Temporal dynamics of cortical activity and postural control in response to the first levodopa dose of the day in people with Parkinson's disease

Gait initiation deficits in Parkinson's disease with freezing of gait: A large-scale force platform study of anticipatory postural adjustments

INTRODUCTION

Freezing of gait (FoG) is a debilitating motor symptom in Parkinson's disease (PD), often occurring during step initiation due to impaired anticipatory postural adjustments (APAs). Previous studies show inconsistent findings regarding APA alterations in people with PD with FoG (PwPD + FoG) and without FoG (PwPD-FoG). This study aimed to investigate APA characteristics using a force platform to assess postural control deficits associated with FoG.

METHODS

We analyzed baseline data from 130 PwPD (70 with FoG) and 41 healthy controls. A force platform during self-initiated stepping measured APA duration, amplitude, and step amplitude. All participants with PD were tested in the ON medication. One-way ANOVA and ANCOVA (controlling for UPDRS-III and medication) were conducted to compare groups.

RESULTS

APA duration was significantly shorter in Healthy compared to PwPD + FoG and PwPD-FoG, with no difference between PD groups. Step amplitude was significantly lower in PwPD + FoG compared to Healthy and PwPD-FoG, but this difference was insignificant after covariate. APA mediolateral amplitude followed PD + FoG < PD-FoG < Healthy; ANCOVA confirmed lower values in PwPD + FoG compared to PwPD-FoG. APA anteroposterior amplitude was also reduced in PwPD + FoG relative to PwPD-FoG and Healthy, with ANCOVA confirming significantly lower values in PwPD + FoG versus PwPD-FoG. NFOG-Q scores were negatively correlated with mediolateral and anteroposterior APA amplitudes.

CONCLUSION

FoG in PD is associated with reduced APA amplitude (mediolateral and anteroposterior), suggesting postural control deficits persist despite dopaminergic medication. These findings highlight the importance of interventions targeting APA improvements to mitigate gait initiation failures in PwPD + FoG.

Effect of Medication and Freezing of Gait on Rambling and Trembling in Quiet Standing in Individuals With Parkinson's Disease

BACKGROUND

Individuals with Parkinson's disease (PD) with freezing of gait (FoG) exhibit difficulty with changes in sensory input, indicating a potential sensorimotor integration deficit. Understanding how levodopa impacts balance particularly in FoG, is critical. As traditional postural sway measures may not fully capture the complexity of balance control, rambling and trembling decomposition of the center of pressure allows a more detailed assessment of postural control by distinguishing between supraspinal and spinal contributions, offering insights into sensorimotor integration deficits. This study aims to analyze the effects of medication and FoG on rambling and trembling in quiet standing in individuals with PD.

METHODS

We analyzed 13 individuals with PD with FoG (PD freezers) and 19 individuals with PD without FoG (PD nonfreezers) while quiet standing on a rigid and malleable surface under (ON) and without (OFF) dopaminergic medication. Area, root mean square, and mean velocity were calculated for rambling and trembling trajectory.

RESULTS

For the rambling, all variables were significantly higher on the malleable compared with the rigid surface. For trembling, (a) all variables were higher on the malleable compared with the rigid surface (p < .001), and (b) area and medial-lateral root mean square were significantly higher ON compared with OFF medication for both groups of participants similarly.

CONCLUSION

Our results strengthen the evidence that PD freezers have the same postural sway in quiet posture as PD nonfreezers, using similar mechanisms to control the posture. In addition, levodopa influences spinal mechanisms more than supraspinal ones in individuals with PD in quiet standing.

Rhythmic auditory cues improve gait asymmetry during unobstructed walking in people with Parkinson's disease but have no effect on obstacle avoidance - AsymmGait-Parkinson study

Introduction

This study investigated the influence of rhythmic auditory cues (RAC) on gait asymmetry (GA) during unobstructed and obstacle avoidance walking in people with Parkinson's disease (PD) and neurologically healthy individuals.

