Motor Signs Research Articles

Effects of 6 months of endurance exercise on motor function, exercise capacity, and autonomic function based on presence of autonomic dysfunction in individuals with early Parkinson's disease

Background Endurance exercise improves aerobic capacity (VO2peak) and motor symptoms in people with early Parkinson's disease (PD). Some people with PD exhibit signs of chronotropic incompetence (CI), which may impact exercise-induced benefits. Objective We investigated whether CI in people with early PD influences the change in motor signs, VO2peak, and peak heart rate (HR) following 6 months of endurance exercise. Methods We performed secondary analyses of the Study in Parkinson's Disease of Exercise (SPARX), which randomized people with early PD into a high-intensity endurance exercise [80–85% of peak HR], moderate-intensity endurance exercise [60–65% of peak HR], or usual care group. MDS-UDPRS Part 3 score, VO2peak, and heart rate (HR) response to maximal cardiopulmonary exercise testing (CPET) were analyzed at baseline and following 6 months of exercise. Participants were divided into three groups: 1) normal chronotropic response at baseline, 2) CI at baseline, and 3) taking medications with a known negative chronotropic effect regardless of CI status. Results Data from 119 individuals (64.0 ± 9.0 years, 57.1% male, 0.3 years since diagnosis [median]) were analyzed. There were no differences among the groups in change in MDS-UPDRS motor score ( p = 0.953), VO2peak ( p = 0.965), or peak HR ( p = 0.388). People randomized into the high-intensity group improved VO2peak compared to usual care ( p < 0.001adj) regardless of CI status. Conclusions Baseline CI did not alter responses to endurance exercise in those with early PD, suggesting that the beneficial effects of endurance exercise on disease progression and VO2peak in people with early PD apply equally to people with CI.

Transcutaneous vagus nerve stimulation for Parkinson’s disease: a systematic review and meta-analysis

BackgroundTranscutaneous vagus nerve stimulation (tVNS) has emerged as a novel noninvasive adjunct therapy for advanced Parkinson’s disease (PD), yet no quantitative analysis had been conducted to assess its therapeutic effect.ObjectivesThis review aimed to investigate the efficacy of tVNS on motor function, other potential clinical targets and its safety in various treatment conditions.MethodsWe searched six databases for randomized controlled trials (RCTs) that involved treating PD patients with tVNS. Primary outcome was motor functions, including severity of motor signs, functional mobility and balance, and gait parameters. Secondary outcomes were cognition, emotion, sleep related impairments, patient reported non-motor outcomes, and any adverse events. All outcomes were classified and analyzed according to the treatment duration and medication condition of an included study. Risk of bias was evaluated by referencing Cochrane risk of bias tool 1.0. Data was analyzed by Revman 5.4.Results6 RCTs with 176 PD patient were included. Several motor functions and non-motor functions measured during on-medication condition (severity of motor signs −0.48 [95% CI −0.93, −0.04], gait −0.48 [95% CI −0.85, −0.1], patients reported non-motor outcomes −0.4 [95% CI −0.78, −0.03]), improved significantly. However, verbal fluency, sleep-related impairment, and fatigue were negatively impacted by tVNS during on-medication condition. No distinct adverse events were reported.ConclusiontVNS is a relatively safe adjunct treatment for PD. It has small to moderate therapeutic effects on motor functions and may negatively impact on a few other outcomes. Quality level of the evidence is low and further research is warranted.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/#recordDetails, identifier CRD42024503322 (PROSPERO).

