Global brain atrophy is associated with physical performance and the risk of falls in older adults with cognitive impairment.

AIM: Falls are common in patients with cognitive disorder. The purpose of this study was to determine whether global brain atrophy is associated with cognitive function, physical performance and fall incidents in older adults with mild cognitive disorder. METHODS: A total of 31 older adults with mild cognitive disorders (mean age 78.9 ± 7.3 years) were studied, and 10 of them had experienced falls and the others had not in the past 1 year. Cognitive function and physical performance were measured in these patients. Global brain atrophy was determined by the Voxel-Based Specific Regional Analysis System for Alzheimer's Disease software. RESULTS: Fallers showed significantly worse scores than the non-fallers in the Global Brain Atrophy Index, Clock Drawing Test (CDT), Verbal Fluency Test (animal), maximum walking time and Timed Up & Go (TUG) Test. The Global Brain Atrophy Index was correlated with the Verbal Fluency Test (animal; r = -0.522), the Verbal Fluency Test with letter (ka; r = -0.337), CDT (r = -0.547), TUG (r = 0.276) and Five Chair Stands Test (r = 0.303) by age-adjusted correlation analyses. Stepwise regression analysis showed that the Global Brain Atrophy Index (ß = 1.265, 95% CI 1.022-1.567) was a significant and independent determinant of falls (R(2) = 0.356, P = 0.003). CONCLUSION: Global brain atrophy might be indicated as one of the risk factors for falls in older adults with mild cognitive disorders.

Effect of the muscle coactivation during quiet standing on dynamic postural control in older adults.

Recently, several studies have reported that muscle coactivation during static postural control increases with aging. Although greater muscle coactivation during quiet standing enhances joint stability, it may reduce dynamic postural control. The purpose of this study was to investigate the effect of muscle coactivation during quiet standing on dynamic postural control. Seventy older adults (81.1 ± 7.2 years) participated in this study. Static postural control was evaluated by postural sway during quiet standing, whereas dynamic postural control was evaluated by the functional reach and functional stability boundary tests. Electromyography of the soleus (SOL) and tibialis anterior (TA) was recorded during quiet standing, then coactivation was evaluated using the co-contraction index (CI). We used multiple regression analysis to identify the effect of muscle coactivation during standing on each dynamic postural control variable using age, body mass index (BMI), gender, timed up and go (TUG) tests, postural sway area and CI during quiet standing as independent variables. TUG tests were added to the model to evaluate the effect of functional mobility on dynamic postural control with a fixed base. The multiple regression analysis revealed that CI during standing was significantly related to all of the dynamic postural control tasks. The functional reach distance was significantly associated with CI during standing, age and TUG (p<0.05). The functional stability boundary for forward and backward were associated only with CI during standing (p<0.05). This study revealed that muscle coactivation during quiet standing is independently associated with dynamic postural control abilities.

Impaired choice stepping in response to a visual-spatial attention demanding task among older adults at high risk of falling: a pilot study.

BACKGROUND AND AIMS: Impairment in visual-spatial attention can cause difficulties in planning and guiding movements, leading to falls in older adults .The purpose of this study was to investigate the relationship between visual-spatial attention during movement and the risk of falling in older adults. METHODS: Thirty-six elderly volunteers (mean age, 73.2±6.8 years) performed a rapid choice stepping task in response to flanker task stimuli. Step errors in congruent or incongruent conditions were recorded as a measure of the accuracy of choice stepping. Four clinical measurements were also assessed: 10-min walking time, timed up and go test, functional reach test and 5- chair stand test. RESULTS: High-risk (HR) participants showed a significantly higher rate of step errors in the incongruent condition than low-risk (LR) ones (HR: 55.5%, LR: 18.5%; p =0.032). Step error in the incongruent condition [odds ratio (OR)=5.5; p=0.041] was the only independent variable which remained significant in the final step of the logistic regression model. CONCLUSION: Impaired choice stepping in response to a visual-spatial attention-demanding task was associated with the risk of falling in older adults.

Reaction time for peripheral visual field increases during stepping task in older adults.

