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Aim: The goal of this study was to analyze the effects of external rhythmic auditory stimulation (RAS) on gait variability in older adults and people with Parkinson's disease (PD). Methods: Academic databases searched included PubMed, Web of Science, PEDro and Cochrane, from inception to September 2021. Eligible articles scored a minimum of 4 on the PEDro scale. Results: Twenty-three papers were included. People with PD show varied responses in gait variability to RAS during cued walking trials. Healthy older adults tended to increase variability during cued trials. Cue rates below preferred walking cadence tend to increase gait variability. Conclusion: Gait variability is closely associated with fall risk and an important consideration in development of gait rehabilitation techniques.

The study examined how clinically measured walking capacity contributes to real-world walking performance in persons with Parkinson's disease (PD).Cross-sectional baseline data (n = 82) from a PD clinical trial were analyzed. The 6-Minute Walk Test (6MWT) and 10-Meter Walk Test (10MWT) were used to generate capacity metrics of walking endurance and fast gait speed, respectively. An activity monitor worn for seven days was used to generate performance metrics of mean daily steps and weekly moderate intensity walking minutes. Univariate linear regression analyses were used to examine associations between each capacity and performance measure in the full sample and less and more active subgroups.Walking capacity significantly contributed to daily steps in the full sample (endurance: RWalking capacity contributed to, but explained a relatively small portion of the variance in, real-world walking performance. The contribution was somewhat greater in less active individuals. The study adds support to the idea that clinically measured walking capacity may have limited benefit for understanding real-world walking performance in PD. Factors beyond walking capacity may better account for actual walking behavior.

There has been increasing research on the impact of dance as a therapeutic intervention and alternative exercise for improving physical health and psychosocial outcomes. Prior reviews center on specific populations, such as those living with Parkinson's disease or older adults, but few center on a specific dance style such as classical ballet. This review aims to synthesize the current literature on classical ballet as a therapeutic intervention for novices and analyze its effects on movement outcomes, perceived value, and other health outcomes to inform future research directions. In total, 23 articles were identified using PubMed and Scopus from inception through March 2022; 14 that met the inclusion criteria are discussed in this review. Altogether, the literature is extremely mixed-spanning different populations, intervention protocols, doses, and measurement tools-making comparisons difficult. Overall, classical ballet appears to be a safe and feasible intervention for multiple populations. Engaging in classical ballet may be associated with improvements in balance and postural control and has a high perceived value among participants and instructors, but the evidence is limited and of poor quality. Rigorous research is required to provide stronger, more credible evidence on the potential value of classical ballet as a therapeutic intervention.

Digital therapeutics, treatments delivered remotely and enabled by modern technology, facilitate the provision of personalized, evidence-based, interdisciplinary interventions to manage the complexities associated with Parkinson’s disease. In the context of the COVID-19 pandemic, the need for digital therapeutics has arguably never been greater. However, despite new advances in technology and a heightened interest due to the pandemic, digital therapeutics remain underdeveloped and underutilized. In this paper, we briefly review practical applications and emerging advances in digital therapeutic platforms that target motor and non-motor signs and healthy lifestyle behaviors such as regular exercise, a healthful diet and optimal sleep hygiene habits. Future applications which could transform personalized self-management and patient care are presented. Opportunities, drawbacks and barriers to access are discussed.

Several case studies and anecdotal reports have shown assorted motor and quality of life benefits from use of a dental mouthpiece among people with Parkinson disease (PD). A larger exploratory study is necessary to assess potential efficacy and feasibility of this treatment strategy. If shown to be effective and feasible in a larger sample of people with PD, mechanistic studies may be warranted to examine a potential relationship between orofacial sensory input and motor function in people with PD.This study was registered on clinicaltrials.gov (NCT: 04082663). Twenty people with PD, Hoehn and Yahr stages I-III, participated in this study. Each participant completed various baseline motor and quality of life assessments before being fitted with a custom mouthpiece. Motor assessments were completed a second time after 25 min of mouthpiece wear. Participants were asked to wear the mouthpiece for 1 month before completing follow-up quality of life assessments and providing feedback about the mouthpiece. Wilcoxon signed-rank tests were used to compare results across conditions.Gait velocity and cadence showed significant (These results do not provide adequate evidence to pursue further this type of mouthpiece as a treatment strategy for motor signs and symptoms or quality of life in people with PD.

BACKGROUND AND PURPOSE Walking activity in persons with Parkinson disease (PD) is important for preventing functional decline. The contribution of walking activity to home and community mobility in PD is poorly understood. METHODS Cross-sectional baseline data (N = 69) were analyzed from a randomized controlled PD trial. The Life-Space Assessment (LSA) quantified the extent, frequency, and independence across 5 expanding levels of home and community mobility, producing individual subscores and a total score. Two additional summed scores were used to represent mobility within (Levels 1-3) and beyond (Levels 4-5) neighborhood limits. An accelerometer measured walking activity for 7 days. Regression and correlation analyses evaluated relationships between daily steps and mobility scores. Mann-Whitney U tests secondarily compared differences in mobility scores between the active and sedentary groups. RESULTS Walking activity contributed significantly to the summed Level 1-3 score (β = 0.001, P = 0.004) but not to the summed Level 4-5 (β = 0.001, P = 0.33) or total (β = 0.002, P = 0.07) scores. Walking activity was significantly related to Level 1 (ρ = 0.336, P = 0.005), Level 2 (ρ = 0.307, P = 0.010), and Level 3 (ρ = 0.314, P = 0.009) subscores. Only the summed Level 1-3 score (P = 0.030) was significantly different between the active and sedentary groups. DISCUSSION AND CONCLUSIONS Persons with PD who demonstrated greater mobility beyond the neighborhood were not necessarily more active; walking activity contributed more so to home and neighborhood mobility. Compared with LSA total score, the Level 1-3 summed score may be a more useful participation-level measure for assessing the impact of changes in walking activity.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A349).

Background Gait deficits in Parkinson disease (PD), including freezing of gait (FOG), can be among the most debilitating symptoms. Rhythmic auditory cueing has been used to alleviate some gait symptoms. However, different cue types, such as externally-generated and self-generated cues, affect gait variability differently. The differential effects of these cue types on people with PD with FOG (PD + FOG), who often have higher gait variability, and those with PD without FOG (PD-FOG) is unknown. Given the relationship of gait variability to fall risk, this is an important area to address. Research question This study aims to 1) confirm the association between falls and gait variability measures in PD-FOG, PD + FOG and age-matched Controls; 2) investigate the effects of different cue types on gait variability in PD-FOG and PD + FOG; and 3) determine whether baseline gait characteristics are associated with response to cues. Methods This cross-sectional study investigated PD-FOG (n = 24), PD + FOG (n = 20), and Controls (n = 24). Gait trials were collected during use of externally-generated and self-generated cues for all participants. Gait variability measures were the primary outcomes to assess the effects of rhythmic auditory cues. Results Logistic regression models showed increased gait variability was associated with falls across groups. Repeated measures ANOVAs showed externally-generated cues increased gait variability, whereas self-generated cues did not, for all groups. Pearson’s correlations showed participants with higher baseline gait variability had greater reduction in gait variability with rhythmic auditory cueing. Significance Higher gait variability is associated with falls. This study demonstrates that PD + FOG are capable of using self-generated cues without increasing gait variability measures, thereby stabilizing gait. People with higher baseline gait variability are likely to experience the largest reductions in variability with the addition of external cues.