Preclinical and clinical study on type 3 metabotropic glutamate receptors in Parkinson’s disease

Metabotropic glutamate (mGlu) receptors are candidate drug targets for therapeutic intervention in Parkinson’s disease (PD). Here we focused on mGlu3, a receptor subtype involved in synaptic regulation and neuroinflammation. mGlu3−/− mice showed an enhanced nigro-striatal damage and microglial activation in response to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Expression of genes encoding anti-inflammatory proteins and neuroprotective factors was reduced in the striatum of MPTP-treated mGlu3−/− mice. We also examined polymorphic variants of GRM3 (the mGlu3 receptor encoding gene) in 723 PD patients and 826 healthy controls. Two GRM3 haplotypes were associated with PD, and gene variants correlated with motor and non-motor signs. Interestingly, PD patients carrying each of the two haplotypes showed an impaired cortical plasticity in the paired associated stimulation paradigm of magnetic transcranial stimulation. These findings suggest that mGlu3 receptors are neuroprotective in mouse models of parkinsonism and shape mechanisms of cortical plasticity in PD.

Pathophysiology of Motor Control Abnormalities in Parkinson's Disease.

Research in the last few decades has brought us closer to an understanding of the brain circuit abnormalities that underlie parkinsonian motor signs. This article summarizes the current knowledge in this rapidly emerging field. Traditional observations of activity changes of basal ganglia neurons that accompany akinesia and bradykinesia have been supplemented with new knowledge regarding specific pathophysiologic changes that are associated with other parkinsonian signs, such as tremor and gait impairments. New research also emphasizes the role of non-basal ganglia structures in parkinsonism, including the pedunculopontine nucleus, the cerebellum, and the cerebral cortex, and the role of structural and functional neuroplasticity. A more detailed understanding of the brain network abnormalities that result from Parkinson's disease is necessary to arrive at more effective and specific treatments for these symptoms in parkinsonian patients through circuit interventions reaching from deep brain stimulation to genetic and chemogenetic treatments.

Creativity and Mental Illness: A Case Study of a Patient with Progressive Bulbar Palsy.

Creativity and the production of artwork can have an impact on the course and treatment of comorbid severe mental illness and neurodegeneration. We report on a 70-year-old male patient with highly original artistic behavior, who suffered from lifelong recurrent major depression and subsequently developed symptoms of progressive bulbar palsy (PBP). In the context of a systematic literature review, we detail the patient's personal and artistic biographies and portray artwork from his artistic portfolio together with his disease history, clinical examination, psychopathological and neuropsychological evaluations, blood and cerebrospinal fluid analyses, neuroimaging, neurophysiological testing, and psychotherapeutic treatment. The patient's 1-2-year history of primarily bulbar motor symptoms and signs aligned with electromyography, showing widespread signs of continuing denervation/chronic neurogenic changes. Slight impairments in semantic fluency, executive control, and visuoconstructive abilities were observed in neuropsychological testing, in conjunction with right-sided medial temporal lobe atrophy in an MRI. He was prescribed medication, including extended-release venlafaxine, trazodone, pramipexole, and zolpidem, and took his medication regularly, usually at high doses. For most of his life, the patient had attributed professional "success" and artistic output to, at times, excessive alcohol consumption. Later, however, his interest in creative work continued despite alcohol reduction and cessation. Psychotherapy grounded him in reality via goal-centered behaviors, making him realize that his physical and mental ailments rather hindered his creative output. In summary, creative behavior can be utilized in the treatment of patients with psychiatric conditions (affective or addictive disorders) and/or neurodegenerative diseases. In the reported case, specific psychopharmacology and psychotherapy that address goal-directed self-efficacy experiences of reality were critical to the patient's treatment.

Functional anatomy of the subthalamic nucleus and the pathophysiology of cardinal features of Parkinson's disease unraveled by focused ultrasound ablation.

The subthalamic nucleus (STN) modulates basal ganglia output and plays a fundamental role in the pathophysiology of Parkinson's disease (PD). Blockade/ablation of the STN improves motor signs in PD. We assessed the topography of focused ultrasound subthalamotomy (n = 39) by voxel-based lesion-symptom mapping to identify statistically validated brain voxels with the optimal effect against each cardinal feature and their respective cortical connectivity patterns by diffusion-weighted tractography. Bradykinesia and rigidity amelioration were associated with ablation of the rostral motor STN subregion connected to the supplementary motor and premotor cortices, whereas antitremor effect was explained by lesioning the posterolateral STN projection to the primary motor cortex. These findings were corroborated prospectively in another PD cohort (n = 12). This work concurs with recent deep brain stimulation findings that suggest different corticosubthalamic circuits underlying each PD cardinal feature. Our results provide sound evidence in humans of segregated anatomy of subthalamic-cortical connections and their distinct role in PD pathophysiology and normal motor control.

