1Neighborhood sidewalk environment and incidence of dementia in older Japanese
adults: the Japan Gerontological Evaluation Study cohort

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Correspondence to Dr. Yukako Tani, Department of Global Health Promotion, Tokyo Medical
and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan (e-mail:ANUtani.hlth@tmd.ac.jp)

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Author affiliations: Department of Global Health Promotion, Tokyo Medical and Dental

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University (Yukako Tani and Takeo Fujiwara); Center for Preventive Medical Sciences, Chiba
University (Masamichi Hanazato, Norimichi Suzuki, and Katsunori Kondo); Department ofED
ITGerontological Evaluation, Center for Gerontology and Social Science, National Center forN

Geriatrics and Gerontology (Katsunori Kondo)

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This study used data from Japan Gerontological Evaluation Study, which was supported by

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Japan Society for the Promotion of Science KAKENHI Grant (JP15H01972), Health Labour
Sciences Research Grants (H28-Choju-Ippan-002), Japan Agency for Medical Research andIN

Development (JP19dk0110034), Research Funding for Longevity Sciences from NationalG

Center for Geriatrics and Gerontology (29-42), and Japan Science and Technology AgencyO

RI(JPMJOP1831(OPERA)). The authors of this paper have no financial disclosures to report.

© The Author(s) 2021. Published by Oxford University Press on behalf of the Johns Hopkins
Bloomberg School of Public Health. This is an Open Access article distributed under the termsof the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/4.0), which permits non-commercial re-use,
distribution, and reproduction in any medium, provided the original work is properly cited. Forcommercial re-use, please contact journalpermissions@oup.com.

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Yukako Tani, Masamichi Hanazato, Takeo Fujiwara, Norimichi Suzuki, Katsunori Kondo

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Conflict of interest: none declared.

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Data Availability: The datasets used and analyzed for the current study are from the JAGES
study. All inquiries are to be addressed to the data management committee via e-mail:ANUdataadmin.ml@jages.net. All JAGES datasets have ethical and legal restrictions for publicEDM

deposition because of the inclusion of sensitive information on the human participants.

Abstract

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Sidewalks are indispensable environmental resources for daily life in that they encourage
physical activity. However, the percentage of sidewalks installation is low even in developedNcountries. We examined the association between neighborhood sidewalk environment andGerontological

Evaluation

Study,

apopulation-based

cohort

study

of

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Japan

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dementia in Japan. We conducted a 3-year follow-up (2010-2013) among participants in acommunity-dwelling older adults. We ascertained the incidence of dementia for 76,053

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participants from the public long-term care insurance system. We calculated sidewalkGcoverage (sidewalk area as a percentage of road area) within 436 residential neighborhood

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units using the geographic information system. Multilevel survival models were used toOestimate hazard ratios (HR) for the incidence of dementia. During the follow-up, 5310
dementia cases were found. In urban areas, compared with the lowest quartile for sidewalk
coverage, the HR was 0.42 (95% confidence interval (CI): 0.33–0.54) for the highest quartile,
adjusting for individual covariates. After successive adjustments for other neighborhood

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Running head: Sidewalk environment and dementia incidence

3factors (land slope, numbers of hospitals, grocery stores, parks, stations and bus stops,
education level, and unemployment rate), the HR remained statistically significant (HR=0.75,
95% CI: 0.59–0.94). Living in neighborhoods with high sidewalks installation was associatedSC

Keywords: sidewalk, dementia, older adults, community dwellers

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Dementia prevention is a priority in the public health sector worldwide given the rapidly
aging population of some countries.(1) Recently, one-third of dementia cases have beenMestimated to be preventable, with nine risk factors being identified: education, hypertension,

EDobesity, hearing loss, depression, diabetes, physical inactivity, smoking, and social
isolation.(1) Physical activity can reduce these preventable risk factors including hypertension,

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obesity, depression, and diabetes.(2)Because the neighborhood environment is an important factor that influences how

Nphysically active older people are in daily life,(3-5) an approach targeting environmental

Ufeatures may be effective in preventing dementia. Recent studies showed that the low

ALavailability of better environmental destinations was associated with cognitive impairment
and dementia.(6-8) However, little is known about the environmental factors that support easeINof access to such destinations.

