Gait Impairment In Parkinson's Disease Research Articles

ID: 317275 Spinal Cord Stimulation for Gait Impairment in Parkinson Disease: Scoping Review and Mechanistic Considerations

ID: 317275 Spinal Cord Stimulation for Gait Impairment in Parkinson Disease: Scoping Review and Mechanistic Considerations

Auditory cues modulate the short timescale dynamics of STN activity during stepping in Parkinson's disease

BackgroundGait impairment has a major impact on quality of life in patients with Parkinson's disease (PD). It is believed that basal ganglia oscillatory activity at β frequencies (15–30 Hz) may contribute to gait impairment, but the precise dynamics of this oscillatory activity during gait remain unclear. Additionally, auditory cues are known to lead to improvements in gait kinematics in PD. If the neurophysiological mechanisms of this cueing effect were better understood they could be leveraged to treat gait impairments using adaptive Deep Brain Stimulation (aDBS) technologies. ObjectiveWe aimed to characterize the dynamics of subthalamic nucleus (STN) oscillatory activity during stepping movements in PD and to establish the neurophysiological mechanisms by which auditory cues modulate gait. MethodsWe studied STN local field potentials (LFPs) in eight PD patients while they performed stepping movements. Hidden Markov Models (HMMs) were used to discover transient states of spectral activity that occurred during stepping with and without auditory cues. ResultsThe occurrence of low and high β bursts was suppressed during and after auditory cues. This manifested as a decrease in their fractional occupancy and state lifetimes. Interestingly, α transients showed the opposite effect, with fractional occupancy and state lifetimes increasing during and after auditory cues. ConclusionsWe show that STN oscillatory activity in the α and β frequency bands are differentially modulated by gait-promoting oscillatory cues. These findings suggest that the enhancement of α rhythms may be an approach for ameliorating gait impairments in PD.

Spinal cord stimulation for gait impairment in Parkinson Disease: scoping review and mechanistic considerations.

Advanced Parkinson's Disease (PD) is associated with Parkinson's Disease gait impairment (PDg), which increases the risk for falls and is often treatment-refractory. Subthalamic nucleus (STN) and globus pallidus pars interna (GPi) deep brain stimulation (DBS) often fails to improve axial symptoms like PDg. Spinal cord stimulation (SCS) has been suggested to improve PDg. SCS may benefit PDg by disrupting pathologic beta-oscillations and hypersynchrony in cortico-striatal-thalamic circuits to override excessive inhibition of brainstem locomotor regions. SCS may potentially improve locomotion by acting at any of these levels, either alone or in combination. We conducted a comprehensive literature search and scoping review, identifying 106 patients in whom SCS was evaluated for PDg. Among the identified patients, 63% carried a pain diagnosis. Overall, the most common stimulation location was thoracic (78%), most commonly T9-T10. Burst (sub-perception) was the most common stimulation modality (59%). Prior treatment with DBS was used in 25%. Motor outcomes were assessed by the Unified Parkinson Disease Rating Scale (UPDRS) III-motor, UPDRS, the Timed Up and Go (TUG), and/or 10-/20-meter walking tests.Among these patients, 95 (90%) had PDg amelioration and improved motor outcomes. Despite small sample sizes, patient heterogeneity, and unblinded evaluations complicating interpretations of efficacy and safety, SCS may be beneficial for at least a subset of PDg. Further research is required to clarify the role of SCS for PDg and the patients most suitable to benefit from this intervention.

