Associations between Active Mobility Index and objectively measured physical activity among older adults.

BACKGROUND: Active mobility index (AMI) is a questionnaire to assess going-out behavior with physical and social activity. The association between AMI scores and objectively measured physical activity (PA) in older adults is unknown. METHODS: Community-dwelling older adults aged ≥ 70 years participated in an examination and wore a triaxial accelerometer for seven or more days. The accelerometer measured the time of moderate-to-vigorous intensity PA (MVPA) and light intensity PA (LPA), and step counts. The AMI assessed life space (distance from the respondent's home: < 1, 1-10, or > 10 km) and related activities during the previous month. The AMI total, physical, and social scores were calculated. RESULTS: The analyzed data were 2499 participants (mean age: 75.5 ± 4.0 years; 54.4% female). Comparing PA among quartile groups of each AMI score, higher AMI total and physical score groups were associated with higher MVPA, LPA, and step counts (all P < 0.01). The Q4 group of AMI social scores showed significantly higher LPA and step counts than the Q1 and Q2 groups (P < 0.01). The logistic regression model showed higher score groups of AMI total and physical scores associated with increased adjusted odds ratio (aOR) of meeting recommended PA, ≥ 150 min/week of MVPA. CONCLUSIONS: Older adults with higher AMI total and physical scores, engaged in more PA. Future studies can use the present findings when estimating PA in older adults from AMI scores and examining the association between AMI scores and health outcomes.

Overlapping status of frailty and fear of falling: an elevated risk of incident disability in community-dwelling older adults.

BACKGROUND: Although overlapping frailty and fear of falling (FoF) are likely to increase with population aging, the combined effect of frailty and FoF on incident disability is not yet well understood. AIMS: The purpose of this study is to examine whether frailty combined with FoF increased the risk of incident disability in older adults. Our secondary purpose was to clarify the synergistic effect of frailty and FoF on incident disability. METHODS: This is a prospective study. Participants were 9372 older adults (mean age 73.5 years). Frailty status was assessed using the Japanese Cardiovascular Health Study index, and FoF was measured using two closed questions. Incident disability was prospectively monitored by their long-term care insurance records. RESULTS: During the follow-up period (mean duration 23.4 months), 487 (5.2%) participants developed disability. The proportion of incident disability linearly increased according to FoF level regardless of baseline frailty status. Frail participants with FoF had a higher risk of incident disability than those with frailty only or neither (adjusted hazard ratio [HR] 2.63, 95% confidence interval [CI] 1.95-3.54). Frailty in combination with excessive FoF further increased the risk of incident disability (adjusted HR 4.30, 95% CI 2.56-7.23) although no synergistic effect was observed (relative excessive risk due to interaction 1.69, 95% CI - 0.55, 3.93). CONCLUSION: The overlapping status of frailty and FoF, especially excessive FoF, increases the risk of incident disability in older adults.

Development of a Questionnaire to Evaluate Older Adults' Total Sedentary Time and Sedentary Time With Cognitive Activity.

This study aimed to develop a questionnaire for evaluating total sedentary time (ST) and ST with cognitive activity, and to examine the association between ST and cognitive function among Japanese older adults. The questionnaire to evaluate ST comprised 12 items regarding behavior in specific settings, including 8 items on ST with cognitive activity, in a usual week. Older adults aged ≥75 years who participated in a health check-up assessing cognitive function completed the developed questionnaire and subsequently wore an accelerometer and recorded a diary of ST with cognitive activity for a week as validity measures. Cognitive function was assessed with neuropsychological tests covering 4 domains: memory, attention, executive function, and processing speed. Fifty-two participants were included in the validity analysis. Spearman's correlation coefficient indicated fair-to-good agreement between the questionnaire-measured and the diary-measured time for ST with cognitive activity (r = 0.59, p < 0.001), but this was not the case for total ST. Bland-Altman plots showed that the questionnaire-measured total ST contained proportional bias (r = 0.51, p < 0.001). Multiple regression analysis (n = 49) showed longer questionnaire-measured ST with cognitive activity was significantly associated with better neuropsychological test scores (attention: ß = -0.38, p = 0.025; executive function: ß = -0.46, p = 0.003; and processing speed: ß = 0.31, p = 0.041), while total ST was not associated with better cognitive performance. The developed questionnaire showed acceptable validity to measure ST with cognitive activity, which was found to be protectively associated with cognitive function.

