Abstract
Background
During the long preclinical phase of dementia, accelerated cognitive impairment is regarded as a cardinal marker. Thus, the identification of risk factors for cognitive impairment is of great significance for dementia prevention. This study aims to examine the joint associations of sleep duration and physical activity with cognitive impairment among rural elderly over 65 years old, and provide suggestions for improving the cognitive function in rural elderly over 65 years old.
Methods
A cross‐sectional study was conducted in rural Nanjing by recruiting 1147 individuals aged above 65 years. Cognitive function was assessed using the brief community screening instrument for dementia. Physical activity was assessed using the Global Physical Activity Questionnaire. Data were analyzed by multivariate logistic regression models, and a significant difference was set at P < 0.05.
Results
Compared with participants with proper sleep duration and sufficient physical activity, participants with short sleep duration and insufficient physical activity (odds ratio (OR): 1.820; 95% CI: 1.265 ~ 2.618), long sleep duration and sufficient physical activity (OR: 2.428; 95% CI: 1.137 ~ 5.183) showed an increased likelihood of cognitive impairment.
Conclusions
Inappropriate sleep duration combined with insufficient physical activity was associated with a significantly higher likelihood of cognitive impairment in rural elderly over 65 years old.
Keywords: cognitive impairment, cross‐sectional study, elderly, physical activity, sleep duration
INTRODUCTION
Dementia is an important public health problem affecting the health of the global elderly population. The global prevalence of dementia is approximately 7% of individuals aged 65 years or older 1 and the prevalence of dementia doubled for every 5 years of age in the population over 60 years. 2 With the deepening of ageing in China, the disease and mental burden of dementia will be increasingly heavy on patients, families and society. It is estimated that the socioeconomic cost due to dementia will be about 114.2 billion US dollars by 2030. 3
Currently, there is no specific method to reverse the progression of dementia, and cognitive impairment as an early symptom has received increasing attention. 4 Current evidence has shown that cognitive impairment is closely related to a variety of diseases and poor living habits, such as traumatic brain injury, hypertension, diabetes, obesity, alcohol consumption, lack of formal education and physical exercise. 5 Recent studies have highlighted the role of exercise to delay cognitive impairment and improve cognition. 6 , 7 Physical exercise can delay certain areas of brain shrinkage to delay cognitive impairment. 8 And physical exercise can increase blood circulation to improve neuro‐plasticity and cognitive function. 9 , 10 In addition, several studies have found that sleep disturbances may increase the risk of cognitive impairment. 5 , 11 The changing of neurophysiological states during sleep, such as secretion of hormones, neurotransmitters and histamines, suggest that sleep is a cognitively altering process. 12 The elderly population experiences changes in sleep patterns with age, with problems such as insomnia, decreased sleep quality, daytime sleepiness, sleep‐disordered breathing and disrupted circadian rhythms, all of which have been linked to cognitive impairment. 13 Extreme sleep duration is an important clinical manifestation of sleep disorders, and it has been found that sleep duration has a certain impact on cognitive impairment. 14 , 15 , 16 , 17 , 18
Until now, studies to evaluate whether sleep and physical activity are independently or jointly associated with cognitive function have been minimal. 19 We thereafter hypothesised that inappropriate sleep duration combined with insufficient physical activity may exert additional influences on cognitive impairment compared with sleep duration or physical activity alone. Earlier studies show that social and economic factors may serve as modifiable and protective factors for cognitive function among older adults. 20 , 21 Most previous studies have focused on the elderly population in developed countries; 5 , 11 , 12 , 13 , 14 less research has been done on the middle and low income elderly populations. Compared to urban counterparts, Chinese older adults residing in rural areas report higher rates of mild cognitive impairment (MCI). 22 Thus, this study aims to examine the joint associations of sleep duration and physical activity with the risk of cognitive impairment using the data from a community‐based cross‐sectional study conducted in the rural areas of Nanjing, China.
METHODS
Study design and sampling
A cross‐sectional study in a rural community‐based setting was designed and conducted among people aged >65 years from December 2021 to June 2022. In this survey, a stratified, multistage probability cluster sampling design was adopted. Briefly, two districts (Pukou and Luhe) were selected for cluster sampling according to the geographic region and economic development status in the first stage, which were the suburbs of Nanjing and had a lower economic development level. In the second and third stage, two subdistricts and two neighbourhood communities were selected for probability proportional to size sampling, respectively. In the fourth stage, 50 households within each neighbourhood community were randomly sampled. In the fifth stage, one person at least 65 years old was randomly selected from each household using the Kish selection grid. Those who had lived in the current residence for at least 18 months were eligible to participate in this study, and elderly with very severe cognitive impairment (late dementia) were excluded. On the basis of informed consent and willingness to cooperate, a total of 1147 elderly were recruited.
