Cognitive impairment is characterized by a decline in one or more cognitive abilities due to various causes, such as reduced language skills, memory loss or even severe dementia, and other psychiatric disorders (Koder, 1998; American Psychiatric Association, 2013; Hu et al., 2021). In China, more than 360,000 people are diagnosed with cognitive impairment each year (Pu et al., 2023), and it is estimated that the total number of people with cognitive impairment in China will reach up to 48.68 million by 2060 (Prince et al., 2016). With the extension of the population's life expectancy, the number of individuals experiencing cognitive impairment has dramatically increased. The prevalence of mild cognitive impairment among Chinese individuals aged 60 years or older is ~14.71%. Furthermore, the annual transition rate from cognitive impairment to dementia is reported to be in the range of 10–30%, which is much higher than that in the elderly individuals with normal cognitive function (1–3%) (Jia et al., 2020). The prevention of cognitive impairment in the elderly is one of the public health priority areas.

The existing evidence for the elderly indicates that physical inactivity is a specific potential variable risk factor that can promote the development of cognitive impairment (Sabia et al., 2017; Livingston et al., 2020). Approximately 3% of cognitive impairment can be prevented by increased physical activity (Li, 2013; Lourenco et al., 2018; Livingston et al., 2020). Given the current dearth of effective treatments for cognitive impairment, identifying potential risk factors for cognitive impairment and dementia, especially those that can be modified such as physical activity, is an effective way to prevent cognitive decline.

In the absence of any visual reference, closed-eye unipedal standing relies solely on the balance receptors in the vestibular organ of the brain and the coordinated movement of the muscles throughout the body to maintain the center of gravity with a single foot supported (Springer et al., 2007). The duration of closed-eye unipedal standing is an important indicator of physical fitness for the elderly (Büchel et al., 2021). During closed-eye unipedal standing, the combined action of the vestibular system and proprioceptors plays a crucial role. The vestibular system is responsible for sensing acceleration and angular changes in the head to maintain balance (Henry and Baudry, 2019). Additionally, the proprioceptors provide important inputs for balance control by sensing information about the body's joint angles, muscle tone, and skin contact (Martínez-Amat et al., 2013). The prefrontal cortex of the brain is involved in regulating attention, somatic movements, and executive functions. Recent studies have shown that single-leg standing can activate the prefrontal cortex to improve cognitive performance (Sugihara et al., 2021). In addition, Morenilla et al. (2020) concluded that balance or cognitive performance decreased in older adults when a cognitive task was performed simultaneously with a postural control task (i.e., dual-task paradigm). Vellas et al. (1997) found that participants with abnormal balance in single-leg standing also scored worse on subjective health status, humor, and neurocognitive function. These evidences imply that common areas of the brain may be used for postural control and cognition. Without the aid of visual sense, closed-eye unipedal standing can accurately measure the relationship between postural control and cognitive function. It is rational to hypothesize that the duration of closed-eye unipedal standing might be a predictive index of cognitive impairment.

Therefore, we conducted a community-based cohort study among the elderly to investigate the relationship between closed-eye unipedal standing and the risk of cognitive impairment by tracking participants over a 7-year period. Optimizing the duration of closed-eye unipedal standing to prevent cognitive impairment may help in obtaining the maximum benefit.

To the best of our knowledge, the relationship between closed-eye unipedal standing and the risk of cognitive impairment was explored for the first time in the Chinese elderly population. By following up on participants for 7 years, we found that the cognitive impairment risks in middle and high closed-eye unipedal standing groups were significantly lower. Furthermore, the results of the RCS analysis indicated that, when the duration exceeded ~2.920 s, the risk of cognitive impairment in the elderly decreased with increasing duration of closed-eye unipedal standing. These relationships remained significant after adjusting for confounders.

After 7 years of follow-up, the follow-up rate of the elderly was only 53.27%, which might limit the extrapolation and accuracy of our results. The reasons for missing follow-up included elderly individuals relocating with their offspring, death, or unwillingness to visit the hospital or accept the doctor's visit due to coronavirus disease (COVID-19), and so on. Finally, the incidence rate of cognitive impairment in the elderly was 17.61%. In the Chinese Longitudinal Healthy Longevity Survey (CLHLS), Zhang et al. (2022) found that, after 3 years of follow-up, 14.4% were diagnosed with cognitive impairment, which is lower than that observed in this study, possibly because the diagnostic criteria for cognitive impairment (MMSE scores < 24) were different and the follow-up interval years were shorter.

During closed-eye unipedal standing, cooperative work of multiple physiological systems is essential. Among these, the neurological system relies on intrinsic sensations, such as proprioceptors and the vestibular system, to visualize the position and movement of the body. Simultaneously, the muscle system and articulations perform an essential role in maintaining the body's stability by adjusting muscle tensions (Serra-Añó et al., 2015; Afschrift et al., 2021). Existing evidence suggests that controlling body posture can improve cognitive performance by stimulating the corresponding functional areas of the brain (Henry and Baudry, 2019). It can be speculated that closed-eye unipedal standing may be much difficult for people with cognitive impairment. This is because they might struggle to effectively perceive their body's position and posture, thereby facing difficulties in making timely adjustments to maintain balance.