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Sidewalks may prompt people to walk and walkability of paths positively motivates

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older people to engage in physical activity.(4, 5) Walking is the most common and preferredO

type of physical activity for older people because it is associated with low costs, has low risk
for ageing bodies (4, 9) and is applicable to various activities such as shopping andsightseeing. A recent study among older people showed that lower time spent walking was
associated with dementia.(10) Older people residing in poor sidewalk environments may not

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with low dementia incidence in urban areas.

4walk frequently, and in turn have an increased dementia.
Even in developed countries, the percentage of sidewalks installation is low in somecountries. The percentage of city residents who agreed that their neighborhoods had sidewalks

Ton most streets was only 59% in Japan whereas these figures were 97% in Hong Kong, 96%

SCsidewalk length per road length showed the percentage of sidewalks installation is only 14%
in Japan in 2010.(12) Moreover, road widths in Japan are narrow, i.e., 6.0 m on average.(12)AN

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Thus, a car can barely pass through and there is little space left for pedestrians to pass. The
role of sidewalks in physical activity can differ between urban and rural areas. WhileM

sidewalks may play an important role for safe walking in urban areas, they may not encourageEDwalking in rural areas because people can walk safely on roads. Therefore, the association
between sidewalks and dementia needs to be separately examined for rural and urban areas.

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One of the reasons for the lack of sidewalk research may be the difficulty inquantifying sidewalk environments. Two methods are mainly used, one involving an objectiveNmeasurement in which a trained observer visits the site to evaluate the sidewalkUenvironment,(6, 7) and the other being a proportion method using the ratio of the sidewalkALlength to the road length.(13, 14) In the first method, although it is possible to carefully
evaluate the quality of the sidewalk environment, e.g. sidewalk width, continuity andINobstacles, it is time-consuming to cover the whole country. In contrast, the second method isGsuitable for large-scale surveys if an existing regional database on sidewalk lengths and road

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lengths is available.(15) Nevertheless, this method only considers the percentage of sidewalkOlength and does not evaluate other quantifiers of sidewalk environments such as width.
Therefore, we measured sidewalk coverage (the ratio of sidewalk area to road area) using thegeographic information system (GIS), adopting the measure to quantify sidewalk
environments in our large-scale survey. This new method takes into account not only road

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in Sweden, 77% in Canada, and 74% in the United States.(11) Objective data by calculating

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length but also width.
The aim of this study was to examine the association between neighborhood
sidewalk environments and dementia in urban and rural areas based on sidewalk coverage

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METHODS
Study Design and Participants

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The Japan Gerontological Evaluation Study (JAGES) project was established in 2010
to evaluate the social determinants of healthy aging among older people in Japan.(16) WeMconducted a baseline survey between August 2010 and January 2012 among older peopleED

aged 65 years or older from 24 municipalities. Self-reported questionnaires were distributedby mail to 106,468 older people who were not eligible for benefits from the long-term careEDIT

insurance system,(17) that is, they were physically and cognitively independent and lived
independently in the community. Random samplings were conducted in 13 largeNmunicipalities, and a complete survey was conducted in the remaining eleven smallerUmunicipalities. A total of 86,055 participants returned the questionnaire (response rate: 66%).

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Among the respondents, 81,980 participants were successfully linked to dementia records
during the 3-year follow-up. The analytic sample for the present study comprised 76,053

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participants aged 65 to 103 years. We excluded respondents with missing data for residentialGsidewalk environments (N =1,432). In addition, to ensure that the analytical sample included

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only participants who were actually physically and cognitively independent, we also excludedO

those who reported limitations (N = 1,627) or provided no answer (N = 2,868) on questions
about daily activities (defined as being unable to walk, take a bath or use the toilet without
assistance).

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using a population-based cohort study of Japanese older adults.

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Outcome variable: Dementia Outcome
The dementia incidence was ascertained during the follow-up period, from 2010 to2013 (mean: 3.0 years), by linking the cohort participants to the standardised in-homeSCelsewhere. (8, 18) Briefly, trained investigators evaluated applicants’ eligibility for benefits
by evaluating the following statuses: 1) physical function; 2) activities of daily living; 3)

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cognitive function; 4) mental and behavioral disorders; 5) adaptation to social life; and 6) past
medical treatment.(8, 19) Investigators classified the applicants on a dementia scale accordingM

to the severity of their cognitive impairment (Web Table 1). As described elsewhere,(8, 18)

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Level II or higher on the dementia scale (manifesting at least some symptoms, behaviours orcommunication difficulties that hinder daily activities; Level II corresponds to a 16-point

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rating on the Mini-Mental State Examination(20)) was defined as dementia in this study.