BACKGROUND AND AIMS: For safe locomotion, visual attention must be directed toward not only the central visual field but also the peripheral visual field. This study explored the effect of stepping task on reaction time for the central and peripheral visual fields in young and older adults. METHODS: Nine older (mean age 83.8±6.8 years) and 11 young adults (mean age 22.9±1.3 years) participated in this study. Reaction times to press a handheld button in response to stimuli for the central and peripheral visual fields were measured in static standing and stepping task conditions. RESULTS: Vision angle and condition were significantly associated with reaction time in the older group (p=0.006), while reaction time in the young group was affected by vision angle only. Reaction times for visual stimulus at a 45° vision angle were significantly longer in the older group in stepping task conditions than in static standing conditions. CONCLUSIONS: Effective visual field may diminish during lightly loaded exercise in older adults.

Reliability and validity of gait analysis by android-based smartphone.

Smartphones are very common devices in daily life that have a built-in tri-axial accelerometer. Similar to previously developed accelerometers, smartphones can be used to assess gait patterns. However, few gait analyses have been performed using smartphones, and their reliability and validity have not been evaluated yet. The purpose of this study was to evaluate the reliability and validity of a smartphone accelerometer. Thirty healthy young adults participated in this study. They walked 20 m at their preferred speeds, and their trunk accelerations were measured using a smartphone and a tri-axial accelerometer that was secured over the L3 spinous process. We developed a gait analysis application and installed it in the smartphone to measure the acceleration. After signal processing, we calculated the gait parameters of each measurement terminal: peak frequency (PF), root mean square (RMS), autocorrelation peak (AC), and coefficient of variance (CV) of the acceleration peak intervals. Remarkable consistency was observed in the test-retest reliability of all the gait parameter results obtained by the smartphone (p<0.001). All the gait parameter results obtained by the smartphone showed statistically significant and considerable correlations with the same parameter results obtained by the tri-axial accelerometer (PF r=0.99, RMS r=0.89, AC r=0.85, CV r=0.82; p<0.01). Our study indicates that the smartphone with gait analysis application used in this study has the capacity to quantify gait parameters with a degree of accuracy that is comparable to that of the tri-axial accelerometer.

Effects of balance training on muscle coactivation during postural control in older adults: a randomized controlled trial.

BACKGROUND: Recently, several studies have reported age-associated increases in muscle coactivation during postural control. A rigid posture induced by strong muscle coactivation reduces the degree of freedom to be organized by the postural control system. The purpose of this study was to clarify the effect of balance training on muscle coactivation during postural control in older adults. METHODS: Forty-eight subjects were randomized into an intervention (mean age: 81.0 ± 6.9 years) and a control group (mean age: 81.6 ± 6.4 years). The control group did not receive any intervention. Postural control ability (postural sway during quiet standing, functional reach, and functional stability boundary) was assessed before and after the intervention. A cocontraction index was measured during the postural control tasks to assess muscle coactivation. RESULTS: Cocontraction index values in the intervention group significantly decreased following the intervention phase for functional reach (p < .0125). Cocontraction index values had a tendency to decrease during functional stability boundary for forward and quiet standing tasks. Functional improvements were observed in some of the tasks after the intervention, that is, functional reach, functional stability boundary for forward, one-leg stance, and timed up and go (p < .05). CONCLUSIONS: Our study raised the possibility that balance training for older adults was associated with decreases in muscle coactivation during postural control. Postural control exercise could potentially lead older adults to develop more efficient postural control strategies without increasing muscle coactivation. Further research is needed to clarify in greater detail the effects of changes in muscle coactivation.

Effects of dual-task switch exercise on gait and gait initiation performance in older adults: preliminary results of a randomized controlled trial.