Subtle bradykinesia features are easier to identify and more prevalent than questionable dystonia in essential tremor.

Essential tremor (ET) is characterized by upper limbs action tremor, sometimes extending to other body parts. However, ET can present with additional neurological features known as "soft signs." These signs of uncertain clinical significance are not sufficient to suggest an alternative neurological diagnosis, and include, among others, questionable dystonia and subtle voluntary movement alterations, i.e., bradykinesia and related features. This study aimed to explore the prevalence and relationship between questionable dystonia and subtle bradykinesia features in ET. Forty ET patients were video-recorded during clinical examination. Five movement disorder experts reviewed the videos to identify soft motor signs, i.e., dystonia and movement alterations during finger-tapping namely, (i) bradykinesia (reduced velocity), (ii) dysrhythmia, and (iii) sequence effect. Inter-rater agreement was quantified using the Fleiss' Kappa index. Data analysis was performed using nonparametric tests. We found a fair inter-rater agreement for upper limb dystonia (Fleiss' K = 0.27). Inter-rater agreement was higher (moderate) for head dystonia (Fleiss' K = 0.49) and finger-tapping assessment (Fleiss' K = 0.45). Upper limb dystonia was identified in 70% of patients, head dystonia in 35%, and finger-tapping alterations (in variable combinations) were observed in 95% of individuals (P < 0.001 by Fisher's exact test), including subtle bradykinesia and related features. No significant concordance or correlation was found between the soft signs. Subtle bradykinesia and related features are the most easily identifiable and frequent soft signs in ET, appearing in a higher percentage of patients than subtle dystonia. These findings provide insights into the clinical and pathophysiological understanding of ET.

Motor signs and incident dementia with Lewy bodies in older adults with mild cognitive impairment.

Motor signs may herald incident dementia and allow the earlier detection of high-risk individuals and the timely implementation of preventive interventions. The current study was performed to investigate the prognostic properties of motor signs with respect to incident dementia with Lewy bodies (DLB) in older adults with mild cognitive impairment (MCI). Emphasis was placed on sex differences. The specificity of these associations was explored. We analyzed data from the National Alzheimer's Coordinating Center Uniform Data Set. Participants 55 + years old with a diagnosis of MCI were included in the analysis. Those with Parkinson's disease (PD) or other parkinsonian disorders at baseline and those with PD dementia at follow-up were excluded. UPDRS III was used to assess the presence or absence of motor signs in nine domains: hypophonia; masked facies; resting tremor; action/postural tremor; rigidity; bradykinesia; impaired chair rise; impaired posture/gait; postural instability. Αdjusted Cox proportional hazards models featuring sex by motor sign interactions were estimated. Throughout the average follow-up of 3.7 ± 3.1 years, among 4623 individuals with MCI, 2211 progressed to dementia (66 of whom converted to DLB). Masked facies [HR = 4.21 (1.74-10.18)], resting tremor [HR = 4.71 (1.44-15.40)], and bradykinesia [HR = 3.43 (1.82-6.45)] exclusively increased the risk of DLB. The HR of DLB was approximately 15 times greater in women compared to men with masked facies. Impaired posture-gait (approximately 10 times) and resting tremor (approximately 8.5 times) exhibited a similar trend (prominent risk-conferring properties in women compared to men) but failed to achieve statistical significance. Rigidity and hypophonia elevated the risk of other dementia entities, as well. The remaining motor features were not related to incident dementia of any type. Specific motor signs may herald DLB among individuals with MCI. Different associations may exist between masked facies, impaired posture-gait, resting tremor, and incident DLB in men versus women.

