Poor self-awareness of levodopa-induced dyskinesias in Parkinson's disease: Clinical features and mechanisms

Tardive dyskinesia in Asia- current clinical practice and the role of neurologists in the care pathway

Tardive dyskinesia (TD) is a movement disorder that can arise as a side effect of treatment with dopamine receptor-blocking agents (DRBAs), including antipsychotic drugs (APDs) used to manage psychotic illnesses. Second-generation APDs (SGAs) are often preferred to first-generation drugs due to their lower propensity to cause TD, however many SGAs-treated patients still develop the condition. Although TD is a global health concern, evidence regarding the occurrence of TD and how it is managed in Asian countries is currently limited. This article reports the results of a systematic review of the published literature on TD focusing on its prevalence, types of patients, knowledge of the condition, causative factors, and usual treatment pathways in clinical practice in Asian countries. Epidemiological data suggest that the prevalence of TD is increasing globally due to an overall rise in APD use, contributing factors being polypharmacy with multiple APDs, the use of higher than necessary doses, and off-label use for non-psychotic indications. Although exact prevalence figures for TD in Asian countries are difficult to define, there is a similar pattern of rising APD use which will result in increasing numbers of TD patients in this region. These issues need to be addressed and strategies developed to minimize TD risk and manage this disabling condition which impacts patients' quality of life and daily functioning. To date, both research into TD has been predominantly psychiatry focused and the perspectives from neurologists regarding the clinical management of this challenging condition are scarce. However, neurologists have an essential role in managing the movement disorders manifestations that characterize TD. Optimum management of TD, therefore, should ideally involve collaboration between psychiatrists and neurologists in joint care pathways, wherever practical. Collaborative pathways are proposed in this article, and the challenges that will need to be addressed in Asian countries to improve the care of people with TD are highlighted, with a focus on the neurologist's viewpoint and the implications for the management of TD globally.

Home-based monitoring of persons with advanced Parkinson's disease using smartwatch-smartphone technology

Movement deterioration is the hallmark of Parkinson's disease (PD), characterized by levodopa-induced motor-fluctuations (i.e., symptoms' variability related to the medication cycle) in advanced stages. However, motor symptoms are typically too sporadically and/or subjectively assessed, ultimately preventing the effective monitoring of their progression, and thus leading to suboptimal treatment/therapeutic choices. Smartwatches (SW) enable a quantitative-oriented approach to motor-symptoms evaluation, namely home-based monitoring (HBM) using an embedded inertial measurement unit. Studies validated such approach against in-clinic evaluations. In this work, we aimed at delineating personalized motor-fluctuations' profiles, thus capturing individual differences. 21 advanced PD patients with motor fluctuations were monitored for 2 weeks using a SW and a smartphone-dedicated app (Intel Pharma Analytics Platform). The SW continuously collected passive data (tremor, dyskinesia, level of activity using dedicated algorithms) and active data, i.e., time-up-and-go, finger tapping, hand tremor and hand rotation carried out daily, once in OFF and once in ON levodopa periods. We observed overall high compliance with the protocol. Furthermore, we observed striking differences among the individual patterns of symptoms' levodopa-related variations across the HBM, allowing to divide our participants among four data-driven, motor-fluctuations' profiles. This highlights the potential of HBM using SW technology for revolutionizing clinical practices.

Neuroplasticity in levodopa-induced dyskinesias: An overview on pathophysiology and therapeutic targets