Few studies have reported the effect of exercise intervention for improving postural control deficit in older adults at high risk of falling. We have developed a "Dual-task Switch Exercise (DSE)" program that focuses on gait initiation performance under the dual-task condition. The purpose of this study was to evaluate whether gait initiation performance could be improved by a specific exercise intervention. Eighteen participants were randomly assigned to either DSE or control groups. The DSE group received focused training to improve the ability to initiate movements quickly under the dual-task condition. The control group received steady-state walking training. After 30-min of seated training sessions, participants received 5-min individualized training sessions once a week for 24 weeks. In the pre- and post-training period, performance of the steady-state gait (10-m walking time) and gait initiation (reaction time, backward center of pressure (COP) displacement) were measured under the single- and dual-task conditions. The results of a randomized clinical trial showed that both groups showed improvement of steady-state walking time under the dual-task condition (main effect of time; p=0.018). However, DSE was more effective in improving both the reaction time and backward COP displacement during gait initiation under the dual-task condition than control (interaction effect of time×group; reaction time, p=0.015; COP displacement, p=0.011). There were no significant differences in steady-state gait and gait initiation performance under the single-task condition between pre- and post-training in both groups. Only the specific exercise intervention improved gait initiation performance under the dual-task condition.

Complex obstacle negotiation exercise can prevent falls in community-dwelling elderly Japanese aged 75 years and older.

OBJECTIVES: The aim of the present study was to evaluate whether a complex course obstacle negotiation exercise (CC), a 24-week exercise program, can reduce falls and fractures in older adults, as compared with a simple course obstacle negotiation exercise (SC). METHODS: This trial was carried out on older adults, aged 75 years and above in Japan. In total, 157 participants were randomized into the CC group (n = 78) and the SC group (n = 79). Participants were enrolled in the exercise class using the CC program or the SC program for 24 weeks. The outcome measure was the number of falls and fracture rates in CC and SC groups for 12 months after the completion of the 24-week exercise class. RESULTS: Two participants (2.8%) in the CC group and 19 (26.0%) in the SC group experienced falls during 12 months. During the 12-month follow-up period after the intervention, the incidence rate ratio (IRR) of falls in the SC group against the CC group was 9.37 (95% CI = 2.26-38.77). One participant (1.4%) in the CC group and eight (10.9%) in the SC group had experienced fractures during 12 months after the exercise class. The IRR of fractures in the SC group compared with the CC group was 7.89 (95% CI = 1.01-61.49). CONCLUSIONS: The results of the present trial show that the participants who received individualized obstacle avoidance training under complex tasks combined with a traditional intervention had a lower incidence rate of falls and fractures during the 12 months after the intervention.

Effects of fear of falling on muscular coactivation during walking.

BACKGROUND AND AIMS: Increased fear of falling is associated with greater muscular coactivation during standing postural control. Excessive muscular coactivation reduces the performance of agonist muscles. Although several recent studies have observed increased muscular coactivation during walking in older adults, little is known about the relationship between fear of falling and muscular coactivation during walking. The purpose of this study was to compare muscular coactivation during walking between older adults with fear of falling and older adults without fear of falling. METHODS: Thirty-eight healthy older adults (82.3 ± 6.8 years) participated in this study. Walking speed and step length were measured. Electromyography (EMG) data were collected from the tibialis anterior and soleus during walking to calculate the co-contraction index (CI). Subjects were divided into those with fear of falling and those without fear of falling, on the basis of a modified Falls Efficacy Scale (FES). Stepwise multiple regression analysis was used, with CI as the dependent variable, and fear of falling, experience of falling (during the past year), walking speed, step length, and age as independent variables. RESULTS: Mean values of CI during walking, walking speed, and step length were 51.9 ± 11.7%, 0.90 ± 0.40 m/s, and 0.43±0.11 m, respectively. Eight subjects (21.1%) had fallen within the past year, and 19 subjects (50.0%) had fear of falling. All subjects without fear of falling had FES scores of 10 (maximum score). Subjects with fear of falling had a median FES score of 17 (interquartile range, 13 to 25). Stepwise multiple regression analysis revealed that fear of falling remained significantly associated with CI (p<0.01): CIs for subjects with fear and those without fear were 59.5 ± 12.2% and 46.7 ± 8.5%, respectively. CONCLUSION: Individuals with a fear of falling have increased muscular co-activation at the ankle joint during walking, at least in a certain subgroup of older adults. Further research is needed to clarify negative and positive effects of muscular coactivation during walking in fearful subjects.

Maladaptive turning and gaze behavior induces impaired stepping on multiple footfall targets during gait in older individuals who are at high risk of falling.