Methods

Thirteen individuals with PD (70.33 ± 6.02 years) and 13 healthy controls (CG) (70.77 ± 7.56 years) participated in this study. They performed a total of five trials during unobstructed walking and 10 trials during obstacle walking under each auditory cue condition (without and with RAC). For obstacle walking, five trials were performed with each limb as leading during obstacle avoidance. First, the volunteers performed the trials without RAC. The trial order, unobstructed or obstacle walking, was randomly defined, and the cues (controlled by a metronome) were personalized according to participants' cadence. The symmetric index of gait parameters was analyzed using 2 × 2 factorial analysis of variance (group and RAC as factors) separately for each gait type (unobstructed and obstructed walking).

Results

A group-by-auditory cue interaction for step velocity (p = 0.027) showed that the PD group exhibited 57.6% reduced asymmetry with RAC during unobstructed walking, with no significant effects observed for the CG. However, RAC had no effect on GA during obstacle avoidance walking in people with PD. Conversely, the CG exhibited 10.5% greater step length asymmetry, 7.1% greater step duration asymmetry, 7.0% greater step velocity asymmetry, and 10.6% greater double support duration asymmetry during obstacle avoidance with RAC (p < 0.001).

Conclusion

We conclude that RAC can reduce GA in people with PD during unobstructed walking, but appear to have no effect and negative effects on GA during obstacle walking in people with PD and neurologically healthy individuals, respectively.

Effect of disease, freezing of gait, and dopaminergic medication in the biomechanics of trunk and upper limbs in the gait of Parkinson's disease

INTRODUCTION

Parkinson's disease (PD) causes gait abnormalities that may be associated with an arm swing reduction. Medication and freezing of gait (FoG) may influence gait characteristics. However, these comparisons do not consider differences in gait speed and clinical characteristics in individuals with PD.

OBJECTIVE

This study aims to analyze the effect of FoG and medication on the biomechanics of the trunk and upper limbs during gait in PD, controlling for gait speed and clinical differences between groups.

METHODS

Twenty-two people with a clinical diagnosis of idiopathic PD in ON and OFF medication (11 FoG), and 35 healthy participants (control) were selected from two open data sets. All participants walked on the floor on a 10-m-long walkway. The joint and linear kinematic variables of gait were compared: (1) Freezers and nonfreezers in the ON condition and control; (2) Freezers and nonfreezers in the OFF condition and control; (3) Group (freezers and nonfreezers) and medication.

RESULTS

The disease affects the upper limbs more strongly but not the trunk. The medication does not significantly influence the joint characteristics but rather the linear wrist displacement. The FoG does not affect trunk movement and partially influences the upper limbs. The interaction between medications and FoG suggests that the medication causes more substantial improvement in freezers than in nonfreezers.

CONCLUSION

The study shows differences in the biomechanics of the upper limbs of people with PD, FoG, and the absence of medication. The future rehabilitation protocol should consider this aspect.

Parkinson's Critical Heart Rate Test: Applying the Critical Power Model for People with Parkinson's Disease

Aerobic exercise with the correct intensity can attenuate motor and non-motor symptoms of Parkinson's disease (PD) and improve the quality of life. However, a specific, validated, non-invasive, and outside the laboratory protocol that assesses physiological variables to prescribe optimal aerobic exercise intensity for people with PD is nonexistent. Therefore, this study aimed to propose a protocol, the Parkinson's critical heart rate test (Parkinson-CHR test), to determine the critical heart rate (CHR) in individuals with PD and verify its validity, reliability, and sensitivity. Fifteen people with idiopathic PD, who were able to practice exercises, were recruited to participate in the study (71.1 ± 6.6 years). The study consisted of two experiments: i) the first one aimed to assess the validity and reliability of the protocol, with participants performing the test twice at a one-week interval; ii) the second experiment aimed to investigate the protocol sensitivity, with individuals being evaluated before and after an 8-week training program according to Parkinson-CHR intensity. In experiment 1, no differences between test and retest were observed in the time to cover the distances (400, 800 and 1200 m), the total heart rate, the critical heart rate, and critical speed (p > 0.05). In experiment 2, there was a reduction in time to cover 400 and 800 m as well as in the total heart rate for all distances after the 8-week training program. The Parkinson-CHR test is a reliable, reproducible, inexpensive, and non-invasive protocol to assess, prescribe, and monitor aerobic exercise intensity in people with PD.