Levodopa-induced dyskinesias (LIDs) are a common complication in patients with Parkinson's disease (PD). A complex cascade of electrophysiological and molecular events that induce aberrant plasticity in the cortico-basal ganglia system plays a key role in the pathophysiology of LIDs. In the striatum, multiple neurotransmitters regulate the different forms of physiological synaptic plasticity to provide it in a bidirectional and Hebbian manner. In PD, impairment of both long-term potentiation (LTP) and long-term depression (LTD) progresses with disease and dopaminergic denervation of striatum. The altered balance between LTP and LTD processes leads to unidirectional changes in plasticity that cause network dysregulation and the development of involuntary movements. These alterations have been documented, in both experimental models and PD patients, not only in deep brain structures but also at motor cortex. Invasive and non-invasive neuromodulation treatments, as deep brain stimulation, transcranial magnetic stimulation, or transcranial direct current stimulation, may provide strategies to modulate the aberrant plasticity in the cortico-basal ganglia network of patients affected by LIDs, thus restoring normal neurophysiological functioning and treating dyskinesias. In this review, we discuss the evidence for neuroplasticity impairment in experimental PD models and in patients affected by LIDs, and potential neuromodulation strategies that may modulate aberrant plasticity.

Dyskinesia and impulsive compulsive behaviour in Parkinson's disease are not related: Insights from a study with a wearable sensor

INTRODUCTION

Previous studies have suggested an association between Impulsive Compulsive Behaviour (ICB) and dyskinesia in Parkinson's disease (PD). However, none of these studies have employed an objective home-based measure of dyskinesia.

OBJECTIVES

To evaluate in advanced PD the relationship between ICB and dyskinesia, objectively measured with a wearable device.

METHODS

In this cross-sectional study, ICB and other neuropsychiatric symptoms were assessed by means of structured clinical interview and specific screening instruments. Presence and severity of motor fluctuations and dyskinesia were rated with patient's and clinician's based rating instruments. Motor fluctuations and dyskinesia were also measured at home for 5-days using a validated wearable devise, the Parkinson's KinetiGraph™(PKG).

RESULTS

We included 89 subjects with PD (29 females, 62 ± 7 years, disease duration 10.3 ± 4.5), of whom 36 (40%) had ICB. Patients with and without ICB did not differ by presence and severity of dyskinesia measured by clinical scales and PKG. There was no association between the presence of ICB and dyskinesia in the whole sample.

CONCLUSION

Our data suggest that ICB and dyskinesia are common but unrelated disorders in advanced PD.

Alterations of PAC-based resting state networks in Parkinson's disease are partially alleviated by levodopa medication

Introduction

Parkinson's disease (PD) is a neurodegenerative disorder affecting the whole brain, leading to several motor and non-motor symptoms. In the past, it has been shown that PD alters resting state networks (RSN) in the brain. These networks are usually derived from fMRI BOLD signals. This study investigated RSN changes in PD patients based on maximum phase-amplitude coupling (PAC) throughout the cortex. We also tested the hypothesis that levodopa medication shifts network activity back toward a healthy state.

Methods

We recorded 23 PD patients and 24 healthy age-matched participants for 30 min at rest with magnetoencephalography (MEG). PD patients were measured once in the dopaminergic medication ON and once in the medication OFF state. A T1-MRI brain scan was acquired from each participant for source reconstruction. After correcting the data for artifacts and performing source reconstruction using a linearly constrained minimum variance beamformer, we extracted visual, sensorimotor (SMN), and frontal RSNs based on PAC.

Results

We found significant changes in all networks between healthy participants and PD patients in the medication OFF state. Levodopa had a significant effect on the SMN but not on the other networks. There was no significant change in the optimal PAC coupling frequencies between healthy participants and PD patients.

Discussion

Our results suggest that RSNs, based on PAC in different parts of the cortex, are altered in PD patients. Furthermore, levodopa significantly affects the SMN, reflecting the clinical alleviation of motor symptoms and leading to a network normalization compared to healthy controls.

Impaired self-awareness of cognitive deficits in Parkinson's disease relates to cingulate cortex dysfunction

BACKGROUND

Impaired self-awareness of cognitive deficits (ISAcog) has rarely been investigated in Parkinson's disease (PD). ISAcog is associated with poorer long-term outcome in other diseases. This study examines ISAcog in PD with and without mild cognitive impairment (PD-MCI), compared to healthy controls, and its clinical-behavioral and neuroimaging correlates.

