Kenta Okuyama

Dr. Kenta Okuyama

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Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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AMAtsushi Motohiro
Atsushi Motohiro
TATakafumi Abe
Takafumi Abe
KOKenta Okuyama
Kenta Okuyama
KOKeiichi Onoda
Keiichi Onoda
TITomoko Ito
Tomoko Ito
SKShunichi Kumakura
Shunichi Kumakura
Although neighborhood environmental factors have been found to be associated with cognitive decline, few longitudinal studies have focused on their effect on older adults living in rural areas. This longitudinal study aimed to investigate the role of neighborhood environmental factors in cognitive decline among rural older adults. The data of 485 older adults aged ≥60 years who were living in Unnan City in Japan and had participated in two surveys conducted between 2014 and 2018 were analyzed. Cognitive function was assessed using the Cognitive Assessment for Dementia, iPad version 2. Elevation, hilliness, residential density, and proximity to a community center were determined using geographic information system. We applied a generalized estimating equation with odds ratios (OR) and 95% confidence intervals (CIs) of cognitive decline in the quartiles of neighborhood environmental factors. A total of 56 (11.6%) participants demonstrated a decrease in cognitive function at follow up. Elevation (adjusted OR 2.58, 95% CI (1.39, 4.77) for Q4 vs. Q1) and hilliness (adjusted OR 1.93, 95% CI (1.03, 3.63) for Q4 vs. Q1) were associated with a higher likelihood of cognitive decline. The second quartiles of residential density showed significantly lower likelihoods of cognitive decline compared with the first quartiles (adjusted OR 0.36, 95% CI (0.19, 0.71) for Q2 vs. Q1). Thus, an elevated hilly environment and residential density predicted cognitive decline among rural older adults.

25 November 2020 in International Journal of Health Geographics
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Journal Article
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KOKenta Okuyama
Kenta Okuyama
TATakafumi Abe
Takafumi Abe
SYShozo Yano
Shozo Yano
KSKristina Sundquist
Kristina Sundquist
TNToru Nabika
Toru Nabika
Background: Sarcopenia, resulting from loss of muscle mass and function, is highly prevalent in the ageing societies and is associated with risk of falls, frailty, loss of independence, and mortality. It is important to identify environmental risk factors, so that evidence-based interventions to prevent sarcopenia can be implemented at the population level. This study aimed to examine the potential effect of several objectively measured neighborhood environmental factors on longitudinal change of muscle mass and function among older adults living in rural Japanese towns where the population is ageing. Methods: This study was based on data from the Shimane CoHRE Study conducted by the Center for Community-based Healthcare Research and Education (CoHRE) at Shimane University in 3 rural towns in the Shimane Prefecture, Japan. Subjects older than 60 years, who participated in an annual health examination in 2016 and any follow-up years until 2019, i.e., 4 possible time points in total, were included (n = 2526). The skeletal muscle mass index (SMI) and grip strength were assessed objectively for each year as a measure of muscle mass and function, respectively. Neighborhood environmental factors, i.e., hilliness, bus stop density, intersection density, residential density, and distance to a community center were measured by geographic information systems (GIS). Linear mixed models were applied to examine the potential effect of each neighborhood environmental factor on the change of SMI and grip strength over time. Results: Males living far from community centers had a less pronounced decline in SMI compared to those living close to community centers. Females living in areas with higher residential density had a less pronounced decline in grip strength compared to those living in areas with lower residential density. Conclusions: Neighborhood environmental factors had limited effects on change of SMI and grip strength among rural older adults within the 3 years follow up. Further long-term follow up studies are necessary by also taking into account other modifiable neighborhood environmental factors.