The Association of Sleep Habits and Advancing Age in Japanese Older Adults: Results from the National Center for Geriatrics and Gerontology Study of Geriatric Syndromes.

BACKGROUND: The association of sleep habits with "advancing age among older adults" is not fully understood. OBJECTIVES: The purpose of the present study was to examine the association of sleep habits with advancing age among community-dwelling older adults in Japan. METHODS: A total of 18,005 older people (mean age: 73.2 ± 6.0 years; 8,070 men and 9,935 women) from the National Center for Geriatrics and Gerontology Study of Geriatric Syndromes were analyzed. Participants were asked in face-to-face interviews about the times they usually go to bed, fall asleep, wake-up, and get up. The amount of time spent in bed and self-reported sleep duration were then calculated from the differences between these times. As other parameters, the subjects were also asked about sleep latency, time spent in bed after waking up, number of nocturnal awakenings, and duration of napping in a typical day. RESULTS: The results of the Jonckheere-Terpstra test showed that all sleep parameters shifted to an earlier time (going to bed, falling asleep, waking up, and getting out of bed), longer duration (sleep duration, time spent in bed, sleep latency, time spent in bed after waking up, and napping), or more nocturnal awakenings with advancing age (all p < 0.01). Among the men, the time of waking up was not significantly associated with age, while among the women, the time of getting up was not significantly associated with age. CONCLUSION: These results from a large cohort show the age-related trends of sleep habits in community-dwelling older adults in Japan. Our results revealed that a longer duration and earlier timing of sleep are associated with advancing age.

Identification of Disability Risk in Addition to Slow Walking Speed in Older Adults.

INTRODUCTION: A cutoff speed of 1.0 m/s for walking at a comfortable pace is critical for predicting future functional decline. However, some older adults with walking speeds below the cutoff point maintain an independent living. We aimed to identify specific predictors of disability development in older adults with slow walking speeds in contrast to those with a normal walking speed. METHODS: This prospective cohort study on 11,987 community-dwelling independent Japanese older adults (mean age, 73.6±5.4 years) was conducted between 2011 and 2015. Participants were classified into slow walking speed (comfortable walking speed slower than 1.0 m/s) and normal walking speed (speed of 1.0 m/s or faster) groups and followed up to assess disability incidence for 24 months after baseline assessments. Cox proportional hazards regression models were used to identify predictors of disability development in the slow and normal walking groups. RESULTS: Overall, 26.7% of participants had a slow walking speed. At follow-up, 11.3% and 2.7% of participants in the slow and normal walking groups, respectively, developed disability (p < 0.01). Cox regression models revealed that age (hazard ratio 1.08, 95% confidence interval 1.06-1.11), walking speed (0.10, 0.05-0.20), grip strength (0.97, 0.95-0.99), Parkinson's disease (4.16, 2.05-8.44), and Symbol Digit Substitution Test (SDST) score (0.98, 0.96-1.00) were significantly associated with disability incidence in the slow walking group. In the normal walking group, age, grip strength, cognition, 15-item Geriatric Depression Scale (GDS) score, and reduced participation in outdoor activity were significantly associated with disability incidence; however, there was no significant association with walking speed. CONCLUSIONS: Decreased walking speeds have considerably greater impact on disability development in older adults with a slow walking speed than in those with a normal walking speed. Health-care providers should explore modifiable factors for reducing walking speed; they should also encourage improvement of risk factors such as muscle weakness and depression to reduce disability risk in older adults with slow walking speeds.

Physical Frailty and Future Costs of Long-Term Care in Older Adults: Results from the NCGG-SGS.

