Maintaining and controlling postural balance is important for activities of daily living, with poor postural balance being predictive of future falls. This study investigated eyes open and eyes ...closed standing posturography with elderly adults to identify differences and determine appropriate outcome measure cut-off scores for prospective faller, single-faller, multi-faller, and non-faller classifications. 100 older adults (75.5 ± 6.7 years) stood quietly with eyes open and then eyes closed while Wii Balance Board data were collected. Range in anterior-posterior (AP) and medial-lateral (ML) center of pressure (CoP) motion; AP and ML CoP root mean square distance from mean (RMS); and AP, ML, and vector sum magnitude (VSM) CoP velocity were calculated. Romberg Quotients (RQ) were calculated for all parameters. Participants reported six-month fall history and six-month post-assessment fall occurrence. Groups were retrospective fallers (24), prospective all fallers (42), prospective fallers (22 single, 6 multiple), and prospective non-fallers (47). Non-faller RQ AP range and RQ AP RMS differed from prospective all fallers, fallers, and single fallers. Non-faller eyes closed AP velocity, eyes closed VSM velocity, RQ AP velocity, and RQ VSM velocity differed from multi-fallers. RQ calculations were particularly relevant for elderly fall risk assessments. Cut-off scores from Clinical Cut-off Score, ROC curves, and discriminant functions were clinically viable for multi-faller classification and provided better accuracy than single-faller classification. RQ AP range with cut-off score 1.64 could be used to screen for older people who may fall once. Prospective multi-faller classification with a discriminant function (-1.481 + 0.146 x Eyes Closed AP Velocity-0.114 x Eyes Closed Vector Sum Magnitude Velocity-2.027 x RQ AP Velocity + 2.877 x RQ Vector Sum Magnitude Velocity) and cut-off score 0.541 achieved an accuracy of 84.9% and is viable as a screening tool for older people at risk of multiple falls.
Wearable sensors could facilitate point of care, clinically feasible assessments of dynamic stability and associated fall risk through an assessment of single-task (ST) and dual-task (DT) walking. ...This study investigated gait changes between ST and DT walking and between older adult prospective fallers and non-fallers. The results were compared to a study based on retrospective fall occurrence. Seventy-five individuals (75.2 ± 6.6 years; 47 non-fallers, 28 fallers; 6 month prospective fall occurrence) walked 7.62 m under ST and DT conditions while wearing pressure-sensing insoles and accelerometers at the head, pelvis, and on both shanks. DT-induced gait changes included changes in temporal measures, centre of pressure (CoP) path stance deviations and coefficient of variation, acceleration descriptive statistics, Fast Fourier Transform (FFT) first quartile, ratio of even to odd harmonics, and maximum Lyapunov exponent. Compared to non-fallers, prospective fallers had significantly lower DT anterior⁻posterior CoP path stance coefficient of variation, DT head anterior⁻posterior FFT first quartile, ST left shank medial⁻lateral FFT first quartile, and ST right shank superior maximum acceleration. DT-induced gait changes were consistent regardless of faller status or when the fall occurred (retrospective or prospective). Gait differences between fallers and non-fallers were dependent on retrospective or prospective faller identification.
Highlights • Gait and balance asymmetry are related post-stroke. • These significant relationships are independent of limb impairment. • Impaired paretic limb control of balance may contribute to ...gait asymmetry.
Abstract Symmetry is a gait characteristic that is increasingly measured and reported, particularly in the stroke patient population. However, there is no accepted standard for assessing symmetry ...making it difficult to compare across studies and establish criteria to guide clinical decision making. This study compares the most common expressions of spatiotemporal gait symmetry to describe post-stroke gait and makes recommendations regarding the most suitable measure for standardization. The following symmetry equations were compared: symmetry ratio, symmetry index, gait asymmetry and symmetry angle using step length, swing time, stance time, double support time and an intra-limb ratio of swing: stance time. Comparisons were made within a group of 161 community-dwelling, ambulatory individuals with stroke and 81 healthy adults as a reference group. Our analysis supports the recommendations of the symmetry ratio as the equation for standardization and step length, swing time and stance time as the gait parameters to be used in the equation. Future work should focus on establishing the intra-individual variability of these measures and linking them to mechanisms of gait dysfunction.
Despite the generally accepted view that aerobic exercise can have positive effects on brain health, few studies have measured brain responses to exercise over a short time span. The purpose of this ...study was to examine the impact within one hour of a single bout of exercise on brain perfusion and neuronal activation.