4 March 2019 in PLOS ONE
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KOKenta Okuyama
Kenta Okuyama
KAKenju Akai
Kenju Akai
TKTsunetaka Kijima
Tsunetaka Kijima
TATakafumi Abe
Takafumi Abe
MIMinoru Isomura
Minoru Isomura
TNToru Nabika
Toru Nabika
Although primary care access is known to be an important factor when seeking care, its effect on individual health risk has not been evaluated by an appropriate spatial measure. This study examined whether geographic accessibility to primary care assessed by a sophisticated form of spatial measure is associated with a risk of hypertension and its treatment status among Japanese people in rural areas, where primary care is not yet established as specialization. We used an enhanced two-step floating catchment area method to calculate the neighborhood residential unit-level primary and secondary care accessibility for 52,029 subjects who participated in the 2015 annual health checkup held at 15 cities in Shimane Prefecture. Their hypertension level and treatment status were examined cross-sectionally with their neighborhood primary care and secondary care accessibility (computed with two separate distance-decay weight: slow and quick) by multivariable logistic regression controlling for demographics and neighborhood income level. The findings showed that greater geographic accessibility to primary care was associated with a decreased risk of hypertension in both slow and quick distance-decay weight, odds ratio (OR) = 0.989 (95% Confidence Interval (CI) = 0.984, 0.994), OR = 0.989 (95%CI = 0.984, 0.993), respectively. On the other hand, better secondary care accessibility was associated with an increased risk of hypertension and untreated hypertension; however, the effect of secondary care was mitigated by the effect of primary care accessibility in both slow and quick distance-decay model, hypertension: OR = 0.974 (95% CI = 0.957, 0.991), OR = 0.981 (95%CI = 0.970, 0.991), untreated hypertension: OR = 0.970 (95%CI = 0.944, 0.996), OR = 0.975 (95%CI = 0.959, 0.991), respectively. In addition, the results revealed that young and fit people were at a higher risk of untreated hypertension, which is a unique finding in the context of the Japanese healthcare system. Our findings indicate the importance of primary care even in Japan, where it is not yet established, and also emphasize the need for a culturally specific perspective in health equity.

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GAGaru A
Garu A
SYShozo Yano
Shozo Yano
ASAbdullah Sheikh
Abdullah Sheikh
AYAorigele Yu
Aorigele Yu
KOKenta Okuyama
Kenta Okuyama
ANAtsushi Nagai
Atsushi Nagai
Fragility fractures (FFxs), which are a common musculoskeletal injury in older adults, is associated with an increased frequency of falls. Both FFxs and falls may result from drugs, habits, and co-occurring diseases. We aimed to evaluate the effects of various diseases on the risk of FFx. This retrospective study included 1420 individuals aged ≥60 years. We evaluated the history of clinical FFx and diseases using a detailed questionnaire and a health examination. The risk of comorbidities was assessed using the Age-Adjusted Charlson Comorbidity (AAC) Index. We performed binary logistic regression analysis to determine the risk of FFx and falls after adjusting for covariates. In elderly men, the incidence of FFx positively correlated with rheumatoid arthritis and parent’s hip fracture. For elderly women, the incidence of FFx positively correlated with rheumatoid arthritis and antihypertensive drugs but was inversely associated with dyslipidemia and antilipidemic drugs. The FFX risk of older adults with an AAC Index ≥6 was higher than those with an AAC Index of 1–3. In addition, the AAC Index and falls were independently and strongly associated with a higher risk of FFx. Taken together, multimorbidity increases the risk of clinical FFx independent of falls in the community-dwelling elderly population.

1 January 2017 in Transportation Research Record: Journal of the Transportation Research Board
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CMCarolyn McAndrews
Carolyn McAndrews
KOKenta Okuyama
Kenta Okuyama
JLJill Litt
Jill Litt
Lessons derived from the urban experience of bicycling may not be broadly supportive of bicycling in rural, small, and low-density (RSLD) places because of differences in built environment, social, and political contexts. In this study, the hypothesis that bicycling was primarily an urban activity was investigated. Binary logistic regression was used to compare the frequency of bicycling and the population characteristics of bicyclists across urban and RSLD places. Multiple operational definitions of urban–rural continua were used to examine whether the results were sensitive to how RSLD places were defined. The data for bicycling were from the 2009 National Household Travel Survey, which was designed to represent the population of the United States. Bicycling was found to be primarily, but not exclusively, an urban activity. Moreover, women and youths were more likely to bicycle in RSLD places compared with urban places. These findings suggest that an urban perspective on bicycling could limit the success of initiatives aiming to increase the diversity of populations that bicycle. Developing a base of empirical knowledge of bicycling in RSLD places is a necessary step toward developing more inclusive and effective multimodal transportation strategies.

19 May 2020 in International Journal of Obesity
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KOKenta Okuyama
Kenta Okuyama
XLXinjun Li
Xinjun Li
TATakafumi Abe
Takafumi Abe
THTsuyoshi Hamano
Tsuyoshi Hamano
PFPaul W. Franks
Paul W. Franks
KSKristina Sundquist
Kristina Sundquist