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Predictor variable: sidewalk environment and other environmental measures

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We calculated the sidewalk coverage by dividing the area of sidewalk by the area ofALthe entire roads including sidewalks within neighborhood unit (Figure. 1). The sidewalk
coverage was calculated using the ArcGIS data collection detail map 2014 (ESRI Japan,

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Tokyo). These data contain polygons in the area of roads and in the area of sidewalks; ArcGIS,

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version 10.1 (ESRI Japan, Tokyo), was used for all spatial calculations. We visuallyRI

confirmed that the newly adopted sidewalk data reflected the sidewalk conditions using theObaseline 2010 photos(Figure. 1). As in previous studies,(21) we defined a neighborhood

unit in accordance with the elementary school district, which is a primary residential spatial
area of community-dwelling people, among who the older people are able to move around by
foot or by bicycle easily. Our study sample (n=76,053) was nested within 436 elementary

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insurance registry.(17) The details of the assessment of dementia have been reportedT

assessment and medical examination conducted under Japan’s public long-term care7school districts, and the average area of elementary school districts was 2.65 km2 (SD = 3.98).
For the analyses, school districts were categorized into quartiles based on the sidewalk
coverage (Web Figure. 1, Table 1).

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Using GIS, we calculated the degree of land slope, population density, area of schoolSC

participants’ residential school districts. Details of the methods are reported elsewhere.(8, 21,22) We calculated the proportion of residents with higher education (total number of highUschool graduates / all residents × 100) and unemployment rate (1 – total number of employeesANaged ≥15 years / labor force of people aged ≥15 years × 100) within the participants’M

residential school districts as the neighborhood socioeconomic status using the National

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Census data in 2010.

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Covariates

Baseline information about age and sex were provided by the municipality. OtherN

covariates were assessed using the self-reported questionnaire. Sociodemographic statusU

included education level, annual household income, living situation, marital status, andAL

employment status. Health status included medical treatments of diseases/symptoms(hypertension, diabetes, hearing loss, heart disease, or stroke), depressive symptoms,

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instrumental activities of daily living and cognitive function. Baseline cognitive function wasGassessed using three items from the Kihon Checklist–Cognitive Function scale, for which

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predictive validity for the dementia incidence was confirmed.(23) Duration of residence wasO

assessed by how long participants had lived in the same municipality. Physical activity
included walking time and frequency of outings. Car use when going out was assessed bywhether participants drove a car by themselves or rode in a family member’s car when goingout.(8) All covariates were controlled as categorical variables (Table 2).

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district, number of hospitals, grocery stores, parks, railway stations, and bus stops within the8Statistical Analysis
Multilevel Weibull survival models with vce (cluster) option were estimated,Tyielding HRs and 95% confidence intervals (CI) for dementia incidence over the 3-yearSCand sidewalk coverage was non-significant. Model 1 was adjusted for age and sex. Model 2

was additionally adjusted for sociodemographic characteristics, health status, and duration ofANUresidence as potential confounders. Model 3 was additionally adjusted for physical activity
and car use when going out as potential mediating factors. Model 4 was simultaneouslyMadjusted for other neighborhood factors (land slope, number of hospitals, grocery stores, park,EDrailway stations and bus stops, education level, unemployment rate, and area of school
district) as well as individual level factors to examine whether the association between

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sidewalk coverage and dementia was independent of these factors. To investigate thedifference according to the city scale, we conducted a stratified analysis specifically of urban
and rural areas. Of the four area levels defined by the Organisation for Economic

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Co-operation and Development’s Functional Urban Areas (large metropolitan areas,AL

metropolitan areas, medium-sized urban areas, and small urban areas),(24) the school districts
included in the large metropolitan areas or the metropolitan areas are distinguished as urban

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and the others as rural. For the sensitivity analysis, a propensity score-matched cohort (theGlowest quartile (Q1) and the highest quartile (Q4) of sidewalk coverage) analysis was

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performed to reduce the potential confounding bias for the association between sidewalkOcoverage and dementia. The propensity score matching was conducted with a ratio of 1:1 anda calliper distance of 0.01 using the variables. The matching generated 3,799 matched pairs
and multi-level Weibull survival models with the vce (cluster) option were estimated. Allanalyses were conducted using Stata version 15.