It was recently reported that the measurement of stepping accuracy while performing a new walking test, a multi-target stepping task (MTST), could contribute to identifying older individuals at high risk (HR) of falling. The present study was designed to identify factors leading HR older individuals to an impaired stepping performance in terms of frequency of maladaptive turning behavior (spin turn) and spatio-temporal patterns of fixations. Eleven HR (80.8±3.6 years), 26 low-risk (LR) (77.1±7.7 years) older individuals, and 20 younger individuals performed the MTST. For the MTST, stepping accuracy was measured with two types of failure (stepping target and avoiding distracters). The frequency of a spin turn (i.e., a crossover step) was compared among the groups. The location and duration of each fixation were also compared. The HR older and younger participants showed a higher rate of spin turns. Whereas the younger participants fixated approximately three steps ahead, the older participants directed their fixation closer toward the imminent footfall target, demonstrating their difficulty to use the visual information regarding the target in a feedforward manner. Such patterns of fixations were significantly associated with the frequency of stepping and avoidance failures. The higher rate of stepping and avoidance failures in the MTST were attributed to maladaptive turning behavior, which is potentially destabilizing, and the tendency to fixate on/around an imminent footfall target, which prevented older individuals from considering the locations of future footfall targets.

Objective assessment of abnormal gait in patients with rheumatoid arthritis using a smartphone.

A disturbance in gait pattern is a serious problem in patients with rheumatoid arthritis (RA). The aim of the present study was to examine the utility of the smartphone gait analysis application in patients with RA. The smartphone gait analysis application was used to assess 39 patients with RA (age 65.9 ± 10.0 years, disease duration 11.9 ± 9.4 years) and age-matched control individuals (mean age, 69.1 ± 5.8 years). For all RA patients, the following data were obtained: disease activity score (DAS) 28, modified health assessment questionnaire (mHAQ), and assessment of walking ability. Patients walked 20 m at their preferred speed, and trunk acceleration was measured using a Smartphone. After signal processing, we calculated the following gait parameters for each measurement terminal: peak frequency (PF), autocorrelation peak (AC), and coefficient of variance (CV) of the acceleration peak intervals. The gait parameters of RA and control groups were compared to examine the comparability of the 2 groups. Criterion-related validity was determined by evaluating the correlation between gait parameters and clinical parameters using Spearman's correlation coefficient. The RA group showed significantly lower scores for the walking speed, AC, and CV than the control group. There were no significant differences in PF. PF (gait cycle) was mildly associated with gait speed (P < 0.05). AC (gait balance) was moderately associated with the DAS, mHAQ, gait ability, and gait speed (P < 0.05). CV (gait variability) was moderately associated with the DAS, gait ability, and gait speed (P < 0.05). This is the first study to examine the use of a smartphone device for gait pattern measurement. The results suggest that some gait parameters recorded using the smartphone represent an acceptable assessment tool for gait in patients with RA.

Fear of falling is associated with prolonged anticipatory postural adjustment during gait initiation under dual-task conditions in older adults.

Little is known about dynamic balance control under dual-task conditions in older adults with fear of falling (FoF). The purpose of this study was to examine the effect of FoF on anticipatory postural adjustment (APA) during gait initiation under dual-task conditions in older adults. Fifty-seven elderly volunteers (age, 79.2 [6.8] years) from the community participated in this study. Each participant was categorised into either the Fear (n=24) or No-fear (n=33) group on the basis of the presence or absence of FoF. Under single- and dual-task conditions, centre of pressure (COP) data were collected while the participants performed gait initiation trials from a starting position on a force platform. We also performed a 10-m walking test (WT), a timed up & go test (TUG), and a functional reach test (FR). The reaction and APA phases were measured from the COP data. The results showed that under the dual-task condition, the Fear group had significantly longer APA phases than the No-fear group, although no significant differences were observed between the 2 groups in the reaction and APA phases under the single-task condition and in any clinical measurements (WT, TUG, and FR). Our findings suggest that specific deficits in balance control occur in subjects with FoF during gait initiation while dual tasking, even if their physical functions are comparable to subjects without FoF.

