Sleep duration and memory in the elderly Chinese: longitudinal analysis of the Guangzhou Biobank Cohort Study

Association between sleep duration and subjective memory complaints: A large-scale cross-sectional study based on NHANES

Objective

When chatting, people often forget what they want to say, that is, they suffer from subjective memory complaints (SMCs). This research examines the Association between sleep duration and self-reported SMC in a sample representing the entire United States.

Methods

We examined data from 5567 individuals (aged 20-80) who participated in the National Health and Nutrition Examination Survey (2015-2018) to evaluate the association between sleep duration and SMC. Odds ratios (ORs) and a restricted cubic spline (RCS) curve were calculated with multiple logistic regression, and subgroup analysis was performed.

Results

Approximately 5.8 % (3 2 3) reported SMC, and most are older people (1 6 3). RCS analysis treating sleep duration as a continuous variable revealed a J-shaped curve association between sleep duration and SMC. Self-reported sleep duration was significantly linked to a 33 % elevated risk of SMC (OR, 1.33; 95 % confidence interval [CI], 1.23-1.43; P < 0.001). In the group analysis, individuals who slept more than 8 h per day had a greater association of experiencing SMC than those who slept for 6-8 h/day (OR, 1.75; 95 % CI, 1.36-2.23; P < 0.001). In the analysis of age groups, the stable association between sleep duration and SMC was observed only in the 60-80 age bracket (OR, 1.59; 95 % CI, 1.09-2.33; P < 0.001).

Conclusions

We found that people with self-report sleep duration exceeding 8 h are more likely to experience SMC, especially older adults. Improving sleep health may be an effective strategy for preventing SMC and cognitive impairment.

Associations of cognitive impairment and longitudinal change in cognitive function with the risk of fatal stroke in middle-aged to older Chinese

It is unclear whether cognitive impairment and the longitudinal change in cognition are associated with the risk of fatal stroke in aging populations. Based on the Guangzhou Biobank Cohort Study data a sum of 26,064 participants at baseline and all deaths caused by stroke in a mean follow-up of 14.3 years (standard deviation = 3.2) were included, and the Cox proportional hazard regression was used in this prospective cohort study. Cognitive impairment was respectively associated with an increased risk of fatal strokes (the adjusted hazard ratio (aHR) = 1.38, 95% CI1.16-1.64, P < 0.001) and fatal ischaemic stroke (aHR = 1.39, 95% CI1.10-1.77, P = 0.007), compared to median cognition; the Delayed Word Recall Test (DWRT) score was associated with a decreasing trend for the risk of fatal strokes in a restricted cubic spline analysis; the longitudinal DWRT score decline was associated with the increased risks of fatal strokes (aHR = 1.42, 95% CI 1.11-1.82, P = 0.006) and fatal haemorrhagic stroke (aHR = 1.75, 95% CI 1.10-2.78, P = 0.02), compared to the longitudinal DWRT score rise. In summary, cognitive impairment and the longitudinal decline in DWRT scores were associated with the increased risk of fatal strokes; early screening of cognitive function should be conducive to predictive intervention in fatal stroke among relatively healthy middle-aged to older populations.

Persistently short or long sleep duration increases the risk of sensory impairment in Chinese older adults

Background

Cross-sectional evidence suggests that persistently short or long sleep duration is associated with sensory impairment. Thus, this study was conducted to investigate the associations between sleep duration and altered sleep duration with sensory impairment in Chinese older adults.

Methods

Longitudinal data (2008-2014) obtained through the Chinese Longitudinal Healthy Longevity Survey (CLHLS) were analyzed. Sleep duration was classified as normal (7-8 h), short (<7 h), or long (≥9 h). Sensory impairment was assessed using individuals' self-reported data on visual and hearing functions. Cox regression was performed to evaluate the effects of sleep duration and altered sleep duration on sensory impairment, including visual impairment (VI) and hearing impairment (HI).

Results

This study included 3,578 older adults (mean age: 78.12 ± 9.59 years). Among them, 2,690 (75.2%) were aged 65-84 years and 1798 (50.3%) were women. The risks of VI (hazard ratio [HR]: 1.14; 95% confidence interval [CI]: 1.02-1.29), HI (HR: 1.14; 95% CI: 1.00-1.30), and dual sensory impairment (both VI and HI; HR: 1.26; 95% CI: 1.03-1.55) were high in older adults with long sleep duration. In addition, the risks of VI, HI, and dual sensory impairment were high in individuals whose sleep duration changed from normal to short or long (HR: 1.20 [95% CI: 1.02-1.42], 1.26 [95% CI: 1.03-1.53], and 1.54 [95% CI: 1.11-2.12], respectively) and those with persistently short or long sleep duration (HR: 1.25 [95% CI: 1.07-1.46], 1.34 [95% CI: 1.11-1.61], and 1.67 [95% CI: 1.22-2.27], respectively).

Conclusion

A prospective association was identified between altered sleep duration and sensory impairment in Chinese older adults. Our findings highlight the importance of optimal sleep duration and healthy sleep habits in preventing sensory impairment in older adults.

Association between sleep hours and changes in cognitive function according to the morningness-eveningness type: A population-based study

OBJECTIVE

The aim of this study was to investigate proper sleep hours to reduce the risk of cognitive decrease considering morningness-eveningness type.

METHODS

The Korean Community Health Survey was used, which includes adults aged over 19 years old. These data were obtained from a cross-sectional study and assessed sleep hours using questionnaire of Pittsburgh Sleep Quality Index. Based on the wake-up time of each participant, they were classified into the morningness, intermediate, eveningness, and none groups. The change in cognitive function was determined by a single question about memory loss experience.

RESULTS

A total of 224,714 participants were included in the analysis. Of the participants, 55.6 % and 5.0 % of whom had morningness and eveningness, respectively. The risk of cognitive decline was significantly different by sleep hours and morningness-eveningness type. Without considering sleep quality, the intermediate and eveningness groups showed a higher risk of cognitive decline than the morningness group, and the risk was lowest in those with 7-9 sleep hours. However, when sleep quality showing significant effect was included in the analysis, sleep hours showing the lowest risk were different among morningness, intermediate, eveningness groups, and it was the shortest in the morningness type at 5-6 h and the longest in the eveningness type at 7-8 h.

CONCLUSION

Proper sleep hours to decrease the risk of cognitive decline may be different by morningness-eveningness types. However, when considering sleep quality, sleep duration had little influence on cognitive decline. Future studies investigating healthy sleep hours need to consider sleep quality as well as the habitual sleep schedules.

LIMITATIONS

The morningness-eveningness types were classified based on wake-up time not morningness-eveningness types. The morningness-eveningness types in this study would be interpreted as habitual sleep schedule rather than chronotype.

Associations of daytime napping and nighttime sleep quality with depressive symptoms in older Chinese: the Guangzhou biobank cohort study

BACKGROUND

Poor sleep quality has been linked to depression in older adults, but results of the association between daytime napping and depression remains limited and conflicting. Moreover, whether the association of daytime napping with depression varies by nighttime sleep quality is unclear. Hence, we examined the associations of daytime napping and nighttime sleep quality with depressive symptoms in older Chinese.

METHODS

A total of 16,786 participants aged ≥50 from the Guangzhou Biobank Cohort Study second-round examination (2008-2012) were included in this cross-sectional study. Geriatric Depression Scale (GDS-15), Pittsburgh Sleep Quality Index (PSQI), napping and demographic data were collected by face-to-face interview using a computerized questionnaire. Logistic regression was used to calculate odds ratio (OR) of depressive symptoms for napping and sleep quality.