Our results showed that, when compared with the low tertile group, the risk of cognitive impairment was 0.601 and 0.508 times higher in the middle and high closed-eye unipedal standing tertile groups, respectively. The RCS results also indicated that higher closed-eye unipedal standing duration was protective against the risk of cognitive impairment in older adults. In spite of reaching a certain duration, the CI included 1, which might be due to a potentially insufficient sample size combined with other confounding factors, such as dietary habits. Similarly, many researchers, such as Rolland et al. (2009) and Tabara et al. (2015), have shown that the single-leg balance standing test can predict cognitive decline in the elderly, possibly due to parietal and hippocampal dysfunction which can lead to memory loss and visual orientation deficits. Sugihara, on the other hand, revealed that activation of the left and right prefrontal cortex was observed during one-legged standing in the absence of a cognitive function task; however, this activation was altered in aging, cognitive impairment, and Parkinson's syndrome subjects (Sugihara et al., 2021). Hence, the closed-eye unipedal standing duration might be a predictive index for cognitive impairment in the elderly.

Furthermore, the histogram in our study showed that the majority of the elderly performed the closed-eye unipedal standing at a lower level. Previous studies have concluded that intensive practice of closed-eye unipedal standing may help activate and improve areas of the brain associated with balance and spatial cognition, thereby facilitating connections and information transfer between neurons (Bustillo-Casero et al., 2017; Papegaaij et al., 2017). Involving the elderly in exercise to improve balance and lower limb muscle strength to prolong closed-eye unipedal standing may be helpful to delay the development of cognitive impairment. Hence, the closed-eye unipedal standing, being a simple and adaptable method, can serve as a predictive index for cognitive impairment in the elderly. Additionally, it might also be considered an intervention method to prevent cognitive dysfunction. Further intervention studies are necessary to confirm this hypothesis.

The stratified analysis showed that, after adjusting for confounders, the risk of cognitive impairment in the female elderly was much lower than the male elderly. It is possible that the female elderly individuals are more prone to mood swings, insomnia, irritability and anxiety, which may affect the brain functions to a certain extent (Livingston et al., 2020). In addition, consistent with the previous findings by Ahn and Kim (2023) and Nagata et al. (2023), closed-eye unipedal standing reduces the risk of cognitive impairment in the elderly in the exercise group but not in the lack of exercise group. With increasing age, certain elderly people lose their ability to balance, along with degenerative changes in the brain tissue, such as amyloidosis and demyelination in nerve cells (Lourenco et al., 2018; Omura et al., 2020; Yang et al., 2023). Furthermore, decreased levels of the acetylcholine mediator contribute to reduced brain function, which in turn leads to the possibility that closed-eye unipedal standing may have a lesser impact on the risk of cognitive impairment in people over 75 years of age.

While this study has important theoretical and practical implications, it also has certain limitations and points to areas for further exploration in the future. First, the rate of loss to follow-up was relatively high. The follow-up assessment was conducted only once. The evolution of the mean cognitive impairment scores over time could not be depicted. Second, the recruited participants were homogeneously aged and sourced from diverse geographical regions within Wuhan City. The definition of cognitive impairment depended only on MMSE scores. Due to sample size limitations, the influence of baseline MMSE scores on the effect of closed-eye unipedal standing duration on the risk of cognitive impairment was not completely excluded. These limitations potentially limited the generalizability of the findings to the broader elderly Chinese population. Finally, the study did not account for all the potential confounding factors, such as diet, sleep, and so on. In the future, we will continue to conduct further rigorous prospective and intervention studies to reveal the relationship and mechanisms between closed-eye unipedal standing and cognitive impairment.

Our results showed that, closed-eye unipedal standing in the elderly was linearly and negatively associated with cognitive impairment. The risk of developing cognitive impairment was decreased when the duration of closed-eye unipedal standing exceeded approximately 2.920 s. The closed-eye unipedal standing duration might be a predictive index for cognitive impairment in the elderly. Further intervention studies are necessary to confirm the protective effects and mechanisms of closed-eye unipedal standing on cognitive impairment in the elderly.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by the Institutional Review Board of Wuhan University of Science Technology (Number: 2023120). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

SW: Conceptualization, Data curation, Formal analysis, Investigation, Software, Writing – original draft, Writing – review & editing. PG: Writing – original draft, Writing – review & editing. CH: Software, Writing – review & editing. YZ: Data curation, Writing – review & editing. BX: Investigation, Writing – review & editing. JZ: Data curation, Writing – review & editing. FZ: Data curation, Writing – review & editing. XX: Conceptualization, Writing – review & editing. YG: Data curation, Writing – original draft. MY: Conceptualization, Investigation, Writing – review & editing.