Faster decline of physical performance in older adults with higher levels of baseline locomotive function.

AIM: The purpose of this longitudinal study was to determine whether the rate of decline in community-dwelling older adults varies according to baseline locomotive function levels. METHODS: This longitudinal study was conducted in community-dwelling older adults in Kyoto, Japan. In addition to information about falls, physical performance was assessed using a series of tests, including 10-m walking time, timed up and go (TUG) test, functional reach, one-leg stand test, and five chair stand test. The outcomes for each patient were measured once in 2009 and then followed up 1 year later. The change in physical performance was then determined. We divided the participants into tertiles (T1, T2, and T3) according to timed up and go test results, and the differences among the three groups were compared. RESULTS: Of the 252 individuals who were enrolled in the study, 231 (91.6%) completed the 12-month follow-up: 77 in the T1 group; 78 in the T2 group; and 76 in the T3 group. The T1 group showed a significantly larger decrease than the T2 and T3 groups in the 10-m walking time and TUG tests (P < 0.05). However, there were no significant differences in functional reach, one-leg standing test, or five chair stand test among the three groups. In the T1 group, the number of falls and elderly who had developed fear of falling increased during the study period. CONCLUSIONS: This study demonstrated that elderly with the highest baseline performances were more likely to show a greater decline in locomotive performance than the other groups. Further study is required to elucidate the mechanism of faster physical functional decline in robust elderly.

Effects of a DVD-based seated dual-task stepping exercise on the fall risk factors among community-dwelling elderly adults.

OBJECTIVE: The purpose of this randomized control trial study was to evaluate the effectiveness of a digital video disc (DVD)-based seated dual-task (DT) stepping exercise to improve the DT walking capability in elderly people. In the DT exercise, participants were asked to perform a verbal fluency task while stepping as quickly as possible. METHODS: Eight clusters (n=93) randomized into a DVD group (4 clusters, n=48) and a nonexercise control group (4 clusters, n=45) participated in this trial. In the DVD group, participants received 20 min of group training twice a week for 24 weeks. The exercise class used an exercise DVD that included a 15-min basic exercise and a 5-min DT exercise. No exercise program was prescribed for the control group. The measurements were based on the difference in physical function, including DT walking, between the DVD and control groups. In the DT walking test, participants walked individually at a comfortable speed while carrying a ball on a tray. The relative DT lag was calculated by using simple walking as the comparison condition. The Timed Up and Go test and the 5-chair stand test were also performed. RESULTS: The median relative adherence to the study was 87.5% (25th-75th percentile, 83.3%-95.8%) in the DVD group. The outcome measurements, including the DT walking time and DT time lag (p<0.05), among participants in the DVD group were significantly improved. However, other outcome measurements were not significantly different between the two groups (p>0.05). CONCLUSION: The current study reports the effectiveness of a DVD-based exercise for the improvement of the DT walking capability. A larger study is needed to confirm the present results. Study of a Web-based exercise regime would be valuable to identify the most effective exercise for prevention of falls and fall-related fractures.

Fallers choose an early transfer gaze strategy during obstacle avoidance in dual-task condition.

BACKGROUND AND AIMS: The aim of the present study is to compare the gaze behavior between fallers and non-fallers during obstacle avoidance in dual-task conditions. METHODS: Nine older adults who had no experience of falling (mean age 79.9 ± 5.4) and 9 older adults with known experience of falling (83.4 ± 3.6) participated in the study. We examined their gaze behavior during obstacle avoidance in singletask (ST) and dual-task (DT) conditions. RESULTS: In the ST condition, compared with the faller group, the non-faller group showed no significant difference in timing of gaze transfer from the obstacle (faller: gaze transfer from obstacle when 1.6 ± 1.1 steps before; non-faller: 1.9 ± 0.7 steps before, p=0.493). In the DT condition, the faller group chose a transfer of gaze strategy significantly earlier than the non-faller group (faller: 2.7 ± 1.4 steps before; non-faller: 1.6 ± 0.5 steps before, p=0.008). CONCLUSION: Our findings suggest that fallers chose an early transfer of gaze strategy when challenged with an obstacle in DT conditions.