In this paper, we develop an algorithm to automatically validate and segment a gait cycle in real time into three gait events, namely midstance, toe-off, and heel-strike, using inertial sensors. We first use the physical models of sensor data obtained from a foot-mounted inertial system to differentiate stationary and moving segments of the sensor data. Next, we develop an optimization routine called sparsity-assisted wavelet denoising (SAWD), which simultaneously combines linear time invariant filters, orthogonal multiresolution representations such as wavelets, and sparsity-based methods, to generate a sparse template of the moving segments of the gyroscope measurements in the sagittal plane for valid gait cycles. Thereafter, to validate any moving segment as a gait cycle, we compute the root-mean-square error between the generated sparse template and the sparse representation of the moving segment of the gyroscope data in the sagittal plane obtained using SAWD. Finally, we find the local minima for the stationary and moving segments of a valid gait cycle to detect the gait events. We compare our proposed method with existing methods, for a fixed threshold, using real data obtained from three groups, namely controls, participants with Parkinson disease, and geriatric participants. Our proposed method demonstrates an average F1 score of 87.78% across all groups for a fixed sampling rate, and an average F1 score of 92.44% across all Parkinson disease participants for a variable sampling rate.

People with Parkinson disease demonstrate increased gait variability, but the primary variability sources are poorly understood. People with Parkinson disease and freezing of gait (freezers) have greater gait impairments than people with Parkinson disease without freezing of gait (nonfreezers), which may relate to cerebellar dysfunction. Thirteen freezers and 31 nonfreezers completed backward, forward, and forward with dual task gait trials. Sagittal joint angle waveforms were extracted for the hip, knee, and ankle using 3D motion capture. Decomposition indices were calculated for the 3 joint combinations. Principal component analysis extracted variance sources from the joint waveforms. Freezers had significantly greater decomposition between hip–ankle (F1,42 = 5.1, P = .03) and hip–knee (F1,42 = 5.3, P = .03) movements. The principal component analysis did not differentiate freezers and nonfreezers; however, primary variance sources differed between conditions. Primary variance during forward and forward with dual task gait came from joint angle magnitude and peak angle timing. Backward gait showed primary variance from joint angle magnitude and range of motion. The results show that freezers decompose movement more than nonfreezers, implicating cerebellar involvement in freezing of gait. Primary variance differs between gait conditions, and tailoring gait interventions to address variability sources may improve intervention efficacy.

Freezing of gait (FOG) is a debilitating symptom of Parkinson’s disease (PD) that remains difficult to assess. Wearable movement sensors and associated algorithms can be used to quantify FOG in laboratory settings, but the utility of such methods for real world use is unclear. We aimed to determine the suitability of our wearable sensor-based FOG assessment method for real world use by assessing its performance during in-clinic simulated real world activities. Accuracy of the sensor-based method during simulated real-world tasks was calculated using expert rated video as the gold standard. To determine feasibility for unsupervised home use, we also determined correlations between the percent of active time spent freezing (%ATSF) during unsupervised home use and in-clinic activities. Nineteen people with PD and FOG participated in this study. Results from our sensor-based method demonstrated an accuracy above 90% compared to gold-standard expert review during simulated real-world tasks. Additionally, %ATSF from our sensor-based method during unsupervised home use correlated strongly with %ATSF from our sensor-based method during in-clinic simulated real-world activities (ρ = 0.73). Accuracy values and correlation patterns suggest our method may be useful for FOG assessment in the real world.

Background and purpose Alzheimer disease (AD) is the most common form of dementia and the sixth leading cause of death in the United States. Falls are associated with AD and can lead to injury. The Balance Evaluation Systems Test (BESTest) is a balance measure used in other neurological conditions to predict fall risk. The purpose of this study is to examine the relationship between MiniBestest, BESTest, and BESTest subsection scores and fall incidence among individuals with a diagnosis of mild AD. Methods The study was a single centre, prospective, observational cohort study. Participants completed baseline questionnaires including a demographic form, a fall history questionnaire and the Barthel Index of Activities of Daily Living (ADLs). Balance and gait were assessed using the MiniBESTest and BESTest. After completing baseline assessment, participants were given monthly fall calendars to track falls for the next 12 months. Results MiniBESTest total raw score for fallers was 13.4 out of 28 (SD = 3.6) and for non-fallers was 18.4 of out 28 (SD = 3.7). MiniBESTest total percentage score for fallers was 47.8% (SD = 12.8%) and for non-fallers was 65.5% (SD = 13.1%). BESTest total percentage scores for fallers was 58.2% (SD = 3.9%) and for non-fallers was 73.9% (SD = 7.9%). Subsections II-IV of the BESTest correlated with faller status. Discussion and conclusions Among individuals with mild AD, fall status was associated with certain balance deficits on the BESTest including moving body outside base of support (subsection II), changing centre of mass (subsection III), and reacting to external perturbations (subsection IV). Future studies could explore differences between AD and other neurological conditions and how physical therapy could improve these areas to reduce fall risk.

PURPOSE: Rhythmic auditory stimulation such as listening to music can alleviate gait bradykinesia in people with Parkinson disease (PD) by increasing spatiotemporal gait features. However, evidence about what specific kinematic alterations lead to these improvements is limited, and differences in responsiveness to cueing likely affect individual motor strategies. Self-generated cueing techniques, such as singing or mental singing, provide similar benefits but no evidence exists about how these techniques affect lower limb joint movement. In this study, we assessed immediate effects of external and self-generated cueing on lower limb movement trajectories during gait. METHODS: Using 3D motion capture, we assessed sagittal plane joint angles at the hip, knee, and ankle across 35 participants with PD, divided into responders (n=23) and non-responders (n=12) based on a clinically meaningful change in gait speed. Joint motion was assessed as overall range of motion as well as at two key time points during the gait cycle: initial contact and toe-off. RESULTS: Responders used both cue types to increase gait speed and induce increases in overall joint ROM at the hip while only self-generated cues also increased ROM at the ankle. Increased joint excursions for responders were also evident at initial contact and toe off. CONCLUSIONS: Our results indicate that self-generated rhythmic cues can induce similar increases in joint excursions as externally-generated cues and that some people may respond more positively than others. These results provide important insight into how self-generated cueing techniques may be tailored to meet the varied individual needs of people with PD.

Background and purpose Previously, we showed that internal cues (such as singing) produce similar motor benefits as external cues (such as listening to music) for people with Parkinson disease (PD). This study takes that research further by exploring how singing-either aloud or mentally-at different tempos can ameliorate gait, and it offers insight into how internal cueing techniques may enhance motor performance for older adults and people with PD. Methods Sixty participants aged 50 years and older (30 female) were recruited; 30 had PD and 30 were healthy age-matched controls. Participants completed walking trials involving internal and external cueing techniques at 90%, 100%, and 110% of preferred cadence. The effects of different cue types and rates were assessed in a repeated-measures cross-sectional study by comparing gait characteristics (velocity, cadence, stride length) and variabilities (coefficients of variation of stride length, stride time, single support time). Results All participants modified their cadence and stride length during cued conditions, resulting in changes in gait velocity closely reflecting expected changes based upon cue rate. External cues resulted in increased gait variability, whereas internal cues decreased gait variability relative to uncued walking. Variability decreases were more substantial during mental singing at tempos at or above preferred cadence. Discussion and conclusions Matching movement to one's own voice improves gait characteristics while reducing gait variability for older adults and people with PD. Optimizing the use of internal cues to facilitate movement is an important step toward more effectively meeting the needs of people with gait disorders related to aging or neurological disease.Video Abstract available for more insights from authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A286).

