ABSTRACT
Aim
Although exercise is considered effective in preventing dementia, it remains unclear whether different types of exercise are differentially associated with dementia risk. The aim of this study was to clarify the relationship between specific types of exercise and the risk of developing dementia.
Methods
We conducted postal surveys of 5074 community‐dwelling older adults in Japan in June 2013 (pre‐baseline wave) and August 2017 (baseline wave). Participants were followed for 4 years, until July 2021. Dementia was assessed using the nationally standardized scale developed by the Ministry of Health, Labour and Welfare of Japan. Participants were grouped based on engagement in 17 exercise types or classified as a non‐exerciser group if they did not participate in any of these activities. Five exercise types with ≥ 150 participants—calisthenics, walking, Japanese croquet, golf, and strength exercise—were included in the analysis. Adjusted Cox proportional hazards models with robust variance estimators were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for dementia development by comparing each exercise group with the non‐exerciser group.
Results
During the follow‐up period (median, 4.0 years; interquartile range, 4.0–4.0 years), 430 participants (8.5%) developed dementia. Compared with non‐exercisers, participation in Japanese croquet and strength exercise was associated with a significantly lower risk of developing dementia, with adjusted HRs of 0.68 (95% CI, 0.46–0.99) and 0.26 (95% CI, 0.08–0.81), respectively.
Conclusions
Participation in Japanese croquet and strength exercise may be beneficial for the prevention of dementia.
Keywords: aging, cognitive decline, cognitive impairment, physical activity, sport
We investigated whether participation in specific exercise types was associated with dementia risk in 5047 older Japanese adults over a 4‐year follow‐up. Compared with non‐exercisers, participation in Japanese croquet and strength exercise was associated with a lower risk of dementia.
1. Background
Dementia is a major public health concern, as it impairs an individual's quality of life [1] and imposes considerable burdens on society, such as increased healthcare expenditure [2] and caregiving responsibilities [3]. In high‐income countries, such as those in Europe and the United States, the prevalence of dementia remained stable—or even declined—between approximately 1980 and 2010 [4, 5, 6]. In contrast, Japan experienced a rising trend in dementia prevalence during the same period [7]. Furthermore, projections suggest that the prevalence of dementia in Japan will continue to rise until at least 2045 [8], highlighting the urgent need for effective preventive strategies. Previous research has identified 14 modifiable risk factors—including alcohol consumption, smoking, social isolation, and diabetes—that can help mitigate the onset of dementia [9].
Physical activity is one such modifiable factor [9]. A meta‐analysis of prospective studies published up to 2016 showed a dose–response relationship between total leisure‐time physical activity and dementia incidence, indicating that greater amounts of leisure‐time physical activity were associated with a lower risk of dementia [10]. Furthermore, a subsequent large‐scale study, involving 431 924 participants in the UK Biobank and a follow‐up period of approximately 10 years, reported that leisure‐time physical activity was associated with a reduced risk of dementia. For weekly physical activity levels up to 1200 metabolic equivalent minutes (MET‐min), every additional 600 MET‐min was associated with a 12% reduction in dementia risk. However, beyond 1200 MET‐min/week, no substantial risk reduction was observed [11].
Most prior studies have primarily examined the total amount of leisure‐time physical activity, while the specific effects of individual types of exercise remain poorly understood. In real‐world settings, older adults participate in a wide range of exercises—such as walking, calisthenics, golf, and dancing—each differing in terms of physical intensity, cognitive stimulation, and opportunities for social interaction. Therefore, the preventive effects of exercise on dementia risk may vary depending on the exercise modality. Several longitudinal studies have investigated specific types of exercises. For instance, a 6‐year follow‐up study of 15 589 older adults in China reported that aerobic exercise and mind–body exercises (Tai Chi and yoga) were associated with a lower risk of dementia [12]. Another 5‐year follow‐up study involving 469 older adults in the United States showed that, among several types of exercise, only dancing was associated with a lower risk of dementia [13]. A further 6‐year follow‐up study of 49 705 older adults in Japan, which examined the relationship between hobby activities and dementia onset, showed that participation in Japanese croquet was associated with a decreased risk of dementia [14]. These findings suggest that focusing on specific exercise types may reveal beneficial elements beyond basic physical activity, such as more complex motor coordination and social engagement, which may be particularly effective in preventing dementia.