INTRODUCTION: Frailty is associated with adverse outcomes, but few studies have determined associations between the frailty phenotype and measures of healthcare burden, including long-term care insurance (LTCI) costs, in older community-dwelling populations. OBJECTIVE: The aim of this study was to examine the association between frailty status and subsequent LTCI costs in Japanese community-dwelling older adults. METHODS: The prospective data were from a cohort study (National Center for Geriatrics and Gerontology-Study of Geriatric Syndromes [NCGG-SGS]). The participants were community-dwelling older adults (mean age 71.8 years, women 50.7%) participating in an NCGG-SGS baseline examination held between August 2011 and February 2012 in Obu, Japan (N = 4,539). At baseline, we assessed the physical frailty phenotype using the Japanese version of the CHS criteria and categorized it as robust, pre-frail, or frail. We also ascertained care-needs certification and total costs using long-term care services in Japan's public LTCI system during the 29 months. RESULTS: During the 29-month follow-up period, 239 participants (5.3%) required the LTCI system's care-needs certification and 163 participants (3.6%) used LTCI services. Participants classified as frail (odds ratio 5.85, 95% confidence interval 3.54-9.66) or pre-frail (2.40, 1.58-3.66) at the baseline assessment had an increased risk of requiring care-needs certification compared with robust participants. The mean total costs for LTCI services during the 29 months were ¥6,434 ($63.1) for robust, ¥19,324 ($189.5) for pre-frail, and ¥147,718 ($1,448.2) for frail participants (1 US dollar = 102 Japanese yen in July 2014). There were significantly higher costs associated with advancing frailty status. Individual frailty components (slowness, weakness, exhaustion, low activity, and weight loss) were also associated with higher total costs for using LTCI services. DISCUSSION/CONCLUSION: Frail community-dwelling older adults had a higher risk of requiring the LTCI system's care-needs certification and the subsequent total LTCI costs.

Car Accidents Associated with Physical Frailty and Cognitive Impairment.

INTRODUCTION: Age-related functional decline elevates the risk of car accidents. Whether specific cognitive impairments and physical frailty increase the risk of car accidents is still unclarified. OBJECTIVE: This study examines the association between car accidents, frailty, and cognitive function, owing to an increase in car accidents related to older adults. METHODS: Data were collected from 12,013 older adults (45.4% women, mean age: 71.7 years [min: 60, max: 96]) enrolled in the National Center for Geriatrics and Gerontology (NCGG) - Study of Geriatric Syndromes. A 2-year self-reported history of car accidents was assessed. The Japanese cardiovascular health study index was used as the criterion and included the following components of frailty: shrinking, weakness, exhaustion, low activity, and slowness. "Frailty" was assigned a value of 1 or more based on these components. Cognitive function was assessed using the NCGG Functional Assessment Tool, and cognitive impairment was assessed using a standardized value. RESULTS: Of the participants, 1,117 (9.3%) had a car accident history. The proportions of the frailty components' applicability were observed in the car accidents group compared to the non-car accidents group: shrinking (p = 0.006), exhaustion (p = 0.031), low activity (p = 0.034), and slowness (p = 0.030), but not weakness (p = 0.452). The proportion of cognitive impairment in executive function was also higher in the car accidents group (p = 0.011). A logistic regression analysis showed that both frailty (OR 1.26, 95% CI 1.11-1.43; p < 0.001) and cognitive impairment (OR 1.26, 95% CI 1.11-1.43, p < 0.001) are associated with car accidents. DISCUSSION: This study's findings contribute to enhancing the utility of risk assessments for older drivers. Further study is required to clarify the risk of car accidents.

Spatio-temporal gait variables predicted incident disability.

BACKGROUND: Assessing the risk of disability in older adults is important for developing prevention and intervention strategies to decrease potential disability and dependency. The aim of this study was to examine the association between spatio-temporal gait variables and disability among older adults. METHODS: We conducted a prospective study in a community setting. We collected data from 4121 subjects (≥ 65 years, mean age: 71.9 years). Gait speed, cadence, stride length, and stride length variability were measured at baseline. Participants were instructed to walk at their usual pace along a 6.4 m straight and flat path on which an electronic gait measuring device was mounted at mid 2.4 m. Subsequent disability was confirmed from long-term care insurance records. RESULTS: During follow-up duration (mean: 49.6 months), 425 participants had incident disability. The cut-off value to detect high or low function in each gait variable was determined using the Youden index. Cox proportional hazard analysis adjusted for covariates showed that disability was significantly predicted by low function in each gait variable using the cut-off values: gait speed (hazard ratio [95% confidential intervals]: 2.06 [1.65-2.57]), stride length (2.17 [1.72-2.73]), cadence (1.49 [1.20-1.86], and stride length variability (1.46 [1.19-1.80]). The number of gait variables that scored in the low function category were also cumulatively related to subsequent disability (p < .001). CONCLUSIONS: This study revealed that spatio-temporal gait variables had a significant predictive value for incident disability. Multifaceted and quantitative gait analysis can contribute to disability risk assessment.