Data collection and measurement
At each surveillance point, trained staff were responsible for face‐to‐face collecting data according to a standard protocol at local community health service centres/stations of the participants' registration addresses.
The brief community screening instrument for dementia (CSI‐D), which has cognitive and informant scales, was used. The cognitive scale, which contained nine question items with dichotomised options (yes or no) having total scores ranging 0–9, was used to assess cognitive function. A score of 0–6 was cognitive impairment, and a score of 7–9 was considered normal. 23 , 24
Physical activity was assessed by the Global Physical Activity Questionnaire, 25 which was categorised into occupational, leisure time, transportation, household work and sedentary activities (e.g., watching television, using a computer, playing video games and reading during leisure time). The frequency and duration of each domain were recorded. Physical activity level was classified as ‘<600 metabolic equivalents (MET)‐min/week” and ‘≥600 MET‐min/week’. Insufficient physical activity was defined as physical activity <600 MET‐min/week. 26 Sleep duration was self‐reported night sleep time.
The Patient Health Questionnaire‐9 which contains nine question items and has total scores ranging 0–27, was used to assess depression. A cut‐off score of 10 or above was defined as positive depressive symptoms. 27
Statistical analysis
Participant characteristics were expressed as counts and percentages and they were stratified by sleep duration and physical activity level. The association of sleep duration and physical activity level with the degree of cognitive impairment was assessed through linear correlation models and estimated by Pearson R. The relationship of sleep duration and physical activity with cognitive impairment was assessed through multivariate logistic regression models. The relative risk was estimated by calculating the odds ratio (OR) and corresponding 95% confidence interval (CI). The confounder variables which were considered in regression models were sex, age, education, income, living arrangement, chronic conditions, depressive symptoms, current smoking and drinking status. A significance level of 0.05 was considered for all analyses. Statistical analysis was done by using SPSS (version 20; IBM, Armonk, NY, USA).
RESULTS
A total of 1147 elderly over 65 years old among rural areas were included in this study. Among all participants, 21.3% of them maintained sleep duration less than 5 h per night, 3.7% had sleep duration more than 9 h per night, whereas the remaining participants had sleep duration ~6 h (27.2%), ~7 h (27.6%), ~8 h (15.2%), ~8.9 h (4.5%), respectively. Women, drinkers and people with one or more chronic conditions and depressive symptoms were more likely to have sleep duration less than 5 h per night. Further, people with sleep duration more than 8 h per night were more likely to live alone and have a habit of smoking. There were 34.6% of participants who maintained a physical activity level < 600 MET‐min/week. Insufficient physical activity was more likely to be reported in current smokers, and those with lower education level, lower income, chronic conditions and depressive symptoms. Furthermore，participants with sleep duration less than 5 h or more than 9 h and physical activity level < 600 MET‐min/week showed a higher proportion of cognitive impairment (Table 1).
Table 1.
