Impact of exercising alone and exercising with others on the risk of cognitive impairment among older Japanese adults
Graphical abstract
Introduction
In 2019, 57.4 million people were suffering from dementia globally, and this number is projected to increase to 152.8 million by 2050 (GBD 2019 Dementia Forecasting Collaborators, 2022). Dementia severely impacts patients’ quality of life (Prince et al., 2015) and imposes a heavy burden on caregivers (Prince et al., 2012). Direct medical costs, direct social care costs, and costs of informal care approaches for dementia are significantly expensive (Wimo et al., 2017). Therefore, currently, there is increasing interest in modifiable risk factors for the prevention of dementia (Livingston et al., 2020).
Physical activity and exercise have been identified as modifiable factors for the prevention of dementia (Livingston et al., 2020). Owing to the advantages of increased accessibility and cost-effectiveness, as well as other health-related benefits, many studies have examined the effects of exercise and physical activity on the prevention of dementia (Northey et al., 2018; Xu et al., 2017). A meta-analysis investigating the association between leisure-time physical activity and dementia found a dose-response relationship (Xu et al., 2017). Another meta-analysis involved the effects of exercise interventions of at least moderate intensity lasting at least 45 min per session on as many days of the week as possible, and established that the approach used was beneficial for maintaining cognitive function among adults aged over 50 years (Northey et al., 2018).
Over recent years, there has been an increased focus on the positive impact of exercising with others on health outcomes (Kanamori et al., 2015). Cross-sectional studies reported higher objective measures of physical and cognitive function and lower rates of falls among individuals who exercised with others than among those who exercised alone (Fujii et al., 2021; Hayashi et al., 2018). Longitudinal studies have established that those who exercised with others have a lower risk of developing depression and functional disability than those who do not exercise. This association was not established among individuals who exercised alone (Fujii et al., 2020; Kanamori et al., 2018). The mechanisms by which exercise with others can affect health outcomes are likely to involve physical activity as well as psychological and social factors (Kanamori et al., 2015). Exercising with others has been reported to ensure a high likelihood of achieving the World Health Organization's recommendation of 150 or more minutes of moderate- to vigorous-intensity physical activity per week (Seino et al., 2019; World Health Organization, 2020), to reduce stress, anxiety, and depression (Street et al., 2007) and promote enhanced social connectedness, social support, and peer bonds (Eime et al., 2013).
Social contact is a modifiable risk factor for dementia (Livingston et al., 2020; Samtani et al., 2022). A recent meta-analysis focusing on social interaction examined its association with cognitive function, and reported that community group engagement and interaction with family and friends were effective in maintaining cognitive function (Samtani et al., 2022). In terms of preventing cognitive impairment, exercising with others may be more beneficial than exercising alone, as it has a positive effect on social factors (Kim et al., 2019). However, few studies have investigated the influence of exercising with others on the prevention of cognitive impairment. A previous study reported that older adults who congregated and participated in social activities involving light physical activity had a lower risk of cognitive impairment in the future (Hikichi et al., 2017). Further, a six-year follow-up study reported that group participation in community-level sports had a preventive effect on cognitive impairment (Tsuji et al., 2019). However, previous studies have only investigated participation in exercise groups, and were unable to examine exercising outside the groups with others (Hikichi et al., 2017; Tsuji et al., 2019). Additionally, existing studies have not stratified the frequency of exercise when examining the relationship between exercise forms and cognitive function (Hikichi et al., 2017; Tsuji et al., 2019). The frequency of exercising is associated with enhanced cognitive function (Northey et al., 2018), and stratifying this frequency is essential for extending exercise-related recommendations, with improved cognitive functions as the outcome. The frequencies of each form of exercise may vary and would affect future cognitive function. Considering this practical information can aid the creation of specific exercise support measures to maintain cognitive function. As the prevalence of specific behaviors is also a crucial factor impacting assessment and decision-making in the field of public health, it is beneficial to show the impact of each form of exercise on the prevention of cognitive impairment by utilizing a population-attributable fraction (PAF) (Zhang et al., 2018). Therefore, in this study, we estimated the PAFs for reducing cognitive impairment resulting from exercising alone and exercising with others.