METHODS

We examined 63 PD patients and 30 age- and education-matched healthy controls. Cognitive state was examined following the Movement Disorder Society Level II criteria. ISAcog was determined by subtracting z-scores (based on controls' scores) of objective tests and subjective questionnaires. Neural correlates were assessed by structural magnetic resonance imaging (MRI) and 2-[fluorine-18]fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET) in 47 patients (43 with MRI) and 11 controls. We analyzed whole-brain glucose metabolism and cortical thickness in regions where FDG-uptake correlated with ISAcog.

RESULTS

PD-MCI patients (N = 23) showed significantly more ISAcog than controls and patients without MCI (N = 40). When all patients who underwent FDG-PET were examined, metabolism in the bilateral superior medial frontal gyrus, anterior and midcingulate cortex negatively correlated with ISAcog (FWE-corrected p < 0.001). In PD-MCI, ISAcog was related to decreased metabolism in the right superior temporal lobe and insula (N = 13; FWE-corrected p = 0.023) as well as the midcingulate cortex (FWE-corrected p = 0.002). Cortical thickness was not associated with ISAcog in these regions. No significant correlations were found between ISAcog and glucose metabolism in controls and patients without MCI.

CONCLUSIONS

Similar to Alzheimer's disease, the cingulate cortex seems to be relevant in ISAcog in PD. In PD-MCI patients, ISAcog might result from a disrupted network that regulates awareness of cognition and error processes.

Exploring impaired self-awareness of motor symptoms in Parkinson's disease: Resting-state fMRI correlates and the connection to mindfulness

OBJECTIVE

To further explore the phenomenon of impaired self-awareness of motor symptoms in patients with Parkinson's Disease by using an evaluated measurement approach applied in previous studies, while also examining its connection with dispositional mindfulness and possible correlates of functional connectivity.

BACKGROUND

Recently, the phenomenon of impaired self-awareness has been studied more intensively by applying different measurement and imaging methods. Existing literature also points towards a possible connection with mindfulness, which has not been examined in a cross-sectional study. There is no data available concerning correlates of functional connectivity.

METHODS

Non-demented patients with idiopathic Parkinson's Disease without severe depression were tested for impaired self-awareness for motor symptoms following a psychometrically evaluated approach. Mindfulness was measured by applying the German version of the Five Facet Mindfulness Questionnaire. A subset of eligible patients underwent functional MRI scanning. Spearman correlation analyses were performed to examine clinical data. Whole-brain voxelwise regressions between seed-based connectivity and behavioral measures were calculated to identify functional connectivity correlates of impaired self-awareness scores.

RESULTS

A total of 41 patients with Parkinson's Disease were included. 15 patients successfully underwent resting-state fMRI scanning. Up to 88% of patients showed signs of impaired self-awareness. Awareness for hypokinetic movements correlated with total mindfulness values and three facets, while awareness for dyskinetic movements did not. Three significant clusters between scores of impaired self-awareness in general and for dyskinetic movements were identified linking behavioral measures with the functional connectivity of the inferior frontal gyrus, the right insular cortex, the supplementary motor area, and the precentral gyrus among others. Impaired self-awareness for hypokinetic movements did not have any neural correlate.

CONCLUSIONS

Clinical data is comparable with results from previous studies applying the same structured approach to measure impaired self-awareness in Parkinson's Disease. Functional connectivity analyses were conducted for the first time to evaluate neural correlates thereof. This data does not support a connection between impaired self-awareness of motor symptoms and dispositional mindfulness.