Relationship between 123I-FP-CIT-SPECT and gait impairments in drug-naïve individuals with Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by loss of nigrostriatal dopaminergic neurons [1]. In addition to cardinal motor symptoms, individuals with PD suffer of gait impairment [2]. Although functional imaging is useful for the diagnosis and pathophysiological evaluation of PD, little is known about the relationship between neuroimaging findings and PD clinical features. A study found a correlation between dopamine denervation and impaired gait automaticity [3]; others reported no association between dopaminergic denervation and some gait parameters, such as stride length and velocity [4,5], assuming that deficits in nondopaminergic neurotransmitter systems played the main role in gait impairments [3]. We aimed to examine the relationship between striatal dopaminergic depletion with disease severity in motor symptoms and gait variables in drug-naïve individuals with PD, in order to find where nigrostriatal pathway mainly acts. A total of 18 drug-naïve individuals with PD (mean age 70.4 ± 7.4 yrs) were enrolled. Motor symptoms were evaluated using the modified Hoehn and Yahr (H&Y) stage. Seven spatiotemporal variables of gait were acquired using a GAITRite® electronic walkway under comfortable walking, of which the coefficient of variation and the asymmetry were then calculated. The extent of striatal dopaminergic depletion was evaluated by dopamine transporter imaging with single-photon emission computed tomography using 123I-FP-CIT. Correlations between H&Y stage and gait variables with the specific binding ratios (SBRs) of the striatum (separated into putamen and caudate nucleus) were assessed with the Spearman's correlation coefficients (r). The mean SBRs of both the putamen and the caudate nucleus were significantly associated with the modified H&Y stage, with correlation coefficient of at least 0.60. A moderate correlation was found also between the asymmetry in the SBR of the putamen and the H&Y stage. Moreover, among the spatiotemporal gait variables, a moderate correlation was found between the mean double support duration and its asymmetry with the mean SBRs of both the putamen and the caudate nucleus (Table 1). On the contrary, stride length and velocity showed a weak correlation (below 0.30). Our findings suggest that both disease severity and gait impairments in early PD are associated with decreased dopamine binding in the striatum. Since the double support time showed a moderate correlation with dopaminergic depletion in particular in caudate nucleus, we propose this variable as a marker of the effect of nigrostriatal denervation on gait in individuals with early PD. On the other hand, the poor correlations found between the reduction of stride length and velocity with the nigrostriatal depletion confirmed the hypothesis of a major involvement of other systems (such as the cholinergic) in the control of these variables. Our findings supported the notion that a large part of gait impairments in PD resulted from multisystem degeneration [6,7].

Gait‐Related Metabolic Covariance Networks at Rest in Parkinson's Disease

BackgroundGait impairments are characteristic motor manifestations and significant predictors of poor quality of life in Parkinson's disease (PD). Neuroimaging biomarkers for gait impairments in PD could facilitate effective interventions to improve these symptoms and are highly warranted.ObjectiveThe aim of this study was to identify neural networks of discrete gait impairments in PD.MethodsFifty‐five participants with early‐stage PD and 20 age‐matched healthy volunteers underwent quantitative gait assessment deriving 12 discrete spatiotemporal gait characteristics and [18F]‐2‐fluoro‐2‐deoxyglucose‐positron emission tomography measuring resting cerebral glucose metabolism. A multivariate spatial covariance approach was used to identify metabolic brain networks that were related to discrete gait characteristics in PD.ResultsIn PD, we identified two metabolic gait‐related covariance networks. The first correlated with mean step velocity and mean step length (pace gait network), which involved relatively increased and decreased metabolism in frontal cortices, including the dorsolateral prefrontal and orbital frontal, insula, supplementary motor area, ventrolateral thalamus, cerebellum, and cuneus. The second correlated with swing time variability and step time variability (temporal variability gait network), which included relatively increased and decreased metabolism in sensorimotor, superior parietal cortex, basal ganglia, insula, hippocampus, red nucleus, and mediodorsal thalamus. Expression of both networks was significantly elevated in participants with PD relative to healthy volunteers and were not related to levodopa dosage or motor severity.ConclusionsWe have identified two novel gait‐related brain networks of altered glucose metabolism at rest. These gait networks could serve as a potential neuroimaging biomarker of gait impairments in PD and facilitate development of therapeutic strategies for these disabling symptoms. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Functional Connectivity of Vermis Correlates with Future Gait Impairments in Parkinson's Disease.

Dysfunction of cerebellar vermis contributes to gait abnormalities in multiple conditions and may play a key role in gait impairment in Parkinson's disease (PD). The purpose of this study was to investigate whether altered resting-state functional connectivity of the vermis relates to subsequent impairment of specific domains of gait in PD. We conducted morphometric and resting-state functional connectivity MRI analyses contrasting 45 PD and 32 age-matched healthy participants. Quantitative gait measures were acquired with a GAITRite walkway at varying intervals after functional connectivity data acquisition. At baseline, PD participants had significantly altered functional connectivity between vermis and sensorimotor cortex compared with controls. Altered vermal functional connectivity with bilateral paracentral lobules correlated with subsequent measures of variability in stride length, step time, and single support time after controlling for confounding variables including the interval between imaging and gait measures. Similarly, altered functional connectivity between vermis and left sensorimotor cortex correlated with mean stride length and its variability. Vermis volume did not relate to any gait measure. PD participants did not differ from controls in vermis volume or cortical thickness at the site of significant regional clusters. Only altered lobule V:sensorimotor cortex functional connectivity correlated with subsequent gait measures in exploratory analyses involving all the other cerebellar lobules. These results demonstrate that abnormal vermal functional connectivity with sensorimotor cortex, in the absence of relevant vermal or cortical atrophy, correlates with subsequent gait impairment in PD. Our data reflect the potential of vermal functional connectivity as a novel imaging biomarker of gait impairment in PD. © 2021 International Parkinson and Movement Disorder Society.