Baseline characteristics of 1147 rural elderly over 65 years old classified by sleep duration and physical activity level
| Variable | N | Sleep duration (h) | Physical activity level (MET‐min/week) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ≤5 | ~6 | ~7 | ~8 | ~8.9 | ≥9 | <600 | ≥600 | ||
| n (%) | 1147 (100.0) | 244 (21.3) | 318 (27.2) | 317 (27.6) | 174 (15.2) | 52 (4.5) | 42 (3.7) | 397 (34.6) | 750 (65.4) |
| Gender | |||||||||
| Male | 570 (49.7) | 100 (41.0) | 151 (47.5) | 163 (51.4) | 103 (59.2) | 30 (57.7) | 23 (54.8) | 197 (49.6) | 373 (49.7) |
| Female | 577 (50.3) | 144 (59.0) | 167 (52.5) | 154 (48.6) | 71 (40.8) | 22 (42.3) | 19 (45.2) | 200 (50.4) | 377 (50.3) |
| Age, years | |||||||||
| 65~ | 805 (70.2) | 177 (72.5) | 213 (67.0) | 229 (72.2) | 125 (71.8) | 35 (67.3) | 26 (61.9) | 264 (66.5) | 541 (72.1) |
| 75~ | 298 (26.0) | 56 (23.0) | 91 (28.6) | 79 (24.9) | 42 (24.1) | 16 (30.8) | 14 (33.3) | 111 (28.0) | 187 (24.9) |
| ≥ 85 | 44 (3.8) | 11 (4.5) | 14 (4.4) | 9 (2.8) | 7 (4.0) | 1 (1.9) | 2 (4.8) | 22 (5.5) | 22 (2.9) |
| Education level | |||||||||
| Primary school and lower | 926 (80.7) | 206 (84.4) | 267 (84.0) | 251 (79.2) | 128 (73.6) | 39 (75.0) | 35 (83.3) | 328 (82.6) | 598 (79.7) |
| Middle school and higher | 221 (19.3) | 38 (15.6) | 51 (16.0) | 66 (20.8) | 46 (26.4) | 13 (25.0) | 7 (16.7) | 69 (17.4) | 152 (20.3) |
| Income (RMB) | |||||||||
| <1500 | 984 (85.8) | 223 (91.4) | 273 (85.8) | 268 (84.5) | 135 (77.6) | 48 (92.3) | 37 (88.1) | 348 (87.7) | 636 (84.8) |
| ≥1500 | 163 (14.2) | 21 (8.6) | 45 (14.2) | 49 (15.5) | 39 (22.4) | 4 (7.7) | 5 (11.9) | 49 (12.3) | 114 (15.2) |
| Living arrangement | |||||||||
| Living alone | 139 (12.1) | 31 (12.7) | 40 (12.6) | 35 (11.0) | 18 (10.3) | 9 (17.3) | 6 (14.3) | 57 (14.4) | 82 (10.9) |
| Others | 1008 (87.9) | 213 (87.3) | 278 (87.4) | 282 (89.0) | 156 (89.7) | 43 (82.7) | 36 (85.7) | 340 (85.6) | 668 (89.1) |
| Chronic conditions | |||||||||
| No | 195 (17.0) | 22 (9.0) | 45 (14.2) | 67 (21.1) | 42 (24.1) | 11 (21.2) | 8 (19.0) | 57 (14.4) | 138 (18.4) |
| Yes | 952 (83.0) | 222 (91.0) | 273 (85.8) | 250 (78.9) | 132 (75.9) | 41 (78.8) | 34 (81.0) | 340 (85.6) | 612 (81.6) |
| Current smoking | |||||||||
| No | 929 (81.0) | 202 (82.8) | 270 (84.9) | 253 (79.8) | 135 (77.6) | 40 (76.9) | 29 (69.0) | 316 (79.6) | 613 (81.7) |
| Yes | 218 (19.0) | 42 (17.2) | 48 (15.1) | 64 (20.2) | 39 (22.4) | 12 (23.1) | 13 (31.0) | 81 (20.4) | 137 (18.3) |
| Drinking | |||||||||
| No | 900 (78.5) | 209 (85.7) | 249 (78.3) | 236 (74.4) | 135 (77.6) | 38 (73.1) | 33 (78.6) | 319 (80.4) | 581 (77.5) |
| Yes | 247 (21.5) | 35 (14.3) | 69 (21.7) | 81 (25.6) | 39 (22.4) | 14 (26.9) | 9 (21.4) | 78 (19.6) | 169 (22.5) |
| Depressive | |||||||||
| No | 1072 (93.5) | 212 (86.9) | 301 (94.3) | 299 (94.3) | 170 (97.7) | 50 (92.6) | 40 (95.2) | 353 (88.9) | 719 (95.9) |
| Yes | 75 (6.5) | 32 (13.1) | 17 (5.3) | 18 (5.7) | 4 (2.3) | 2 (3.8) | 2 (4.8) | 44 (11.1) | 31 (4.1) |
| Cognitive impairment | |||||||||
| No | 791 (69.0) | 152 (62.3) | 211 (66.4) | 229 (72.2) | 136 (78.2) | 39 (75.0) | 24 (57.1) | 244 (61.5) | 547 (72.9) |
| Yes | 356 (31.0) | 92 (37.7) | 107 (33.6) | 88 (27.8) | 38 (21.8) | 13 (25.0) | 18 (42.9) | 153 (38.5) | 203 (27.1) |
Abbreviations: MET, metabolic equivalents; RMB, renminbi (Chinese yuan).