Background People with Parkinson disease (PD) frequently experience low back pain (LBP), yet the impact of LBP on functional mobility, physical activity, and quality of life (QOL) has not been described in PD. Objective The objectives of this study were to describe body positions and functional activities associated with LBP and to determine the relationships between LBP-related disability and PD motor sign severity, physical activity level, and QOL. Design The study was a cross-sectional study. Methods Thirty participants with idiopathic PD (mean age = 64.6 years [SD = 10.3]; 15 women) completed the Revised Oswestry Disability Questionnaire (RODQ), a measure of LBP-related disability. PD motor symptom severity was measured using the Movement Disorder Society-Unified Parkinson Disease Rating Scale Part III (MDS-UPRDS III). The Physical Activity Scale for the Elderly (PASE) was used to measure self-reported physical activity. The Parkinson Disease Questionnaire-39 (PDQ-39) was used to measure QOL. Descriptive statistics were used to characterize LBP intensity and LBP-related disability. Spearman correlations were used to determine relationships between the RODQ and the MDS-UPDRS III, PASE, and PDQ-39. Results LBP was reported to be of at least moderate intensity by 63.3% of participants. LBP most frequently impaired standing, sleeping, lifting, and walking. The RODQ was significantly related to the MDS-UPDRS III (r = 0.38), PASE (r = −0.37), PDQ-39 summary index (r = 0.55), PDQ-39 mobility subdomain (r = 0.54), and PDQ-39 bodily pain subdomain (r = 0.44). Limitations Limitations included a small sample of people with mild to moderate PD severity, the fact that RODQ is a less frequently used measure of LBP-related disability, and the lack of a non-PD control group. Conclusions LBP affected walking, sleeping, standing, and lifting in this small sample of people with mild to moderate PD. Greater LBP-related disability was associated with greater motor sign severity, lower physical activity level, and lower QOL in people with PD.

Advances in medical management of Parkinson's disease (PD) have resulted in living longer with disability. Although disability worsens over the course of the disease, there are signs of disability even in the early stages. Several studies reveal an early decline in gait and balance and a high prevalence of nonmotor signs in the prodromal period that contribute to early disability. There is a growing body of evidence revealing the benefits of physical therapy and exercise to mitigate motor and nonmotor signs while improving physical function and reducing disability. The presence of early disability coupled with the benefits of exercise suggests that physical therapy should be initiated earlier in the disease. In this review, we present the evidence revealing early disability in PD and the effectiveness of physical therapy and exercise, followed by a discussion of a secondary prevention model of rehabilitation to reduce early disability and optimize long-term outcomes.

Aim: To determine the effectiveness of a targeted dance intervention to improve walking speed for people with Parkinson disease (PD) by increasing motor motivation. Materials & methods: 11 participants with PD participated in a 6-week pilot study in which they learned a contemporary dance composed of walking steps and designed to mimic everyday walking. 1 h classes occurred twice-weekly. Results: Pre- and post-intervention assessments revealed a significant increase in gait speed (t9 = 3.30; p = 0.009), cadence (t9 = 2.345; p = 0.044), and stride length (t9 = 3.757; p = 0.005), and a significant decrease (improvement) in single support time variability (t9 = -2.744; p = 0.022). There were no significant changes in other measures of gait variability nor in motor symptoms, mood and anxiety, extent of life-space mobility, or quality of life. No adverse events were reported. Conclusion: Joywalk provides preliminary evidence that a targeted physical intervention for people with PD may specifically counter bradykinesia.

Background and purpose Improvement of walking performance is a primary goal for individuals poststroke or with Parkinson disease (PD) who receive physical therapy. More data about day-to-day variability of walking performance are critical for determining if changes in performance have occurred. Methods Baseline assessments were utilized from an ongoing, observational, prospective cohort study including 84 individuals poststroke (n = 37) or with PD (n = 47) receiving outpatient physical therapy services to improve mobility. Participants wore step activity monitors for up to 7 days to measure walking performance (steps per day, walking duration, maximum 30-minute output, and peak activity index) in daily life. Correlation analyses evaluated relationships between both capacity and performance measures as well as the relationships between mean performance variables and day-to-day variability. Regression analyses explored factors that contribute to variability in day-to-day performance variables. Results Mean steps per day for participants poststroke (5376 ± 2804) and with PD (8149 ± 4490) were consistent with previously reported cohorts. Greater amounts of walking were related to more day-to-day variability, with moderate correlations found between the mean and day-to-day variability of each performance measure, regardless of medical diagnosis or walking speed. Day-to-day variability is large (upwards of 50% of the mean), with the amount of walking performance serving as the primary predictor of day-to-day variability in walking performance. Discussion and conclusions The results of this study elucidate the factors that are related to and predict day-to-day variability of performance. Walking performance metrics should be evaluated over multiple days and greater variability should be anticipated with greater amounts of performance.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A319).

In this paper, we develop new methods to automatically detect the onset and duration of freezing of gait (FOG) in people with Parkinson disease (PD) in real time, using inertial sensors. We first build a physical model that describes the trembling motion during the FOG events. Then, we design a generalized likelihood ratio test framework to develop a two-stage detector for determining the zero-velocity and trembling events during gait. Thereafter, to filter out falsely detected FOG events, we develop a point-process filter that combines the output of the detectors with information about the speed of the foot, provided by a foot-mounted inertial navigation system. We computed the probability of FOG by using the point-process filter to determine the onset and duration of the FOG event. Finally, we validate the performance of the proposed system design using real data obtained from people with PD who performed a set of gait tasks. We compare our FOG detection results with an existing method that only uses accelerometer data. The results indicate that our method yields 81.03% accuracy in detecting FOG events and a threefold decrease in the false-alarm rate relative to the existing method.

Introduction Parkinson’s disease (PD) is a movement disorder caused by dysfunction in the basal ganglia (BG). Clinically relevant gait deficits, such as decreased velocity and increased variability, may be caused by underlying neural dysfunction. Reductions in resting-state functional connectivity (rs-FC) between networks have been identified in PD compared to controls; however, the association between gait characteristics and rs-FC of brain networks in people with PD has not yet been explored. The present study aimed to investigate these associations. Methods Gait characteristics and rs-FC MRI data were collected for participants with PD (N = 50). Brain networks were identified from a set of seeds representing cortical, subcortical, and cerebellar regions. Gait outcomes were correlated with the strength of rs-FC within and between networks of interest. A stepwise regression analysis was also conducted to determine whether the rs-FC strength of brain networks, along with clinical motor scores, were predictive of gait characteristics. Results Gait velocity was associated with rs-FC within the visual network and between motor and cognitive networks, most notably BG-thalamus internetwork rs-FC. The stepwise regression analysis showed strength of BG-thalamus internetwork rs-FC and clinical motor scores were predictive of gait velocity. Conclusion The results of the present study demonstrate gait characteristics are associated with functional organization of the brain at the network level, providing insight into the neural mechanisms of clinically relevant gait characteristics. This knowledge could be used to optimize the design of gait rehabilitation interventions for people with neurological conditions.