RESULTS

The prevalence of depressive symptoms (GDS score > 5) and poor global sleep quality (PSQI score ≥ 6) was 5.3 and 31.9%, respectively. Compared to non-nappers, nappers showed significantly higher odds of depressive symptoms, with OR (95% confidence interval (CI)) being 1.28 (1.11-1.49). The odds of depressive symptoms for daytime napping varied by nighttime sleep quality (P for interaction = 0.04). In good-quality sleepers, compared to non-nappers, nappers had significantly higher odds of depressive symptoms, with OR (95% CI) being 1.57 (1.23-2.01), whereas no association was found in poor-quality sleepers (OR = 1.13, 0.94-1.36).

CONCLUSION

Napping was associated with higher odds of depressive symptoms in older people, and the association was stronger in good-quality sleepers.

Association of perceived stress with memory decline in older Chinese: The Guangzhou Biobank Cohort Study

BACKGROUND

Previous studies on associations of perceived stress with poor memory performance in older adults showed inconsistent results. We examined the prospective associations of perceived stress with memory decline using data from Guangzhou Biobank Cohort Study (GBCS).

METHODS

Perceived stress was measured by the Perceived Stress Scale (PSS) at baseline (2003-2006), with greater scores indicating greater stress. Memory function was measured by delayed 10-word recall test (DWRT) and immediate 10-word recall test (IWRT), with greater scores indicating better performance, at baseline and follow-up (2008-2012) examinations, analyzed as mean annual change in scores.

RESULTS

9656 participants (72 % women) with mean age 61.6 (standard deviation = 6.4) years were included. During an average of 4.4 years of follow-up, after adjusting for confounders, each one-point greater PSS score was associated with mean annual decline in DWRT scores (β (95 % CI) = -0.005 (-0.008 to -0.002)). Greater Perceived Helplessness (PH) scores, but not Perceived Self-efficacy scores, was associated with greater mean annual decline in DWRT and IWRT scores (β (95 % CI) = -0.005 (-0.009 to -0.001) and - 0.012 (-0.018 to -0.005), respectively), and similar patterns were observed in five out of seven PH items (βs from -0.02 to -0.07). Interaction analysis showed that the association of greater PSS with greater decline in DWRT scores was observed only in those with low family income (β (95 % CI) = -0.08 (-0.13 to -0.04), P for interaction = 0.03).

CONCLUSIONS

Greater perceived stress was associated with a greater decline in delayed recall memory, especially in those with low family income.

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.

The association of previous night's sleep duration with cognitive function among older adults: a pooled analysis of three Finnish cohorts

STUDY OBJECTIVES

Sleep duration has been shown to associate with cognitive function, but little is known about the short-term effect of sleep duration on the previous night. This study examines how usual sleep duration and previous night's sleep duration are associated with cognitive function in older adults.

METHODS

The study population consisted of 2949 adults aged 59-92 years (mean 72.6, SD 5.7) derived from three Finnish cohorts. Participants' self-reported usual sleep duration was categorized into short (< 7 h, 19%), mid-range (7- < 9 h, 64%), and long (≥ 9 h, 17%). Self-reported sleep duration on the night prior to cognitive testing was categorized into shorter (59%), same (35%), and longer (5.9%) than usual sleep duration. Computerized Cambridge Neuropsychological Test Automated Battery (CANTAB®) was used to assess: (1) learning and memory, (2) working memory, (3) information processing, and (4) reaction time.

RESULTS

Participants with self-reported long, but not short, usual sleep duration had poorer learning and memory (p = .004), information processing (p = .003), and reaction time (p = .006) when compared to those with mid-range sleep duration. Those who slept more than usually the night prior to cognitive testing had poorer information processing (p = .019) than those sleeping the same as usually, while sleeping less than usually was not associated with cognitive function.

CONCLUSIONS

This study suggests that while long sleep duration was associated with worse cognitive function, sleeping more than usually the night prior to cognitive testing was only associated with information processing, and sleeping less than usually is not associated with cognitive function.

Characteristics of the cognitive function transition and influencing factors among Chinese older people: An 8-year longitudinal study

BACKGROUND

Cognitive impairment among older people is an important public health problem in developing countries. Therefore, it is necessary to identify the subtypes of cognitive function among older people in China, and explore the transformation patterns and influencing factors.

METHODS

Longitudinal data from the China Health and Retirement Longitudinal Study (CHARLS) were used, and included 2140 women and 2049 men aged over 60 years. Latent profile and latent transition analysis (LPA&LTA) were used to identify subgroups and transitions between the profiles over time. Influencing factors were identified by multinomial logistic regression analysis.

RESULTS

According to the LPA model, three subgroups of cognitive function were identified: Cognitive Impairment, Mild Cognitive Impairment (MCI) and Normal Cognitive Function. Concurrently, >50 % of participants were likely to progress to MCI after seven years, whereas participants with cognitive impairment had a probability of 54.2 % of transitioning to a better cognitive profile. Older adults are less likely to experience cognitive improvement, higher levels of education affect changes in cognition, and having depression are at a lower risk of cognitive decline.

LIMITATIONS

Due to the incompleteness of the cognitive assessment and the large time span, there was a certain bias in the classification and analysis of latent cognitive profiles.

CONCLUSION

This study identified three latent profiles among Chinese older people and showed the stability and heterogeneity. It demonstrated the effects of higher age or levels of education, and depression on changes in cognitive function in older people.

Can afternoon napping protect against the negative effect of short or long sleep duration on cognitive function? A prospective study

OBJECTIVES

Afternoon napping has been found to be able to compensate for the negative health effects of less optimal nighttime sleep duration. Our study aimed to investigate whether napping can protect against the negative effects of short or long sleep duration on cognitive function among middle-aged and older adults.

METHODS

A total of 8107 participants (men, 53.19%) aged 45 and older from the China Health and Retirement Longitudinal Study were followed prospectively for 7 years. The primary outcome was cognitive function (episodic memory and mental status). Afternoon napping was categorized into three groups including non- (0 min), moderate (1-30 min) and long (>30 min) duration. Nighttime sleep was also categorized into three groups including short (<7 h), normal (7-8 h), and long (>8 h) duration. Linear mixed models were used with napping and sleep duration at baseline as predictors. Potential confounders including baseline cognitive function were adjusted.

RESULTS

Shorter sleep duration (B = -0.01, p = 0.048) was independently associated with a faster decline in episodic memory. For participants with shorter sleep duration, either non-napping (B = -0.03, p = 0.017) or longer napping (B = -0.04, p = 0.018) showed a significant decline of episodic memory. For participants with longer sleep duration, non-napping was associated with a significant decline of episodic memory (B = -0.07, p = 0.003).

CONCLUSIONS

This study found that moderate napping could protect against the negative effects of short or long sleep duration on episodic memory, which implied that middle-aged and older adults who have a less optimal sleep duration might benefit from moderate napping for their cognitive function.

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.

Association of sleep duration and napping with stroke mortality in older Chinese: A 14-year prospective cohort study of the Guangzhou Biobank Cohort study

STUDY OBJECTIVE

Evidence regarding the association of short sleep duration and napping with stroke remains limited and controversial. We examined the association of sleep duration and napping with risk of stroke mortality in an older Chinese cohort.