Sleep condition and cognitive decline in Japanese community-dwelling older people: Data from a 4-year longitudinal study.

This study examined whether sleep duration and excessive daytime sleepiness (EDS) are related to cognitive decline among community-dwelling older adults with intact cognition at baseline, using 4-year longitudinal data. A total of 3,151 community-dwelling older individuals aged ≥65 years were studied. They were assessed for cognitive function, including memory, attention, executive function and processing speed. Cognitive impairment was defined based on a score >1.5 standard deviations below the age- and education-specific mean. Cognitive decline was defined in one or more cognitive tests at follow-up. Self-reported sleep duration (short, ≤6.0 hr; medium, 6.1-8.9 hr; long, ≥9.0 hr) and EDS at first-wave examination were assessed and logistic regression analyses were used to examine the associations of sleep duration and EDS with cognitive status at second-wave examination. The incidence of cognitive decline differed significantly among the sleep-duration groups (short, 15.9%; medium, 11.9%; long, 20.1%; p = 0.001). The prevalence of having EDS was 13.1%, which was associated with a higher rate of cognitive decline than having no EDS (18.9% vs. 12.5%, p = 0.004). Long sleep duration compared with medium sleep duration (OR, 1.50; 95% CI, 1.05-2.13) and EDS (1.43; 1.01-2.03) independently impacted the incidence of cognitive decline. The results were similar after multiple imputations (long, 1.68, 1.12-2.52; EDS, 1.55, 1.05-2.29). In conclusion, our study revealed that both long sleep duration and EDS were independent risk factors associated with cognitive decline after 4 years among older adults.

Effects of Driving Skill Training on Safe Driving in Older Adults with Mild Cognitive Impairment.

BACKGROUND: Driving cessation is strongly associated with adverse health outcomes in the older adults. Although there were numerous documentations of driving rehabilitation in disabled adults, the effects of interventions on safe driving were not clear in older adults with cognitive impairment who had low driving skills. OBJECTIVE: This randomized controlled trial was designed to determine whether a safe driving skill program consisting of classroom and on-road training could enhance driving performance of older drivers with cognitive impairment in Japan. METHODS: A total of 160 community-living older drivers participated in the randomized controlled trial with blinded endpoint assessment. Participants randomized to intervention underwent 10 1-h classroom sessions and 10 1-h on-road sessions focused on common problem areas of older drivers. Controls received 1 classroom education. On-road driving performance was assessed by certified driving school instructors in a driving school. The participants carried out dynamic vision and cognitive performance tests. RESULTS: One hundred and forty-six (intervention group, n = 71) subjects completed the 3-month follow-up. Mean adherence to classroom-based vision training and driving simulator training and on-road training programs, including the 71 participants, was 99.0 ± 6.4 and 99.0 ± 7.2%, respectively. Regarding the safe driving skill score, there were group × time interactions (p < 0.01) indicating benefits of the intervention over time. Although there were no significant group × time interactions in cognitive tests, dynamic vision showed group × time interactions (p < 0.01). CONCLUSION: The driving skill program significantly improved safe driving performance in older adults with cognitive impairment who were at a potentially high risk of a car accident.

Behavioral protective factors of increased depressive symptoms in community-dwelling older adults: A prospective cohort study.

BACKGROUND: It remains unclear what kinds of behavior prevent the development of geriatric depression. This study aimed to elucidate behavioral predictors of increased depressive symptoms in older adults focusing on gender differences. METHODS: A total of 3106 community-dwelling older people aged older than or equal to 65 years without depressive symptoms at baseline participated. The 15-item Geriatric Depression Scale was used to assess depressive symptoms with a score of 6 or more at baseline and 15 month follow-up. Behavioral status was investigated by using dichotomous questions about the aspects of physical, cognitive, and social activities. Each category included 3 specific items. Demographic data and other potential confounding factors were also assessed. RESULTS: In the 15 month follow-up survey, 239 participants (7.7%) reported increased depressive symptoms. Multiple logistic regression analysis indicated that engagement in light physical exercise (odds ratio = 0.74, 95%, CI = 0.56-0.98), taking enrichment lessons (0.62, 0.46-0.85), using a personal computer (0.68, 0.48-0.97), participation in events at the community center (0.54, 0.40-0.72), and attending a community meeting (0.69, 0.52-0.92) were independently associated with lower risk of increased depressive symptoms. In a separate analysis for each gender, significant odds ratios of using a personal computer were observed in men, whereas significant odds ratios of light physical exercise, participation in events at the community center, and attending a community meeting were observed in women. CONCLUSIONS: Light physical exercise, taking lessons, usage of a computer, and participation in community events showed protective effects against depressive symptoms. However, the significance of each behavioral factor may vary according to gender.