BACKGROUND AND PURPOSE The Maximum Step Length Test (MSLT), a measure of one's capacity to produce a large step, has been studied in older adults, but not in people with Parkinson disease (PD). We characterized performance and construct validity of the MSLT in PD. METHODS Forty participants (mean age: 65.12 ± 8.20 years; 45% female) with idiopathic PD completed the MSLT while "OFF" and "ON" anti-PD medication. Construct validity was investigated by examining relationships between MSLT and measures of motor performance. The following measures were collected: Mini-Balance Evaluation Systems Test (Mini-BESTest), Activities-specific Balance Confidence (ABC) scale, gait velocity, 6-minute walk test (6MWT), Movement Disorder Society-Unified Parkinson Disease Rating Scale subsection III (MDS-UPDRS III), and Timed Up and Go (TUG) test. A repeated-measures analysis of variance tested for main effects of medication and stepping direction and the interaction between the 2. Pearson or Spearman correlations were used to assess the relationships between MSLT and motor performance measures (α = 0.05). RESULTS Regardless of medication status, participants stepped further in the forward direction compared with the backward and lateral directions (P < 0.001). Participants increased MSLT performance when ON-medication compared with OFF-medication (P = 0.004). Regardless of medication status, MSLT was moderately to strongly related to Mini-BESTest, TUG, and 6MWT. DISCUSSION AND CONCLUSIONS People with PD stepped furthest in the forward direction when performing the MSLT. Increased MSLT performance was observed in the ON-medication state compared with OFF-medication; however, the small increase may not be clinically meaningful. Given the relationships between the MSLT and the Mini-BESTest, 6MWT, and TUG, MSLT performance appears to be associated with balance and gait hypokinesia in people with PD.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A186).

Background Freezing of gait (FOG) affects approximately 50% of people with Parkinson Disease (PD), impacting quality of life and placing financial and emotional strain on the individual and caregivers. People with PD and FOG have similar deficits in motor adaptation and cognition as individuals with cerebellar lesions, indicating the cerebellum may play a role in FOG. Objective To examine potential differences in cerebellar volumes and their relationships with cognition between PD with (FOG+) and without FOG (FOG-). Methods Sixty-three participants were divided into two groups, FOG+ (n = 25) and FOG- (n = 38), based on the New Freezing of Gait Questionnaire. Cognitive assessment included Trail Making, Stroop, Verbal Fluency, and Go-NoGo executive function tasks. All participants completed structural T1- and T2-weighted MRI scans. Imaging data were processed with FreeSurfer and the Spatially Unbiased Infratentorial toolbox to segment the cerebellum into individual lobules. Results FOG+ performed significantly worse on phonemic verbal fluency (F(1, 22) = 7.06, p = 0.01) as well as the Go-NoGo task (F(1, 22) = 9.00, p = 0.004). We found no differences in cerebellar volumes between groups (F(4, 55) = 1.42, p = 0.24), but there were significant relationships between verbal fluency measures and lobule volumes in FOG-. Conclusions These findings underscore the need for longitudinal studies to better characterize potential changes in cerebellar volume, cognitive function, and functional connectivity between people with PD with and without FOG.

We investigated the relationships between average gait speed collected with the 10 Meter Walk Test (Comfortable and Fast) and 6 Minute Walk Test (6MWT) in 346 people with Parkinson disease (PD) and how the relationships change with increasing disease severity. Pearson correlation and linear regression analyses determined relationships between 10 Meter Walk Test and 6MWT gait speed values for the entire sample and for sub-samples stratified by Hoehn & Yahr (H&Y) stage I (n=53), II (n=141), III (n=135) and IV (n=17). We hypothesized that redundant tests would be highly and significantly correlated (i.e. r > 0.70, p < 0.05) and would have a linear regression model slope of 1 and intercept of 0. For the entire sample, 6MWT gait speed was significantly (p

Background Rhythmic auditory cueing has been widely studied for gait rehabilitation in Parkinson's disease (PD). Our research group previously showed that externally generated cues (i.e., music) increased gait variability measures from uncued gait, whereas self-generated cues (i.e., mental singing) did not. These different effects may be due to differences in underlying neural mechanisms that could be discerned via neuroimaging; however, movement types that can be studied with neuroimaging are limited. Objective The primary aim of the present study was to investigate the effects of different cue types on gait, finger tapping, and foot tapping, to determine whether tapping can be used as a surrogate for gait in future neuroimaging studies. The secondary aim of this study was to investigate whether rhythm skills or auditory imagery abilities are associated with responses to these different cue types. Methods In this cross-sectional study, controls (n = 24) and individuals with PD (n = 33) performed gait, finger tapping, and foot tapping at their preferred pace (UNCUED) and to externally generated (MUSIC) and self-generated (MENTAL) cues. Spatiotemporal parameters of gait and temporal parameters of finger tapping and foot tapping were collected. The Beat Alignment Task (BAT) and Bucknell Auditory Imagery Scale (BAIS) were also administered. Results The MUSIC cues elicited higher movement variability than did MENTAL cues across all movements. The MUSIC cues also elicited higher movement variability than the UNCUED condition for gait and finger tapping. Conclusions This study shows that different cue types affect gait and finger tapping similarly. Finger tapping may be an adequate proxy for gait in studying the underlying neural mechanisms of these cue types.

Individuals with Parkinson’s disease (PD) experience postural instability, low-back pain (LBP), and anxiety. These symptoms increase the risk of falls and decrease quality of life. Research shows yoga improves balance and decreases LBP and anxiety in healthy adults, but its effects in PD are poorly understood. All participants were part of a larger intervention study. Participants received pretest and posttest evaluations, including the Balance Evaluation Systems Test (BESTest), Beck Anxiety Inventory (BAI), and Revised Oswestry Disability Index (ROSW). Total scores for each measure, as well as individual balance system section scores from the BESTest (biomechanical constraints, stability limits/verticality, transitions/anticipatory, reactive, sensory orientation, and stability in gait) were compared within groups pre- to posttest. Participants in the yoga group (n = 13) completed a twice-weekly 12-week yoga interve n t i o n , whereas controls (n = 13) continued their usual routines for 12 weeks. Both the yoga (Z = −3.20, p = 0.001) and control (Z = −2.10, p = 0.040) groups improved on the BESTest total score. The control group showed no changes in individual balance systems, whereas the yoga group improved in stability limits/verticality (Z = −2.3, p = 0.020), transitions/ anticipatory (Z = −2.50, p = 0.010), reactive (Z = −2.70, p = 0.008), and sensory orientation (Z = −2.30, p = 0.020). ROSW decreased in the yoga group only (Z = −2.10, p = 0.030). BAI did not change in either group. Yoga is a nonpharmacological intervention that can improve balance and LBP in people with PD. This study demonstrated that yoga is feasible for people with PD, and participants reported high levels of enjoyment and intent to practice yoga after the study.