METHODS

Sleep duration and daytime napping were assessed by face-to-face interview during 2003-2008. Information of causes of death until April 30, 2021 was collected via record linkage with the Death Registry. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

Of 27,254 participants aged average 62.0 (standard deviation = 7.1) years, 818 stroke deaths occurred within 388,798 person-years (mean = 14.3 years) of follow-up. A U-shaped relation between sleep duration and risk of stroke mortality was observed. Participants with short (≤5 h/day) or long sleep duration (≥9 h/day) showed higher risks of total stroke mortality, with adjusted HRs (95% CIs) being 1.27 (1.01-1.59) and 1.37 (1.07-1.75), respectively. However, non-significant association of short or long sleep duration with hemorrhagic or ischemic stroke mortality was found. The associations of short and long sleep duration with total stroke mortality were more pronounced in those with hypertension (P for interaction with hypertension = 0.01), with HRs (95% CIs) being 1.37 (1.04-1.82) and 1.77 (1.33-2.36), respectively. No association between napping and risk of stroke mortality was found.

CONCLUSIONS

Both short and long sleep duration, but not daytime napping, were associated with higher risk of stroke mortality. Public health messages to encourage good sleep hygiene may be important, especially for people with hypertension.

Longitudinal associations between sleep duration and cognitive impairment in Chinese elderly

BACKGROUND

Age-associated cognitive decline has become a major threat to both personal welfare and public health and can further develop into Dementia/Alzheimer's disease. Sleep is significantly correlated with cognitive function, but both cognitive impairment and sleep problems increase with normal aging. This study explored how sleep duration affects cognitive performance among older adults in China.

METHODS

Using data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) in 2014 and 2018, cognitive function was assessed via the Mini-Mental State Examination (MMSE), which included five domains: orientation, registration, attention or calculation, recall, and language. Logistic regression was used to examine whether the change in sleep duration was a risk factor for cognitive impairment. We also used multinomial logistic regression to study the impact of sleep duration and the changes in sleep duration on cognitive changes during the follow-up period.

RESULTS

The empirical study showed a U-shaped relationship between sleep duration and increased risk of cognitive impairment. Short (< 6 hours) and long (> 8 hours) sleep durations were positively associated with cognitive impairment. Tests of interactions between sleep duration and sleep quality showed that short sleep durations with fair sleep quality had an increased risk of cognitive impairment. Further, the participants were divided into three groups: normal cognition (MMSE > 24), mild cognitive impairment (MCI, 18 ≤ MMSE score ≤ 24), and severe cognitive impairment (MMSE < 18). First, of the participants with normal cognition at baseline, those who sleeping > 7 h at follow-up and > 7 h at both baseline and 4-year follow-up assessments could increase the risk of cognitive impairment. Second, for individuals with MCI at baseline, those who transitioned to sleeping > 7 h at follow-up period and > 7 h at both baseline and 4-year follow-up assessments had a lower chance of reverting to normal cognition.

CONCLUSION

Excessive sleep may be a major risk for cognitive impairment among older adults. Furthermore, a moderate amount of sleep could be a possible strategy to prevent cognitive impairment.

Both Short and Long Sleep Durations Are Associated with Poor Cognition and Memory in Chinese Adults Aged 55+ Years-Results from China Health and Nutrition Survey

We aimed to examine the associations between sleep duration and cognitive functions and memory in older Chinese adults attending the China Health and Nutrition Survey. A total of 7924 participants 55 years and older who reported their sleep duration and had a cognitive screen test in 2004, 2006, and 2015 were included in the analysis. Mixed-effects logistic regression models were used to assess the associations. A short sleep duration (≤6 h/day) and long sleep duration (≥10 h/day) were positively associated with a low global cognitive score (odds ratio-OR: 1.23, 95% CI: 1.01-1.50; OR: 1.47, 95% CI: 1.17-1.79, respectively). Both short sleepers and long sleepers had an increased risk of self-reported poor memory (OR: 1.63, 95% CI: 1.39-1.91; OR: 1.48, 95% CI: 1.25-1.74, respectively). No differences in the above associations were found for income, education, and urbanity. In conclusion, both the short and long sleep duration were associated with declined cognition and memory. Maintaining a normal sleep duration may aid in the prevention of cognitive function decline in older adults.

Association of alcohol use with memory decline in middle-aged and older Chinese: a longitudinal cohort study

BACKGROUND

Previous studies on associations of alcohol use with memory decline showed inconclusive results. We examined these associations using longitudinal data from the Guangzhou Biobank Cohort Study (GBCS) and explored whether these associations varied by sex and age group.

METHODS

Memory function was assessed by delayed 10-word recall test (DWRT) and immediate 10-word recall test (IWRT) at both baseline (2003-2008) and follow-up (2008-2012) examinations, expressed as the mean annual change and mean annual rate of change in scores. Memory cognitive impairment was defined by DWRT scores of less than 4. Multivariable linear regression models and restricted cubic spline were used for data analysis.

RESULTS

Of 14,827 participants without memory cognitive impairment at baseline, 90.2% were never or occasional drinkers, 5% moderate drinkers, 1.5% excessive drinkers, and 3.3% former drinkers. The mean (standard deviation) age was 60.6 (6.6) years old. During an average of 4.1 years follow-up, 1000 (6.7%) participants developed memory cognitive impairment. After adjusting for confounders, compared with never or occasional drinkers, moderate and excessive drinkers had significant decline in DWRT scores (β, 95% confidence interval (CI) = -0.04 (-0.08 to -0.01), and - 0.07 (-0.14 to 0.01), respectively), and IWRT scores (β, 95% CI = -0.10 (-0.19 to -0.01), and - 0.15 (-0.30 to 0.01), respectively) annually. With respect to the mean annual rate of change, moderate and excessive drinkers also showed greater decline in DWRT scores (β, 95% CI = -1.02% (-1.87% to -0.16%), and - 1.64% (-3.14% to -0.14%), respectively). The associations did not vary by sex and age group (all P values for interaction ≥ 0.10).

CONCLUSION

Compared to never or occasional alcohol use, moderate and excessive alcohol users had greater memory decline and the associations did not vary by sex and age group.

Association of alcohol drinking with incident type 2 diabetes and pre-diabetes: The Guangzhou Biobank Cohort Study

AIMS

We examined associations of baseline alcohol drinking with incident type 2 diabetes (T2D) or impaired fasting glucose (IFG), and explore whether the associations were modified by genetic polymorphisms of aldehyde dehydrogenase-2 (ALDH2) and alcohol dehydrogenase-1B (ADH1B).

MATERIALS AND METHODS

All participants were aged 50+ (mean = 60.45; standard deviation = 6.88) years. Information of alcohol consumption was collected at baseline from 2003 to 2008. Incident T2D was defined as fasting glucose ≥7.0 mmol/L or post-load glucose ≥11.1 mmol/L at follow-up examination (2008-2012), self-reported T2D and/or initiation of hypoglycaemia medication or insulin during follow-up. Impaired fasting glucose was defined as fasting glucose ≥5.6 mmol/L and <7 mmol/L.

RESULTS

Of 15,716 participants without diabetes and 11,232 participants without diabetes and IFG at baseline, 1624 (10.33%) developed incident T2D and 1004 (8.94%) developed incident IFG during an average 4 years of follow-up. After multivariable adjustments, compared with never drinking, occasional or moderate alcohol drinking was not associated with risk of incident hyperglycaemia (T2D + IFG) (odds ratio (OR) = 1.10, 95% confidence interval (CI) 0.95-1.27, and 0.90 (0.69-1.18), respectively), whereas heavy alcohol drinking was associated with a higher risk of incident hyperglycaemia (T2D + IFG) (OR = 1.82, 95% CI 1.24-2.68). No interactions of sex, overweight/obesity and genetic polymorphisms of ADH1B/ALDH2 genes with alcohol drinking on incident T2D and/or IFG were found (P for interaction from 0.12 to 0.85).