This study aimed to compare the influence of each exercise form on the prevention of cognitive impairment and examine the influence of the stratified frequency of exercising alone and exercising with others on the prevention of cognitive impairment to identify the exercise form that is most beneficial in preserving cognitive function. We hypothesized that exercising with others would be more influential than exercising alone for preventing cognitive impairment, and that this influence would increase with the increase in frequency.
Section snippets
Study design and participants
This study is part of the Kasama study, which is an inventory mail survey that targeted community-dwelling older residents (aged ≥ 65 years) in Kasama City, Ibaraki, Japan. Supplementary Fig. 1 shows the flow of the participants involved in this study. The data obtained from the second-wave survey were used as the baseline. In the first wave, self-report questionnaires were sent to 16,870 older adults who were not receiving long-term care insurance (Tsutsui & Muramatsu, 2005). A total of 10,339
Results
Table 1 presents the descriptive data of the sample. At the baseline, the mean age was 76.9 ± 5.6 years, and 51.8% of the participants were female. Supplementary Tables 1 and 2 show the demographic characteristics of the groups involving the participants exercising alone and those exercising with others. Significant differences were established in exercise practice frequency and age, education level, subjective economic status, living alone, smoking, BMI, dyslipidemia, sleep duration, and
Discussion
To the best of our knowledge, this is the first study to compare the impact of exercise forms (exercising alone and exercising with others) and the effect of the frequency of practicing these exercise forms on the prevention of cognitive impairment. In the multivariable-adjusted Cox proportional hazards model, it was established that exercising with others may be more effective than exercising alone, with regard to the prevention of cognitive impairment. Additionally, exercising alone or with
Conclusion
This study established that both forms of exercise were effective in preventing cognitive impairment. Furthermore, exercising with others may be more useful in reducing the risk of cognitive impairment than exercising alone, which was the prevalent exercise form in this study. Regarding the scenario in which all participants exercised with others for ≥ 2 times a week, the risk of developing cognitive impairment decreased by 29.2%. This impact was larger than the scenario in which participants
Author contributions
KN and KT designed the study and analyzed the data. KN drafted the manuscript. All authors collected the data. KN, KT, TJ, and TO acquired the funding required to conduct this study. TO administered the project. All the authors critically revised the manuscript, interpreted the results, and approved the final version of the manuscript for submission.
Funding
This study was supported by a JSPS KAKENHI Grant-in-Aid for Scientific Research (B) (20H04063) to TO and by grants from Young Scientists (B) (26750348) to KT, JST COI-NEXT (JPMJPF2017) to TO, JST SPRING (JPMJSP2124) to KN, the Meiji Yasuda Life Foundation of Health and Welfare to TJ, and the Japan Sports Association to TO.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgments
We thank the participants involved in this study and Kasama City officials for their cooperation throughout this study. We would like to thank Editage (www.editage.com) for English language editing.
References (44)
- et al.
Social interaction and cognitive decline: Results of a 7-year community intervention
Alzheimer's & Dementia: Translational Research & Clinical Interventions
(2017) - et al.
Acute moderate exercise enhances compensatory brain activation in older adults
Neurobiology of Aging
(2012) - et al.
Social relationships and risk of dementia: A systematic review and meta-analysis of longitudinal cohort studies
Ageing Research Reviews
(2015) - et al.
Dementia prevention, intervention, and care: 2020 report of the Lancet Commission
Lancet
(2020) - et al.
The burden of disease in older people and implications for health policy and practice
Lancet
(2015) - et al.
Associations between social connections and cognition: A global collaborative individual participant data meta-analysis
The Lancet Healthy Longevity
(2022) - et al.
The worldwide costs of dementia 2015 and comparisons with 2010
Alzheimer's & Dementia
(2017) Role of exercise on the brain
Journal of Exercise Rehabilitation
(2016)- et al.
A systematic review of the psychological and social benefits of participation in sport for children and adolescents: Informing development of a conceptual model of health through sport
The International Journal of Behavioral Nutrition and Physical Activity
(2013) - et al.
Effect of exercising with others on incident functional disability and all-cause mortality in community-dwelling older adults: A five-year follow-up survey
International Journal of Environmental Research and Public Health
(2020)