Validation of the PD home diary for assessment of motor fluctuations in advanced Parkinson's disease

The Parkinson's disease (PD) home diary is frequently used in clinical trials to measure efficacy of medical treatments for motor fluctuations in advanced PD. This prospective study in fluctuating PD patients examines the validity of the diary for quantification of motor states in comparison to direct clinical observation. 51 patients (median age: 65 years, disease duration: 11 years) completed the diary half-hourly for two consecutive days and were simultaneously rated by an experienced observer, who independently evaluated motor states half-hourly throughout daytime. Overall agreement (Cohen's kappa) between patient and observer diary entries was 59.8% (0.387). Patients documented more On without dyskinesia (52.3% vs. 38.9%, P < 0.001) and less On with dyskinesia (21.5% vs. 34.2%, P < 0.001), whereas proportions for Off intervals were not different between patient and observer diaries (26.2% vs. 27.0%, P = 0.97). Temporal agreement between diary ratings was unsatisfactory, particularly for On with dyskinesia. Taken together, our study suggests that the PD home diary only inadequately reflects actual motor states compared to direct clinical observation.

Pilot Study of Mindfulness Training on the Self-Awareness of Motor Symptoms in Parkinson's Disease - A Randomized Controlled Trial

Objective: This study aims to evaluate feasibility and effects of a newly developed mindfulness intervention tailored to specific needs of patients with Parkinson’s disease (PD).

Background: The phenomenon of impaired self-awareness of motor symptoms (ISAm) in PD might be reduced by increasing patients’ mindfulness. A PD-specific mindfulness intervention has been developed and evaluated as a potential treatment option: IPSUM (“Insight into Parkinson’s Disease Symptoms by using Mindfulness”).

Methods: IPSUM’s effectiveness is evaluated by comparing an intervention with a waitlist-control group. Applying a pre-post design, patients were assessed before, directly after and 8weeks after treatment. The primary outcome was the change in a quantitative ISAm score from baseline to post-assessment. Secondary outcome measures were PD-related affective changes and neuropsychological test performance. Feasibility was evaluated via feedback forms.

Results: In total, 30 non-depressed and non-demented PD patients were included (intervention: n=14, waitlist-control: n=16). ISAm score did not change significantly, but the training group showed greater performance in sustained attention and language tasks over time. Additional changes included greater mindfulness as well as less sleeping problems and anxiety. Cognitive disturbances, apathy, and sleeping problems worsened only in the waitlist-control group. Patients’ feedback regarding the training concept and material was excellent.

Conclusion: Insight into Parkinson’s Disease Symptoms by using Mindfulness has not been capable of reducing ISAm in PD patients but appears to be a feasible and effective concept to, among others, support mental health in the mid-term. It has to be noted though that the study was stopped beforehand because of the SARS CoV-2 pandemic. The lack of findings might therefore be caused by a lack of statistical power. The need for further research to better understand the mechanisms of ISAm and its connection to mindfulness in PD is highlighted.

Comparing subjective and objective response to medications in Parkinson's disease patients using the Personal KinetiGraph™

BACKGROUND

Management of motor symptoms in Parkinson's Disease(PD) relies on subjective information provided by patients, the quality of which can be affected by many factors.

RATIONALE

Objective data collected during daily life could complement this information and improve management of motor symptoms.

OBJECTIVES

To assess the usefulness of the Personal KinetiGraph (PKG) in characterizing the intensity and timing of motor symptoms in PD patients.

METHODS

Retrospective study of all PD patients followed at a tertiary academic movement disorders center assessed by PKG between December 1, 2016 and October 30, 2018. PKG was worn for 7 days prior to the clinical visit. We compared the information obtained from the interview and the clinical visit, and assessed the impact of the PKG on treatment decision making.

RESULTS

170 PKG results were reviewed. PKG complemented patient input in 82.9%(141/170) and led to medication changes in 71%(100/141) of the complemented inputs. PKG contributed the least to correcting or complementing patients' input when patients self-reported as undertreated (22%) and the most when patient were unable to answer all questions regarding motor response to individual doses (100%) (Fisher, p < 0.0001). The majority of patient undergoing 3 or 4 PKG encounters did not reach a controlled state as defined by PKG until the 3rd or 4th encounter, suggesting that repeated use of the PKG might be needed to help optimize motor control as therapy changes done after one encounter might not be enough.

CONCLUSIONS

PKG might be useful in supplementing patient-provided information for accurate assessment and treatment plan.