However, previous studies vary considerably in terms of geographic regions, cultural contexts, and the types of exercise assessed. Thus, the associations between different exercise types and dementia risk have not been fully explored in Japan, a country facing a rapid rise in dementia cases. Accordingly, this study aimed to evaluate how participation in diverse forms of exercise is associated with the risk of dementia onset among older Japanese adults. These findings may help inform the development of practical dementia prevention strategies and exercise guidelines.
2. Methods
2.1. Study Design and Participants
This study was a 4‐year follow‐up of a mail‐based survey conducted among community‐dwelling older adults (aged ≥ 65 years) in Kasama City, Ibaraki, Japan. Figure 1 illustrates the flow of the participants in this study. On June 1, 2013, we collected pre‐baseline data, including sociodemographic and lifestyle factors, anthropometry, and health status. Self‐report questionnaires were mailed to 16 870 older adults who were not receiving long‐term care insurance [15]. A total of 10 339 individuals returned completed questionnaires. On August 1, 2017, we collected baseline data on the types of exercises performed by these participants. At this time, self‐report questionnaires were sent to 8870 of the 10 339 participants who had not relocated, received long‐term care insurance, or died. A total of 6291 completed questionnaires were returned. We excluded participants who had a history of dementia or stroke (n = 327) or were certified for long‐term care insurance before baseline (n = 105). Of the remaining participants (n = 5859), those with missing data (n = 785) were further excluded, leaving 5074 participants for analysis. Participants were followed using the municipal database until they developed dementia, moved to another city, died, or reached the end of the follow‐up period (July 31, 2021).
FIGURE 1.
Flowchart illustrating the inclusion and exclusion criteria for study participants. LTCI, long‐term care insurance.
All participants were informed of the purpose of the study through written documents, and informed consent was implied by the voluntary return of the questionnaire. This study was conducted in accordance with the guidelines of the Declaration of Helsinki, and the study protocol was approved by the Ethics Committee of the University of Tsukuba (Approval numbers: Tai 025‐121).
2.2. Assessment of Dementia
Dementia was assessed using the Activities of Daily Living Independence Assessment Criteria for Elderly Individuals with Dementia developed by the Ministry of Health, Labour and Welfare of Japan [16, 17]. This scale classifies dementia severity into five ranks—I, II, III, IV, and M—based on the degree of cognitive decline, with Rank I being the least severe and Rank M the most severe. For example, Rank II indicates the presence of symptoms, behavioral issues, or communication difficulties that may interfere with daily activities; however, individuals at this stage can still live independently if adequate support is provided. This scale has shown good agreement with the Clinical Dementia Rating [18] and the Mini‐Mental State Examination scores (Spearman's ρ = −0.74, p < 0.001) [19]. Rank II or higher is considered an appropriate cut‐off point for identifying dementia [20]. This outcome measure for dementia has been widely adopted in several epidemiological studies [21, 22].
2.3. Exercise Participation
Using an open‐ended format, the participants provided written descriptions of the types of exercise in which they regularly engaged. Based on a previous study of exercise types commonly practiced by older Japanese adults, these responses were categorized into 17 distinct groups: calisthenics, walking, Japanese croquet (including ground golf, gateball, and traditional croquet), golf, strength exercise, ball games, bicycling, jogging, aqua exercise, hiking, yoga, quoits, Tai Chi, dance, martial arts, bowling, and others [23, 24]. Blank responses were treated as indicating nonparticipation.
2.4. Covariates
To minimize the potential for reverse causation [25], all covariates were evaluated using the data from the pre‐baseline survey (2013), conducted approximately 4 years before exposure assessment. The following variables were assessed at baseline: age (65–69, 70–74, 75–79, or ≥ 80 years), sex (male or female), education (compulsory education, high school, or college/junior college), subjective economic status (very poor/poor, normal, or very good/good), living alone (no or yes), sleep duration (< 6.0, 6.0–8.9, or ≥ 9.0 h/day), subjective memory complaints (0, 1, or ≥ 2 points), depressive mood (0–1 or ≥ 2 points), body mass index (BMI) (< 18.5, 18.5–24.9, or ≥ 25.0 kg/m2), and medical history (hypertension, dyslipidemia, diabetes, heart disease, and arthralgia/neuralgia).