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follow-up period. Data were analyzed for both sexes because the interaction term between sex

9Ethical consideration
The Human Subjects Committees of Nihon Fukushi University (No. 10-05) andT

Chiba University Faculty of Medicine (No. 1777) approved the JAGES protocol. Participants

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RESULTS

The mean sidewalk coverage within elementary school districts was 13.8%, givingM

an estimated sidewalk installation percentage of 37.9% (Table 1). The sidewalk coverage forED

Q4 was more than three times higher than that for Q1, and the difference in estimatedpercentage of sidewalk installation was 58% for Q4 and 18% for Q1. Sidewalk coverage wasEDITpositively correlated with sidewalk area, population density, and number of hospitals, grocery
stores, parks, and railway stations, proportion of higher education, and unemployment rate,Nand inversely correlated with road area, area of school district, and land slope (Web Table 2).

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The characteristics of the participants are summarized in Table 2. Among allALparticipants, 47% were male, 12% lived alone, 69% were married, 21% were working, 40%
were under treatment for hypertension, and 13% were under treatment for diabetes. AboutIN

30% of participants walked for more than 1 hour a day, >50% went out more than four times

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per week, and 66% used a car when going out.
During the follow-up, 5310 dementia cases were found among the analytical sample.

O(cumulative dementia; 7.0% of all participants). The incidence rate of dementia per 100 000
person-years was 8.0 in Q1 of sidewalk coverage and 6.7 in Q4 (Web Table 3). Comparedwith Q1 of sidewalk coverage, the HR was 0.81 (95% CI: 0.69–0.94) for Q2, 0.67 (95% CI:
0.55–0.80) for Q3, and 0.55 (95% CI: 0.45–0.68) for Q4, adjusting for age, sex,

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the questionnaire via mail indicated their consent to participate in the study.

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were informed that participation in the study was voluntary and that completing and returning

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sociodemographics, health status, and duration of residence (Table 3). Similar results wereobtained using continuous values for sidewalk coverage (Web Table 4). Adjusting forpotential mediating factors including physical activity and car use reduced the correlationT

only slightly. After adjusting for other neighborhood features (land slope, number of hospitals,

SCarea of school district), higher sidewalk coverages were significantly associated with a lower
dementia incidence (Model 4 in Table 3). Among neighborhood features, sidewalk coverageANUshowed the most protective association with dementia incidence (Figure 2, Web Table 5). A
propensity-score matched cohort (Q1 and Q4 of sidewalk coverage) analysis was further

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employed for the sensitivity analysis. The characteristics of the participants before and afterED

propensity-score matching are shown in Web Table 6. We confirmed that compared with Q1,
the HR for Q4 was 0.52 (95% CI: 0.37–0.74) (Web Table 7).

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From the analyses stratified by city scale, higher sidewalk coverage was associatedwith lower dementia incidence in urban areas, but not in rural areas (Table 3). Similar resultsN

were obtained in the stratified analyses using the population density of inhabitable areas.

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Higher sidewalk coverage was significantly associated with lower dementia incidence inALschool districts with high population density, but not in school districts with low population
density (data not shown). From the analyses stratified by driving status, higher sidewalk

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coverage was associated with lower dementia incidence only among non-car users (Web tableO

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DISCUSSION
This is the first study to examine the association between neighborhood sidewalk

environments and dementia both in urban and rural areas. We found that higher sidewalk
coverage was associated with lower dementia incidence in urban areas.
One previous study examined the link between sidewalks and cognitive functions,

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grocery stores, park, railway stations and bus stops, education level, unemployment rate, and11and it found no significant association.(7) The difference in the installation percentage ofsidewalks and the sidewalk measurement method may explain the contradictory findings. In
the previous study conducted in Chicago, about 90% of participants lived in neighborhoods

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where sidewalks were fully installed. In contrast, in our study, the percentage of roads withSC

width of sidewalks, whereas we assessed sidewalks taking into account both length and width.
Little attenuation of the association between sidewalk coverage and dementia wasANUfound after adjustments for physical activity. One reason may be mismeasurement of physicalactivities. As we examined only the self-reported walking times, the frequency of outings andM

car use, it may not reflect the actual physical activities of older people. Even if participants goEDout frequently, they may take the car for transport rather than go by foot. We found that higher
sidewalk coverage was related to lower dementia incidence among only non-car users (WebED
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table 8). Because older people may be unable to use a car for several reasons such as loss ofdriving licence or loss of family member responsible for driving, this result may be importantNfor public health. We found that walking time does not vary with sidewalk coverage. We