Impact of Deep Brain Stimulation on Addictive Behaviors A Case Series of Parkinsonians Patients

Deep brain stimulation of the Subthalamic Nucleus (STN-DBS) is a recognized treatment in Parkinson’s disease (PD), but knowledge is still limited regarding its possible impact on patients with Behavioral Addiction (BA) who undergo surgery. To assess this effect of STN-DBS, we carried out a prospective study of the follow-up of 12 PD patients with pre-existing BA (9 with pathological gambling disorder, 2 with hypersexual disorder, and 1 with compulsive shopping disorder), from 3-months pre-surgery to 12-months post-surgery, in a multicenter study. The patients were assessed for BA, mental status with anxiety, depression, mania, emotional process and for PD, using the Unified Parkinson’s Disease Rating Scale Motor Examination (UPDRS3) and cumulative daily L-Dopa Equivalent Daily Dose (LEDD). Mean 6 and 12-month post-surgery scores were compared to baseline. After one year of STN-DBS, our results indicated that the treatment remained generally effective and stable. There was no effect on mania state or negative impact on motor signs. A significant improvement of the anxiety score was also observed. STN is an interesting target for new therapeutic stimulation in BA and more works performed to investigate this neurobiological architecture should be performed in the future.

Impairment of Neuronal Activity in the Dorsolateral Prefrontal Cortex Occurs Early in Parkinsonism.

Parkinson's disease (PD) is often characterized by altered rates and patterns of neuronal activity in the sensorimotor regions of the basal ganglia thalamocortical network. Little is known, however, regarding how neuronal activity in the executive control network of the brain changes in the parkinsonian condition. Investigate the impact of parkinsonism on neuronal activity in the dorsolateral prefrontal cortex (DLPFC), a key region in executive control, during a go/nogo reaching task. Using a within-subject design, single and multi-unit neuronal activity was recorded in the DLPFC of a nonhuman primate before and after the induction of mild parkinsonism using the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Coincident with development of mild parkinsonian motor signs, there was a marked reduction in the percentage of DLPFC cells with significant task-related firing rate modulation during go and nogo conditions. These results suggest that DLPFC dysfunction may occur early in parkinsonism and contribute to cognitive impairments and disrupted executive function often observed in PD patients.

An Exploratory Study on the Effects of Souchard Postural Gymnastics in Parkinson's Disease Patients with Camptocormia: A Quasi-Experimental Approach.

Background/Objective: Parkinson's disease (PD), a prevalent neurodegenerative disorder, leads to motor and non-motor impairments, affecting quality of life. Camptocormia can be one of the motor signs of PD, characterized by a severe and abnormal forward flexion of the thoracolumbar spine that typically occurs when walking or standing. The following study aims to verify whether postural gymnastics can be an effective treatment for trunk control, balance, activities of daily living, and general well-being in patients with early-stage PD and camptocormia. Methods: Nine participants (mean age 67.7 ± 7.8) with early PD (Hoehn and Yahr Scale ≤ 2) received 10 biweekly physiotherapy sessions. Outcomes were measured using the Parkinson's Disease Questionnaire (PDQ-39) and Berg Balance Scale (BBS) along with trunk mobility and muscle tests according to the Medical Research Council (MRC) scale. Results: Statistically significant results were noted in the PDQ-39 mobility, ADLs and emotional well-being subscales and in the BBS; statistically significant improvements were also seen in trunk mobility and muscle strength. Conclusions: This study shows that the postural gymnastic treatment, according to Souchard, in patients with PD's camptocormia has obtained good results and has the potential timprove mobility and balance, encouraging and motivating patients in their rehabilitation journeys.

Refining Research Diagnostic Criteria for Catatonia Among Delirium, Medical, Affective, and Psychosis Patient Groups.