CONCLUSIONS

Our results support a detrimental effect of heavy alcohol use on IFG and T2D. No protective effect was found for those carrying lower risk alleles for ADH1B/ALDH2 genes.

Changes in blood pressure and cardiovascular disease in middle-aged to older Chinese: the Guangzhou Biobank Cohort Study

BACKGROUND

Most studies on the associations of blood pressure (BP) with cardiovascular disease (CVD) risk were based on single or average BP levels. Knowledge on the association between BP trajectories and CVD in middle-aged individuals who are not on antihypertensive medication may inform the care of individuals in this group whose BPs are not controlled.

METHODS

Eight thousand nine hundred and sixty-nine participants aged 50-70 years, without CVD at baseline and not taking antihypertensive medication throughout the study, were included. Four time-points data from the Guangzhou Biobank Cohort Study were used to identify BP trajectories using latent class mixed model. Cox regression was used to investigate the association of BP trajectories with fatal and nonfatal CVD till April 2021.

RESULTS

Three SBP trajectories were identified: 'low-slow-increase' characterized by SBP from 110 to 125 mmHg (86.5%); 'low-increase' from 110 to 150 mmHg (8.1%) and 'moderate-increase' from 125 to 155 mmHg (5.4%). Compared with the low-slow-increase group, the moderate-increase had the highest risk of CVD (hazard ratio = 1.76, 95% confidence interval = 1.34-2.29), ischemic heart disease (1.77, 1.01-3.09), myocardial infarction (3.52, 1.58-7.85), all strokes (1.88, 1.37-2.60), ischemic stroke (1.65, 1.10-2.49), haemorrhagic stroke (3.98, 1.30-12.12) and CVD mortality (2.41, 1.55-3.76). Higher risks of CVD (1.27, 1.01-1.61) and ischemic stroke (1.49, 1.07-2.09) in the low-increase group were also found.

CONCLUSION

Most people between 50 and 70 years of age and not taking antihypertensive medication maintained a slow increase SBP trajectory over a follow-up period of approximately 7 years. However, those whose SBPs increased from low and moderate levels were associated with higher CVD risks.

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 of Hand Grip Strength with Mild Cognitive Impairment in Middle-Aged and Older People in Guangzhou Biobank Cohort Study

Background: Lower hand grip strength has been linked to cognitive impairment, but studies in older Chinese are limited. We examined the association of hand grip strength with cognitive function in a large sample of older Chinese. Methods: 6806 participants aged 50+ years from the Guangzhou Biobank Cohort Study (GBCS) were included. Relative grip strength was calculated by absolute handgrip strength divided by the body mass index (BMI). Cognitive function was assessed using the Delayed Word Recall Test (DWRT, from 0 to 10) and the Mini Mental State Examination (MMSE, from 0 to 30), with higher scores indicating better cognition. Results: After adjusting for multiple potential confounders, lower absolute grip strength and relative grip strength were significantly associated with lower DWRT (all p < 0.05) in all participants. No significant interaction effects between sex and handgrip strength on cognitive impairment were found (p from 0.27 to 0.87). No significant association between handgrip strength and total MMSE scores was found in the total sample or by sex (p from 0.06 to 0.50). Regarding the individual components of MMSE, lower absolute and relative grip strength were significantly associated with lower scores of the recall memory performance in all participants (p from 0.003 to 0.04). Conclusion: We have shown for the first time a positive association of grip strength with recall memory performance, but not general cognitive function in older people, which warrants further investigation.

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

Long Sleep Duration Associated With Cognitive Impairment in Chinese Community-Dwelling Older Adults

ABSTRACT

We aimed to examine the association between sleep duration and impaired cognitive function in different cognitive domains in Chinese community-dwelling older adults. A total of 1591 participants (≥60 years) were divided into five groups: ≤6 hours (very short sleep duration), >6 to 7 hours (short sleep duration), ≥7 to 8 hours (moderate sleep duration), >8 to 9 hours (moderately long sleep duration), and >9 hours (long sleep duration), according to sleep duration. Cognitive function was assessed using the Mini-Mental State Examination. Long sleep duration significantly increased the likelihood of cognitive impairment. In addition to attention, long sleep duration was negatively related to poorer global cognition and other cognitive domain functions. With the stratification of age groups, long sleep duration was negatively associated with other cognitive domain functions except delayed recall in older elderly (≥75 years) people, but not in younger elderly (60-74 years) people. Long sleep duration was associated with higher rates of cognitive impairment, poorer global cognition, and declined orientation, memory, language ability, and executive function in Chinese community-dwelling older adults, which was more significant in older elderly people.

Mortality in relation to changes in physical activity in middle-aged to older Chinese: An 8-year follow-up of the Guangzhou Biobank Cohort Study

BACKGROUND

Physical activity (PA) is generally encouraged. Studies from developed countries in the West have shown that maintenance of adequate PA or increasing PA are associated with lower mortality risk. It is unclear whether these associations apply to an older Chinese population. Hence, we examined the changes in PA prospectively among a middle-aged and older Chinese population over an average of 4 years and explored their subsequent mortality risks.

METHODS

Metabolic equivalent scores of PA among participants in the Guangzhou Biobank Cohort Study were calculated. Participants were divided into 3 groups related to PA level, and changes in PA were classified into 9 categories. Information on vital status and causes of death from March 2008 to December 2012 (the first repeated examination) until December 31, 2017, was obtained via record linkage with the Death Registry.

RESULTS

Of 18,104 participants aged 61.21 ± 6.85 years (mean ± SD), 1461 deaths occurred within 141,417 person-years. Compared to participants who maintained moderate PA, those who decreased PA from moderate or high levels to a low level had increased risks for all-cause mortality (hazard ratio (HR) = 1.47, 95% confidence interval (95%CI): 1.11-1.96). Participants who maintained a high level of PA (HR = 0.83, 95%CI: 0.70-0.98) or increased PA from low to high levels (HR = 0.71, 95%CI: 0.52-0.97) showed lower all-cause mortality risks. Those who maintained low PA levels showed a higher all-cause mortality risk, whereas those who increased their PA levels showed a non-significantly lower risk. Similar results were found for cardiovascular disease risk.

CONCLUSION

Even at an older age, maintaining a high PA level or increasing PA from low to high levels results in lower mortality risks, suggesting that substantial health benefits might be achieved by maintaining or increasing engagement in adequate levels of PA. The increased risk of maintaining a low PA level or decreasing PA to a low level warrants the attention of public health officials and clinicians.

Prospective associations between change in sleep duration and cognitive impairment: Findings from the Singapore Chinese Health Study

BACKGROUND

The relation of changes in sleep duration with risk of cognitive impairment are inconclusive. This study evaluated the prospective relationships of changes in sleep duration with risk of cognitive impairment in Singapore Chinese.

METHODS

We used data from 16,948 Chinese men and women who were aged 45-74 years at baseline (1993-1998) during recruitment into the Singapore Chinese Health Study cohort. Daily sleep duration was assessed at baseline, follow-up 2 (2006 to 2010) and follow-up 3 interviews (2014-2016). Cognitive function was evaluated with a Singapore-Modified Mini-Mental State Examination at follow-up 3 interviews when participants were 61-96 years old. Multivariable logistic regression models were used to calculate odd ratios (ORs) and 95% confidence intervals (95% CIs) for cognitive impairment.