Cognitive-motor dual-tasking involves concurrent performance of two tasks with distinct cognitive and motor demands and is associated with increased fall risk. In this hypothesis-driven study, younger (18–30 years, n = 24) and older (60–75 years, n = 26) adults completed six walking tasks in triplicate. Participants walked forward and backward along a GAITRite mat, in isolation or while performing a verbal fluency task. Verbal fluency tasks involved verbally listing or typing on a smartphone as many words as possible within a given category (e.g., clothes). Using repeated measures MANOVA models, we examined how age, method of fluency task (verbal or texting), and direction of walking altered dual-task performance. Given that tasks like texting and backward walking require greater cognitive resources than verbal and forward walking tasks, respectively, we hypothesized older adults would show higher dual-task costs (DTCs) than younger adults across different task types and walking directions, with degree of impairment more apparent in texting dual-task trials compared to verbal dual-task trials. We also hypothesized that both age groups would have greater DTCs while walking backward than while walking forward, regardless of task. Independent of age group, velocity and stride length were reduced for texting compared to the verbal task during both forward and backward walking; cadence and velocity were reduced while walking forward compared to walking backward for the texting task; and stride length was reduced for forward walking compared to backward walking during the verbal task. Younger adults performed better than older adults on all tasks with the most pronounced differences seen in velocity and stride length during forward-texting and backward-texting. Interaction effects for velocity and stride length while walking forward indicated younger adults performed better than older adults for the texting task but similarly during the verbal task. An interaction for cadence during the verbal task indicated younger adults performed better than older adults while walking backward but similarly while walking forward. In summary, older adults experienced greater gait decrement for all dual-task conditions. The greater declines in velocity and stride length in combination with cadence being stable suggest reductions in velocity during texting were due to shorter strides rather than a reduced rate of stepping. Contrary to our hypotheses, we found greater DTCs while walking forward rather than backward, which may be due to reduced gait performance during single-task backward walking; thus, further decrements with dual-tasking are unlikely. These findings underscore the need for further research investigating fall risk potential associated with texting and walking among aging populations and how interventions targeting stride length during dual-task circumstances may improve performance.

Postural control integrates somatosensory, vestibular, and visual input to maintain balance. Age, dual-tasking (DT), and varying surfaces may impact postural control and lead to falls. Research suggests smartphone use is a growing safety hazard, as it reduces situational awareness while increasing dual-task costs (DTCs). Therefore, we examined postural control using a modern, motor-cognitive, dual-task paradigm and examined DTCs associated with age, surface characteristic, and type of DT. Younger (n=24) and older (n=26) participants completed three 30- second trials of six different task conditions. Participants either stood quietly (single-task) or performed a secondary, word generation task (dual-task) that included verbally listing words (verbal) or typing words (texting) on a smartphone within a given category (e.g., vegetables) while on a firm, stable surface (level floor) or compliant, unstable surface (foam pad). Repeated-measures MANOVAs tested differences in postural sway (measured by sway angle, velocity, and acceleration) between age groups and task conditions. Results indicated poorer performance on the verbal DT than texting DT while standing on the level floor; performance was similar between the two DTs when standing on the foam pad. We also found poorer performance on the foam pad compared to level floor while texting; performance was similar between surfaces for the verbal DT. Younger adults generally had better performance than older adults within each task, particularly for texting on the level floor. In summary, older age, verbal tasks, and compliant, unstable surfaces have greater impact on postural control parameters compared to younger age, texting, and firm, stable surfaces.

Mobility and gait limitations are major issues for people with Parkinson disease (PD). Identification of factors that contribute to these impairments may inform treatment and intervention strategies. In this study we investigated factors that predict mobility and gait impairment in PD. Participants with mild to moderate PD and without dementia (n=114) were tested in one session ‘off’ medication. Mobility measures included the 6-Minute Walk test and Timed-Up-and-Go. Gait velocity was collected in four conditions: forward preferred speed, forward dual task, forward fast as possible and backward walking. The predictors analyzed were age, gender, disease severity, balance, balance confidence, fall history, self-reported physical activity, and executive function. Multiple regression models were used to assess the relationships between predictors and outcomes. The predictors, in different combinations for each outcome measure, explained 55.7% to 66.9% of variability for mobility and 39.5% to 52.8% for gait velocity. Balance was the most relevant factor (explaining up to 54.1% of variance in mobility and up to 45.6% in gait velocity). Balance confidence contributed to a lesser extent (2.0% to 8.2% of variance) in all models. Age explained a small percentage of variance in mobility and gait velocity (up to 2.9%). Executive function explained 3.0% of variance during forward walking only. The strong predictive relationships between balance deficits and mobility and gait impairment suggest targeting balance deficits may be particularly important for improving mobility and gait in people with PD, regardless of an individual’s age, disease severity, fall history, or other demographic features.

People with Parkinson disease (PD) demonstrate improvements in motor function following group tango classes, but report long commutes as a barrier to participation. To increase access, we investigated a telerehabilitation approach to group tango instruction. Twenty-six people with mild-to-moderate PD were assigned based on commute distance to either the telerehabilitation group (Telerehab) or an in-person instruction group (In-person). Both groups followed the same twice-weekly, 12-week curriculum with the same instructor. Feasibility metrics were participant retention, attendance and adverse events. Outcomes assessed were balance, PD motor sign severity and gait. Participant retention was 85% in both groups. Attendance was 87% in the Telerehab group and 84% in the In-person group. No adverse events occurred. Balance and motor sign severity improved significantly over time ( p

Objective Freezing of gait (FOG) is a locomotor disturbance in Parkinson disease (PD) related to impaired motor automaticity. In this study, we investigated the impact of freezing on automaticity in the oculomotor system using an anti-saccade paradigm. Methods Subjects with PD with (PD–FOG, n =13) and without (PD–NON, n =13) FOG, and healthy age-matched controls (CTRL, n =12) completed automatic pro-saccades and non-automatic anti-saccades. Primary outcomes were saccade latency, velocity, and gain. Results PD–FOG (pro-saccade latency=271ms, anti-saccade latency=412ms) were slower to execute both types of saccades compared to PD–NON (253ms, 330ms) and CTRL (246ms, 327ms). Saccade velocity and gain variability was also increased in PD–FOG. Conclusions Saccade performance was affected in PD–FOG for both types of saccades, indicating differences in automaticity and control in the oculomotor system related to freezing. Significance These results and others show that FOG impacts non-gait motor functions, suggesting global motor impairment in PD–FOG.

Impaired gait, balance, and motor function are common in Parkinson disease (PD) and may lead to falls and injuries. Different forms of exercise improve motor function in persons with PD, but determining which form of exercise is most effective requires a direct comparison of various approaches. In this prospective, controlled trial, we evaluated the impact of tango, treadmill walking, and stretching on gait, balance, motor function, and quality of life. We hypothesized tango and treadmill would improve forward walking and motor symptom severity, and tango would also improve backward walking, balance, and quality of life.Ninety-six participants (age: 67.2 ± 8.9 years, 42% female) with mild to moderate idiopathic PD were serially assigned to tango, treadmill walking, or stretching (active control group) and attended 1-hour classes twice weekly for 12 weeks. Assessments occurred OFF anti-PD medication before and after the intervention and at follow-up 12 weeks after the intervention.Forward velocity and backward velocity improved for the treadmill group from baseline to posttest and improvements persisted at follow-up. Backward velocity and motor functioning improved for the stretching group from baseline to posttest, but results did not persist at follow-up. There were no significant changes in the tango group across time points.Contrary to our hypotheses, only treadmill improved forward walking, while backward walking improved with treadmill and stretching. Future research should examine combinations of exercises with a focus on optimizing dosing and examining whether specific characteristics of people with PD correlate with different types of exercise.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A237).