BMI was calculated using self‐reported height and weight. Subjective memory complaints and depressive mood were evaluated using the Kihon Checklist, a validated tool for assessing frailty in older adults [26]. It comprehensively examines multiple domains, including physical and oral function, nutritional status, cognitive ability, social participation, and depressive mood. Subjective memory complaints and depressive mood were assessed using three and five yes/no items (score ranges: 0–3 and 0–5), respectively, with higher scores indicating more severe symptoms.
Missing values were as follows: sex (n = 7), education (n = 33), subjective economic status (n = 63), living alone (n = 81), sleep duration (n = 491), subjective memory complaints (n = 30), depressive mood (n = 67), BMI (n = 76), hypertension (n = 115), dyslipidemia (n = 115), diabetes (n = 115), heart disease (n = 115), and arthralgia/neuralgia (n = 115).
2.5. Statistical Analysis
We examined the association between specific types of exercise and the development of dementia during follow‐up using Cox proportional hazards regression with robust variance estimators. Participants were followed from baseline until the earliest occurrence of dementia onset, relocation to another city, death, or the end of follow‐up, whichever came first. Death was treated as a competing event, with individuals censored at the time of death in a cause‐specific hazard model. Cause‐specific hazard models estimate the effect of covariates on the rate of event occurrence among individuals who are currently event‐free and are therefore well suited for addressing etiological research questions [27]. We analyzed the relationship between the five exercise types, each with more than 150 participants, and the development of dementia, as the other exercise types were considered to have insufficient statistical power owing to their small sample sizes. Each type of exercise was analyzed in a separate model, and the participants in each exercise group may have engaged in other types of exercise.
Three regression models were constructed: Model 1 was unadjusted; Model 2 was adjusted for age and sex; and Model 3 was adjusted for age, sex, education, subjective economic status, living alone, sleep duration, subjective memory complaints, depressive mood, BMI, and medical history (hypertension, dyslipidemia, diabetes, heart disease, and arthralgia/neuralgia).
All statistical analyses were conducted using StataNow/MP 19.5 (StataCorp LLC, College Station, TX, USA). Visual evaluation of the Schoenfeld residual plot confirmed that the proportional hazards assumption was satisfied. Results were reported as hazard ratios (HRs) with 95% confidence intervals (CIs). All tests were two‐sided, and p < 0.05 was considered statistically significant.
3. Results
The 5074 participants contributed 19 018 person‐years of observation. The median follow‐up duration was 4.0 years (interquartile range, 4.0–4.0 years). During follow‐up, 430 participants (8.5%) developed dementia, corresponding to an incidence rate of 22.6 cases per 1000 person‐years. A total of 387 participants (7.6%) died, including 271 (5.3%) who died before developing dementia. Table 1 presents the pre‐baseline characteristics of the participants according to dementia development during follow‐up. The mean age at pre‐baseline was 73.0 years (standard deviation = 5.7), and 52.3% of the participants were female.
TABLE 1.
Pre‐baseline characteristics and dementia development among older adults in Kasama City, Japan (n = 5074).
| Total, n (%) | Dementia development, n (%) | |
|---|---|---|
| Age, years | ||
| Continuous, M (SD) | 73.0 (5.7) | |
| 65–69 | 1822 (35.9) | 37 (2.0) |
| 70–74 | 1535 (30.3) | 83 (5.4) |
| 75–79 | 1033 (20.4) | 141 (13.7) |
| ≥ 80 | 684 (13.5) | 169 (24.7) |
| Sex | ||
| Male | 2418 (47.7) | 193 (8.0) |
| Female | 2656 (52.3) | 237 (8.9) |
| Education | ||
| Compulsory education | 1455 (28.7) | 164 (11.3) |
| High school | 2656 (52.3) | 205 (7.7) |
| College/junior college | 963 (19.0) | 61 (6.3) |
| Subjective economic status | ||
