Associations between sleep duration patterns and cognitive decline trajectories in older Chinese adults

Trajectories of sleep duration and quality and their association with mild cognitive impairment, frailty, and all-cause mortality

OBJECTIVES

To identify longitudinal trajectories of sleep duration and quality and estimate their association with mild cognitive impairment, frailty, and all-cause mortality.

METHODS

We used data from three waves (2009, 2014, 2017) of the WHO Study on Global Aging and Adult Health in Mexico. The sample consisted of 2722 adults aged 50 and over. Sleep duration and quality were assessed by self-report. Sleep trajectories were determined by applying growth mixture models. Mixed-effects logistic (mild cognitive impairment) and ordinal logistic (frailty), and Cox proportional hazards (all-cause mortality) models were fitted.

RESULTS

Three classes for sleep duration ("optimal-stable," "long-increasing," and "short-decreasing") and quality ("very good-increasing," "very good-decreasing," and "moderate/poor stable") were identified. Compared to the optimal-stable group, the long-increasing trajectory had greater odds for mild cognitive impairment (odds ratio=1.68, 95% CI: 1.01-2.78) and frailty (odds ratio=1.66, 95% CI: 1.13-2.46), and higher risk for all-cause mortality (hazard ratio=1.91, 95% CI: 1.14-3.19); and the short-decreasing class had a higher probability of frailty (odds ratio=1.83, 95% CI: 1.26-2.64). Regarding the sleep quality, the moderate/poor stable trajectory had higher odds of frailty (odds ratio=1.71, 95% CI: 1.18-2.47) than very good-increasing group.

CONCLUSIONS

These results have important implications for clinical practice and public health policies, given that the evaluation and treatment of sleep disorders need more attention in primary care settings. Interventions to detect and treat sleep disorders should be integrated into clinical practice to prevent or delay the appearance of alterations in older adults' physical and cognitive function. Further research on sleep quality and duration is warranted to understand their contribution to healthy aging.

Trajectories of health conditions and their associations with the risk of cognitive impairment among older adults: insights from a national prospective cohort study

BACKGROUND

The associations between trajectories of different health conditions and cognitive impairment among older adults were unknown. Our cohort study aimed to investigate the impact of various trajectories, including sleep disturbances, depressive symptoms, functional limitations, and multimorbidity, on the subsequent risk of cognitive impairment.

METHODS

We conducted a prospective cohort study by using eight waves of national data from the Health and Retirement Study (HRS 2002-2018), involving 4319 adults aged 60 years or older in the USA. Sleep disturbances and depressive symptoms were measured using the Jenkins Sleep Scale and the Centers for Epidemiologic Research Depression (CES-D) scale, respectively. Functional limitations were assessed using activities of daily living (ADLs) and instrumental activities of daily living (IADLs), respectively. Multimorbidity status was assessed by self-reporting physician-diagnosed diseases. We identified 8-year trajectories at four examinations from 2002 to 2010 using latent class trajectory modeling. We screened participants for cognitive impairment using the 27-point HRS cognitive scale from 2010 to 2018 across four subsequent waves. We calculated hazard ratios (HR) using Cox proportional hazard models.

RESULTS

During 25,914 person-years, 1230 participants developed cognitive impairment. In the fully adjusted model 3, the trajectories of sleep disturbances and ADLs limitations were not associated with the risk of cognitive impairment. Compared to the low trajectory, we found that the increasing trajectory of depressive symptoms (HR = 1.39; 95% CI = 1.17-1.65), the increasing trajectory of IADLs limitations (HR = 1.88; 95% CI = 1.43-2.46), and the high trajectory of multimorbidity status (HR = 1.48; 95% CI = 1.16-1.88) all posed an elevated risk of cognitive impairment. The increasing trajectory of IADLs limitations was associated with a higher risk of cognitive impairment among older adults living in urban areas (HR = 2.30; 95% CI = 1.65-3.21) and those who smoked (HR = 2.77; 95% CI = 1.91-4.02) (all P for interaction < 0.05).