Impact of fear of falling and fall history on disability incidence among older adults: Prospective cohort study.

OBJECTIVE: Fear of falling (FOF) is a major health problem for older adults, present not just in fallers, but also nonfallers. This study examined the impact of FOF and fall history on disability incidence among community-dwelling older adults from a prospective cohort study. METHODS: A total of 5104 older adults living in community settings participated in baseline assessment and were followed up for about 4 years (median 52 mo, range 49-55 mo). At baseline, participants were assessed the presence of FOF and their fall history, and divided into 4 groups: Fall (-) FOF (-), Fall (+) FOF (-), Fall (-) FOF (+), and Fall (+) FOF (+). Disability incidence was defined as national long-term care insurance certification for personal support or care. RESULTS: During the follow-up period, 429 participants (9.9%) were newly certified as having a disability and needing personal support for long-term care insurance. Fall (-) FOF (+) group and Fall (+) FOF (+) group showed a significantly higher risk of disability incidence than Fall (-) FOF (-) group even after adjusting for covariates (Fall (-) FOF (+): hazard ratio 1.28, 95% confidence interval, 1.01-1.62, Fall (+) FOF (+): hazard ratio 1.44, 95% confidence interval, 1.05-1.98). CONCLUSIONS: Fear of falling could be a simple and useful predictor of disability incidence in community-dwelling older adults. Identifying and decreasing fall risk factors may prevent fall-related injuries, but excessive FOF may be associated with increased risk of disability incidence.

Associations of Near-Miss Traffic Incidents with Attention and Executive Function among Older Japanese Drivers.

BACKGROUND: Attention and executive function may play an important role in ensuring safe driving as they involve paying attention to complex information and making an instantaneous judgment during driving. We hypothesized that poor performance in attention and executive function may increase the risk of near-miss incidents among older drivers. OBJECTIVE: The aim of this study was to examine associations of current experience of near-miss traffic incidents with attention and executive function among older Japanese drivers. METHODS: The study included 3,421 general older drivers (mean age: 71.7 ± 4.9 years; 56.3% men) with a valid driver's license who were currently driving at least once per week and who had participated in a community-based cohort study between February 2015 and August 2016. The participants were asked about their experiences of near-miss traffic incidents in 10 situations that had almost happened during driving in the previous year. RESULTS: Of the 3,421 older drivers, 1,840 (53.8%) had experienced near-miss incidents during driving in the previous year at least once. Male sex (OR 1.46, 95% CI 1.27-1.69) and high driving frequency (OR 1.11, 95% CI 1.07-1.15) were significantly associated with the current experience of near-miss traffic incidents when the overall data were analyzed. In young-old drivers aged 65-74 years, poor performance in attention as assessed by the Trail Making Test-part A (OR 1.45, 95% CI 1.05-2.00) was significantly associated with near-miss traffic incidents. CONCLUSION: Male sex, high driving frequency, and poor performance in attention (in young-old drivers) were associated with near-miss traffic incidents. Improvement in attention may play a role in decreasing the risk of traffic accidents among older drivers.

Subjective Memory Complaints are Associated with Incident Dementia in Cognitively Intact Older People, but Not in Those with Cognitive Impairment: A 24-Month Prospective Cohort Study.

OBJECTIVE: Although subjective memory complaints (SMCs) are considered a risk factor for incident dementia in older people, the effect might differ based on cognitive function. The aim of the present study was to investigate whether the effect of SMCs on the incidence of dementia in older people differed based on cognitive function. DESIGN: A 24-month follow-up cohort study. SETTING: Japanese community. PARTICIPANTS: Prospective, longitudinal data for incident dementia were collected for 3,672 participants (mean age: 71.7 years; 46.5% men) for up to 24 months. MEASUREMENTS: Baseline measurements included covariates for incident dementia, SMCs, and cognitive function. Associations between SMCs, cognitive impairment, and incident dementia were examined using Cox proportional hazards models. RESULTS: Incidences of dementia in the cognitively intact without SMC, cognitively intact with SMC, cognitive impairment without SMC, and cognitive impairment with SMC groups were 0.3%, 1.8%, 3.4%, and 4.8%, respectively. In the cognitively intact participants, SMCs were associated with a significantly higher risk of dementia (hazard ratio [HR]: 4.95, 95% confidence interval [CI]: 1.52-16.11, p = 0.008). Incident dementia with cognitive impairment was not significantly different based on SMC presence (p = 0.527). Participants with cognitive impairment in multiple domains had a significantly higher risk of incident dementia (HR: 2.07, 95% CI: 1.01-4.24, p = 0.046) CONCLUSION: SMCs were related with dementia in cognitively intact older people, but not in those with cognitive impairment.Multiple domains of cognitive impairment were associated with a higher risk of incident dementia.