The authors proposed catatonia diagnostic criteria that require the presence of three neuropsychiatric symptom clusters, rated over 24 hours; this system differs from other symptom clustering proposals and is intended to increase diagnostic rigor over Bush-Francis Catatonia Rating Scale (BFCRS) or DSM-5 criteria. By applying new BFCRS item score thresholds, symptoms were clustered into three categories to comprise the Research Diagnostic Criteria for Catatonia (RDCC): akinesia (criterion A), unusual motor signs (criterion B), and behavioral signs (criterion C). RDCC symptom clusters were analyzed in four prospectively evaluated patient groups (delirium, medical, affective, and psychosis) (N=341). Use of the RDCC, compared with the DSM-5-TR and BFCRS, resulted in far fewer diagnoses of catatonia in the four patient groups: medical, N=1 out of 42 (2%); affective, N=1 out of 45 (2%); psychosis, N=3 out of 53 (6%); and delirium, N=0 out of 201. Permutations of the RDCC with more relaxed criteria were assessed, requiring either symptom thresholds or numbers of symptoms to meet criteria, resulting in catatonia rate gradations between those obtained with the RDCC and those obtained with current systems. The Cochrane Q test found that the DSM-5-TR was not dissimilar to the RDCC, if fulfilling numerical thresholds for criteria A-C, although any level of symptom severity was allowed. Confirmatory factor analysis with three goodness-of-fit indexes validated the RDCC. The RDCC requires akinetic symptoms on the basis of literature demonstrating their high BFCRS prevalence and exploratory factor analysis co-loadings, plus symptoms from unusual motor and behavioral signs. Compared with current lenient diagnostic approaches, having the symptoms required by the RDCC produced lower catatonia rates in the psychosis, affective, and medical groups and revealed no patients with catatonia in the delirium group. Subdividing DSM-5-TR symptoms into several different criteria may improve diagnosis. RDCC symptom clusters are both research data-based and amenable to further research for validation.

Improvements in clinical signs and symptoms of Parkinson’s disease using photobiomodulation: a five-year follow-up

BackgroundParkinson’s disease is a progressive neurodegenerative disease characterized by clinical motor signs and non-motor symptoms that severely impact quality of life. There is an urgent need for therapies that might slow, halt or even reverse the progression of existing symptoms or delay the onset of new symptoms. Photobiomodulation is a therapy that has shown potential to alleviate some symptoms of Parkinson’s disease in animal studies and in small clinical trials.ObjectiveTo assess long-term effectiveness of photobiomodulation therapy in a cohort of Parkinson’s disease individuals after five years of continuing therapy.MethodsEight participants of the initial 12 in a previously published study agreed to be reassessed after five years. Seven of these participants had continued home-based, self-applied photobiomodulation therapy three times per week for five years. One participant had discontinued treatment after one year. Participants were assessed for a range of clinical motor signs, including MDS-UPDRS-III, measures of mobility and balance. Cognition was assessed objectively, and quality of life and sleep quality were assessed using self-reported questionnaires. A Wilcoxon Signed Ranks test was used to evaluate change in outcome measures between baseline (before treatment) and after five years, with the alpha value set to 0.05.ResultsOf the seven participants who had continued photobiomodulation therapy, one had a preliminary diagnosis of multisystem atrophy and was excluded from the group analysis. For the remaining six participants, there was a significant improvement in walk speed, stride length, timed up-and-go tests, tests of dynamic balance, and cognition compared to baseline and nonsignificant improvements in all other measures, apart from MDS-UPDRS-III, which was unchanged and one measure of static balance (single leg stance, standing on the unaffected leg with eyes open) which declined. Five of six participants either improved or showed no decline in MDS-UPDRS-III score and most participants showed improvement or no decline in all other outcome measures. No adverse effects of the photobiomodulation therapy were reported.ConclusionsThis study provides a signal that photobiomodulation therapy might safely reduce important clinical motor signs and non-motor symptoms in some Parkinson’s disease patients, with improvements maintained over several years. Home-based photobiomodulation therapy has the potential to complement standard therapies to manage symptoms and potentially delay Parkinson’s symptom progression.Trial registrationAustralian New Zealand Clinical Trials Registry, registration number ACTRN12618000038291p, registered on 12/01/2018.