Cholinergic Basal Forebrain Volumes Predict Gait Decline in Parkinson's Disease.

ABSTRACTBackgroundGait disturbance is an early, disabling feature of Parkinson's disease (PD) that is typically refractory to dopaminergic medication. The cortical cholinergic system, originating in the nucleus basalis of Meynert of the basal forebrain, has been implicated. However, it is not known if degeneration in this region relates to a worsening of disease‐specific gait impairment.ObjectiveTo evaluate associations between sub‐regional cholinergic basal forebrain volumes and longitudinal progression of gait impairment in PD.Methods99 PD participants and 47 control participants completed gait assessments via an instrumented walkway during 2 minutes of continuous walking, at baseline and for up to 3 years, from which 16 spatiotemporal characteristics were derived. Sub‐regional cholinergic basal forebrain volumes were measured at baseline via MRI and a regional map derived from post‐mortem histology. Univariate analyses evaluated cross‐sectional associations between sub‐regional volumes and gait. Linear mixed‐effects models assessed whether volumes predicted longitudinal gait changes.ResultsThere were no cross‐sectional, age‐independent relationships between sub‐regional volumes and gait. However, nucleus basalis of Meynert volumes predicted longitudinal gait changes unique to PD. Specifically, smaller nucleus basalis of Meynert volume predicted increasing step time variability (P = 0.019) and shortening swing time (P = 0.015); smaller posterior nucleus portions predicted shortening step length (P = 0.007) and increasing step time variability (P = 0.041).ConclusionsThis is the first study to demonstrate that degeneration of the cortical cholinergic system predicts longitudinal progression of gait impairments in PD. Measures of this degeneration may therefore provide a novel biomarker for identifying future mobility loss and falls. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Effects of virtual reality environments on overground walking in people with Parkinson disease and freezing of gait

Background Freezing of gait (FoG) is a common target of rehabilitative interventions for people with Parkinson disease (PD). Virtual reality (VR) holds potential for advancing research and clinical management of FoG through flexible creation of FoG-provoking environments that are not easily or safely replicated in the clinic. Objective The aim of this study was to investigate whether VR environments that replicate FoG-provoking situations would exacerbate gait impairments associated with FoG compared to unobstructed VR and physical laboratory environments. Methods Gait characteristics (pace, rhythm, variability, asymmetry, and postural control domains) and festination were measured using motion capture while people with PD walked in VR environments based on FoG-provoking situations (doorway, hallway, and crowd environments) compared to unobstructed VR and physical laboratory environments. The effect of VR environments was assessed using one-way repeated measures ANOVAs with planned contrasts. Results Ten participants (mean age 74.1 years, 3 females, Hoehn and Yahr stage 2–3) with PD who self-reported FoG participated. Gait speed and step length were reduced in all VR environments compared to the physical laboratory. Step width was wider, step length was more variable, and festination was more common for some of the VR environments compared to the physical laboratory environment. Compared to the unobstructed virtual laboratory environment, step length was more variable in VR crowd and doorway environments. Conclusions The exacerbation of gait impairments that are characteristic precursors of FoG in FoG-provoking VR environments supports the potential utility of VR technology in the assessment and treatment of gait impairments in PD. Implications for rehabilitation Freezing increases fall risk and reduces quality of life in Parkinson disease (PD). Virtual reality (VR) can simulate visuospatial environments that provoke freezing. Immersive VR doorway, hallway, and crowd environments were developed. Gait speed slowed when people with PD walked overground in all VR environments. Step variability and festination increased in freeze-provoking environments.

Cholinergic nucleus 4 atrophy and gait impairment in Parkinson's disease.