Ufound that walking time did not vary with sidewalk coverage. One possibility is that weALshould account for landscapes such as roadside vegetation to encourage walking, because
older people place importance on “changing landscapes” such as growth of plants whenINselecting places to walk.(25)G

The association between the sidewalk coverage and dementia remained after

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adjusting for other neighborhood factors, suggesting that additional unobserved factors may

Oexplain this relationship. Field surveys investigating the association between road types withsidewalk environments and the conscientiousness of residents showed that community roads
that have a sufficient sidewalk width are places where not only passing is possible but also
daily social interactions happen.(26) Therefore, higher sidewalk coverage may facilitate theDownloaded from https://academic.oup.com/aje/advance-article/doi/10.1093/aje/kwab043/6144850 by guest on 22 March 2021

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sidewalks installed was around 38%. The previous study in Chicago did not account for the12social activities of people living there. Another possibility is that in the case of wide sidewalks,
there are tree planting zones that can increase pedestrians’ exposure to greenness, which is
linked to beneficial cognitive function.(27) Because the mechanisms underlying thisSC

We found that higher sidewalk coverage was associated with lower dementia

incidence only in urban areas and not in rural areas. This finding is plausible as people livingANUin rural areas can walk about and talk safely without sidewalks without the worry of trafficthat plagues urban areas. We found differences in frequency of going out and use of a car byMcity scale (Web Table 9). In rural areas, the percentage of people using cars is higher and theEDfrequency of going out is lower than in urban areas. These factors suggest that rural people
may be less exposed to sidewalks and sidewalks may therefore not be associated withEDIT

dementia incidence. Given the potential role of sidewalks in encouraging safe walking andphysical and social activities, it is convincing that there was a protective association only inNurban areas and only among non-car users.

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This study had several limitations. First, the definition of dementia in this studyALmight underestimate the dementia incidence. A nationwide survey aimed at estimating theprevalence of dementia reported that 34% of cases of dementia were not identified in theINlong-term care insurance registry; however, three-quarters of these cases were mild cases ofGdementia.(28) Because assessment of dementia is not considered to depend on the size of

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sidewalk coverage, the bias from nondifferential misclassification of dementia may tendO

toward a null value. Second, we evaluated sidewalk conditions at one point only and useddata at 4 years after the baseline. Therefore, it was not possible to evaluate the secular change
in sidewalk environments. During the 10-year period from 2008 to 2018, the percentage ofsidewalk installation increased slightly from 13.7% to 14.0% and the total road length

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mediate the association between sidewalk coverage and dementia incidence.

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association can be complex and multiple, future studies should investigate factors that13

increased by 1.07 times.(29) Considering the past exposure, the sidewalk coverage used thisstudy may have been slightly overestimated. Third, we could account for the length and widthof the sidewalk but no other features of sidewalks such as obstacles, unevenness, andT

maintenance requirements, and more generally those features that affects walking gaits.

SCyounger, had higher socioeconomic status, and had higher physical activities than those in the
excluded sample. This suggests that our sample lacked subjects who were vulnerable toANUdementia, which may have led to underestimation of the effect of sidewalk coverage on

dementia. Fifth, because we did not have a clinical test for dementia in participants at baseline,Mpeople with mild dementia who were able to live independently may have been included inEDthe analysis. However, the results were similar when we analysed only participants with nocognitive complaints at baseline (Web Table 10). Sixth, generalizability may not be high,EDIT

because differences in factors such as city scale, traffic volume, and cultural background may
affect the association between sidewalks and dementia. Seventh, we were only able to provideNfollow-up for 3 years. Considering the pathology of dementia, long-term follow-up is needed.

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Finally, we cannot rule out the possibility of a reverse association. However, the results wereAL

substantially similar when we excluded participants with early dementia incidence (within 1year) from the analysis, or participants who had lived in the same municipality for fewer thanIN

5 years (Web Table 11 and 12).