INTRODUCTION: Exercise improves gait in Parkinson disease (PD), but whether exercise differentially affects people with PD with (freezers) and without freezing of gait (non-freezers) remains unclear. This study examines exercise’s effects on gait performance, neural correlates related to these effects, and potential neural activation differences between freezers and non-freezers during motor imagery (MI) of gait. METHODS: Thirty-seven participants from a larger exercise intervention completed behavioral assessments and functional magnetic resonance imaging (fMRI) scans before and after a 12-week exercise intervention. Gait performance was characterized using gait velocity and stride length, and a region of interest (ROI) fMRI analysis examined task-based blood oxygen-level dependent (BOLD) signal changes of the somatomotor network (SMN) during MI of forward (IMG-FWD) and backward (IMG-BWD) gait. RESULTS: Velocity (F(1,34)=55.04, p

Introduction Gait dysfunction is common in people with Parkinson's disease (PD). Freezing of gait (FOG) is one such gait disturbance that significantly impacts mobility and quality of life in PD. Recent evidence suggests that cerebellar connectivity may differ in people with PD and FOG (PD+FOG) relative to those without FOG (PD-FOG). Investigation of gait adaptation, or the ability to change gait patterns in response to external perturbations, is cerebellum-dependent, is a practical means of probing cerebellar integrity and may provide additional insights regarding the FOG phenomenon. Methods In this study, we investigated gait adaptation in PD and FOG by measuring after-effects, namely whole-body rotation, following stepping on a rotating disc in PD+FOG compared to PD-FOG and older healthy adults. We refer to the period of stepping on the rotating disc as the podokinetic (PK) stimulation and after-effects as podokinetic after-rotation (PKAR). Our primary measure of adaptation was the magnitude and rate of decay of the after-effects. Results We noted that PKAR was diminished in PD+FOG compared to the other groups, indicating reduced storage of the adapted gait pattern in PD+FOG. In the PD groups, FOG explained about 20% of the variability in peak velocity. Furthermore, these differences were independent of stepping cadence or motor sign severity. Conclusion Our results show that gait adaptation is impaired in PD+FOG, suggesting the cerebellum may be differentially impacted in PD+FOG compared to PD-FOG. This supports previous neuroimaging evidence of cerebellar dysfunction in PD+FOG. Overall, these data further our understanding of gait deficits in PD+FOG.

Evidence indicates exercise is beneficial for motor and non-motor function in older adults and people with chronic diseases including Parkinson disease (PD). Dance may be a relevant form of exercise in PD and older adults due to social factors and accessibility. People with PD experience motor and non-motor symptoms, but treatments, interventions, and assessments often focus more on motor symptoms. Similar non-motor symptoms also occur in older adults. While it is well-known that dance may improve motor outcomes, it is less clear how dance affects non-motor symptoms. This review aims to describe the effects of dance interventions on non-motor symptoms in older adults and PD, highlights limitations of the literature, and identifies opportunities for future research. Overall, intervention parameters, study designs, and outcome measures differ widely, limiting comparisons across studies. Results are mixed in both populations, but evidence supports the potential for dance to improve mood, cognition, and quality of life in PD and healthy older adults. Participation and non-motor symptoms like sleep disturbances, pain, and fatigue have not been measured in older adults. Additional well-designed studies comparing dance and exercise interventions are needed to clarify the effects of dance on non-motor function and establish recommendations for these populations.

Background Freezing of gait (FOG) is a relatively common and remarkably disabling impairment associated with Parkinson disease (PD). Laboratory-based measures indicate that individuals with FOG (PD + FOG) have greater balance deficits than those without FOG (PD − FOG). Whether such differences also can be detected using clinical balance tests has not been investigated. We sought to determine if balance and specific aspects of balance, measured using Balance Evaluation Systems Test (BESTest), differs between PD + FOG and PD − FOG. Furthermore, we aimed to determine if time-efficient clinical balance measures (i.e. Mini-BESTest, Berg Balance Scale (BBS)) could detect balance differences between PD + FOG and PD − FOG. Methods Balance of 78 individuals with PD, grouped as either PD + FOG ( n = 32) or PD − FOG ( n = 46), was measured using the BESTest, Mini-BESTest, and BBS. Between-groups comparisons were conducted for these measures and for the six sections of the BESTest using analysis of covariance. A PD composite score was used as a covariate. Results Controlling for motor sign severity, PD duration, and age, PD + FOG had worse balance than PD − FOG when measured using the BESTest ( p = 0.008, F = 7.35) and Mini-BESTest ( p = 0.002, F = 10.37), but not the BBS ( p = 0.27, F = 1.26). BESTest section differences were noted between PD + FOG and PD − FOG for reactive postural responses ( p F = 14.42) and stability in gait ( p = 0.003, F = 9.18). Conclusions The BESTest and Mini-BESTest, which specifically assessed reactive postural responses and stability in gait, were more likely than the BBS to detect differences in balance between PD + FOG and PD − FOG. Because it is more time efficient to administer, the Mini-BESTest may be the preferred tool for assessing balance deficits associated with FOG.

BackgroundDeclining ambulatory activity represents an important facet of disablement in Parkinson disease (PD).ObjectiveThe primary study aim was to compare the 2-year trajectory of ambulatory activity decline with concurrently evolving facets of disability in a small cohort of people with PD. The secondary aim was to identify baseline variables associated with ambulatory activity at 1- and 2-year follow-up assessments.DesignThis was a prospective, longitudinal cohort study.MethodsSeventeen people with PD (Hoehn and Yahr stages 1–3) were recruited from 2 outpatient settings. Ambulatory activity data were collected at baseline and at 1- and 2-year annual assessments. Motor, mood, balance, gait, upper extremity function, quality of life, self-efficacy, and levodopa equivalent daily dose data and data on activities of daily living also were collected.ResultsParticipants displayed significant 1- and 2-year declines in the amount and intensity of ambulatory activity concurrently with increasing levodopa equivalent daily dose. Worsening motor symptoms and slowing of gait were apparent only after 2 years. Concurrent changes in the remaining clinical variables were not observed. Baseline ambulatory activity and physical performance variables had the strongest relationships with 1- and 2-year mean daily steps.LimitationsThe sample was small and homogeneous.ConclusionsFuture research that combines ambulatory activity monitoring with a broader and more balanced array of measures would further illuminate the dynamic interactions among evolving facets of disablement and help determine the extent to which sustained patterns of recommended daily physical activity might slow the rate of disablement in PD.

Assessment of fall risk in an individual with Parkinson disease (PD) is a critical yet often time consuming component of patient care. Recently a simple clinical prediction tool based only on fall history in the previous year, freezing of gait in the past month, and gait velocity1.1 m/s was developed and accurately predicted future falls in a sample of individuals with PD.We sought to externally validate the utility of the tool by administering it to a different cohort of 171 individuals with PD. Falls were monitored prospectively for 6 months following predictor assessment.The tool accurately discriminated future fallers from non-fallers (area under the curve [AUC] = 0.83; 95% CI 0.76-0.89), comparable to the developmental study.The results validated the utility of the tool for allowing clinicians to quickly and accurately identify an individual's risk of an impending fall.