RESULTS

Of the 16,948 participants, 14.4% were defined to have cognitive impairment. Compared with 7 h/day sleep at both baseline and follow-up 2, the OR (95% CI) for cognitive impairment was 1.50 (1.04-2.16) for those who maintained long sleep duration (≥9 h/day), 2.18 (1.37-3.45) for those who prolonged sleep from short duration (≤5 h/day) to long duration (≥9 h/day), and 1.55 (1.20-2.02) for those who prolonged sleep from recommended duration (7 h/day) to long duration. The highest risk was observed in those who shortened sleep from long to short duration (2.93, 1.35-6.34).

LIMITATIONS

Measures of sleep were self-reported.

CONCLUSIONS

Substantial changes in sleep duration over time were associated with higher risks of cognitive impairment. The findings underscore the importance of maintaining optimal sleep duration for the prevention of cognitive impairment.

Adiposity change and mortality in middle-aged to older Chinese: an 8-year follow-up of the Guangzhou Biobank Cohort Study

OBJECTIVE

To examine the associations of change in body mass index (BMI) and waist circumference (WC) over an average of 4 years with subsequent mortality risk in middle-aged to older Chinese.

DESIGN

Prospective cohort study based on the Guangzhou Biobank Cohort Study.

SETTING

Community-based sample.

PARTICIPANTS

17 773 participants (12 956 women and 4817 men) aged 50+ years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measure was all-cause mortality. Secondary outcome measures were cardiovascular disease (CVD) and cancer mortality. Causes of death were obtained via record linkage, and coded according to the International Classification of Diseases (tenth revision).

RESULTS

1424 deaths (53.4% women) occurred in the 17 773 participants (mean age 61.2, SD 6.8 years) during an average follow-up of 7.8 (SD=1.5) years, and 97.7% of participants did not have an intention of weight loss . Compared with participants with stable BMI, participants with BMI loss (>5%), but not gain, had a higher risk of all-cause mortality (HR=1.49, 95% CI 1.31 to 1.71), which was greatest in those who were underweight (HR=2.45, 95% CI 1.31 to 4.59). Similar patterns were found for WC. In contrast, for participants with a BMI of ≥27.5 kg/m², BMI gain, versus stable BMI, was associated with 89% higher risk of all-cause mortality (HR=1.89, 95% CI 1.25 to 2.88), 72% higher risk of CVD mortality (HR=1.72, 95% CI 0.80 to 3.72) and 2.27-fold risk of cancer mortality (HR=2.27, 95% CI 1.26 to 4.10).

CONCLUSION

In older people, unintentional BMI/WC loss, especially in those who were underweight was associated with higher mortality risk. However, BMI gain in those with obesity showed excess risks of all-cause and cancer mortality, but not CVD mortality. Frequent monitoring of changes in body size can be used as an early warning for timely clinical investigations and interventions and is important to inform appropriate health management in older Chinese.

Improvement in sleep duration was associated with higher cognitive function: a new association

Objectives: Previous studies have indicated that improvement in sleep duration might correlate with better cognition. We aimed to examine the associations between changes in sleep duration and cognitive function.

Results: A change from short sleep duration (SSD) to moderate sleep duration (MSD) was associated with better global cognition scores (β=0.54, P <0.01). A change from SSD to long sleep duration (LSD) (β=-0.94, P <0.001) or a change from LSD to SSD (β=-1.38, P <0.01) was associated with lower global cognition. For individuals with MSD, a≥2 h increase (β=-0.89, P <0.001) or decrease (β=-0.70, P <0.001) in sleep duration was associated with lower global cognition.

Conclusions: For short sleepers, improvement in sleep duration correlated with better cognition. For long sleepers, there was no need to reduce sleep duration. Excessive changes or deviation from the moderate duration was associated with lower cognition.

Methods: A total of 10325 individuals aged 45 and older from the China Health and Retirement Longitudinal Study (CHARLS) were included. Self-reported nocturnal sleep duration and cognitive function were assessed in the three waves of CHARLS from 2011 to 2015. Cognitive function was assessed by a global cognition score, which included episodic memory, visuospatial abilities, calculation, orientation and attention.

Association Between Sleep Duration and Cognitive Decline

Importance

An association between sleep duration and the trajectory of cognitive decline has not been conclusively demonstrated.

Objective

To investigate the association between sleep duration and cognitive decline by a pooled analysis of 2 nationally representative aging cohorts.

Design, Setting, and Participants

A pooled cohort study using data from waves 4 to 8 (2008-2009 to 2016-2017) in the English Longitudinal Study of Ageing and waves 1 to 3 (2011 to 2015) in the China Health and Retirement Longitudinal Study in a population-based setting. Participants were 2 randomly enrolled cohorts comprising 28 756 individuals living in England who were 50 years or older and those living in China who were 45 years or older.

Exposure

Self-reported sleep duration per night according to face-to-face interviews.

Main Outcomes and Measures

Global cognitive z scores were calculated according to immediate and delayed recall test, an animal fluency test, the serial sevens test, an intersecting pentagon copying test, and a date orientation test.

Results

Data were analyzed from 20 065 participants, including 9254 from the English Longitudinal Study of Ageing (mean [SD] age, 64.6 [9.8] years; 55.9% [5174 of 9254] women; median follow-up duration, 8 [interquartile range, 6-8] years) and 10 811 from the China Health and Retirement Longitudinal Study (mean [SD] age, 57.8 [9.0] years; 50.2% [5425 of 10 811] men; median follow-up duration, 4 [interquartile range, 4-4] years). During 100 000 person-years of follow-up, global cognitive z scores in individuals with 4 hours or less (pooled β = -0.022; 95% CI, -0.035 to -0.009 SD per year; P = .001) and 10 hours or more (pooled β = -0.033; 95% CI, -0.054 to -0.011 SD per year; P = .003) of sleep per night declined faster than in the reference group (7 hours per night) after adjusting for a number of covariates. An inverted U-shaped association between sleep duration and global cognitive decline was also observed.

Conclusions and Relevance

In this pooled cohort study, an inverted U-shaped association between sleep duration and global cognitive decline was found, indicating that cognitive function should be monitored in individuals with insufficient (≤4 hours per night) or excessive (≥10 hours per night) sleep duration. Future studies are needed to examine the mechanisms of the association between sleep duration and cognitive decline.

Sleep and the aging brain. A multifaceted approach

In the current review we provide a theoretical background on studies examining the association between sleep and brain function. We focus on the association between sleep and cognitive performance, cognitive changes over time and incident dementia as well. We then present some data on the link between sleep and subjective cognitive complaints, in participants without any objective clinical cognitive decline. We conclude with investigating the association between sleep and brain biomarkers, by highlighting the importance of specific genes and specific brain regions' morphometry. The role of sleep is vital in maintaining a healthy aging brain, and multiple factors should be taken under account when investigating this association.