There is evidence that cortical cholinergic denervation contributes to gait and balance impairment in Parkinson's Disease (PD), especially reduced gait speed. The objective of this study was to determine the relationship between cholinergic basal forebrain gray matter density (GMD) and gait in PD patients. We investigated 66 PD patients who underwent a pre-surgical evaluation for a neurosurgical procedure to treat motor symptoms of PD. As part of this evaluation patients had a brain MRI and formal gait assessments. By applying probabilistic maps of the cholinergic basal forebrain to voxel-based morphometry of brain MRI, we calculated gray matter density (GMD) for cholinergic nucleus 4 (Ch4), cholinergic nucleus 1, 2, and 3 (Ch123), and the entire cortex. Reduced Ch4 GMD was associated with reduced Fast Walking Speed in the "on" medication state (FWSON, p = 0.004). Bilateral cortical GMD was also associated with FWSON (p = 0.009), but Ch123 GMD was not (p = 0.1). Bilateral cortical GMD was not associated with FWSON after adjusting for Ch4 GMD (p = 0.44). While Ch4 GMD was not associated with improvement in Timed Up and Go (TUG) or Cognitive TUG in the "on" medication state, reduced Ch4 GMD was associated with greater percent worsening based on dual tasks (p = 0.021). Reduced Ch4 GMD is associated with slower gait speed in PD and greater percent worsening in TUG during dual tasks in patients with PD. These findings have implications for planning of future clinical trials investigating cholinergic therapies to improve gait impairment in PD.

Physical Therapy for Freezing of Gait and Gait Impairments in Parkinson Disease: A Systematic Review.

Freezing of gait (FOG) is a major cause of falls and disability in Parkinson disease (PD). As FOG only partially improves in response to dopaminergic medication, physical therapy is an important element of its management. To assess the evidence for the physical interventions for FOG and gait impairments and to establish recommendations for clinical practice. This review follows the guidelines for systematic reviews: the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Systematic search in PubMed, Embase, Physiotherapy Evidence Databases, and CINAHL for randomized controlled trials of PT interventions for FOG in PD patients until April 2018. Twenty randomized controlled trials (RCTs) were reviewed. In 12 RCTs, PT for FOG was assessed, which was the primary outcome measure in nine of these RCTs. In eight RCTs, PT for gait impairment (not targeting specifically FOG) in PD was assessed. The following PT interventions reduce FOG with a good category A recommendation: cueing strategies (P < .05) (visual and auditory); treadmill walking (P < .05); aquatic obstacle training (P < .01); supervised slackline training (P < .05). These interventions can be combined and maintain their efficacy when being applied concurrently: though there is a lack of long-term follow-up studies. The following PT interventions show possible benefit and need further investigations: balance and coordination training; aquatic gait training; sensory (tactile) cues. The treadmill training and auditory and visual cues are effective also for other gait disturbances in PD and improve gait kinematics. Visual and auditory cueing and the treadmill training are effective interventions for FOG and gait impairments in PD patients (evidence level A- according to the European Federation of Neurological Societies). Tactile cues and other specific therapies targeting FOG are probably effective but need further studies.

Compensation Strategies for Gait Impairments in Parkinson Disease

Compensation Strategies for Gait Impairments in Parkinson Disease

Galvanic Vestibular Stimulation (GVS) Augments Deficient Pedunculopontine Nucleus (PPN) Connectivity in Mild Parkinson's Disease: fMRI Effects of Different Stimuli.

Falls and balance difficulties remain a major source of morbidity in Parkinson's Disease (PD) and are stubbornly resistant to therapeutic interventions. The mechanisms of gait impairment in PD are incompletely understood but may involve changes in the Pedunculopontine Nucleus (PPN) and its associated connections. We utilized fMRI to explore the modulation of PPN connectivity by Galvanic Vestibular Stimulation (GVS) in healthy controls (n = 12) and PD subjects even without overt evidence of Freezing of Gait (FOG) while on medication (n = 23). We also investigated if the type of GVS stimuli (i.e., sinusoidal or stochastic) differentially affected connectivity. Approximate PPN regions were manually drawn on T1 weighted images and 58 other cortical and subcortical Regions of Interest (ROI) were obtained by automatic segmentation. All analyses were done in the native subject's space without spatial transformation to a common template. We first used Partial Least Squares (PLS) on a subject-by-subject basis to determine ROIs across subjects that covaried significantly with the voxels within the PPN ROI. We then performed functional connectivity analysis on the PPN-ROI connections. In control subjects, GVS did not have a significant effect on PPN connectivity. In PD subjects, baseline overall magnitude of PPN connectivity was negatively correlated with UPDRS scores (p < 0.05). Both noisy and sinusoidal GVS increased the overall magnitude of PPN connectivity (p = 6 × 10−5, 3 × 10−4, respectively) in PD, and increased connectivity with the left inferior parietal region, but had opposite effects on amygdala connectivity. Noisy stimuli selectively decreased connectivity with basal ganglia and cerebellar regions. Our results suggest that GVS can enhance deficient PPN connectivity seen in PD in a stimulus-dependent manner. This may provide a mechanism through which GVS assists balance in PD, and may provide a biomarker to develop individualized stimulus parameters.