Visuomotor adaptation to gaze-shifting prism glasses requires recalibration of the relationship between sensory input and motor output. Healthy individuals flexibly adapt movement patterns to many external perturbations; however, individuals with cerebellar damage do not adapt movements to the same extent. People with Parkinson disease (PD) adapt normally, but exhibit reduced after-effects, which are negative movement errors following the removal of the prism glasses and are indicative of true spatial realignment. Walking is particularly affected in PD, and many individuals experience freezing of gait (FOG), an episodic interruption in walking, that is thought to have a distinct pathophysiology. Here, we examined how individuals with PD with (PD + FOG) and without (PD - FOG) FOG, along with healthy older adults, adapted both reaching and walking patterns to prism glasses. Participants completed a visually guided reaching and walking task with and without rightward-shifting prism glasses. All groups adapted at similar rates during reaching and during walking. However, overall walking adaptation rates were slower compared to reaching rates. The PD - FOG group showed smaller after-effects, particularly during walking, compared to PD + FOG, independent of adaptation magnitude. While FOG did not appear to affect characteristics of prism adaptation, these results support the idea that the distinct neural processes governing visuomotor adaptation and storage are differentially affected by basal ganglia dysfunction in PD.

It is important for our aging population to remain active, particularly those with chronic diseases, like Parkinson disease (PD), which limit mobility. Recent studies in older adults and people with PD suggest dance interventions provide various motor benefits. The literature for dance in PD is growing, but many knowledge gaps remain, relative to what is known in older adults. The purpose of this review is to: (1) detail results of dance intervention studies in older adults and in PD, (2) describe limitations of dance research in these populations, and (3) identify directions for future study. Generally, a wide variety of dance styles have been investigated in older adults, while a more limited subset has been evaluated in PD. Measures vary widely across studies and a lack of standardized outcomes measures hinders cross-studies comparisons. Compared to the dance literature in older adults, there is a notable absence of evidence in the PD literature in outcome domains related to cardiovascular health, muscle strength, body composition, flexibility, and proprioception. As a whole, the dance literature supports substantial and wide-ranging benefits in both populations, but additional effort should be dedicated to well-designed comparative studies using standardized outcome measures to identify optimal treatment programs.

Cortical activity during motor task performance is attenuated in individuals with Parkinson disease (PD) relative to age-matched adults without PD, and this activity is enhanced with antiparkinson medication. It remains unclear, however, whether the relative change in cortical activity over the duration of the task, i.e., central adaptation, is affected individuals with PD, and if so, whether medication corrects for any unique behaviors. Movement-related cortical potentials (MRCPs) were recorded from scalp electrode sites Cz and C1 during 150 repetitive handgrip contractions at 70% of maximal voluntary contraction, in individuals with PD (n = 10) both ON and OFF of their PD medication, and neurologically normal age- and sex-matched controls (n = 10). Repetitions were divided into two Blocks (Block 1 and 2: repetitions 1 – 60 and 91 – 150, respectively), and the composite MRCP slopes were calculated during periods representing movement initiation (−2s to movement onset) and execution (movement onset to 1s). No significant interactions were noted for either comparison (PD OFF vs. control; PD OFF vs. PD ON), irrespective of electrode site (Cz or C1) or movement period (initiation or execution). Despite similar MRCP slopes and task performance, PD OFF endorsed greater perceived exertion during task performance than controls. In the present study, we observed attenuated task-related cortical activity among individuals with PD OFF relative to controls, but a similar relative adaptive response to a fatiguing task. Additionally, although antiparkinson medication enhanced cortical activity (PD OFF vs. PD ON), central adaptation was similar.

To determine the effects of participation in a 2-year community-based dance class on disease severity and functional mobility in people with Parkinson disease (PD).Randomized controlled trial.Dance classes took place in a community-based location. Outcome measures were collected in a university laboratory.Ten individuals with PD were randomly assigned to the Argentine tango (AT) group (n=5 [4 men]; mean age±standard deviation, 69.6±6.6 years) or the control group (n=5 [4 men]; mean age±standard deviation, 66±11.0 years).The AT group participated in a community-based AT class for 1 hour twice weekly for 2 years. Control group participants were given no prescribed exercise. Blinded assessments occurred at baseline and 12 and 24 months.Movement Disorder Society-Unified Parkinson Disease Rating Scale (MDS-UPDRS) III, Mini-Balance Evaluation Systems Test (Mini-BESTest), gait velocity (forward and backward), Timed Up and Go and dual-task Timed Up and Go, Six-Minute Walk Test (6MWT), MDS-UPDRS II, MDS-UPDRS I, and Freezing of Gait Questionnaire.There were no differences between groups at baseline. A significant group-by-time interaction (F [2,8]=17.59; p0.0001) was noted for the MDS-UPDRS III, with the AT group having lower scores at 12 and 24 months than the controls. Significant interactions were also noted for the Mini-BESTest, MDS-UPDRS II and I, and 6MWT.This is believed to be one of the longest-duration studies to examine the effects of exercise on PD. Participation in community-based dance classes over 2 years was associated with improvements in motor and nonmotor symptom severity, performance on activities of daily living, and balance in a small group of people with PD. This is noteworthy given the progressive nature of PD and the fact that the control group declined on some outcome measures over 2 years.

Successful locomotion depends on postural control to establish and maintain appropriate postural orientation of body segments relative to one another and to the environment and to ensure dynamic stability of the moving body. This article provides a framework for considering dynamic postural control, highlighting the importance of coordination, consistency, and challenges to postural control posed by various locomotor tasks, such as turning and backward walking. The impacts of aging and various movement disorders on postural control are discussed broadly in an effort to provide a general overview of the field and recommendations for assessment of dynamic postural control across different populations in both clinical and research settings. Suggestions for future research on dynamic postural control during locomotion also are provided and include discussion of opportunities afforded by new and developing technologies, the need for long-term monitoring of locomotor performance in everyday activities, gaps in our knowledge of how targeted intervention approaches modify dynamic postural control, and the relative paucity of literature regarding dynamic postural control in movement disorder populations other than Parkinson's disease.

Parkinson disease (PD) is a progressive, neurodegenerative movement disorder. PD was originally attributed to neuronal loss within the substantia nigra pars compacta, and a concomitant loss of dopamine. PD is now thought to be a multisystem disorder that involves not only the dopaminergic system, but other neurotransmitter systems whose role may become more prominent as the disease progresses (189). PD is characterized by four cardinal symptoms, resting tremor, rigidity, bradykinesia, and postural instability, all of which are motor. However, PD also may include any combination of a myriad of nonmotor symptoms (195). Both motor and nonmotor symptoms may impact the ability of those with PD to participate in exercise and/or impact the effects of that exercise on those with PD. This article provides a comprehensive overview of PD, its symptoms and progression, and current treatments for PD. Among these treatments, exercise is currently at the forefront. People with PD retain the ability to participate in many forms of exercise and generally respond to exercise interventions similarly to age-matched subjects without PD. As such, exercise is currently an area receiving substantial research attention as investigators seek interventions that may modify the progression of the disease, perhaps through neuroprotective mechanisms.