| Very poor/poor | 801 (15.8) | 64 (8.0) |
| Normal | 3751 (73.9) | 313 (8.3) |
| Very good/good | 522 (10.3) | 53 (10.2) |
| Living alone | ||
| No | 4534 (89.4) | 360 (7.9) |
| Yes | 540 (10.6) | 70 (13.0) |
| Sleep duration, h/day | ||
| < 6.0 | 747 (14.7) | 58 (7.8) |
| 6.0–8.9 | 4126 (81.3) | 332 (8.1) |
| ≥ 9.0 | 201 (4.0) | 40 (19.9) |
| Subjective memory complaints, points | ||
| 0 | 3524 (69.5) | 270 (7.7) |
| 1 | 1273 (25.1) | 119 (9.4) |
| ≥ 2 | 277 (5.5) | 41 (14.8) |
| Depressive mood, points | ||
| 0–1 | 4217 (83.1) | 311 (7.4) |
| ≥ 2 | 857 (16.9) | 119 (13.9) |
| Body mass index, kg/m2 | ||
| < 18.5 | 255 (5.0) | 27 (10.6) |
| 18.5–24.9 | 3617 (71.3) | 302 (8.4) |
| ≥ 25.0 | 1202 (23.7) | 101 (8.4) |
| Hypertension | ||
| No | 2755 (54.3) | 209 (7.6) |
| Yes | 2319 (45.7) | 221 (9.5) |
| Dyslipidemia | ||
| No | 4025 (79.3) | 358 (8.9) |
| Yes | 1049 (20.7) | 72 (6.9) |
| Diabetes | ||
| No | 4417 (87.1) | 358 (8.1) |
| Yes | 657 (12.9) | 72 (11.0) |
| Heart disease | ||
| No | 4500 (88.7) | 369 (8.2) |
| Yes | 574 (11.3) | 61 (10.6) |
| Arthralgia/neuralgia | ||
| No | 4006 (79.0) | 330 (8.2) |
| Yes | 1068 (21.0) | 100 (9.4) |
Abbreviations: M, mean; SD, standard deviation.
Table 2 summarizes the number and percentage of participants performing each type of exercise. Among the participants, 3120 (61.5%) reported participating in some form of exercise. The most commonly reported type of exercise at baseline was calisthenics (n = 2357, 46.5%), followed by walking (n = 1559, 30.7%), other exercises (n = 387, 7.6%), Japanese croquet (n = 385, 7.6%), golf (n = 283, 5.6%), and strength exercise (n = 193, 3.8%). The number of participants engaged in ball games, bicycling, jogging, aqua exercise, hiking, yoga, quoits, Tai Chi, dance, martial arts, and bowling was less than 150 for each activity.
TABLE 2.
Participation in each type of exercise among older adults in Kasama City, Japan (n = 5074).
| n (%) | |
|---|---|
| Exercise participation | 3120 (61.5) |
| Calisthenics | 2357 (46.5) |
| Walking | 1559 (30.7) |
| Other | 387 (7.6) |
| Japanese croquet | 385 (7.6) |
| Golf | 283 (5.6) |
| Strength exercise | 193 (3.8) |
| Ball games | 134 (2.6) |
| Bicycling | 132 (2.6) |
| Jogging | 123 (2.4) |
| Aqua exercise | 108 (2.1) |
| Hiking | 81 (1.6) |
| Yoga | 56 (1.1) |
| Quoits | 52 (1.0) |
| Tai Chi | 50 (1.0) |
| Dance | 48 (0.9) |
| Martial arts | 16 (0.3) |
| Bowling | 4 (0.1) |
Table 3 provides the results of the Cox proportional hazards regression analysis with robust variance estimators evaluating the association between participation in each exercise type and the risk of developing dementia. In Model 3 (fully adjusted), participants who engaged in Japanese croquet or strength exercise had significantly lower risks of developing dementia compared with non‐exercisers, with HRs of 0.68 (95% CI, 0.46–0.99) and 0.26 (95% CI, 0.08–0.81), respectively. In contrast, participation in calisthenics, walking, or golf was not significantly associated with dementia risk compared with non‐exercisers, with HRs of 0.87 (95% CI, 0.71–1.06), 0.86 (95% CI, 0.67–1.09), and 0.48 (95% CI, 0.22–1.04), respectively.
TABLE 3.
Cox proportional hazards regression analysis for the association between types of exercise and the risk of developing dementia among older adults in Kasama City, Japan.
| n | Person‐year | Incidence (%) | Model 1 a | Model 2 b | Model 3 c | |
|---|---|---|---|---|---|---|
| HR (95% CI) | HR (95% CI) | HR (95% CI) | ||||
| Nonparticipation | 1954 | 7142 | 212 (10.9) | Reference | Reference | Reference |
| Calisthenics | 2357 | 8953 | 177 (7.5) | 0.66 (0.54–0.81) | 0.82 (0.67–0.997) | 0.87 (0.71–1.06) |
| Walking | 1559 | 5959 | 105 (6.7) | 0.59 (0.47–0.74) | 0.81 (0.64–1.03) | 0.86 (0.67–1.09) |
| Japanese croquet | 385 | 1447 | 29 (7.5) | 0.67 (0.46–0.99) | 0.62 (0.42–0.91) | 0.68 (0.46–0.99) |
| Golf | 283 | 1102 | 7 (2.5) | 0.21 (0.10–0.45) | 0.39 (0.18–0.85) | 0.48 (0.22–1.04) |
| Strength exercise | 193 | 754 | 3 (1.6) | 0.13 (0.04–0.42) | 0.22 (0.07–0.70) | 0.26 (0.08–0.81) |
Abbreviations: CI, confidence interval; HR, hazard ratio.