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In conclusion, sidewalk coverage has been associated with a decreased incidence ofRI

dementia only in urban areas. This study provides new evidence that place of residence canOaffect dementia risk and describes the potential impact of these findings on dementia researchby proposing a new modifiable environmental risk factor. Indeed, urban planning could be a
new way to promote healthy aging, if the present results are confirmed. Further studies areneeded to elucidate the mechanisms underlying this association.

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Fourth, there is a possibility of selection bias. The participants included in the analysis were

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Yorifuji T, Kashima S, Tsuda T, et al. Long-term exposure to traffic-related air pollution and

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mortality in Shizuoka, Japan. Occup Environ Med 2010;67(2):111-7.
Fujita M, Yamaoka S, Matsui H. Evaluation for three types of access roads on the basis of

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26.

questionnaire and field surveys. Journal of the City Planning Institute of Japan 2001;36:607-12. [inJapanese]de Keijzer C, Gascon M, Nieuwenhuijsen MJ, et al. Long-Term Green Space Exposure and

N

27.

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Cognition Across the Life Course: a Systematic Review. Curr Environ Health Rep 2016;3(4):468-77.
Asada T. Prevalence of dementia in urban areas and functional disability in dementia for

AL

28.

IN

FY2011-2012, Tokyo, Japan: Ministry of Health, Labour and Welfare. Published 2013.

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http://www.tsukuba-psychiatry.com/wp-content/uploads/2013/06/H24Report_Part1.pdf. [inRIJapanese].

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29.

Ministry of Land, Infrastructure, Transport and Tourism. Annual Report of Road Statistics FY2018.
Tokyo, Japan: Japan Highway Users Conference.
https://www.mlit.go.jp/road/ir/ir-data/tokei-nen/2018tokei-nen.html. Published 2017. Accessed
November 14, 2019 [in Japanese].

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23.

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Table 1: Characteristics of sidewalk coverage, Japan Gerontological Evaluation Study, 2010-2013 (n=436).

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AN

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Sidewalk coveragea within residential elementary Estimated mean percentage
Quartile of Sidewalk
school district (%)
Nof sidewalk installationb
Coverage(%)
Mean (SD)Median (Min–Max)
1 (lowest)
109
6.6 (2.5)
6.9 (0.5-9.9)
18.1
2
109
11.9 (1.0)
12.0 (10.0-13.7)
32.7
3
109
15.4 (1.0)
15.4 (13.7-17.1)
42.3
4 (highest)
109
21.2 (3.5)
20.1 (17.1-34.3)
58.2
All
436
13.8 (5.8)
13.7 (0.5-34.3)
37.9
Max = maximum; Min = minimum; SD = standard deviationa
Sidewalk area as a percentage of area of all roads within neighborhood unit (%)
b
Estimated mean percentage of sidewalk installation (%) was defined as the percentage of roadways withsidewalks on both sides. Estimated mean percentage of sidewalk installation was calculated under the
standard road conditions, i.e., the road width should be 6.0 m or more for two lanes, the sidewalk width
should be 4.0 m or more (2.0 m or more/lane), and the road shoulder should be 1.0 m or more (0.5 m or
more/lane), according to the Japanese Road Construction Ordinance. For example, as the average sidewalk
coverage in this study was 13.8%, it is estimated that the sidewalk is installed 37.9% (13.8 divided by
36.4×100) on the road.

18

Table 2: Baseline characteristics of older Japanese adults, Japan Gerontological Evaluation Study,
2010-2013 (n=76 053)
Total
Characteristic

Sidewalk coverageN%

Q1 (lowest)

Q2

Q3

Q4 (highest)

Male

35475

46.6

46.5

47.2

46.4

46.1

Female

40578

53.4

53.5

52.8

53.6

53.9

65–69

24259

31.9

32.2

34.3

30.0

27.8

70–74

21797

28.7

27.7

28.6

30.5

29.8

75–79

16493

21.7

21.4

20.5

22.7

80 ≤

13504

17.8

18.8

16.6

16.8

Low (≤9)

35736

47.0

52.4

Middle (10–12)

24125

31.7

28.5

High (≥13)

12097

15.9

13.2

Other/Missing

4095

5.4

Low (<2.00)

29686

39.0

Middle (2.00–3.99)

23927

High (≥4.00)