Background and purpose The Four Square Step Test (4SST), a quick and simple test of multidirectional stepping, may be useful in predicting falls in people with Parkinson disease (PD). We studied the reliability of the 4SST and its ability to discriminate between freezers and nonfreezers, between fallers and nonfallers, and factors predictive of 4SST performance in people with PD. Methods Fifty-three individuals with idiopathic PD completed the full protocol, including the 4SST as well as measures of balance, walking, and disease severity on anti-PD medication. Results Interrater (intraclass correlation coefficient [ICC] = 0.99) and test-retest reliability were high (ICC = 0.78). The median 4SST performance was 9.52 seconds. There was a significant difference between 4SST time on-medication versus off (P = 0.03), while differences between fallers and nonfallers (P = 0.06) and between freezers and nonfreezers (P = 0.08) did not reach significance. All outcome measures were significantly related to 4SST time. In an exploratory, simultaneous regression analysis, 56% of the variance in 4SST performance could be accounted for by 3 measures: Mini-Balance Evaluation Systems Test (Mini-BESTest), Five Time Sit to Stand, and Nine Hole Peg Test. The 4SST cutoff score for distinguishing fallers from nonfallers was 9.68 seconds (Area under curve = 0.65, sensitivity = 0.73, specificity = 0.57). The posttest probability of an individual with a score greater than the cutoff being a faller was 31% (pretest probability = 21%). Discussion and conclusions The 4SST is a reliable, quick test that can distinguish between on-and off-medication conditions in PD but is not as good as other tests (eg, Mini-BESTest) for distinguishing between fallers and nonfallers. Video Abstract available (see the Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A31) for more insights from the authors.

Objectives The effects of subthalamic nucleus (STN) deep brain stimulation (DBS) on gait and balance vary and the underlying mechanisms remain unclear. DBS location may alter motor benefit due to anatomical heterogeneity in STN. The purposes of this study were to (1) compare the effects of DBS of dorsal (D-STN) versus ventral (V-STN) regions on gait, balance and regional cerebral blood flow (rCBF) and (2) examine the relationships between changes in rCBF and changes in gait and balance induced by D-STN or V-STN DBS. Methods We used a validated atlas registration to locate and stimulate through electrode contacts in D-STN and V-STN regions of 37 people with Parkinson's disease. In a within-subjects, double-blind and counterbalanced design controlled for DBS settings, we measured PET rCBF responses in a priori regions of interest and quantified gait and balance during DBS Off, unilateral D-STN DBS and unilateral V-STN DBS. Results DBS of either site increased stride length without producing significant group-level changes in gait velocity, cadence or balance. Both sites increased rCBF in subcortical regions and produced variable changes in cortical and cerebellar regions. DBS-induced changes in gait velocity are related to premotor cortex rCBF changes during V-STN DBS ( r = − 0.40, p = 0.03) and to rCBF changes in the cerebellum anterior lobe during D-STN DBS ( r = − 0.43, p = 0.02). Conclusions DBS-induced changes in gait corresponded to rCBF responses in selected cortical and cerebellar regions. These relationships differed during D-STN versus V-STN DBS, suggesting DBS acts through distinct neuronal pathways dependent on DBS location.

Objective To determine the effects of a 12-month community-based tango dance program on activity participation among individuals with Parkinson's disease (PD). Design Randomized controlled trial with assessment at baseline, 3, 6, and 12 months. Setting Intervention was administered in the community; assessments were completed in a university laboratory. Participants Volunteers with PD (n=62) enrolled in the study and were randomized to a treatment group; 10 participants did not receive the allocated intervention, and therefore the final analyzed sample included 52 participants. Interventions Participants were randomly assigned to the tango group, which involved 12 months of twice-weekly Argentine tango dance classes, or to the no intervention control group (n=26 per group). Main Outcome Measure Current, new, and retained participation in instrumental, leisure, and social activities, as measured by the Activity Card Sort (with the dance activity removed). Results Total current participation in the tango group was higher at 3, 6, and 12 months compared with baseline ( P s≤.008), while the control group did not change ( P s≥.11). Total activity retention (since onset of PD) in the tango group increased from 77% to 90% ( P =.006) over the course of the study, whereas the control group remained around 80% ( P =.60). These patterns were similar in the separate activity domains. The tango group gained a significant number of new social activities ( P =.003), but the control group did not ( P =.71). Conclusions Individuals with PD who participated in a community-based Argentine tango class reported increased participation in complex daily activities, recovery of activities lost since the onset of PD, and engagement in new activities. Incorporating dance into the clinical management of PD may benefit participation and subsequently quality of life for this population.

Purpose. Motor freezing, the inability to produce effective movement, is associated with decreasing amplitude, hastening of movement, and poor coordination. We investigated how manipulations of movement amplitude and cadence affect upper extremity (UE) coordination as measured by the phase coordination index (PCI)—only previously measured in gait—and freezing of the upper extremity (FO-UE) in people with Parkinson's disease (PD) who experience freezing of gait (PD + FOG), do not experience FOG (PD-FOG), and healthy controls.Methods. Twenty-seven participants with PD and 18 healthy older adults made alternating bimanual movements between targets under four conditions: Baseline; Fast; Small; SmallFast. Kinematic data were recorded and analyzed for PCI and FO-UE events. PCI and FO-UE were compared across groups and conditions. Correlations between UE PCI, gait PCI, FO-UE, and Freezing of Gait Questionnaire (FOG-Q) were determined.Results. PD + FOG had poorer coordination than healthy old during SmallFast. UE coordination correlated with number of FO-UE episodes in two conditions and FOG-Q score in one. No differences existed between PD−/+FOG in coordination or number of FO-UE episodes.Conclusions. Dyscoordination and FO-UE can be elicited by manipulating cadence and amplitude of an alternating bimanual task. It remains unclear whether FO-UE and FOG share common mechanisms.

Background Dopaminergic medications and subthalamic nucleus deep brain stimulation (STN-DBS) alleviate motor symptoms in Parkinson disease, but balance and gait are more variably affected. Balance reports are particularly inconsistent. Further, despite their prevalence in daily life, complex gait situations including backward and dual task gait are rarely studied. We aimed to assess how medications, STN-DBS, and both therapies combined affect balance and complex gait.

We determined the number of days required, and whether to include weekdays and/or weekends, to obtain reliable measures of ambulatory physical activity in people with Parkinson's disease (PD). Ninety-two persons with PD wore a step activity monitor for seven days. The number of days required to obtain a reliable estimate of daily activity was determined from the mean intraclass correlation (ICC2,1) for all possible combinations of 1-6 consecutive days of monitoring. Two days of monitoring were sufficient to obtain reliable daily activity estimates (ICC2,1 > 0.9). Amount (p = 0.03) but not intensity (p = 0.13) of ambulatory activity was greater on weekdays than weekends. Activity prescription based on amount rather than intensity may be more appropriate for people with PD.

Brain regions important for controlling movement are also responsible for rhythmic processing. In Parkinson disease (PD), defective internal timing within the brain has been linked to impaired beat discrimination, and may contribute to a loss of ability to maintain a steady gait rhythm. Less rhythmic gait is inherently less efficient, and this may lead to gait impairment including reduced speed, cadence, and stride length, as well as increased variability. While external rhythmic auditory stimulation (e.g. a metronome beat) is well-established as an effective tool to stabilize gait in PD, little is known about whether self-generated cues such as singing have the same beneficial effect on gait in PD. Thus, we compared gait patterns of 23 people with mild to moderate PD under five cued conditions: uncued, music only, singing only, singing with music, and a verbal dual-task condition. In our single-session study, singing while walking did not significantly alter velocity, cadence, or stride length, indicating that it was not excessively demanding for people with PD. In addition, walking was less variable when singing than during other cued conditions. This was further supported by the comparison between singing trials and a verbal dual-task condition. In contrast to singing, the verbal dual-task negatively affected gait performance. These findings suggest that singing holds promise as an effective cueing technique that may be as good as or better than traditional cueing techniques for improving gait among people with PD.