Unadjusted.
Adjusted for age and sex.
Adjusted for age, sex, education, subjective economic status, living alone, sleep duration, subjective memory complaints, depressive mood, body mass index, and medical history (hypertension, dyslipidemia, diabetes, heart disease, and arthralgia/neuralgia).
4. Discussion
We conducted a 4‐year longitudinal study among older Japanese adults to identify specific types of exercise associated with a lower risk of developing dementia. Our findings indicated that individuals who engaged in Japanese croquet and strength exercise had a lower risk of developing dementia than non‐exercisers. These findings suggest that engaging in Japanese croquet and strength exercise may be particularly beneficial for dementia prevention in older Japanese adults.
The present study demonstrated that individuals who engaged in Japanese croquet had a lower risk of developing dementia than non‐exercisers. This finding is consistent with previous research showing that Japanese croquet participants had a lower risk of developing dementia than nonparticipants [14]. Japanese croquet requires the use of specialized equipment to aim and strike a ball toward a target and is therefore considered a coordination exercise involving complex motor control [28]. A meta‐analysis of 80 randomized controlled trials conducted across various age groups found that coordination exercises led to greater improvements in cognitive function than endurance or resistance exercises [28], partially supporting the present results. Furthermore, Japanese croquet is played in social group settings. A previous study revealed that exercising with others is associated with a lower risk of dementia than exercising alone [22]. Potential explanations include the tendency for group‐based exercise to involve longer durations [29], lower risk of depression [30], and stronger social connections [31]—all of which have been shown to contribute to dementia prevention [9]. In contrast, participation in golf was not significantly associated with dementia risk in the fully adjusted model, although the point estimate indicated a lower risk. This finding may reflect limited statistical power, as indicated by the wide CI. Given that golf, similar to Japanese croquet, is a coordination exercise often performed in group settings, it may be associated with a lower risk of developing dementia.
The present study demonstrated that individuals who engaged in strength exercise had a lower risk of developing dementia compared with non‐exercisers. This aligns with findings from a meta‐analysis of randomized controlled trials, which has shown that strength exercise can effectively enhance cognitive function in middle‐aged and older adults [32]. The cognitive benefits of strength exercise are thought to arise from mechanisms such as altered blood flow, stimulation of neurotransmitter metabolism, increased release of neurotrophic factors, and endocrine hormone modulation, which promote cerebral angiogenesis and increase gray matter volume [33]. These physiological changes may contribute to the preservation of cognitive function, thereby lowering the risk of developing dementia.
In the present study, engaging in calisthenics or walking was not associated with a lower risk of developing dementia compared with non‐exercisers, which contradicts previous research findings. Specifically, a longitudinal study conducted in Japan among older adults demonstrated that those who engaged in calisthenics had a lower risk of developing dementia compared with those who did not [21]. In addition, a UK‐based longitudinal study of middle‐aged and older adults reported that a higher daily step count was associated with a decreased risk of developing dementia [34]. Given these prior findings, our results were unexpected. Several explanations may account for these unexpected findings. First, our study did not assess the duration or intensity of exercise. Because the total volume of leisure‐time physical activity is an important factor in lowering the risk of developing dementia [10, 11], the calisthenics or walking groups may have included individuals who did not engage in sufficient physical activity to reduce dementia risk. Second, the present study was conducted among older adults in a rural area of Japan, where social capital is higher than in urban areas [35]. Given that social engagement is a protective factor against dementia [9], individuals in communities with high social capital may benefit from social interactions regardless of exercise participation. Therefore, social capital may act as a potential effect modifier; the protective effect of exercise against incident dementia might be less pronounced in such high‐social‐capital communities, whereas it could be more evident in areas with lower social capital.