In our study, the association of sleep duration and physical activity level with the degree of cognitive impairment are shown in Table 2. In the sleep duration less than 8 h per night group, the CSI‐D score increased with the extension of sleep duration (Pearson R: 0.149, P < 0.001). And in the 8 h or more of sleep per night group, the CSI‐D score decreased with the extension of sleep duration (Pearson R: −0.264, P = 0.001). Further, physical activity level showed a positive correlation with the CSI‐D score (Pearson R: 0.129, P < 0.001).
Table 2.
The relationship between sleep duration and physical activity level with community screening instrument for dementia scores in 1147 rural elderly over 65 years old
| Variable | Pearson R | P |
|---|---|---|
| Sleep duration <8 h | 0.149 | <0.001 |
| Sleep duration ≥8 h | −0.264 | 0.001 |
| Physical activity level (MET‐min/week) | 0.129 | <0.001 |
Abbreviation: MET, metabolic equivalents.
After adjusting for sex, age, education level, income, living arrangement, chronic conditions, depressive symptoms, smoking status and alcohol consumption, the highest likelihood of cognitive impairment was detected in participants with sleep duration ≥9 h (OR: 2.513, 95% CI: 1.193 ~ 5.293) than those who maintained sleep duration ~8 h. In addition, compared with those who maintained sleep duration ~8 h, participants with sleep duration ≤5 h (OR: 1.593, 95% CI: 1.017 ~ 2.495) and ~6 h (OR: 1.572, 95% CI: 1.004 ~ 2.461) showed a higher odds of cognitive impairment, respectively. However, no significant difference in cognitive impairment was detected between those who maintained sleep durations of ~7, ~8, and ~8.9 h (Table 3). Based on this finding, sleep duration was classified into three groups as short sleep duration (<6), proper sleep duration (6 ~ <9) and long sleep duration (≥9) in this study.
Table 3.
Odds ratios (95% CIs) of cognitive impairment in 1147 rural elderly over 65 years old classified by sleep duration
| Sleep duration, h | OR | 95% CI |
|---|---|---|
| ~8 | 1.000 | |
| ≤5 | 1.593 | 1.017 ~ 2.495 |
| ~6 | 1.572 | 1.004 ~ 2.461 |
| ~7 | 1.266 | 0.801 ~ 2.000 |
| ~8.9 | 1.118 | 0.0.520 ~ 2.405 |
| ≥9 | 2.513 | 1.193 ~ 5.293 |
Abbreviations: OR, odds ratio; CI, confidence interval.
Compared with participants with proper sleep duration, those with short (OR: 1.339, 95% CI: 1.014 ~ 1.767) and long (OR: 2.100, 95% CI: 1.077 ~ 4.096) sleep duration showed a higher likelihood of cognitive impairment. Further, the likelihood of cognitive impairment was 61.1% (OR: 1.485, 95% CI: 1.126 ~ 1.959) higher in participants with physical activity level < 600 MET‐min/week than those with ≥600 MET‐min/week (Table 4).
Table 4.
Odds ratios (95% CIs) of cognitive impairment in 1147 rural elderly over 65 years old classified by sleep duration and physical activity level
| Variable | OR | 95% CI |
|---|---|---|
| Sleep duration, h | ||
| 6 ~ <9 | 1.000 | |
| <6 | 1.339 | 1.014 ~ 1.767 |
| ≥ 9 | 2.100 | 1.077 ~ 4.096 |
| Physical activity level (MET‐min/week) | ||
| ≥600 | ||
| <600 | 1.485 | 1.126 ~ 1.959 |
Abbreviations: MET, metabolic equivalents; OR, odds ratio; CI, confidence interval.
Subsequently, the joint associations of sleep duration (short sleep duration vs. proper sleep duration or long sleep duration vs. proper sleep duration) and physical activity level (<600 MET‐min/week vs. ≥600 MET‐min/week) with cognitive impairment in rural elderly over 65 years old were respectively assessed. Compared with those with proper sleep duration and sufficient physical activity, odds of cognitive impairment were higher in participants with proper sleep duration and insufficient physical activity (OR: 1.765; 95% CI: 1.158 ~ 2.692), and those with short sleep duration and sufficient physical activity (OR: 1.559; 95% CI: 1.090 ~ 2.230), while odds of cognitive impairment were 82% higher in participants with both short sleep duration and insufficient physical activity (OR: 1.820; 95% CI: 1.265 ~ 2.618) (Table 5). Moreover, the likelihood of cognitive impairment was 142.8% higher in participants with long sleep duration and sufficient physical activity (OR: 2.428; 95% CI: 1.137 ~ 5.183) than those with proper sleep duration and sufficient physical activity. And there was no significant difference in cognitive impairment detected between the long sleep duration and insufficient physical activity group and the control group (Table 6).