Modern views on gait impairment in Parkinson`s disease and its correction

The article reviews the causes of gait impairment in patients with Parkinson's disease (PD). The emphasis is made on modern ideas, according to which gait impairment in PD is caused by a multisystem lesion and non-dopaminergic dependent mechanisms play the leading role. It is highlighted that gait impairment in PD is associated with the disruption of frontal/subcortical neural pathways which requires a special approach to pharmacological and non-pharmacological therapy. Based on pathogenetic mechanisms, much attention is paid to anti-dementia medications. Attention is drawn to the fact that the use of memantine hydrochloride (akatinol memantine) is a promising direction for gait impairment correction in the advanced and late stages of PD due to the improvement of glutamatergic transfer from the striatum to the specific areas of the cerebral cortex involved in gait control. The results of the latest clinical trials are analyzed.

Overload From Anxiety: A Non-Motor Cause for Gait Impairments in Parkinson’s Disease

Threatening situations lead to observable gait deficits in individuals with Parkinson's disease (PD) who suffer from high trait anxiety levels. The specific characteristics of gait that are affected appear to be similar to behaviors observed while walking during a dual-task (DT) condition. Yet, it remains unclear whether anxiety is similar to a cognitive load. If it were, then those with PD who have high trait anxiety might be expected to be more susceptible to DT interference during walking. Thus, the overall aim of this study was to evaluate whether trait anxiety influences gait during single-task (ST) and DT walking. Seventy participants (high-anxiety PD [HA-PD], N=26; low-anxiety PD [LA-PD], N=26; healthy control [HC], N=18) completed three ST and three DT walking trials on a data-collecting carpet. The secondary task consisted of digit monitoring while walking. Results showed that during both ST and DT gait, the HA-PD group demonstrated significant reductions in walking speed and step length, as well as increased step length variability and step time variability compared with healthy controls and the LA-PD group. Notably, ST walking in the HA-PD group resembled (i.e., it was not significantly different from) the gait behaviors seen during a DT in the LA-PD and HC groups. These results suggest that trait anxiety may consume processing resources and limit the ability to compensate for gait impairments in PD.

Direct and indirect effects of attention and visual function on gait impairment in Parkinson's disease: influence of task and turning.

Gait impairment is a core feature of Parkinson's disease (PD) which has been linked to cognitive and visual deficits, but interactions between these features are poorly understood. Monitoring saccades allows investigation of real-time cognitive and visual processes and their impact on gait when walking. This study explored: (i) saccade frequency when walking under different attentional manipulations of turning and dual-task; and (ii) direct and indirect relationships between saccades, gait impairment, vision and attention. Saccade frequency (number of fast eye movements per-second) was measured during gait in 60 PD and 40 age-matched control participants using a mobile eye-tracker. Saccade frequency was significantly reduced in PD compared to controls during all conditions. However, saccade frequency increased with a turn and decreased under dual-task for both groups. Poorer attention directly related to saccade frequency, visual function and gait impairment in PD, but not controls. Saccade frequency did not directly relate to gait in PD, but did in controls. Instead, saccade frequency and visual function deficit indirectly impacted gait impairment in PD, which was underpinned by their relationship with attention. In conclusion, our results suggest a vital role for attention with direct and indirect influences on gait impairment in PD. Attention directly impacted saccade frequency, visual function and gait impairment in PD, with connotations for falls. It also underpinned indirect impact of visual and saccadic impairment on gait. Attention therefore represents a key therapeutic target that should be considered in future research.

Spotlight on the April 18 issue

#### Notable in Neurology This issue features an article that investigates the role of CSF biomarkers in predicting progression of dopa-resistant gait impairments in Parkinson disease and another that illustrates how stroke engenders global alterations of lesion-spared network architecture over time. A featured article assesses the feasibility and accuracy of telemedical concussion evaluations for real-time sideline concussion assessment during athletic events. ### Predictive markers for early conversion of iRBD to neurodegenerative synucleinopathy diseases![Graphic][1] This study elucidates the value of clinical assessment and dopamine transporter (DAT) uptake in predicting idiopathic REM sleep behavior disorder (iRBD)conversion to neurodegenerative synucleinopathy diseases. The authors found … [1]: /embed/inline-graphic-1.gif

Decrease in Aβ42 predicts dopa-resistant gait progression in early Parkinson disease.