Key strengths of the present study include the use of a systematic dementia registration system for dementia ascertainment, adjustment for potential confounding factors assessed before baseline, and evaluation of associations between multiple exercise types and the development of dementia among older Japanese adults. However, this study has certain limitations. First, the follow‐up period was limited to 4 years, so the possibility of reverse causation cannot be entirely ruled out. Previous research suggests that physical activity levels may decline approximately 10 years before the onset of dementia [36], indicating that our findings may reflect early behavioral changes related to dementia. Second, because the types of exercise were assessed using a self‐administered questionnaire, recall bias may have influenced the results. Participants who developed dementia may have had poorer memory function at baseline and thus failed to accurately recall their exercise habits, potentially leading to an overestimation of the protective effect of exercise on the development of dementia. Third, because exercise types were assessed only at baseline, exposure misclassification due to changes in exercise behavior during follow‐up may have occurred, potentially biasing the estimated association. Therefore, future studies are needed to incorporate longitudinal assessments of exercise habits to better capture changes over time. Fourth, participants in the exercise groups may have engaged in multiple types of exercise. Therefore, the observed associations may reflect not only the exercise of interest but also other concurrent exercises, potentially resulting in overestimation. Fifth, the small number of incident dementia cases for some exercise types may have resulted in imprecise estimates and wide CIs. Therefore, these findings should be interpreted with caution. Sixth, the study did not assess the etiologies of dementia, such as Alzheimer's disease or vascular dementia. Prior evidence from a cohort of 117 616 adults followed for up to 43 years showed that leisure‐time physical activity was associated with a lower risk of non‐Alzheimer's dementia but not with Alzheimer's disease [37]. Finally, because all participants were recruited from a single rural region in Japan, the findings may not be generalizable to the broader population of older Japanese adults.
5. Conclusions
In this longitudinal study of older Japanese adults, individuals who engaged in Japanese croquet and strength exercise had a lower risk of developing dementia than non‐exercisers. These findings suggest that these specific activities may be effective and practical strategies for dementia prevention in this population.
Author Contributions
K.N. and K.S. designed this study. K.N. and K.T. analyzed the data. K.N., K.T., Y.F., J.S., T.J., and K.S. drafted the manuscript. K.N., Y.F., J.S., and T.J. collected data. K.N., K.T., T.J., and T.O. acquired the funding required to conduct this study. T.O. administered the project. All authors critically revised the manuscript, interpreted the results, and approved the final version for submission.
Funding
This work was supported by Japan Society for the Promotion of Science (20H04063, 26750348, and 23K19919), Japan Science and Technology Agency (JPMJPF2017 and JPMJSP2124), Meiji Yasuda Life Foundation of Health and Welfare, Japan Sport Association.
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgments
We would like to thank Editage (www.editage.jp) for English language editing.
Data Availability Statement
The authors have nothing to report.
References
- 1. Prince M. J., Wu F., Guo Y., et al., “The Burden of Disease in Older People and Implications for Health Policy and Practice,” Lancet 385 (2015): 549–562. [DOI] [PubMed] [Google Scholar]
- 2. Patterson C., World Alzheimer Report 2018. The State of the Art of Dementia Research: New Frontiers (Alzheimer's Disease International, 2018). [Google Scholar]