Sustained effect of prasinezumab on Parkinson’s disease motor progression in the open-label extension of the PASADENA trial

The Phase II trial of Anti-alpha-Synuclein Antibody in Early Parkinson’s Disease (PASADENA) is an ongoing double-blind, placebo-controlled trial evaluating the safety and efficacy of prasinezumab in early-stage Parkinson’s disease (PD). During the double-blind period, prasinezumab-treated individuals showed less progression of motor signs (Movement Disorders Society-sponsored revision of the Unified Parkinson’s Disease Rating Scale (MDS–UPDRS) Part III) than placebo-treated individuals. We evaluated whether the effect of prasinezumab on motor progression, assessed as a change in MDS–UPDRS Part III score in the OFF and ON states, and MDS–UPDRS Part II score, was sustained for 4 years from the start of the trial. We compared participants enrolled in the PASADENA open-label extension study with those enrolled in an external comparator arm derived from the Parkinson’s Progression Markers Initiative observational study. The PASADENA delayed-start (n = 94) and early-start (n = 177) groups showed a slower decline (a smaller increase in score) in MDS–UPDRS Part III scores in the OFF state (delayed start, −51%; early start, −65%), ON state (delayed start, −94%; early start, −118%) and MDS–UPDRS Part II (delayed start, −48%; early start, −40%) than did the Parkinson’s Progression Markers Initiative external comparator (n = 303). This exploratory analysis, which requires confirmation in future studies, suggested that the effect of prasinezumab in slowing motor progression in PD may be sustained long term. PASADENA ClinicalTrials.gov no. NCT03100149.

Subtle motor signs in children with ADHD and their white matter correlates.

Subtle motor signs are a common feature in children with attention-deficit/hyperactivity disorder (ADHD). It has long been suggested that white matter abnormalities may be involved in their presentation, though no study has directly probed this question. The aim of this study was to investigate the relationship between white matter organization and the severity of subtle motor signs in children with and without ADHD. Participants were 92 children with ADHD aged between 8 and 12 years, and 185 typically developing controls. Subtle motor signs were examined using the Physical and Neurological Examination for Soft Signs (PANESS). Children completed diffusion MRI, and fixel-based analysis was performed after preprocessing. Tracts of interest were delineated using TractSeg including the corpus callosum (CC), the bilateral corticospinal tracts (CST), superior longitudinal fasciculus, and fronto-pontine tracts (FPT). Fiber cross-section (FC) was calculated for each tract. Across all participants, lower FC in the CST was associated with higher PANESS Total score (greater motor deficits). Within the PANESS, similar effects were observed for Timed Left and Right maneuvers of the hands and feet, with lower FC of the CST, CC, and FPT associated with poorer performance. No significant group differences were observed in FC in white matter regions associated with PANESS performance. Our data are consistent with theoretical accounts implicating white matter organization in the expression of motor signs in childhood. However, rather than contributing uniquely to the increased severity of soft motor signs in those with ADHD, white matter appears to contribute to these symptoms in childhood in general.

Asymmetry and rehabilitation of the subjective visual vertical in unilateral vestibular hypofunction patients.