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SC

40.6

40.5

33.6

M

35.2

33.7

16.0

19.4

20.3

5.8

5.0

4.9

5.5

38.3

38.4

40.1

31.5

29.9

33.0

32.9

31.4

7061

9.3

8.6

9.7

10.1

9.8

Missing

15379

20.2

22.1

19.0

18.6

18.7

Living situation

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IT

39.5

63849

84.0

85.2

85.1

82.1

79.5

8866

11.7

10.1

10.8

13.8

16.0

3338

4.4

4.7

4.1

4.1

4.5

52295

68.8

68.4

70.2

68.1

67.2

Widowed

16120

21.2

22.0

20.5

20.8

20.6

Divorced

2344

3.1

2.3

3.1

4.1

4.4

Not married

1369

1.8

1.4

1.6

2.4

3.1

Other/Missing

3925

5.2

5.9

4.7

4.5

4.8

Working

15667

20.6

21.1

20.6

19.6

20.1

Retired

41040

54.0

50.9

55.5

57.5

56.3

Never worked

8497

11.2

11.4

11.0

11.4

10.7

Missing

10849

14.3

16.7

12.9

11.5

12.8

Annual income (million yen)

U

Live with others

Missing
Marital status

RI

IN

MarriedAL

Live alone

ED

45.5

N

AN

U

18.2

G

Education (years)

24.2

O

Employment status

Health status

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Age (years)

Sociodemographics

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Sex

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39.4

39.2

39.4

39.3

39.8

Diabetes mellitus (Yes)

9640

12.7

12.1

13.1

13.2

13.0

Hearing loss (Yes)

5573

7.3

7.9

6.9

6.9

7.1

Heart disease (yes)

9052

11.9

11.6

12.1

12.7

11.6

Stroke (Yes)

1025

1.3

1.4

1.3

1.4

1.2

Non-depressed (GDS<5)

45029

59.2

58.4

60.1

59.8

59.3

Depressed (GDS≥5)

17245

22.7

23.0

22.9

22.4

21.5

Missing

13779

18.1

18.6

17.1

17.8

19.2

Fully capable

28617

37.6

37.1

39.1

37.7

35.9

Less capable

37836

49.7

49.9

49.4

49.6

50.3

Missing

9600

12.6

13.0

11.6

12.7

13.8

No

45269

59.5

58.6

60.3

60.0

60.4

Yes

24978

32.8

33.8

32.7

31.9

31.2

Missing

5806

7.6

7.7

7.0

8.1

8.4

SC

9314

12.2

11.8

8.7

8.9

5-9 years

11492

15.1

17.5

15.7

10.8

11.1

10-19 years

12043

15.8

18.2

17.3

11.4

10.0

≥20 years

ED
IT

14.9

16845

22.1

26.4

24.7

15.4

10.3

MissingNAN<5 years

26359

34.7

23.0

30.5

53.7

59.7

11514

15.1

16.3

15.0

13.9

13.1

11135

14.6

14.2

14.6

15.3

15.4

30-59min/day

24476

32.2

30.3

33.2

33.3

34.6

<30min/day

23728

31.2

31.9

30.9

30.9

29.8

G

Duration of residenceED

Cognitive complaints

U

Instrumental activities of daily living

RI
P

Depressive symptoms

5200

6.8

7.3

6.3

6.6

7.0

≥ 4 times/week

39479

51.9

48.7

53.5

55.2

54.6

1-3 times/week

27212

35.8

37.4

35.3

33.5

34.2

≤ 1 time/week

11116

14.6

17.2

13.3

12.1

12.2

Missing

4680

6.2

6.3

5.7

6.3

6.6

50001

65.7

79.3

69.0

44.3

39.4

U

Physical activity≥90min/day

AL

Walking timeIN

60-89min/day

RI

MissingO

Frequency of going out

Car use when going out
Car user

GDS = geriatric Depression Scale; Q = quartile.