- 3. Prince M., Brodaty H., Uwakwe R., et al., “Strain and Its Correlates Among Carers of People With Dementia in Low‐Income and Middle‐Income Countries. A 10/66 Dementia Research Group Population‐Based Survey,” International Journal of Geriatric Psychiatry 27 (2012): 670–682. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Langa K. M., Larson E. B., Crimmins E. M., et al., “A Comparison of the Prevalence of Dementia in the United States in 2000 and 2012,” JAMA Internal Medicine 177 (2017): 51–58. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. Prince M., Ali G.‐C., Guerchet M., Prina A. M., Albanese E., and Wu Y.‐T., “Recent Global Trends in the Prevalence and Incidence of Dementia, and Survival With Dementia,” Alzheimer's Research & Therapy 8 (2016): 23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6. Wu Y. T., Fratiglioni L., Matthews F. E., et al., “Dementia in Western Europe: Epidemiological Evidence and Implications for Policy Making,” Lancet Neurology 15 (2016): 116–124. [DOI] [PubMed] [Google Scholar]
- 7. Sekita A., Ninomiya T., Tanizaki Y., et al., “Trends in Prevalence of Alzheimer's Disease and Vascular Dementia in a Japanese Community: The Hisayama Study,” Acta Psychiatrica Scandinavica 122 (2010): 319–325. [DOI] [PubMed] [Google Scholar]
- 8. Nakahori N., Sekine M., Yamada M., Tatsuse T., Kido H., and Suzuki M., “Future Projections of the Prevalence of Dementia in Japan: Results From the Toyama Dementia Survey,” BMC Geriatrics 21 (2021): 602. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Livingston G., Huntley J., Liu K. Y., et al., “Dementia Prevention, Intervention, and Care: 2024 Report of the Lancet Standing Commission,” Lancet 404 (2024): 572–628. [DOI] [PubMed] [Google Scholar]
- 10. Xu W., Wang H. F., Wan Y., Tan C.‐C., Yu J.‐T., and Tan L., “Leisure Time Physical Activity and Dementia Risk: A Dose‐Response Meta‐Analysis of Prospective Studies,” BMJ Open 7 (2017): e014706. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11. Huang S.‐Y., Li Y.‐Z., Zhang Y.‐R., et al., “Sleep, Physical Activity, Sedentary Behavior, and Risk of Incident Dementia: A Prospective Cohort Study of 431,924 UK Biobank Participants,” Molecular Psychiatry 27 (2022): 4343–4354. [DOI] [PubMed] [Google Scholar]
- 12. Lee A. T. C., Richards M., Chan W. C., Chiu H. F. K., Lee R. S. Y., and Lam L. C. W., “Intensity and Types of Physical Exercise in Relation to Dementia Risk Reduction in Community‐Living Older Adults,” Journal of the American Medical Directors Association 16 (2015): 899.e1–899.e7. [DOI] [PubMed] [Google Scholar]
- 13. Verghese J., Lipton R. B., Katz M. J., et al., “Leisure Activities and the Risk of Dementia in the Elderly,” New England Journal of Medicine 348 (2003): 2508–2516. [DOI] [PubMed] [Google Scholar]
- 14. Ling L., Tsuji T., Nagamine Y., Miyaguni Y., and Kondo K., “Types and Number of Hobbies and Incidence of Dementia Among Older Adults: A Six‐Year Longitudinal Study From the Japan Gerontological Evaluation Study (JAGES),” Nihon Koshu Eisei Zasshi 67 (2020): 800–810. [DOI] [PubMed] [Google Scholar]
- 15. Tsutsui T. and Muramatsu N., “Care‐Needs Certification in the Long‐Term Care Insurance System of Japan,” Journal of the American Geriatrics Society 53 (2005): 522–527. [DOI] [PubMed] [Google Scholar]
- 16. Hikichi H., Aida J., Kondo K., et al., “Increased Risk of Dementia in the Aftermath of the 2011 Great East Japan Earthquake and Tsunami,” Proceedings of the National Academy of Sciences of the United States of America 113 (2016): E6911–E6918. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17. Ministry of Health, Labour and Welfare , “The Degree of Autonomy in the Daily Lives of Elderly Individuals With Dementia Scale,” accessed September 4, 2025, http://www.mhlw.go.jp/topics/2013/02/dl/tp0215‐11‐11d.pdf.
