Hippocampal PER1: a circadian sentinel controlling RSKy activity during memory formation

The association between sleep duration, bedtime, and cognitive ability in Chinese adults: Evidence from the China family panel studies

Introduction

Dementia is marked by a steady decline or worsening in cognitive abilities, affecting memory, logic, and social competencies. While many studies suggest a potential link between the amount of sleep and dementia risk, the outcomes are not yet consistent. This research delved into the relationship between sleep length and bedtime on cognitive abilities using an extensive dataset from the China Family Panel Studies (CFPS) from 2014 to 2020.

Methods

Data from 175,702 observations were collected, including cognitive function test data from 22,848 participants. Various cognitive tests were used to assess cognitive function. Restricted cubic spline (RCS) models were used for data analysis.

Results

The optimal sleep duration for cognitive function was found to be 6-7 h, and the optimal bedtime was generally between 22:00-23:00. Longitudinal analysis revealed that sleep duration four years prior had a significant impact on current cognitive function. After accounting for various factors, those who slept for 7-8 h and over 8 h displayed lower cognitive function scores. Conversely, individuals sleeping less than 6 h had higher scores on the Vocabulary Test. Bedtime before 22:00 was associated with lower scores on the Vocabulary Test and Mathematical Test. Subgroup analyses based on age, gender, and urban residence showed variations in optimal sleep duration for different populations. Propensity Score Matching (PSM) analysis supported the findings.

Conclusions

Maintaining a sleep duration of 6-7 h and a regular bedtime between 22:00-23:00 is important for optimizing cognitive performance.

Association between all-cause mortality and trajectories across quality and duration of sleep and cognitive function: based on Group-Based Multivariate Trajectory modeling

BACKGROUND

Sleep duration and quality are associated with cognition, but the interaction of the 3 indicators and their association with all-cause mortality is unclear.

METHODS

We used data from the Chinese Longitudinal Healthy Longevity Survey from 2005-2018 to identify latent trajectories of sleep duration, sleep quality, and cognitive function. Secondly, the multinomial logistic model was adopted to determine predictors of trajectory groups. Finally, the Cox regression model was used to examine the association between these trajectory groups and all-cause mortality.

RESULTS

A total of 5046 adults (49% women) with an average age of 76.34 were included in the study. The median follow-up period was 11.11 years, during which 1784 (35%) participants died. We identified 4 latent groups among older adults: 'Good-performance' (51%), 'Decreasing' (26%), 'Oversleep & cognitive impairment' (12%), and 'Sleep-deprived' (11%). Individuals in the 'Decreasing' had a 51% increased risk of all-cause mortality (HR = 1.51, 95% CI: 1.25 - 1.81, p < .001). Individuals in the 'Oversleep & cognitive impairment' had a 170% increased risk of all-cause mortality (HR = 2.7 95% CI: 2.13 - 3.43, p < .001). Women had a higher risk of all-cause mortality regardless of trajectory group (47-143% men VS. 74-365% women). Both urban and rural areas have a similarly increased risk of all-cause mortality (48-179%).

CONCLUSIONS

Our study reveals the latent trajectories across sleep duration, sleep quality, and cognitive function in older Chinese and further explores their association with death. These findings provide a rational basis for cognitive interventions and reduce all-cause mortality.

Sex, Sleep Duration, and the Association of Cognition: Findings from the China Health and Retirement Longitudinal Study

BACKGROUND

We aimed to examine the association between sleep duration and cognitive impairment among elderly Chinese people.

METHODS

generalized linear modeling was used to analyze the baseline data for adults aged 65 years and over (n = 4785) selected from the 2011 China Health and Retirement Longitudinal Study (CHARLS). The two aspects of cognitive impairment assessed in the study were mental status and memory. Sex-stratified logistic regression models were conducted to identify the effect of sleep duration in the different gender groups.

RESULTS

of all the participants, 49.8% were females and 32.5% aged 75 years and over. Of the participants, 59.7% had short sleep duration (<7 h/day), and 9.0% of them had long sleep duration (>8 h/day). Compared to normal sleep duration, long sleep duration was associated with lower mental status scores (β = -0.43, p = 0.001) and lower memory scores (β = -0.26, p = 0.006). Long sleep duration was associated with lower mental status in both men (β = -0.37, p = 0.033) and women (β = -0.46, p = 0.025), however, only in men was long sleep duration found to be associated with low memory scores (β = -0.26, p = 0.047).

CONCLUSIONS

Our study showed that long sleep duration was significantly associated with poorer mental status and memory scores in elderly Chinese people. Paying greater attention to the effects of sleep patterns on the risk of cognitive decline may yield practical implications for dementia prevention and health promotion, especially among older women with lower educational attainment, living in rural areas, and those who have long sleep duration.