Unraveling the threads of stability: A review of the neurophysiology of postural control in Parkinson's disease

Postural instability is a detrimental and often treatment-refractory symptom of Parkinson's disease. While many existing studies quantify the biomechanical deficits among various postural domains (static, anticipatory, and reactive) in this population, less is known regarding the neural network dysfunctions underlying these phenomena. This review will summarize current studies on the cortical and subcortical neural activities during postural responses in healthy subjects and those with Parkinson's disease. We will also review the effects of current therapies, including neuromodulation and feedback-based wearable devices, on postural instability symptoms. With recent advances in implantable devices that allow chronic, ambulatory neural data collection from patients with Parkinson's disease, combined with sensors that can quantify biomechanical measurements of postural responses, future work using these devices will enable better understanding of the neural mechanisms of postural control. Bridging this knowledge gap will be the critical first step towards developing novel neuromodulatory interventions to enhance the treatment of postural instability in Parkinson's disease.

Postural control of prolonged standing in people with Parkinson's disease

People with Parkinson's disease (pwPD) have reduced adaptability to postural control during prolonged standing compared to neurologically healthy individuals (control). Objective. The study aimed to characterize postural changes during prolonged standing and their effect on postural control in pwPD compared to control. We recorded the body sway of the second lumbar vertebra of 23 pwPD and 23 control while they performed prolonged standing (15 min). The number and amplitude of the body sway patterns (shifts, fidgets, and drifts), the root mean square, velocity, and frequency of the body sway were analyzed. The number of shifts in the anterior-posterior (AP) and medial-lateral (ML) directions was greater for the pwPD than the control. In addition, the amplitudes of shifts in the AP direction and fidgets in the AP and ML directions were greater for the pwPD than the control. Our results show that: (1) A larger number of shifts of body sway suggest references positions are frequently changing; (2) Fidgets is a pumping mechanism and can be sensory-demand action to restore mechanoreceptors activity on the foot sole; and (3) No drift changes may suggest there is no slow migration of reference position. We conclude that pwPD exhibits different behavior than healthy ones during prolonged standing, suggesting that prolonged standing could distinguish individuals with Parkinson's disease.

Translating digital healthcare to enhance clinical management: a protocol for an observational study using a digital health technology system to monitor medication adherence and its effect on mobility in people with Parkinson's

INTRODUCTION

In people with Parkinson's (PwP) impaired mobility is associated with an increased falls risk. To improve mobility, dopaminergic medication is typically prescribed, but complex medication regimens result in suboptimal adherence. Exploring medication adherence and its impact on mobility in PwP will provide essential insights to optimise medication regimens and improve mobility. However, this is typically assessed in controlled environments, during one-off clinical assessments. Digital health technology (DHT) presents a means to overcome this, by continuously and remotely monitoring mobility and medication adherence. This study aims to use a novel DHT system (DHTS) (comprising of a smartphone, smartwatch and inertial measurement unit (IMU)) to assess self-reported medication adherence, and its impact on digital mobility outcomes (DMOs) in PwP.

METHODS AND ANALYSIS

This single-centre, UK-based study, will recruit 55 participants with Parkinson's. Participants will complete a range of clinical, and physical assessments. Participants will interact with a DHTS over 7 days, to assess self-reported medication adherence, and monitor mobility and contextual factors in the real world. Participants will complete a motor complications diary (ON-OFF-Dyskinesia) throughout the monitoring period and, at the end, a questionnaire and series of open-text questions to evaluate DHTS usability. Feasibility of the DHTS and the motor complications diary will be assessed. Validated algorithms will quantify DMOs from IMU walking activity. Time series modelling and deep learning techniques will model and predict DMO response to medication and effects of contextual factors. This study will provide essential insights into medication adherence and its effect on real-world mobility in PwP, providing insights to optimise medication regimens.