Patients with acute unilateral peripheral vestibular hypofunction (AUVP) show postural, ocular motor, and perceptive signs on the diseased side. The subjective visual vertical (SVV) test measures the perceived bias in earth-vertical orientation with a laser line in darkness. This study was aimed at (1) examining whether SVV bias could depend on preset line orientation and angles, and (2) investigating whether vestibular rehabilitation (VR) can improve SVV normalization. To our knowledge, SVV symmetry/asymmetry and impact of VR on SVV normalization have never been documented in the literature. We investigated the SVV bias in a retrospective study (Study 1: n = 42 AUVP patients) comparing the data recorded for line orientation to the ipsilateral and contralateral sides at preset angles of 15° and 30°. We investigated the effects of VR on SVV normalization in a prospective study (Study 2: n = 20 AUPV patients) in which patients were tilted in the roll plane using a support tilted to the hypofunction side with the same amplitude as the SVV bias. This VR protocol was performed twice a week for 4 weeks. Supplementary data on body weight distribution and medio-lateral position of the center of foot pressure (CoP) were obtained using posturography recordings. Study 1 showed asymmetrical values of the SVV bias. On average, the SVV errors were significantly higher for ipsilateral compared to contralateral line orientation (6.98° ± 3.7° vs. 4.95° ± 3.6°; p < 0.0001), and for 30° compared to 15° preset angle (6.76° ± 4.2° vs. 5.66° ± 3.3°; p < 0.0001). Study 2 showed a fast SVV normalization with VR. Non-pathological SVV bias (below ±2°) was found after only 3 to 5 VR sessions while pathological SVV values were still observed at the same time after symptoms onset in patients without VR (1.25° ± 1.46° vs. 4.32° ± 2.81°, respectively; p < 0.0001). A close temporal correlation was observed in the time course of body weight distribution, mediolateral CoP position, and SVV bias over time, suggesting beneficial effects of the VR protocol at both the perceptive and postural levels. We recommend routine assessment of the ipsilateral and contralateral SVV bias separately for a better evaluation of otolith organs imbalance that can trigger chronic instability and dizziness. The SVV bias and the postural impairment caused by the imbalanced otolith inputs after unilateral vestibular loss can be rapidly normalized by tilting the patients in the roll plane, an additional means in the physiotherapist's toolbox. The protocol likely reweights the visual and somatosensory cues involved in the perception of verticality.

Modeling of Parkinson's Disease Progression and Implications for Detection of Disease Modification in Treatment Trials.

Objectively measuring Parkinson's disease (PD) signs and symptoms over time is critical for the successful development of treatments aimed at halting the disease progression of people with PD. To create a clinical trial simulation tool that characterizes the natural history of PD progression and enables a data-driven design of randomized controlled studies testing potential disease-modifying treatments (DMT) in early-stage PD. Data from the Parkinson's Progression Markers Initiative (PPMI) were analyzed with nonlinear mixed-effect modeling techniques to characterize the progression of MDS-UPDRS part I (non-motor aspects of experiences of daily living), part II (motor aspects of experiences of daily living), and part III (motor signs). A clinical trial simulation tool was built from these disease models and used to predict probability of success as a function of trial design. MDS-UPDRS part III progresses approximately 3 times faster than MDS-UPDRS part II and I, with an increase of 3 versus 1 points/year. Higher amounts of symptomatic therapy is associated with slower progression of MDS-UPDRS part II and III. The modeling framework predicts that a DMT effect on MDS-UPDRS part III could precede effect on part II by approximately 2 to 3 years. Our clinical trial simulation tool predicted that in a two-year randomized controlled trial, MDS-UPDRS part III could be used to evaluate a potential novel DMT, while part II would require longer trials of a minimum duration of 3 to 5 years underscoring the need for innovative trial design approaches including novel patient-centric measures.

Quality of Life after Deep Brain Stimulation in Parkinson's Disease: Does the Target Matter?

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) is an accepted therapy for Parkinson's disease (PD) with disabling motor complications. For elderly patients with poorer cognition and postural instability, GPi has been proposed as the preferable DBS target based on expert opinion, arguing GPi-DBS may be less complicated by depression, apathy, worsened verbal fluency, and executive dysfunction, resulting in greater improvement in quality of life (QoL). However, data supporting such patient-tailored approach are lacking. The aims were to analyze whether the DBS target influences QoL in a PD cohort and a matched subgroup of frail patients with poor cognitive status and reduced postural stability, and whether other factors affect the QoL outcomes. In this retrospective study, we analyzed a single-center cohort of 138 PD patients who received bilateral STN-DBS (117) or GPi-DBS (21) using the mentioned approach for target selection. All patients underwent standardized clinical evaluations of motor- and nonmotor signs as well as QoL before and 1 year after surgery. DBS of both targets improved motor signs, dyskinesias, and pain. QoL improved without significant difference between the targets, but with a trend for greater improvement across all QoL domains in favor of the STN, even in an STN subgroup matched to the GPi group. Our results contradict the prevailing belief that GPi-DBS is superior in frail PD patients with cognitive decline and postural instability, questioning the proposed patient-tailored approach of DBS target selection. Further studies are needed for a data-driven approach.