Behavioral and Psychological Symptoms that Predict Cognitive Decline or Impairment in Cognitively Normal Middle-Aged or Older Adults: a Meta-Analysis

Epidemiological studies have revealed that behavioral and psychological (or non-cognitive) symptoms are risk factors for cognitive decline in older adults. This study aimed to systematically review the literature and determine which behavioral and psychological symptoms are most predictive of future cognitive decline among individuals with no pre-existing cognitive impairments. The selected studies included middle-aged or older adults without cognitive impairments. The predictors were assessed using behavioral and psychological questionnaires, or diagnostic interviews, to identify non-cognitive symptoms or psychiatric clinical conditions. The follow-up period was at least one year, and the design of the selected studies was either retrospective or prospective. This study compared individuals with and without non-cognitive manifestations and resulted in one of three outcomes: (a) a score change on a cognitive measure, (b) a diagnosis of mild cognitive impairment, or (c) a diagnosis of Alzheimer's disease or dementia. Four online databases were searched for eligible studies from the database inception to January 17, 2017: MEDLINE (PubMed), Embase (OVID), PsycINFO, and Web of Science. Pooled effect sizes were estimated using a random-effect model. Higgins I², the Q statistic, and tau-squared were used to quantify the observed heterogeneity between the studies. Results indicate that depression and sleep duration (long and short) were the most consistent associations between behavioral or psychological symptoms and cognitive decline. This meta-analysis supports the need to assess behavioral and psychological symptoms in cognitively intact older adults to identify those who are at risk for cognitive decline.

Changes in sleep duration and 3-year risk of mild cognitive impairment in Chinese older adults

Objective: This study aimed to determine whether changes in sleep duration are associated with a higher risk of mild cognitive impairment (MCI) in older adults.

Results: By the 3-year follow-up, 592 participants developed MCI. Compared with the individuals who had an unchanged sleep duration, the odds ratio (95% confidence interval) for MCI was 1.44 (1.08-1.91) for those whose sleep duration increased by ≥2 h after multivariate adjustments. Moreover, changing from a long to moderate, but not short, sleep duration was negatively associated with the incidence of MCI (odds ratio: 0.65; 95% confidence interval, 0.45-0.93).

Conclusions: These findings suggest that increased sleep duration is associated with a higher risk of MCI in the elderly. Furthermore, a moderate duration of sleep (6-9 h) could serve as a possible strategy for prevention of MCI.

Methods: This longitudinal study was conducted with a nationally representative sample of 5419 older Chinese adults (≥65 years) from the 2008 and 2011 waves of the Chinese Longitudinal Healthy Longevity Survey. Sleep duration was assessed by a self-administered questionnaire. MCI was defined according to the Mini-Mental State Examination. An adjusted logistic regression model was used to explore the associations between changes in sleep duration and MCI.

Sleep quality and cognitive impairment in older Chinese: Guangzhou Biobank Cohort Study

BACKGROUND

evidence concerning the relationship between sleep quality and cognitive impairment is limited and inconsistent.

OBJECTIVE

to examine the association of sleep quality with memory impairment and poor cognitive function in a large sample of older Chinese.

METHODS

15,246 participants aged 50+ years of the Guangzhou Biobank Cohort Study who attended the second physical examination from 2008 to 2012 were included. Sleep quality was assessed using Pittsburgh Sleep Quality Index (PSQI), and cognitive performance was assessed using both Delayed Word Recall Test (DWRT) and Mini-Mental State Examination (MMSE). Memory impairment was defined by DWRT score < 4 and poor cognitive function by MMSE score < 25.

RESULTS

after adjusting for potential confounders, lower habitual sleep efficiency was associated with a higher risk of memory impairment and poor cognitive function with a dose-response pattern (both P for trend <0.001). The adjusted odds ratio (OR, 95% confidence interval (CI)) for poor cognitive function in those with the sleep efficiency of 75-85%, 65-75% and <65%, versus ≥85%, was 1.31 (1.12-1.53), 1.41 (1.16-1.73) and 1.33 (1.09-1.63), respectively. No association of the global PSQI score with memory impairment or poor cognitive function was found.

CONCLUSIONS

in older Chinese people, lower habitual sleep efficiency was associated with a higher risk of memory impairment and poorer cognitive function.

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

OBJECTIVE

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

STUDIES

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

PARTICIPANTS

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

MEASUREMENTS

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

RESULTS

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

CONCLUSION

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

Work by day and sleep by night, do not sleep too little or too much: Effects of sleep duration, time of day and circadian synchrony on flanker-task performance in internet brain-game users from teens to advanced age

Research elucidating the effects of sleep and circadian rhythm on cognitive performance is advancing, yet many important questions remain. Using flanker-task performance scores from a large internet sample (N = 48,881) with repeated measures of cognitive performance and linked prior-night self-reported sleep duration, we analysed the relationship between sleep duration, time of day of task performance, and chronotype synchrony with performance in participants aged 15-80 years. Results indicate a performance peak at 7 hr habitual sleep duration, and point to a variable effect of deviation from habitual sleep duration depending on users' habitual sleep duration and age. Time-of-day effects were notable for a steady decline in performance up until 01:00 hours-02:00 hours for the group as a whole, which was accounted for by nighttime deterioration on trials requiring inhibitory executive functioning, particularly in older subjects. Analyses did not demonstrate an advantage for playing in synchrony with self-identified chronotype. Results strengthen findings indicating an inverted U-shaped relationship between sleep duration and cognitive performance across a broad spectrum of age groups. These findings underscore the importance of daytime task performance for tasks requiring inhibitory function, especially in elderly people. Findings highlight the utility of large-scale internet data in contributing to sleep and circadian science.

Sleep and subjective cognitive decline in cognitively healthy elderly: Results from two cohorts

Subjective cognitive decline may reflect a dementia prodrome or modifiable risk factor such as sleep disturbance. What is the association between sleep and subjective cognitive decline? Cross-sectional design, from two studies of older adults: the WHICAP in the USA and the HELIAD in Greece. A total of 1,576 WHICAP and 1,456 HELIAD participants, without mild cognitive impairment, dementia or severe depression/anxiety, were included. Participants were mostly women, with 12 (WHICAP) and 8 (HELIAD) mean years of education. Sleep problems were estimated using the Sleep Scale from the Medical Outcomes Study. Subjective cognitive decline was assessed using a structured complaint questionnaire that queries for subjective memory and other cognitive symptoms. Multinomial or logistic regression models were used to examine whether sleep problems were associated with complaints about general cognition, memory, naming, orientation and calculations. Age, sex, education, sleep medication, use of medications affecting cognition, co-morbidities, depression and anxiety were used as co-variates. Objective cognition was also estimated by summarizing neuropsychological performance into composite z-scores. Sleep problems were associated with two or more complaints: WHICAP: β = 1.93 (95% confidence interval: 1.59-2.34), p ≤ .0001; HELIAD: β = 1.48 (95% confidence interval: 1.20-1.83), p ≤ .0001. Sleep problems were associated with complaints in all the cognitive subcategories, except orientation for the WHICAP. The associations were noted regardless of objective cognition. At any given level of objective cognition, sleep disturbance is accompanied by subjective cognitive impairment. The replicability in two ethnically, genetically and culturally different cohorts adds validity to our results. The results have implications for the correlates, and potential aetiology of subjective cognitive decline, which should be considered in the assessment and treatment of older adults with cognitive complaints.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

The bidirectional relationship between sleep duration and depression in community-dwelling middle-aged and elderly individuals: evidence from a longitudinal study

BACKGROUND

There are several studies that have focused on the relationship between sleep duration and depression, however, only a few prospective studies have centered on the bidirectional relationship between them. This four-year longitudinal study aimed to identify the association between sleep duration and depression in community-dwelling mid-age and elderly individuals.