Table 5.
Joint associations of short sleep duration and physical activity with the likelihood of cognitive impairment in rural elderly over 65 years old
| Short sleep duration | Insufficient physical activity | No. with cognitive impairment | Proportion of cognitive impairment (%) | OR | 95% CI |
|---|---|---|---|---|---|
| No | No | 100 | 21.6 | 1.000 | |
| No | Yes | 87 | 37.0 | 1.765 | 1.158 ~ 2.692 |
| Yes | No | 89 | 34.9 | 1.559 | 1.090 ~ 2.230 |
| Yes | Yes | 62 | 40.5 | 1.820 | 1.265 ~ 2.618 |
Abbreviations: OR, odds ratio; CI, confidence interval.
Table 6.
Joint associations of long sleep duration and physical activity with the likelihood of cognitive impairment in rural elderly over 65 years old
| Long sleep duration | Insufficient physical activity | No. with cognitive impairment | Proportion of cognitive impairment (%) | OR | 95% CI |
|---|---|---|---|---|---|
| No | No | 100 | 21.6 | 1.000 | |
| No | Yes | 87 | 37.0 | 1.816 | 1.262 ~ 2.613 |
| Yes | No | 14 | 42.4 | 2.428 | 1.137 ~ 5.183 |
| Yes | Yes | 4 | 44.4 | 2.374 | 0.587 ~ 9.605 |
Abbreviations: OR, odds ratio; CI, confidence interval.
DISCUSSION
Our results showed that rural elderly with inappropriate sleep duration and insufficient physical activity had a higher likelihood of cognitive impairment. Elderly with short and long sleep durations showed 33.9% and 110% higher likelihood of cognitive impairment than those with proper sleep duration, respectively. Further, the likelihood of cognitive impairment was 48.5% higher in rural elderly with insufficient physical activity than those with sufficient physical activity. Compared to those with proper sleep duration and sufficient physical activity, rural elderly with short sleep duration and insufficient physical activity showed 82% higher likelihood of cognitive impairment, and elderly with long sleep duration and sufficient physical activity showed 142.8% higher likelihood of cognitive impairment.
In our study, rural elderly with 8 h or less of sleep per night showed that sleep duration has a negative correlation with the degree of cognitive impairment. Reversely, sleep duration showed a positive correlation with the degree of cognitive impairment in those with sleep duration more than 8 h per night. Moreover, rural elderly with 6 h or less and 9 h or more of sleep per night had a higher risk of cognitive decline. Similar to our results, based on two nationally representative longitudinal cohorts of ageing, Ma et al 28 found an inverted U‐shaped association: those with 4 h or less and 10 h or more of sleep per night had worse cognition and faster decline in cognitive function and memory. Lo et al 29 systematically reviewed 11 cross‐sectional studies and seven cohort studies, and also found a V‐shaped relationship between sleep duration and cognitive impairment. In the Cognitive Function and Ageing Study, elderly over 65 years old with 6.5 h or less sleep per night at baseline significantly increased the risk of cognitive impairment 10 years later. 17 Self‐reported shorter sleep duration was linearly associated with higher amyloid‐β burden, which has negative impact on cognitive ageing, and short sleep duration was associated with reduced cognition that was mostly in memory domains. 30 , 31 Shorter sleep duration may also contribute to cognitive impairment via degeneration of the hippocampus through multiple pathways, including changes in neuronal excitability, decreasing synaptic plasticity, and decreasing neurogenesis. 32 Further, the Northern Manhattan Study found people with 9 h or more of sleep per night had a 2.4 higher risk of cognitive impairment than those with 6 ~ 8.9 h. 33 Previous reports showed that long sleep duration was associated with rapid shrinkage of the cortex in the frontal and temporal regions of the brain, which were associated with language and executive function. 34
Physical exercise as a low‐cost, low‐risk and readily available lifestyle intervention has been extensively investigated because of its well‐known benefits to brain health promotion in elderly care practice. 35 According to a systematic review of 11 randomised controlled trials of physical exercise, including aerobics and resistance training, shows physical exercise exhibits low to moderate positive effects on the cognitive function of individuals with MCI. 36 Based on the data collected by the Global Physical Activity Questionnaire, our results revealed that physical activity level has a negative correlation with the degree of cognitive impairment and the likelihood of cognitive impairment was 48.5% higher in rural elderly with physical activity level < 600 MET‐min/week than those with ≥600 MET‐min/week. Physical exercise could improve cardiovascular function, which increases cerebral blood flow and oxygenation to the brain tissue and thus enhances the neurotransmitter availability and neural efficiency and promotes cognitive function. 37 , 38 Specifically, physical activity improved cognition, especially executive functioning, memory and independent functioning in individuals with MCI and dementia. 39 Amjad et al. 40 found that 20 min of aerobic exercise could significantly slow down the progress of MCI. And several studies demonstrated that aerobic exercise, such as martial arts, table tennis, dance, could reduce the risk of cognitive impairment. 9 , 41