Healthy adults (n = 16; age range: 20-35 yrs) were scanned using Magnetic Resonance Imaging (MRI) before and after 20 minutes of exercise at 70% of their age-predicted maximal heart rate. Pseudo-continuous arterial spin labeling (pcASL) was used to measure absolute cerebral blood flow (CBF) prior to exercise (pre) and at 10 min (post-10) and 40 min (post-40) post-exercise. Blood oxygenation level dependent (BOLD) functional MRI (fMRI) was performed pre and post-exercise to characterize activation differences related to a go/no-go reaction time task.
Compared to pre-exercise levels, grey matter CBF was 11% (±9%) lower at post-10 (P<0.0004) and not different at post-40 (P = 0.12), while global WM CBF was increased at both time points post-exercise (P<0.0006). Regionally, the hippocampus and insula showed a decrease in perfusion in ROI-analysis at post-10 (P<0.005, FDR corrected), whereas voxel-wise analysis identified elevated perfusion in the left medial postcentral gyrus at post-40 compared to pre (pcorrected = 0.05). BOLD activations were consistent between sessions, however, the left parietal operculum showed reduced BOLD activation after exercise.
This study provides preliminary evidence of regionalized brain effects associated with a single bout of aerobic exercise. The observed acute cerebrovascular responses may provide some insight into the brain's ability to change in relation to chronic interventions.
Background: balancing reactions that involve rapid stepping or reaching movements are critical for preventing falls. These compensatory reactions are much more rapid than volitional limb movements ...and can be very effective in decelerating the centre-of-mass motion induced by sudden unpredictable balance perturbation; however, age-related deterioration in the neural, sensory and/or musculoskeletal systems may impede the ability to execute these reactions effectively. Objective: this paper summarises recent research regarding age-related changes in compensatory stepping and reaching reactions and the practical implications of these findings for fall prevention programmes. Results: even healthy older adults experience pronounced difficulties. For stepping reactions, the main problems pertain to control of lateral stability—arresting the lateral body motion that occurs during forward and backward steps, and controlling lateral foot movement so as to avoid collision with the stance limb during lateral steps. Older adults appear to be more reliant on arm reactions than young adults but are less able to execute reach-to-grasp reactions rapidly. Conclusions: it is important for clinicians to assess compensatory stepping and reaching, in order to identify individuals who are at risk of falling and to pinpoint specific control problems to target for balance or strength training or other intervention. More effective use of stepping and reaching reactions can be promoted through improved design and appropriate use of sensory aids, mobility aids, footwear, handrails and grab-bars. It is particularly important to address the problems associated with the control of lateral stability because it is the lateral falls that are most likely to result in hip fracture.
Gait performance is affected by neurodegeneration in aging and has the potential to be used as a clinical marker for progression from mild cognitive impairment (MCI) to dementia. A dual-task gait ...test evaluating the cognitive-motor interface may predict dementia progression in older adults with MCI.
To determine whether a dual-task gait test is associated with incident dementia in MCI.
The Gait and Brain Study is an ongoing prospective cohort study of community-dwelling older adults that enrolled 112 older adults with MCI. Participants were followed up for 6 years, with biannual visits including neurologic, cognitive, and gait assessments. Data were collected from July 2007 to March 2016.
Incident all-cause dementia was the main outcome measure, and single- and dual-task gait velocity and dual-task gait costs were the independent variables. A neuropsychological test battery was used to assess cognition. Gait velocity was recorded under single-task and 3 separate dual-task conditions using an electronic walkway. Dual-task gait cost was defined as the percentage change between single- and dual-task gait velocities: (single-task gait velocity - dual-task gait velocity/ single-task gait velocity) × 100. Cox proportional hazard models were used to estimate the association between risk of progression to dementia and the independent variables, adjusted for age, sex, education, comorbidities, and cognition.
Among 112 study participants with MCI, mean (SD) age was 76.6 (6.9) years, 55 were women (49.1%), and 27 progressed to dementia (24.1%), with an incidence rate of 121 per 1000 person-years. Slow single-task gait velocity (<0.8 m/second) was not associated with progression to dementia (hazard ratio HR, 3.41; 95% CI, 0.99-11.71; P = .05)while high dual-task gait cost while counting backward (HR, 3.79; 95% CI, 1.57-9.15; P = .003) and naming animals (HR, 2.41; 95% CI, 1.04-5.59; P = .04) were associated with dementia progression (incidence rate, 155 per 1000 person-years). The models remained robust after adjusting by baseline cognition except for dual-task gait cost when dichotomized.
Dual-task gait is associated with progression to dementia in patients with MCI. Dual-task gait testing is easy to administer and may be used by clinicians to decide further biomarker testing, preventive strategies, and follow-up planning in patients with MCI.
clinicaltrials.gov: NCT03020381.