T

29941

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Hypertension (Yes)

M

Under medical treatment

20

Table 3 Hazard ratios and 95% confidence intervals for association of dementia with neighborhood sidewalk
coverage in older Japanese adults by city scale (urban/rural), Japan Gerontological Evaluation Study,
2010-2013
Model 1aModel 2bModel 3c

Model 4d

Variable
95%CI

HR

95%CI

HR

95%CI

HR

95%CI

All (n=76,035)
Sidewalk coverage
Quartile 1 (lowest)
Quartile 2

1.00
0.78

Referent
0.66 - 0.91

1.00
0.81

Referent
0.69 - 0.94

1.00
0.82

Referent
0.71 - 0.96

1.00
0.81

Quartile 3

0.63

0.52 - 0.76

0.67

0.55 - 0.80

0.69

0.57 - 0.84

0.78

0.62 - 0.98

Quartile 4 (highest)

0.51

0.42 - 0.63

0.55

0.45 - 0.68

0.58

0.47 - 0.71

0.73

0.58 - 0.92

City scale (urban/rural)
Urban (n=47,364)
Sidewalk coverage
Quartile 1 (lowest)
Quartile 2

1.00
0.74

Referent
0.61 - 0.91

1.00
0.79

Referent
0.65 - 0.96

1.00
0.80

Quartile 3

0.58

0.46 - 0.72

0.65

0.52 - 0.82

Quartile 4 (highest)
Rural (n=28,689)
Sidewalk coverage
Quartile 1 (lowest)
Quartile 2

0.42

0.33 - 0.54

0.49

0.38 - 0.63

1.00
0.81

Referent
0.64 - 1.03

1.00
0.85

Referent
0.67 - 1.08

Quartile 3

1.13

0.71 - 1.81

1.12

Quartile 4 (highest)

1.27

T

HR

RI
P

SC
Referent
0.66 - 0.95

0.69

0.55 - 0.86

0.85

0.67 - 1.08

0.52

0.41 - 0.68

0.71

0.54 - 0.92

ED

U

1.00
0.79

1.00
0.87

Referent
0.68 - 1.11

1.00
1.09

Referent
0.81 - 1.45

0.70 - 1.80

1.13

0.70 - 1.80

0.80

0.49 - 1.30

1.28

0.91 - 1.81

1.27

0.89 - 1.80

0.73

0.52 - 1.02

ED
IT

M

AN

Referent
0.66 - 0.97

0.90 - 1.81

O

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IN

AL

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N

HR = hazard ratio; CI = confidence interval.
aModel 1 included individual neighborhood features and was adjusted for age and sex.
b
Model 2: Model 1 adjusted for sociodemographics (education, annual income, living situation, marital
status, employment status), health status (hypertension, diabetes mellitus, hearing loss, heart disease, stroke,
depressive symptoms, instrumental activities of daily living, cognitive complaints), and duration ofresidence.
cModel 3: Model 2 adjusted for physical activity (walking time, frequency of going out) and car use whengoing out.
dModel 4: Model 1 simultaneously adjusted for all types of neighborhood features (sidewalk, land slope,
numbers of hospitals, grocery stores, parks, railway stations, bus stops, education level, unemployment rate,
and area of school district) and individual factors (education, annual income, living situation, marital status,
employment status, health status [hypertension, diabetes mellitus, hearing loss, heart disease, stroke,
depressive symptoms, instrumental activities of daily living, cognitive complaints], and duration ofresidence).

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Referent
0.68 - 0.96

21

Figure 1. Methods of calculating sidewalk coverage. Sidewalk coverage (%) = (sidewalk area withinneighborhood unit / area of entire road within a neighborhood unit)×100. Area of entire road = road area
(grey area) + sidewalk area (yellow area). A-B) Example of neighborhood unit with high sidewalk coverage

T

and Aerial photograph: sidewalk coverage = 19.5%. C-D) Example of neighborhood unit with low sidewalk

sidewalk coverage and Aerial photograph: sidewalk coverage = 5.3%. Aerial photograph by The Geospatial

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Information Authority of Japan in 2010.

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Figure 2. Hazard ratios and 95% confidence intervals for association of dementia with neighborhoodMmeasures in older Japanese adults (n = 76,053) Model simultaneously adjusted for all types of neighborhood

EDfeatures (sidewalk, land slope, numbers of hospitals, grocery stores, parks, railway stations, bus stops,
education level, unemployment rate, and area of school district) and individual level factors (age, sex,EDIT

sociodemographics [education, annual income, living situation, marital status, employment status], healthstatus [hypertension, diabetes mellitus, hearing loss, heart disease, stroke, depressive symptoms,

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IN

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instrumental activities of daily living, cognitive complaints], and duration of residence).

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coverage and Aerial photograph: sidewalk coverage = 9.6%. E-F) Example of neighborhood unit with low

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