- 18. Meguro K., Tanaka N., Kasai M., et al., “Prevalence of Dementia and Dementing Diseases in the Old‐Old Population in Japan: The Kurihara Project. Implications for Long‐Term Care Insurance Data,” Psychogeriatrics 12 (2012): 226–234. [DOI] [PubMed] [Google Scholar]
- 19. Hisano S., “The Relationship Between Revised Hasegawa Dementia Scale (HDS‐R), Mini‐Mental State Examination (MMSE) and Bed‐Fast Scale, Dementia Scale,” Japanese Journal of Geriatric Psychiatry 20 (2009): 883–891. [Google Scholar]
- 20. Noda H., Yamagishi K., Ikeda A., Asada T., and Iso H., “Identification of Dementia Using Standard Clinical Assessments by Primary Care Physicians in Japan,” Geriatrics & Gerontology International 18 (2018): 738–744. [DOI] [PubMed] [Google Scholar]
- 21. Kanamori S., Kawaguchi K., Tsuji T., et al., “Taiso Practice and Risk of Functional Disability and Dementia Among Older Adults in Japan: The JAGES Cohort Study,” SSM‐Population Health 28 (2024): 101731. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22. Nagata K., Tsunoda K., Fujii Y., Jindo T., and Okura T., “Impact of Exercising Alone and Exercising With Others on the Risk of Cognitive Impairment Among Older Japanese Adults,” Archives of Gerontology and Geriatrics 107 (2023): 104908. [DOI] [PubMed] [Google Scholar]
- 23. Osuka Y., Kojima N., Yoshida Y., et al., “Exercise and/or Dietary Varieties and Incidence of Frailty in Community‐Dwelling Older Women: A 2‐Year Cohort Study,” Journal of Nutrition, Health & Aging 23 (2019): 425–430. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24. Osuka Y., Suzuki T., Kim M., et al., “Association Between Exercise Type and the Decline in Instrumental Activities of Daily Living in Community‐Dwelling Older Women: A 4‐Year Prospective Study,” Preventive Medicine 112 (2018): 23–30. [DOI] [PubMed] [Google Scholar]
- 25. VanderWeele T. J., “Principles of Confounder Selection,” European Journal of Epidemiology 34 (2019): 211–219. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26. Sewo Sampaio P. Y., Sampaio R. A. C., Yamada M., and Arai H., “Systematic Review of the Kihon Checklist: Is It a Reliable Assessment of Frailty?,” Geriatrics & Gerontology International 16 (2016): 893–902. [DOI] [PubMed] [Google Scholar]
- 27. Austin P. C., Lee D. S., and Fine J. P., “Introduction to the Analysis of Survival Data in the Presence of Competing Risks,” Circulation 133 (2016): 601–609. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28. Ludyga S., Gerber M., Puhse U., Looser V. N., and Kamijo K., “Systematic Review and Meta‐Analysis Investigating Moderators of Long‐Term Effects of Exercise on Cognition in Healthy Individuals,” Nature Human Behaviour 4 (2020): 603–612. [DOI] [PubMed] [Google Scholar]
- 29. Firestone M. J., Yi S. S., Bartley K. F., and Eisenhower D. L., “Perceptions and the Role of Group Exercise Among New York City Adults, 2010‐2011: An Examination of Interpersonal Factors and Leisure‐Time Physical Activity,” Preventive Medicine 72 (2015): 50–55. [DOI] [PubMed] [Google Scholar]
- 30. Kanamori S., Takamiya T., Inoue S., Kai Y., Tsuji T., and Kondo K., “Frequency and Pattern of Exercise and Depression After Two Years in Older Japanese Adults: The JAGES Longitudinal Study,” Scientific Reports 8 (2018): 11224. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31. Yamakita M., Kanamori S., Kondo N., and Kondo K., “Correlates of Regular Participation in Sports Groups Among Japanese Older Adults: JAGES Cross‐Sectional Study,” PLoS One 10 (2015): e0141638. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32. Northey J. M., Cherbuin N., Pumpa K. L., Smee D. J., and Rattray B., “Exercise Interventions for Cognitive Function in Adults Older Than 50: A Systematic Review With Meta‐Analysis,” British Journal of Sports Medicine 52 (2018): 154–160. [DOI] [PubMed] [Google Scholar]
- 33. Cheng A., Zhao Z., Liu H., Yang J., and Luo J., “The Physiological Mechanism and Effect of Resistance Exercise on Cognitive Function in the Elderly People,” Frontiers in Public Health 10 (2022): 1013734. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34. del Pozo Cruz B., Ahmadi M., Naismith S. L., and Stamatakis E., “Association of Daily Step Count and Intensity With Incident Dementia in 78 430 Adults Living in the UK,” JAMA Neurology 79 (2022): 1059–1063. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35. Qin Z., Tanaka K., and Matsuoka S., “Regional Disparities in Bonding and Bridging Social Capital: An Empirical Study of Rural and Urban Japan,” Japanese Journal of Sociology 31 (2022): 110–126. [Google Scholar]
- 36. Kivimaki M., Singh‐Manoux A., Pentti J., et al., “Physical Inactivity, Cardiometabolic Disease, and Risk of Dementia: An Individual‐Participant Meta‐Analysis,” BMJ 365 (2019): l1495. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37. Juul Rasmussen I., Rasmussen K. L., Thomassen J. Q., et al., “Physical Activity in Leisure Time and at Work and Risk of Dementia: A Prospective Cohort Study of 117,616 Individuals,” Atherosclerosis 360 (2022): 53–60. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The authors have nothing to report.