CONCLUSIONS

The results suggest that tracking trajectories of depressive symptoms, instrumental functioning limitations, and multimorbidity status may be a potential and feasible screening method for identifying older adults at risk of cognitive impairment.

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.

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.

The associations between sleep duration, cognitive function, and depressive symptoms: An analysis of Chinese adolescents from China Family Panel Studies

BACKGROUND

The adverse impact of depressive symptoms on adolescents' physical and psychological health is becoming increasingly prominent. This study aims to examine the association between sleep duration, cognitive function, and depressive symptoms among Chinese adolescents.

METHODS

This study used data on a sample of 3724 adolescents collected from the China Family Panel Studies (CFPS). The multivariate logistic regression was conducted to estimate the association between sleep duration, cognitive function (measured by mathematics and vocabulary), and depressive symptoms among Chinese adolescents; the mediating effects of cognitive function were calculated by mediating model.

RESULTS

The study found that approximately 6.49 % of Chinese adolescents had depressive symptoms, with an average CES-D8 score of 4.27 (SD: 3.11). Adolescents who reported a sleep duration of <6 h/night (OR = 2.34; 95 % CI = 1.30, 4.24) were at a higher risk of depressive symptoms, and the adolescents who had higher mathematics scores (>75 %) were more likely to be at a lower risk of depressive symptoms. Besides, the cognitive function competitively mediated the effect of sleep duration on depressive symptom (indirect effect = 0.043; 95 % CI = 0.023, 0.064).

LIMITATIONS

This is a cross-sectional study; all questions were self-reported; the sleep variable only included the sleep duration.

CONCLUSIONS

Our study highlights that short sleep duration might increase the risk of depressive symptoms, and increasing cognitive function might reduce the occurrence of depressive symptoms in Chinese adolescents. The results displayed that sleep duration had a negatively direct effect on depressive symptoms, but the indirect effects of sleep duration on depressive symptoms via the cognitive function (i.e., mathematics and vocabulary tests) were significantly positive, indicating that the relationship between sleep duration and depressive symptoms was competitively mediated by cognitive function.

Effects of cognitive ageing trajectories on multiple adverse outcomes among Chinese community-dwelling elderly population

BACKGROUND

Whether cognitive ageing trajectory is related to common functional deficits independent of initial cognitive function remains inconclusive. We aimed to explore the adverse health effect and potential predictive factors of distinct cognitive trajectories among Chinese older adults.

METHODS

Three thousand five hundred eighty-one community-dwelling older adults who completed three consecutive cognitive function examinations with the Mini-Mental State Examination (MMSE) over 5 years and were without cognitive impairment at enrollment were included. A group-based trajectory model was used to estimate cognitive ageing trajectories. Multivariable-adjusted odds ratio (OR) and 95% confidence intervals (CI) were computed with logistic regression models to identify potential baseline determinants and health effect of cognitive trajectories on various adverse outcomes.

RESULTS

Two distinct cognitive ageing trajectories were identified with about 5.3% of the study participants ascribed to the rapidly decreasing group. Subjects with rapidly decreasing cognition showed significantly higher odds (OR, 95%CI) of experiencing frailty (4.04, 2.77-5.86), falls (2.01, 1.05-3.70), balance impairment (4.20, 2.75-6.38), high fall risk (5.66, 2.67-11.77) based on the Tinetti total score, disability in activities of daily living (1.76, 1.19-2.56), disability in instrumental activities of daily living (1.52, 1.05-2.19), and motor cognitive risk syndrome (2.24, 1.23-3.98) compared with their steadily decreasing counterparts. Individuals with older age, low education level, no marriage, high score of rapid eye movement behavior disorders, poor physical and cognitive function at baseline were more predisposed to an accelerated cognitive decline.

CONCLUSIONS

Faster cognitive decline was independently associated with higher risk of multiple adverse events. Our findings put more emphasis on a routine and constant surveillance of cognitive function among community-dwelling older adults.