ETHICS AND DISSEMINATION

Ethical approval was granted by London-142 Westminster Research Ethics Committee (REC: 21/PR/0469), protocol V.2.4. Results will be published in peer-reviewed journals. All participants will provide written, informed consent.

TRIAL REGISTRATION NUMBER

ISRCTN13156149.

Cholinergic system correlates of postural control changes in Parkinson's disease freezers

Postural instability and freezing of gait are the most debilitating dopamine-refractory motor impairments in advanced stages of Parkinson's disease because of increased risk of falls and poorer quality of life. Recent findings suggest an inability to efficaciously utilize vestibular information during static posturography among people with Parkinson's disease who exhibit freezing of gait, with associated changes in cholinergic system integrity as assessed by vesicular acetylcholine transporter PET. There is a lack of adequate understanding of how postural control varies as a function of available sensory information in patients with Parkinson's disease with freezing of gait. The goal of this cross-sectional study was to examine cerebral cholinergic system changes that associate with inter-sensory postural control processing features as assessed by dynamic computerized posturography and acetylcholinesterase PET. Seventy-five participants with Parkinson's disease, 16 of whom exhibited freezing of gait, underwent computerized posturography on the NeuroCom© Equitest sensory organization test platform, striatal dopamine, and acetylcholinesterase PET scanning. Findings demonstrated that patients with Parkinson's disease with freezing of gait have greater difficulty maintaining balance in the absence of reliable proprioceptive cues as compared to those without freezing of gait [β = 0.28 (0.021, 0.54), P = 0.034], an effect that was independent of disease severity [β = 0.16 (0.062, 0.26), P < 0.01] and age [β = 0.092 (-0.005, 0.19), P = 0.062]. Exploratory voxel-based analysis revealed an association between postural control and right hemispheric cholinergic network related to visual-vestibular integration and self-motion perception. High anti-cholinergic burden predicted postural control impairment in a manner dependent on right hemispheric cortical cholinergic integrity [β = 0.34 (0.065, 0.61), P < 0.01]. Our findings advance the perspective that cortical cholinergic system might play a role in supporting postural control after nigro-striatal dopaminergic losses in Parkinson's disease. Failure of cortex-dependent visual-vestibular integration may impair detection of postural instability in absence of reliable proprioceptive cues. Better understanding of how the cholinergic system plays a role in this process may augur novel treatments and therapeutic interventions to ameliorate debilitating symptoms in patients with advanced Parkinson's disease.

A public data set of walking full-body kinematics and kinetics in individuals with Parkinson's disease

Background

To our knowledge, there is no Parkinson's disease (PD) gait biomechanics data sets available to the public.

Objective

This study aimed to create a public data set of 26 idiopathic individuals with PD who walked overground on ON and OFF medication.

Materials and methods

Their upper extremity, trunk, lower extremity, and pelvis kinematics were measured using a three-dimensional motion-capture system (Raptor-4; Motion Analysis). The external forces were collected using force plates. The results include raw and processed kinematic and kinetic data in c3d and ASCII files in different file formats. In addition, a metadata file containing demographic, anthropometric, and clinical data is provided. The following clinical scales were employed: Unified Parkinson's disease rating scale motor aspects of experiences of daily living and motor score, Hoehn & Yahr, New Freezing of Gait Questionnaire, Montreal Cognitive Assessment, Mini Balance Evaluation Systems Tests, Fall Efficacy Scale-International-FES-I, Stroop test, and Trail Making Test A and B.

Results

All data are available at Figshare (https://figshare.com/articles/dataset/A_dataset_of_overground_walking_full-body_kinematics_and_kinetics_in_individuals_with_Parkinson_s_disease/14896881).

Conclusion

This is the first public data set containing a three-dimensional full-body gait analysis of individuals with PD under the ON and OFF medication. It is expected to contribute so that different research groups worldwide have access to reference data and a better understanding of the effects of medication on gait.