This prospective observational study investigates the role of CSF biomarkers in predicting progression of dopa-resistant gait impairments in Parkinson disease (PD) in the first 36 months from diagnosis. Quantitative gait analysis was carried out longitudinally using an instrumented walkway (GAITRite) in 108 people with PD and 130 age-matched controls. A subgroup of 44 people with PD underwent lumbar puncture from which a battery of CSF biomarkers was measured: β-amyloid 1-42 and 1-40 (Aβ42 and Aβ40), total and phosphorylated tau protein (t-tau/p-tau181), and α-synuclein (αSyn). Linear mixed models examined the association between CSF and dopa-resistant gait characteristics (defined as substantial progression despite optimal medication). Low baseline CSF Aβ42, and to a lesser extend Aβ40, predicted decline in gait characteristics in the first 3 years following diagnosis, independently explaining up to 12% of progression of step time variability (single task) and step length variability (dual-task). Interestingly, these findings were independent of age and cognition. These findings implicate underlying amyloid pathology in neural networks involved in locomotor control. Results suggest that disturbed Aβ metabolism may be a biomarker for dopa-resistant gait impairments in early PD. Our findings raise interesting questions regarding therapeutic interventions such as compounds or molecules aimed at reducing amyloid burden to mitigate gait disturbance in early PD and potentially falls risk. Finally, progression of discrete gait characteristics suggests they may have potential as clinical biomarkers of pathology and disease progression.

Investigation of factors impacting mobility and gait in Parkinson disease

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.

Associations Between Cognitive and Gait Performance During Single- and Dual-Task Walking in People With Parkinson Disease

Cognitive impairments in Parkinson disease (PD) manifest as deficits in speed of processing, working memory, and executive function and attention abilities. The gait impairment in PD is well documented to include reduced speed, shortened step lengths, and increased step-to-step variability. However, there is a paucity of research examining the relationship between overground walking and cognitive performance in people with PD. This study sought to examine the relationship between both the mean and variability of gait spatiotemporal parameters and cognitive performance across a broad range of cognitive domains. A cross-sectional design was used. Thirty-five participants with no dementia and diagnosed with idiopathic PD completed a battery of 12 cognitive tests that yielded 3 orthogonal factors: processing speed, working memory, and executive function and attention. Participants completed 10 trials of overground walking (single-task walking) and 5 trials of overground walking while counting backward by 3's (dual-task walking). All gait measures were impaired by the dual task. Cognitive processing speed correlated with stride length and walking speed. Executive function correlated with step width variability. There were no significant associations with working memory. Regression models relating speed of processing to gait spatiotemporal variables revealed that including dual-task costs in the model significantly improved the fit of the model. Participants with PD were tested only in the on-medication state. Different characteristics of gait are related to distinct types of cognitive processing, which may be differentially affected by dual-task walking due to the pathology of PD.

Virtual reality and motor imagery: Promising tools for assessment and therapy in Parkinson's disease

Motor imagery (MI) and virtual reality (VR) are two evolving therapeutic approaches that make use of cognitive function to study and enhance movement, in particular, balance and mobility of people with Parkinson's disease (PD). This review examines the literature on the use of VR and MI in the assessment of mobility and as a therapeutic intervention to improve balance and gait in patients with PD. A study was eligible for inclusion if MI or VR were used to assess motor or cognitive function to improve gait, balance, or mobility in patients with PD. Data were extracted on the following categories: participants; study design; intervention (type, duration, and frequency); and outcomes. Intervention studies were evaluated for quality using the Physiotherapy Evidence Database scale. Sixteen studies were identified; 4 articles used MI and 12 used VR for assessment and treatment of gait impairments in PD. The studies included small samples and were diverse in terms of methodology. Quality of the intervention trials varied from fair for VR to good for MI. The benefits of using MI and VR for assessment and treatment were noted. Encouraging findings on the potential benefits of using MI and VR in PD were found, although further good-quality research is still needed. Questions remain on the optimal use, content of interventions, and generalizability of findings across the different stages of the disease. The possible mechanisms underlying MI and VR and recommendations for future research and therapy are also presented.