Pathophysiological Mechanisms and Experimental Pharmacotherapy for L-Dopa-Induced Dyskinesia

L-dopa-induced dyskinesia (LID) is the most frequent motor complication associated with chronic L-dopa treatment in Parkinson’s disease (PD). Recent advances in the understanding of the pathophysiological mechanisms underlying LID suggest that abnormalities in multiple neurotransmitter systems, in addition to dopaminergic nigrostriatal denervation and altered dopamine release and reuptake dynamics at the synaptic level, are involved in LID development. Increased knowledge of neurobiological LID substrates has led to the development of several drug candidates to alleviate this motor complication. However, with the exception of amantadine, none of the pharmacological therapies tested in humans have demonstrated clinically relevant beneficial effects. Therefore, LID management is still one of the most challenging problems in the treatment of PD patients. In this review, we first describe the known pathophysiological mechanisms of LID. We then provide an updated report of experimental pharmacotherapies tested in clinical trials of PD patients and drugs currently under study to alleviate LID. Finally, we discuss available pharmacological LID treatment approaches and offer our opinion of possible issues to be clarified and future therapeutic strategies.

Experience and Impact of OFF Periods in Parkinson's Disease: A Survey of Physicians, Patients, and Carepartners

BACKGROUND

OFF periods impair quality of life in Parkinson's disease but the nature and degree of this impact is largely unquantified. Optimal treatment relies on assessing the experience and impact of these periods on patients and their carepartners.

OBJECTIVES

To understand the experience and impact of OFF periods on their lives.

METHODS

Informed by qualitative interviews we designed questionnaires and surveyed neurologists, people with Parkinson's disease and carepartners.

RESULTS

50 general neurologists, 50 movement disorder neurologists, 442 patients (median disease duration 5 years) and 97 carepartners were included. The most common OFF symptoms reported by patients and carepartners were stiffness, slowness of movement and changes in gait. Non-motor symptoms were less common. A higher proportion of carepartners reported each symptom. A minority of neurologists recognized pain, sweating and anxiety as possible symptoms of OFF periods. The three OFF symptoms most frequently designated as having great impact by people with Parkinson's disease were changes in gait, slowness and stiffness. In contrast, cognitive impairment was most frequently rated as having great impact on carepartners. OFF periods were reported to impact many aspects of the lives of both patients and carepartners.

CONCLUSIONS

In people with Parkinson's disease of under 10 years duration, motor symptoms of OFF periods predominate in impact, however cognitive impairment has great impact on carepartners. Education is needed for neurologists regarding the non-motor aspects of OFF. The importance of involving carepartners in the assessment regarding OFF periods is supported by the higher frequency of symptom reporting by carepartners, and the significant impact on their lives.

Smartwatch inertial sensors continuously monitor real-world motor fluctuations in Parkinson's disease

Longitudinal, remote monitoring of motor symptoms in Parkinson's disease (PD) could enable more precise treatment decisions. We developed the Motor fluctuations Monitor for Parkinson's Disease (MM4PD), an ambulatory monitoring system that used smartwatch inertial sensors to continuously track fluctuations in resting tremor and dyskinesia. We designed and validated MM4PD in 343 participants with PD, including a longitudinal study of up to 6 months in a 225-subject cohort. MM4PD measurements correlated to clinical evaluations of tremor severity (ρ = 0.80) and mapped to expert ratings of dyskinesia presence (P < 0.001) during in-clinic tasks. MM4PD captured symptom changes in response to treatment that matched the clinician's expectations in 94% of evaluated subjects. In the remaining 6% of cases, symptom data from MM4PD identified opportunities to make improvements in pharmacologic strategy. These results demonstrate the promise of MM4PD as a tool to support patient-clinician communication, medication titration, and clinical trial design.

