clinical visit that included the Free and Cued Selective Reminding test, the Logical Memory Delayed Recall assessment, the Digit Symbol Substitution test and the Mini-Mental State Examination. Performance on each of these four tests was Z-scored within the cohort and averaged to calculate a preclinical Alzheimer cognitive composite score. We estimated the effect of cross-sectional sleep parameters on longitudinal cognitive performance using generalized additive mixed effects models. Generalized additive models allow for non-parametric and non-linear model fitting and are simply generalized linear mixed effects models; however, the linear predictors are not constant values but rather a sum of spline fits. We found that longitudinal changes in cognitive function measured by the cognitive composite decreased at low and high values of total sleep time (P < 0.001), time in non-REM (P < 0.001) and REM sleep (P < 0.001), sleep efficiency (P < 0.01) and <1 Hz and 1-4.5 Hz non-REM slow wave activity (P < 0.001) even after adjusting for age, CSF total tau/amyloid-β42 ratio, APOE ε4 carrier status, years of education and sex. Cognitive function was stable over time within a middle range of total sleep time, time in non-REM and REM sleep and <1 Hz slow wave activity, suggesting that certain levels of sleep are important for maintaining cognitive function. Although longitudinal and interventional studies are needed, diagnosing and treating sleep disturbances to optimize sleep time and slow wave activity may have a stabilizing effect on cognition in preclinical or early symptomatic Alzheimer's disease.

Sleep Characteristics and Cognitive Function in Older Adults Without Dementia: The CABLE Study

BACKGROUND

The associations between sleep characteristics and cognition are complicated. Alzheimer's disease (AD) pathologies have been proven to be associated with sleep characteristics.

OBJECTIVE

We aimed to investigate the associations between sleep characteristics and cognitive function and examine the roles of AD pathologies in modulating the association of sleep duration with cognition.

METHODS

A total of 974 participants who had measurements of cerebrospinal fluid (CSF) amyloid-β (Aβ), phosphorylated tau (P-tau), total tau proteins (T-tau), cognitive function, and sleep characteristics were included from the Chinese Alzheimer's Biomarker and Lifestyle (CABLE) study. Linear regression analyses were utilized to explore the associations of sleep characteristics with cognition. Non-linear regression analyses were utilized to explore the associations of sleep habits with cognition. Causal mediation analyses were conducted to explore the mediation effects of AD pathologies on cognition.

RESULTS

The Pittsburgh Sleep Quality Index (PSQI) total score was significantly negatively correlated with Montreal Cognitive Assessment (MoCA) score (p = 0.0176). Long latency (p = 0.0054) and low efficiency (p = 0.0273) were associated with cognitive impairment. Habitual nap behavior was associated with lower MoCA scores (p = 0.0045). U-shaped associations were observed between sleep habits (bedtime and nocturnal sleep duration) and cognition. A causal mediation analysis indicated that P-tau/Aβ42 mediated the association of sleep duration with cognition.

CONCLUSION

These findings showed sleep characteristics were associated with cognitive functions. Sleep habits (duration, bedtime) had U-shaped associations with cognition. AD core pathologies might partially mediate the influence of sleep duration on cognitive impairments.

Cardiovascular Endurance Modifies the Link between Subjective Sleep Quality and Entorhinal Cortex Thickness in Younger Adults

INTRODUCTION

Poor sleep is linked to impaired cognitive function, cortical brain atrophy, and lower cortical thickness. Independently, higher cardiovascular endurance has neuroprotective effects. It remains in question, however, whether cardiovascular endurance moderates the relationship between sleep and brain health. The aims of this study included the following: 1) the association between subjective sleep quality and cognitive performance, hippocampus volume, and entorhinal cortex (EC) thickness, and 2) the moderating effects of cardiovascular endurance on the associations of sleep quality with cognitive and magnetic resonance imaging measures in healthy younger adults.

METHODS

A total of 1095 younger adults (28.8 ± 3.6 yr) from the Human Connectome Project were included in the analyses. The 2-min walk test was used as a proxy of cardiovascular endurance. Self-reported sleep quality was measured using the Pittsburgh Sleep Quality Index. Composite cognitive tests were used to assess global cognition, and T1-weighted structural magnetic resonance imaging data (obtained using Siemens 3T scanner) was used to assess hippocampus volume and EC thickness. Linear regression was used to examine the moderating effects of fitness on the relationships between sleep and each of these neurocognitive outcomes after controlling for age, sex, and education year.

RESULTS

Poorer sleep quality was associated with both a lower crystalized intelligence score (B = -0.198, P = 0.034) and lower EC thickness (B = -0.013, P = 0.003). With greater 2-min walk test score, the association between greater Pittsburgh Sleep Quality Index score and lower EC thickness was attenuated (B = 0.0008, P = 0.028).

CONCLUSIONS

Higher cardiovascular endurance may mitigate the relationship between poorer subjective sleep quality and lower EC thickness. Future longitudinal studies should examine the interactive effects of sleep and fitness on brain health among older and more vulnerable populations.

Is Oxidative Stress the Link Between Cerebral Small Vessel Disease, Sleep Disruption, and Oligodendrocyte Dysfunction in the Onset of Alzheimer's Disease?

Oxidative stress is an early occurrence in the development of Alzheimer’s disease (AD) and one of its proposed etiologic hypotheses. There is sufficient experimental evidence supporting the theory that impaired antioxidant enzymatic activity and increased formation of reactive oxygen species (ROS) take place in this disease. However, the antioxidant treatments fail to stop its advancement. Its multifactorial condition and the diverse toxicological cascades that can be initiated by ROS could possibly explain this failure. Recently, it has been suggested that cerebral small vessel disease (CSVD) contributes to the onset of AD. Oxidative stress is a central hallmark of CSVD and is depicted as an early causative factor. Moreover, data from various epidemiological and clinicopathological studies have indicated a relationship between CSVD and AD where endothelial cells are a source of oxidative stress. These cells are also closely related to oligodendrocytes, which are, in particular, sensitive to oxidation and lead to myelination being compromised. The sleep/wake cycle is another important control in the proliferation, migration, and differentiation of oligodendrocytes, and sleep loss reduces myelin thickness. Moreover, sleep plays a crucial role in resistance against CSVD, and poor sleep quality increases the silent markers of this vascular disease. Sleep disruption is another early occurrence in AD and is related to an increase in oxidative stress. In this study, the relationship between CSVD, oligodendrocyte dysfunction, and sleep disorders is discussed while focusing on oxidative stress as a common occurrence and its possible role in the onset of AD.

Mutual Interactions between Brain States and Alzheimer's Disease Pathology: A Focus on Gamma and Slow Oscillations

Brain state varies from moment to moment. While brain state can be defined by ongoing neuronal population activity, such as neuronal oscillations, this is tightly coupled with certain behavioural or vigilant states. In recent decades, abnormalities in brain state have been recognised as biomarkers of various brain diseases and disorders. Intriguingly, accumulating evidence also demonstrates mutual interactions between brain states and disease pathologies: while abnormalities in brain state arise during disease progression, manipulations of brain state can modify disease pathology, suggesting a therapeutic potential. In this review, by focusing on Alzheimer's disease (AD), the most common form of dementia, we provide an overview of how brain states change in AD patients and mouse models, and how controlling brain states can modify AD pathology. Specifically, we summarise the relationship between AD and changes in gamma and slow oscillations. As pathological changes in these oscillations correlate with AD pathology, manipulations of either gamma or slow oscillations can modify AD pathology in mouse models. We argue that neuromodulation approaches to target brain states are a promising non-pharmacological intervention for neurodegenerative diseases.