Neurophysiological markers of motor compensatory mechanisms in early Parkinson's disease.

Compensatory mechanisms in Parkinson's disease are defined as the changes that the brain uses to adapt to neurodegeneration and progressive dopamine reduction. Motor compensation in early Parkinson's disease could, in part, be responsible for a unilateral onset of clinical motor signs despite the presence of bilateral nigrostriatal degeneration. Although several mechanisms have been proposed for compensatory adaptations in Parkinson's disease, the underlying pathophysiology is unclear. Here, we investigate motor compensation in Parkinson's disease by investigating the relationship between clinical signs, dopamine transporter imaging data and neurophysiological measures of the primary motor cortex (M1), using transcranial magnetic stimulation in presymptomatic and symptomatic hemispheres of patients. In this cross-sectional, multicentre study, we screened 82 individuals with Parkinson's disease. Patients were evaluated clinically in their medication OFF state using standardized scales. Sixteen Parkinson's disease patients with bilateral dopamine transporter deficit in the putamina but unilateral symptoms were included. Twenty-eight sex- and age-matched healthy controls were also investigated. In all participants, we tested cortical excitability using single- and paired-pulse techniques, interhemispheric inhibition and cortical plasticity with paired associative stimulation. Data were analysed with ANOVAs, multiple linear regression and logistic regression models. Individual coefficients of motor compensation were defined in patients based on clinical and imaging data, i.e. the motor compensation coefficient. The motor compensation coefficient includes an asymmetry score to balance motor and dopamine transporter data between the two hemispheres, in addition to a hemispheric ratio accounting for the relative mismatch between the magnitude of motor signs and dopaminergic deficit. In patients, corticospinal excitability and plasticity were higher in the presymptomatic compared with the symptomatic M1. Also, interhemispheric inhibition from the presymptomatic to the symptomatic M1 was reduced. Lower putamen binding was associated with higher plasticity and reduced interhemispheric inhibition in the presymptomatic hemisphere. The motor compensation coefficient distinguished the presymptomatic from the symptomatic hemisphere. Finally, in the presymptomatic hemisphere, a higher motor compensation coefficient was associated with lower corticospinal excitability and interhemispheric inhibition and with higher plasticity. In conclusion, the present study suggests that motor compensation involves M1-striatal networks and intercortical connections becoming more effective with progressive loss of dopaminergic terminals in the putamen. The balance between these motor networks seems to be driven by cortical plasticity.

Chronic adaptive deep brain stimulation versus conventional stimulation in Parkinson's disease: a blinded randomized feasibility trial.

Deep brain stimulation (DBS) is a widely used therapy for Parkinson's disease (PD) but lacks dynamic responsiveness to changing clinical and neural states. Feedback control might improve therapeutic effectiveness, but the optimal control strategy and additional benefits of 'adaptive' neurostimulation are unclear. Here we present the results of a blinded randomized cross-over pilot trial aimed at determining the neural correlates of specific motor signs in individuals with PD and the feasibility of using these signals to drive adaptive DBS. Four male patients with PD were recruited from a population undergoing DBS implantation for motor fluctuations, with each patient receiving adaptive DBS and continuous DBS. We identified stimulation-entrained gamma oscillations in the subthalamic nucleus or motor cortex as optimal markers of high versus low dopaminergic states and their associated residual motor signs in all four patients. We then demonstrated improved motor symptoms and quality of life with adaptive compared to clinically optimized standard stimulation. The results of this pilot trial highlight the promise of personalized adaptive neurostimulation in PD based on data-driven selection of neural signals. Furthermore, these findings provide the foundation for further larger clinical trials to evaluate the efficacy of personalized adaptive neurostimulation in PD and other neurological disorders. ClinicalTrials.gov registration: NCT03582891 .