METHODS

10,704 participants from the China Health and Retirement Longitudinal Study (CHARLS) were included for baseline and four-year follow up. Of these individuals, 7866 and 2956 were used to identify the effects of sleep duration on onset and recurrent depression respectively. 4504 individuals with normal sleep duration at baseline were included to examine the effects of depression on changes of sleep time. The 10-item version of the Centre for Epidemiological Studies Depression scale (CESD-10) was used to access depressive symptoms, as well sleep duration was self-reported.

RESULTS

Participants with short sleep duration (<5 and 5-6 h) had a higher risk of depression onset (OR 1.69 [1.36-2.11], 1.48 [1.19-1.84]) and recurrent depression (OR 1.44 [1.12-1.86], 1.32 [1.00-1.74]) compared to participants with normal sleep durations (7-8 h). Long sleep durations (>9 h) had no significant risks for depression. Males and the elderly (over 60 years-old) were more sensitive to short sleep durations and experienced a higher incidence of depression. Individuals with depression were more likely to have short sleep durations instead of long ones (RRR 1.20 [1.02-1.43]).

CONCLUSIONS

The present study identified the bidirectional relationship between sleep duration and depression. Short sleep durations were a risk factor for the onset and recurrent depression. Conversely, depression induced short sleep durations rather than excessive sleep durations. Future studies need to focus on identifying the mechanism between sleep duration and depression, and develop additional evidence-based cost-effective interventions to prevent depression and sleep problems.

Inflammatory potential of diet is associated with cognitive function in an older adult Korean population

OBJECTIVE

To examine the association between the inflammatory potential of diet and the quality of cognitive function in an older adult Korean population.

METHODS

A total of 239 participants (88 men and 151 women) ages ≥65 y were selected from various health centers in Korea. To assess the inflammatory potential of diet, Energy-adjusted Dietary Inflammatory Index (E-DII) scores were computed based on a single 24-h recall. Cognitive function was assessed using the Korean Mini-Mental State Examination. Multiple linear and logistic regression models were fit to estimate the association between E-DII scores and the degree of cognitive function.

RESULTS

E-DII scores were significantly inversely associated with Korean Mini-Mental State Examination score in both unadjusted and adjusted models, after controlling for sex, age, body mass index, sleep hours, supplement use, education level, self-reported health conditions, history of dementia, and physical activity (β = -1.33, 95% confidence interval [CI] = -1.95, -0.71, P <0.0001; β = -0.58, 95% CI = -1.11, -0.06, P = 0.03, respectively). Participants in the highest E-DII tertile had increased risk for mild or moderate cognitive impairment compared with those in the lowest E-DII tertile (adjusted odds ratio 6.32, 95% CI 1.18-33.78; P for trend = 0.0031).

CONCLUSIONS

Higher E-DII scores were associated with increased risk of cognitive impairment, suggesting that consuming a proinflammatory diet is associated with increased risk for cognitive impairment in the older Korean adults.

Sleep and Cognitive Performance From Teens To Old Age: More Is Not Better

Objectives

To determine the interaction of age and habitual sleep duration in predicting cognitive performance in a large sample of participants aged 15 to 89 years.

Methods

This study is a cross-sectional analysis of performance data gathered between January 2012 and September 2013. First-time players (N = 512823) of three internet cognitive training games measuring processing speed, working memory, visuospatial memory, and arithmetic participated in the study.

Results

Performance was based on a measure of speed and accuracy for each game. The relationship between performance and self-reported habitual sleep duration was examined in the sample as a whole and across 10-year age groups starting at age 15 and ending at 75 and older. Performance peaked at 7 h of sleep duration for all three games in the sample as a whole, and the decrements in performance for sleep durations greater than 7 h were either comparable or greater in the youngest as compared to the oldest age groups.

Conclusions

These findings challenge the hypothesis that deteriorating cognitive performance with long sleep duration is driven by medical comorbidities associated with aging. Further, these data are consistent with an optimal dose model of sleep and suggest that the model for the homeostatic recovery of cognitive function as a function of sleep duration should incorporate a curvilinear decline with longer duration sleep, indicating that there may be a cost to increased sleep. Replication and further research is essential for clarifying the sleep duration-cognition relationship in youth and adults of all ages.

Adiposity and incident diabetes within 4 years of follow-up: the Guangzhou Biobank Cohort Study

AIM

Whether different adiposity measures predict incident diabetes differentially in general Chinese populations is unclear. We investigated this in Chinese people aged 50+ years in the Guangzhou Biobank Cohort Study.

METHODS

Waist circumference and BMI were measured at baseline, and fasting glucose was measured at both baseline and follow-up examinations. Incident diabetes was defined as fasting glucose ≥ 7.0 mmol/l, glucose after 2-h oral glucose tolerance test ≥ 11.1 mmol/l, and/or self-reported physician-diagnosed diabetes during the follow-up period.

RESULTS

Of 15 752 people without diabetes at baseline from 2003 to 2008, 1779 (11.3%) developed incident diabetes during the follow-up from 2008 to 2012 (mean = 3.6 years, sd = 1.0). After mutually adjusting each other and adjusting for other potential confounders, waist circumference showed a higher predictive value than BMI. The odds ratio (OR) (95% confidence interval (CI) was 1.50 (95% CI 1.37-1.64) for a 1 sd increment in waist circumference and 1.21 (95% CI 1.11-1.33), for a 1 sd increment in BMI. Similarly, after mutual adjustment, abdominal obesity was associated with an almost twofold odds of incident diabetes (OR 1.93, 95% CI 1.71-2.17), which was higher than that for general obesity (OR 1.76, 95% CI 1.50-2.06). The area under receiver operating characteristic curve (AUC) for waist circumference was higher than that for BMI [AUC = 0.676 (95% CI 0.660-0.686) vs. 0.665 (95% CI 0.651-0.678), P = 0.02].

CONCLUSION

Abdominal obesity predicted incident diabetes in older people better than general obesity. Our findings may be an early warning signal for local government or public health practitioners to develop and investigate more effective intervention programmes for diabetes, and should also be disseminated to the public to pay more attention to this important public health issue.

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.

Changes in adiposity in an older Chinese population in rapid economic transition

OBJECTIVE

To examine the changes in body mass index (BMI) and waist circumference (WC) in Guangzhou, South China, which is probably experiencing the most rapid economic transition in history.

METHODS

In this study, 17,786 Chinese aged 50+ years were recruited from 2003 to 2008 and followed up until 2012. BMI and WC were measured at two time points.

RESULTS

During the mean follow-up of 3.6 years (median = 3, interquartile = 1), age-adjusted mean BMI increased only slightly. By contrast, mean WC increased sharply by 0.94 cm (95% confidence interval 0.93-0.94) annually in men and 1.29 cm (1.28-1.29) annually in women. In 77% of women and 69% of men, WC increased, and among them, the mean annual increase was 2.01 cm and 1.70 cm, respectively. Among healthy, never-smoking participants, the incidence of central obesity was 29.0% (36.4% in women and 14.2% in men). The incidence of general obesity was 1.9% and was similarly low in both men and women (2.1% vs. 1.8%). Conversely, 20.3% of individuals with general obesity became nonobese, and 12.8% of individuals with central obesity returned to normal.

CONCLUSIONS

Central obesity has risen sharply in this cohort. Such increases may have been greatly underestimated previously and should form the basis of an even stronger warning for regions undergoing economic transitions in China and elsewhere.