A growing number of studies have demonstrated that sleep duration and physical activity significantly influence the primary, secondary and tertiary prevention of cognitive impairment. 19 , 28 , 29 , 31 , 32 , 33 , 34 , 35 , 36 A small number of studies suggest that physical activity may attenuate some of the negative impacts that poor sleep has on cognition, and also that sleep may be a mechanism through which physical activity improves cognitive abilities. 19 Song et al. 36 observed that the cognitive‐enhancing effects of exercise are mediated by improved sleep quality. Bloomberg et al. 42 found that higher‐intensity physical activity was insufficient to ameliorate the more rapid cognitive decline associated with short sleep. The improvement of sleep through exercise would promote the clearance of amyloid‐β oligomers and increase in neural synchrony in the prefrontal cortex to benefit cognition. 43 Our study found that inappropriate sleep duration combined with insufficient physical activity was significantly associated with a higher likelihood of cognitive impairment in rural elderly. Either short sleep duration (55.9%) or insufficient physical activity (75.5%) was independently correlated with the increased likelihood of cognitive impairment in rural elderly, and notably, their combination resulted in a 82% higher likelihood of cognitive impairment. Regrettably, there was no statistical significance between the long sleep duration combined with insufficient physical group and the proper sleep duration combined with sufficient physical activity group in our study. We speculated that the statistical error was due to the small number of cases in long sleep duration combined with the insufficient physical group: only four participants. But we still found long sleep duration (142.8%) and insufficient physical activity (81.6%) were independently correlated with the increased likelihood of cognitive impairment in the elderly. Therefore, it is of great significance for rural elderly over 65 years old to maintain proper sleep duration and at the same time, avoiding bad habits of insufficient physical activity, thus reducing the risk of cognitive impairment.
Limitations of this study
There were some limitations to this study. First, several studies found that excessive daytime sleepiness was associated with cognitive impairment. 44 , 45 Due to the limit of nap time information collection, we only considered the effect of night sleep duration in this study. Second, we failed to assess the volume and frequency of physical activity in elderly to explore the most beneficial pattern of physical activity. Lastly, the findings of this study were not supported by a large population‐based sample and is subject to the limitations commonly associated with a cross‐sectional analysis. In a follow‐up study, we would further expand the sample size of the investigation and conduct intervention studies to explore the extensibility of the results of this study.
CONCLUSIONS
Sleep duration and physical activity significantly influence the prevention and progressing of cognitive impairment. Considering their synergistic effect, we recommend that proper sleep duration (6 ~ < 9 h) combined with sufficient physical activity (≥600 MET‐min/week) should be adopted as the self‐management approach to cognitive function promotion in rural elderly over 65 years old. Large‐scale randomised controlled trials are still needed in the future to validate our findings, and it is also necessary to identify the potential influence of the volume and frequency of physical activity on cognitive function in rural elderly over 65 years old.
AUTHOR CONTRIBUTIONS
X.H. conceived the idea. J.W. contributed to data analysis and manuscript drafting; C.W., S.Q. Z.Q. and H.X. were responsible for data collection and manuscript revision. All the authors read and approved the final manuscript.
FUNDING INFORMATION
This research was funded by the Medical Science and Technology Development Foundation, Nanjing Municipality Health Bureau (grant no. 2021‐ZKX21054); the Medical Scientific Research Project, Jiangsu Provincial Health Commission (grant no. M2022028). The funder had no role in the decision to collect data, data analysis, or reporting of the results.
ETHICS STATEMENT
This study was approved by the academic and ethics committee of Nanjing CDC, and written informed consent was obtained from all participants prior to the survey. All methods were carried out in accordance with the Declaration of Helsinki.
ACKNOWLEDGMENTS
We are grateful to all the dedicated fieldworkers who have been involved in the surveys and all participants who have facilitated the survey implementation in each community.
Disclosure: The authors declare no conflict of interest.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.