Does poor sleep impair cognition during aging? Longitudinal associations between changes in sleep duration and cognitive performance among older Mexican adults

Alterations in sleep patterns are common among older adults; further, short and long sleep durations have been linked with impaired cognitive performance in older individuals. Yet most research examining these relationships has been cross-sectional, limited to high-income nations, and has failed to consider how changes in sleep duration may impact cognitive decline. The present longitudinal study uses nationally-representative data to test whether changes in sleep length among "healthy" baseline sleepers are associated with reduced cognitive function in older Mexican adults (>50 years old) at follow-up. Data were drawn from the first and second waves of the World Health Organization's Study on global AGEing and adult health. Self-report data captured sleep duration over two nights, and five cognitive tests (immediate and delayed verbal recall, forward and backward digit span, and verbal fluency) were used to measure various cognitive domains and create a composite z-score of cognitive performance. Linear regressions were performed to assess associations between sleep length changes and cognitive decline, controlling for relevant lifestyle and health factors. Increased sleep durations at follow-up among individuals who reported intermediate sleep durations (6-9 h/night) at baseline were significantly associated with greater rates of decline in overall cognitive function. Longer sleepers also trended toward greater rates of decline for attention/working memory and executive function. This study suggests that long sleep durations are a risk factor for certain types of impaired cognition among older adults living in a middle-income country. These findings are clinically important given the growing rates of dementia and aging populations globally.

Clocking In Time to Gate Memory Processes: The Circadian Clock Is Part of the Ins and Outs of Memory

Learning, memory consolidation, and retrieval are processes known to be modulated by the circadian (circa: about; dies: day) system. The circadian regulation of memory performance is evolutionarily conserved, independent of the type and complexity of the learning paradigm tested, and not specific to crepuscular, nocturnal, or diurnal organisms. In mammals, long-term memory (LTM) formation is tightly coupled to de novo gene expression of plasticity-related proteins and posttranslational modifications and relies on intact cAMP/protein kinase A (PKA)/protein kinase C (PKC)/mitogen-activated protein kinase (MAPK)/cyclic adenosine monophosphate response element-binding protein (CREB) signaling. These memory-essential signaling components cycle rhythmically in the hippocampus across the day and night and are clearly molded by an intricate interplay between the circadian system and memory. Important components of the circadian timing mechanism and its plasticity are members of the Period clock gene family (Per1, Per2). Interestingly, Per1 is rhythmically expressed in mouse hippocampus. Observations suggest important and largely unexplored roles of the clock gene protein PER1 in synaptic plasticity and in the daytime-dependent modulation of learning and memory. Here, we review the latest findings on the role of the clock gene Period 1 (Per1) as a candidate molecular and mechanistic blueprint for gating the daytime dependency of memory processing.

Sleep quality and duration in relation to memory in the elderly: Initial results from the Hellenic Longitudinal Investigation of Aging and Diet

BACKGROUND

Sleep is crucial for cognition, particularly for memory, given its complex association with neurodegenerative processes. The aim of the present study was to examine the association between sleep quality as well as sleep duration and memory performance in a Greek elderly population.

SETTING

Cross-sectional design in the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD), a population representative study of Greek elderly (65years or older).

METHODS

Data from 1589 participants free of sleep medication were included. Sleep quality was estimated by using the Sleep Scale from the Medical Outcomes Study. An extensive neuropsychological assessment examining memory was administered to each participant. Linear regression analyses were used to examine whether sleep quality (higher score, poor quality) and/or sleep duration were associated with memory expressed in the form of a z-score. Age, sex, education, and body mass index were included as covariates. The main analyses were conducted first on the total sample, then with the exclusion of demented participants, and finally with the exclusion of both demented and participants with Mild Cognitive Impairment (MCI). We then conducted further analyses on the non-demented, non-MCI group, initially stratified by Apolipoprotein E-ε4 gene. We further examined the role of co-morbidities, as well as the association between sleep duration groups and memory. We also explored any interaction effect between sex and sleep quality/duration on memory. We then examined the associations between components of sleep measures and memory scores. Lastly, we examined the associations between sleep quality/duration and verbal/non-verbal memory separately.

RESULTS

In the total sample, we noted significant associations between sleep duration and memory (B=-0.001, p≤0.0001), but not for sleep quality and memory (B=-0.038, p=0.121). After excluding the demented participants, the associations were significant for: sleep quality and memory (B=-0.054, p=0.023), and sleep duration and memory (B=-0.001, p≤0.0001). After excluding both the MCI and the demented subjects, the associations between sleep quality and memory (B=-0.065, p=0.006), and sleep duration and memory (B=-0.001, p=0.003) were still significant. The association between the sleep duration groups and memory function was also significant, such that poor memory performance was associated with the longer sleep duration group. The results remained significant even after controlling for the co-morbidities, as well as after adding in the model anxiety and depression as covariates. Associations between sleep quality and memory, and sleep duration and memory were present in the ApoE-ε4 non-carriers. The individual sleep questions that were probably shown to be driving the associations between sleep and memory were: time to fall asleep, sleep not quiet, getting enough sleep to feel rested upon waking in the morning, and getting the amount of sleep needed. Sleep duration was associated with both verbal and non-verbal memory, while sleep quality was only associated with verbal memory.

CONCLUSION

Poor sleep quality and longer sleep duration were linked to low memory performance, independent of demographic and clinical factors, in a large sample of cognitively healthy older Greek adults. Other parameters than sleep and memory measurements could play an important role on the association. Levels of melatonin, or circadian rhythms dysregulation might play a crucial role in the above associations.