Genetically predicted 17beta-estradiol, cognitive function and depressive symptoms in women: A Mendelian randomization in the Guangzhou Biobank Cohort Study

OBJECTIVE

The role of estrogen in cognitive function and depressive symptoms is controversial due to discrepancies between results from randomized controlled trials (RCT) and observational studies. Mendelian randomization analysis may provide further insights concerning the role of estrogen in these outcomes as it assesses the effect of lifelong endogenous exposure but is less vulnerable to confounding than observational studies.

METHOD

We used separate sample instrumental variable analysis to estimate the association of log 17β estradiol with cognitive function (Delayed 10 word recall, and Mini Mental State Examination (MMSE)) and depressive symptoms (Geriatric Depression Scale (GDS)) in older Chinese women of the Guangzhou Biobank Cohort Study (GBCS, n=3086). The estimate was derived based on the Wald estimator, the ratio of the association of genetic determinants (rs1008805 and rs2175898) of log 17β-estradiol with cognitive function and depressive symptoms in GBCS and the association of log 17β-estradiol with genetic determinants in the sample of young women in Hong Kong (n=236).

RESULTS

Genetically predicted 17β-estradiol was not associated with delayed 10-word recall (0.42 words per log increase in 17β-estradiol (pmol/L), 95% confidence interval (CI) -0.49 to 1.34) MMSE (0.39 per log increase in 17β-estradiol (pmol/L), 95% CI -0.87 to 1.65) or GDS (0.24 per log increase in 17β-estradiol (pmol/L), 95% CI -0.57 to 1.05).

CONCLUSION

These results were largely consistent with evidence from RCTs and did not show any beneficial effect of estrogen on cognitive function and depressive symptoms. However, larger Mendelian randomization analyses are needed to identify any minor effects.

Smoking and serum vitamin D in older Chinese people: cross-sectional analysis based on the Guangzhou Biobank Cohort Study

OBJECTIVE

Studies on serum vitamin D in smokers showed conflicting results. We examined the association of smoking status with serum vitamin D in older Chinese men, taking advantage of a community-based sample with natural exposure to vitamin D.

DESIGN

Cross-sectional study based on the Guangzhou Biobank Cohort Study (GBCS).

SETTING

Community-based sample from the Guangzhou Biobank Cohort Study.

PARTICIPANTS

612 male participants aged 50+years recruited from 2009 to 2011.

RESULTS

The mean (SD) of vitamin D concentration was 58.3 (17.2), 57.0 (15.0) and 54.7 (15.4) nmol/L for never, former and current smokers, respectively. Adjusted for multiple confounders, vitamin D decreased from never to former, then to current smokers (P for trend 0.02). Compared to never smokers, current smokers had lower serum concentrations of vitamin D, and the concentrations decreased with the increasing number of cigarettes per day (-3.11 (95% CI -9.05 to 2.82), -3.29 (-8.3 to 1.72) and -4.61 (-8.89 to -0.33) for 1-9, 10-19 and 20+cigarettes per day, respectively; p for trend 0.01), duration of smoking (-1.39 (-6.09 to 3.30) and -5.39 (-9.42 to -1.35) for 1-39 and 40+years, respectively; p for trend 0.008) as well as pack-years (-2.89 (-6.78 to 1.01) and -5.58 (-10.48 to -0.67) for 1-39 and 40+pack-years, respectively; p for trend 0.009). Longer duration of quitting smoking was associated with higher vitamin D than was current smoking (P for trend 0.04).

CONCLUSIONS

Current smokers had lower vitamin D than never smokers, and the association showed a dose-response pattern.

Association between nighttime sleep and successful aging among older Chinese people

OBJECTIVE

This study aims to assess the association between sleep and successful aging among Chinese ≥60 years of age.

METHODS

Data were collected from the baseline survey of the China Health and Retirement Longitudinal Study. Two self-reported questions about sleep quality and duration were examined. Successful aging was defined following Rowe and Kahn's multidimensional model. To assess the adjusted association between sleep and successful aging, multivariable logistic regression was applied.

RESULTS

The average number of self-reported hours of sleep was 6.2 ± 2.0 among older Chinese people. Successful aging was related to sleep duration, with the proportion of those adults considered to be aging successfully falling into the following sleep duration categories (<6 h - 7.8%; 6 h - 16.3%; 7 h - 19.1%; 8 h - 14.7%; and ≥9 h - 12.8%). The plots between sleep duration and successful aging were an inverse U-shape. Participants who slept less than 6 h per day had lower odds ratios of successful aging [odds ratio (OR) = 0.52, 95% confidence interval (CI) 0.40-0.67] relative to those who slept for 7 h per day. Compared with those who reported poor sleep less than once a week, older people who reported poor sleep five to seven days a week showed a lower ratio of successful aging (OR = 0.29, 95% CI 0.21-0.39).

CONCLUSION

Older age, shorter or longer sleep, and poor sleep were related to lower odds of, rates of successful aging. Most older Chinese adults experience insufficient sleep and poor sleep quality, which could be an important influential factor in successful aging.

Daytime somnolence as an early sign of cognitive decline in a community-based study of older people

OBJECTIVE

This study aimed to examine the association between self-reported sleep problems and cognitive decline in community-dwelling older people. We hypothesized that daytime somnolence predicts subsequent cognitive decline.

METHODS

This is a longitudinal study in a 3.2-year follow-up, with 18-month intervals. The setting is the Washington Heights-Inwood Community Aging Project. There were 1098 participants, who were over 65 years old and recruited from the community. Sleep problems were estimated using five sleep categories derived from the RAND Medical Outcome Study Sleep Scale: sleep disturbance, snoring, awaken short of breath/with a headache, sleep adequacy, and daytime somnolence. Four distinct cognitive composite scores were calculated: memory, language, speed of processing, and executive functioning. We used generalized estimating equations analyses with cognitive scores as the outcome, and time, sleep categories and their interactions as the main predictors. Models were initially unadjusted and then adjusted for age, gender, education, ethnicity, depression, and apolipoprotein E-ε4 genotype.

RESULTS

Increased daytime somnolence (including feeling drowsy/sleepy, having trouble staying awake, and taking naps during the day) was linked to slower speed of processing both cross-sectionally (B = -0.143, p = 0.047) and longitudinally (B = -0.003, p = 0.027). After excluding the demented participants at baseline, the results remained significant (B = -0.003, p = 0.021).

CONCLUSIONS

Our findings suggest that daytime somnolence may be an early sign of cognitive decline in the older population.

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

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

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

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

Influence of Alzheimer's disease genes on cognitive decline: the Guangzhou Biobank Cohort Study

Cognitive decline is a reduction in cognitive ability usually associated with aging, and those with more extreme cognitive decline either have or are at risk of progressing to mild cognitive impairment and dementia including Alzheimer's disease (AD). We hypothesized that genetic variants predisposing to AD should be predictive of cognitive decline in elderly individuals. We selected 1325 subjects with extreme cognitive decline and 1083 well-matched control subjects from the Guangzhou Biobank Cohort Study in which more than 30,000 southern Chinese older people have been recruited and followed up. Thirty single-nucleotide polymorphisms in 29 AD-associated genes were genotyped. No statistically significant allelic associations with cognitive decline were found by individual variant analysis. At the level of genotypic association, we confirmed that the APOE ε4 homozygote significantly accelerated cognitive decline and found that carriers of the ACE rs1800764_C allele were more likely to show cognitive decline than noncarriers, particularly in those without college education. However, these effects do not survive after multiple testing corrections, and together they only explain 1.7% of the phenotypic variance in cognitive score change. This study suggests that AD risk variants and/or genes are not powerful predictors of cognitive decline in our Chinese sample.