Abstract Dual-task (DT) gait involves walking while simultaneously performing an attention-demanding task and can be used to identify impaired gait or executive function in older adults. Advancment ...is needed in techniques that quantify the influence of dual tasking to improve predictive and diagnostic potential. This study investigated the viability of wearable sensor measures to identify DT gait changes in older adults and distinguish between elderly fallers and non-fallers. A convenience sample of 100 older individuals (75.5±6.7 years; 76 non-fallers, 24 fallers based on 6 month retrospective fall occurrence) walked 7.62 m under single-task (ST) and DT conditions while wearing pressure-sensing insoles and tri-axial accelerometers at the head, pelvis, and left and right shanks. Differences between ST and DT gait were identified for temporal measures, acceleration descriptive statistics, Fast Fourier Transform (FFT) quartiles, ratio of even to odd harmonics, center of pressure (CoP) stance path coefficient of variation, and deviations to expected CoP stance path. Increased posterior CoP stance path deviations, increased coefficient of variation, decreased FFT quartiles, and decreased ratio of even to odd harmonics suggested increased DT gait variability. Decreased gait velocity and decreased acceleration standard deviations (SD) at the pelvis and shanks could represent compensatory gait strategies that maintain stability. Differences in acceleration between fallers and non-fallers in head posterior SD and pelvis AP ratio of even to odd harmonics during ST, and pelvis vertical maximum Lyapunov exponent during DT gait were identified. Wearable-sensor-based DT gait assessments could be used in point-of-care environments to identify gait deficits.
Background. Cognitive benefits obtained from exercise in healthy populations support the idea that aerobic and resistance training (AT+RT) would confer benefit for poststroke recovery. However, there ...is little evidence regarding the effectiveness of such programs. Objective. To evaluate the effects of a 6-month exercise program of AT+RT on cognition in consecutively enrolled patients with motor impairments ≥10 weeks poststroke. Methods. Outcomes were measured before and after 6 months of AT+RT on 41 patients. Cognition was measured by the Montreal Cognitive Assessment (MoCA). Secondary measures included evaluation of gas exchange anaerobic threshold (ATge), body composition by dual energy X-ray absorptiometry, and depressive symptoms by questionnaire. Results. There were significant improvements in overall MoCA scores (22.5 ± 4.5 to 24.0 ± 3.9, P < .001) as well as in the subdomains of attention/concentration (4.7 ± 1.7 to 5.2 ± 1.3, P = .03) and visuospatial/executive function (3.4 ± 1.1 to 3.9 ± 1.1, P = .002). There was a significant reduction in the proportion of patients meeting the threshold criteria for mild cognitive impairment (MCI) at baseline compared with posttraining (65.9% vs 36.6%, P < .001). In a linear regression model, there was a positive association between change in cognitive function and change in fat-free mass of the nonaffected limbs (β = .002; P = .005) and change in attention/concentration and change in ATge (β = .383; P ≤ .001), independent of age, sex, time from stroke, and change in fat mass and depression score. Conclusion. A combined training model (AT+RT) resulted in improvements in cognitive function and a reduction in the proportion of patients meeting the threshold criteria for MCI. Change in cognition was positively associated with change in fat-free mass and ATge.
The ability to correct balance disturbances is essential for the maintenance of upright stability. Although information about how the central nervous system controls balance reactions in humans ...remains limited, recent literature highlights a potentially important role for the cerebral cortex. The objective of this study was to determine the neural source of the well-reported balance-evoked N1 response. It was hypothesized that the N1 is associated with an "error-detection" event in response to the induced perturbation and therefore may be associated with activity within the anterior cingulate cortex (ACC). The localized source of the N1 evoked by perturbations to standing balance was compared, within each participant, to the location of an error-related negativity (ERN) known to occur within the ACC while performing a flanker task. In contrast to the main hypotheses, the results revealed that the location of the N1 was not within the ACC. The mean Talairach coordinates for the ERN were (6.47, -4.41, 41.17) mm, corresponding to the cingulate gyrus Brodmann area (BA) 24, as expected. However, coordinates for the N1 dipole were (5.74, -11.81, 53.73) mm, corresponding to the medial frontal gyrus (BA 6), specifically the supplementary motor area. This may suggest the N1 is linked to the planning and execution of elements of the evoked balance reactions rather than being associated with error or event detection. Alternatively, it is possible that the N1 is associated with variation in the cortical representation due to task-specific differences in the activation of a distributed network of error-related processing. Subsequent work should focus on disentangling these two possible explanations as they relate to the cortical processing linked to reactive balance control.
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