Prospective associations between sedentary behaviour and incident depressive symptoms in older people: a 15-month longitudinal cohort study.

OBJECTIVE: This study aimed to investigate whether sitting time, as a form of sedentary behaviour, is related to incident depressive symptoms in older people. METHODS: This study included 3503 participants (mean age 71.7 years, 50.1% female) from the 'Obu Study of Health Promotion for the Elderly' cohort study. At baseline and then 15 months later, the participants reported their status of depressive symptoms using the 15-item Geriatric Depression Scale. During the baseline assessment, the participants were also asked about their sedentary behaviour on weekdays over the past 7 days and, from there, categorized into three groups (<240, 240-480, ≥480 min/day). Demographic data and the other health behaviours were also assessed at the baseline. RESULTS: Cross-sectional analysis revealed that 437 participants (12.0%) had depressive symptoms. In a prospective analysis, the logistic regression model revealed that the odds ratio for depressive symptom incidence was higher in participants who, at baseline, spent 480 min or more per day sitting (1.636; 95% confidence interval [CI] 1.015 to 2.636, p = 0.043), and in those who spent 240-480 min (1.605; 95% CI 1.085 to 2.375, p = 0.018) in comparison with those who spent less than 240 min. CONCLUSIONS: Sedentary behaviour significantly affects the risk of incident depressive symptoms. Further research is needed to develop an intervention strategy to manage depressive symptoms, as the second most common cause of burden of disease among older adults. Copyright © 2016 John Wiley & Sons, Ltd.

Reduced prefrontal oxygenation in mild cognitive impairment during memory retrieval.

BACKGROUND: Memory impairment is considered a hallmark of amnestic mild cognitive impairment (aMCI) and dementia. Emerging evidence suggests that the prefrontal lobe is required to maintain memory functions. The purpose of this study was to clarify whether older adults with aMCI have decreased prefrontal oxygenation during memory encoding and retrieval compared with age-matched healthy older adults, using multi-channel near-infrared spectroscopy. METHODS: We examined 64 older adults with aMCI (mean 71.8 years) and 66 cognitively healthy control subjects comparable in age and gender (mean 71.7 years). The concentration of oxy-hemoglobin, which is a reliable biomarker of changes in regional cerebral blood flow, was measured in the prefrontal cortex during encoding and delayed retrieval of a list of 10 target words. Task performance was evaluated as average number of correct answers in the retrieval task. RESULTS: Subjects with aMCI showed reduced activation in the bilateral dorsolateral cortex (approximately Brodmann area 9) and provided fewer correct answers in the retrieval period than control subjects. There were no significant differences during encoding. CONCLUSIONS: Reduced activation in the dorsolateral cortex during retrieval may cause deficits in memory performance, which may be used as a marker of aMCI. Further studies are required to examine the predictive validity of this decreased activation pattern for the incidence of Alzheimer's disease.

Driving and Incidence of Functional Limitation in Older People: A Prospective Population-Based Study.

BACKGROUND: Many studies have examined the negative social and health consequences of driving cessation in later life. However, whether the transition to driving cessation results in the incidence of functional limitation in older people remains unclear. OBJECTIVE: The aim of this study was to examine whether driving cessation was associated with the incidence of functional limitation in older Japanese individuals. METHODS: The study included 3,556 participants (mean age: 71.5 ± 5.3 years, 50.2% women) enrolled in the 'Obu Study of Health Promotion for the Elderly' cohort study between August 2011 and February 2012. The participants were classified into three groups according to their driving status: driving, driving cessation, and nondriving. We assessed new incidence of functional limitation over a 24- month period and examined several confounding factors. RESULTS: The incidence rates for functional limitation in the driving, driving cessation, and nondriving groups were 0.9, 10.8, and 5.6%, respectively (p < 0.001). The fully adjusted Cox proportional hazard model showed that hazard ratios (HRs) for functional limitation in nondrivers [HR: 2.37, 95% confidence interval (CI): 1.27-4.44] and those who had ceased driving (HR: 7.80, 95% CI: 2.61-23.36) were significantly higher relative to those observed in current drivers. CONCLUSION: Driving cessation exerted a strong impact on the risk of functional limitation. Further study is required to determine appropriate intervention strategies to help older people to maintain the abilities required for safe driving and delay the functional limitation associated with driving cessation.

[Abdominal obesity mediates the association between a low physical activity and a decline in gait speed in community-dwelling elderly people: A cross-sectional study].

AIM: A low physical activity leads to obesity and a decline in the physical function. The aim of this cross-sectional study was to examine whether the association between a low physical activity and low physical function was mediated by obesity. METHODS: A total of 73 community-dwelling elderly people participated in this study. The analysis included 56 participants without knee and hip osteoarthritis, low cognitive function (the Mini Mental State Examination score <24) and rheumatoid arthritis (mean age±SD: 73.3±4.1, female: 50%). The daily step count was collected as a measure of physical activity by a single axial accelerometer. The physical function was measured by the gait speed. Obesity was measured by the body mass index and waist circumference. To assess whether the association between the physical activity and physical function was mediated by obesity, linear regression models were fitted according to Baron and Kenny procedures for a mediation analysis. A p value <0.05 was considered to be statistically significant. RESULTS: The body mass index did not act as a mediator in the association between the physical activity and gait speed, whereas the waist circumference acted as a full mediator in the association between the physical activity and gait speed. CONCLUSION: An increased waist circumference mediates the association between a low physical activity and a low physical function in community-dwelling elderly people.

Olfactory identification and cognitive performance in community-dwelling older adults with mild cognitive impairment.

Olfactory impairment constitutes one of the earliest signs of Alzheimer's disease in older adults with mild cognitive impairment. We investigated which aspects of neuropsychological measures are correlated with olfactory identification performance among older adults with mild cognitive impairment. Total of 220 participants with mild cognitive impairment (mean age 71.7 years) were examined. Odor identification was assessed using the Open Essence test. Participants underwent comprehensive neurocognitive evaluation, including measures of verbal memory, visual memory, working memory, attention/executive function, and processing speed. We examined associations between olfactory function and cognitive performance scores. Participants with severe hyposmia exhibited significantly poor verbal and visual memory performance, attention/executive function, and slower processing speed scores compared with those without severe hyposmia. In multivariable logistic regression models, better performance scores on verbal and visual memory were significantly associated with decreased likelihood of severe hyposmia after adjusting for age, sex, education, and other cognitive performance scores. These findings suggest that olfactory impairment might be more closely associated with memory loss compared with other aspects of cognitive functioning in mild cognitive impairment subjects.

Cognitive function and gait speed under normal and dual-task walking among older adults with mild cognitive impairment.

BACKGROUND: Gait ability and cognitive function are interrelated during both normal walking (NW) and dual-task walking (DTW), and gait ability is thus adversely affected by cognitive impairment in both situations. However, this association is insufficiently understood in people with mild cognitive impairment (MCI). Here, we conducted a study with MCI participants, to examine whether the association depends on walking conditions and MCI subtypes. METHODS: We classified 389 elderly adults into amnestic MCI (n = 191) and non-amnestic MCI (n = 198), assessed their cognitive functions, and administered gait experiments under NW and DTW conditions. Gait ability was defined as gait speed. Five aspects of cognitive function were assessed: processing speed, executive function, working memory, verbal memory, and visual memory. RESULTS: Regression analysis adjusted for covariates showed a significant association between cognitive functions and gait speed. Processing speed and executive function correlated with gait speed during both NW and DTW (p < .05). Gait speed during DTW was also significantly associated with working memory (p < .001). Visual memory was associated during NW and DTW, particularly for amnestic MCI participants (p < .05). CONCLUSIONS: Our findings support the idea that the association between gait speed and cognitive function depends on walking condition and MCI subtypes. Additional studies are necessary to determine the neural basis for the disruption in gait control in older adults with MCI.