Establishment of a Visual Analog Scale for DBS Programming (VISUAL-STIM Trial)

Background: Deep brain stimulation (DBS) has become a standard treatment for advanced stages of Parkinson's disease, essential tremor, and dystonia. In addition to the correct surgical device implantation, effective programming is regarded to be the most important factor for clinical outcome. Despite established strategies for adjusting neurostimulation, DBS programming remains time- and resource-consuming. Although kinematic and neuronal biosignals have recently been examined as potential feedback for closed-loop DBS (CL-DBS), there is an ongoing need for programming strategies to adapt the stimulation parameters and electrode configurations accurately and effectively.

Methods: Here, we tested the usefulness of a patient-rated visual analog scale (VAS) for real-time adjustment of DBS parameters. The stimulation parameters (contact and amplitude) in Parkinson's patients with STN-DBS (n = 17) were optimized based on the patient's subjective VAS rating. A Minkowski distance (M_d) was calculated to compare the individual combination of contact selection and amplitude to the stimulation parameters that resulted from classical programming based on clinical signs and symptoms.

Results: We found no statistically significant difference between VAS-based and classical programming in regard to the specific contact or amplitude used or in regard to the clinical disease severity (UPDRS).

Conclusions: Our data suggest that VAS-based and classical programming strategies both lead to similar short-term results. Although further research will be required to assess the validity of VAS-based DBS programming, our results support the investigation of the patient's subjective rating as an additional and valid feedback signal for individualized DBS adjustment.

Altered awareness of motor symptoms in Parkinson's disease and Dementia with Lewy Bodies: A systematic review

OBJECTIVES

Altered awareness of motor symptoms is reported in people with Parkinson's disease and Dementia with Lewy Bodies, and may adversely affect quality of life and medication concordance. How symptom awareness is influenced by motor and cognitive disease severity, age and medication use is not fully understood. We carried out a systematic review of the literature on motor symptom awareness in Parkinson's disease and Dementia with Lewy Bodies.

METHODS

Pubmed and Wed of Science were searched for relevant articles published in or prior to March 2019. Data regarding participant demographics, diagnosis, cognitive status, method of assessing awareness and study findings were extracted from relevant publications.

RESULTS

Sixteen relevant publications were identified. Motor symptom awareness appears to decline over the course of Parkinson's disease. Imaging studies implicate the prefrontal cortex, with different mechanisms involved in hypokinesia and dyskinesia awareness. The hypothesis that people with right hemisphere based disease would have more severely reduced awareness is only weakly supported. Most studies focused on cognitively intact individuals, and on awareness of dyskinesia rather than hypokinesia.

CONCLUSIONS

Whilst reduced awareness of dyskinesia and to a lesser extent hypokinesia is common, there is a lack of longitudinal data on how awareness changes over time, and how it interacts with global cognitive changes. Motor symptom awareness in Dementia with Lewy Bodies is understudied. Future studies of symptom awareness should include robust assessment of overall cognitive functioning, and use a longitudinal design to elucidate how awareness changes over time. J Am Geriatr Soc 68:-, 2020.

Awareness of Dystonic Posture in Patients With Cervical Dystonia

Background

Cervical dystonia (CD) is a focal dystonia characterized by sensorimotor integration abnormalities and proprioceptive dysfunction. Since proprioception is essential for bodily awareness, we hypothesized that CD patients may have an impairment in dystonic posture awareness. More information on this issue could be useful to better understand whether dystonic posture affects bodily perception in CD and could help in the development of specific rehabilitation strategies based on proprioceptive input manipulation to restore bodily awareness.

Objectives

The aim of our study was to investigate dystonic posture and head tremor awareness in CD patients by comparing evaluations performed by CD patients with those performed by a neurologist expert in movement disorders.

Methods

We enrolled 25 CD patients. We investigated dystonic posture and head tremor awareness in CD patients using a standardized protocol in which patients were asked to describe the type of dystonic pattern, both while viewing standardized images of different CD subtypes (torticollis, laterocollis, anterocollis, and retrocollis) and after watching a video recording of their dystonic posture and head tremor.

Results

We found that 72% of CD patients correctly recognized their dystonic posture when viewing standardized images, whereas 84% of CD patients were able to identify their dystonic pattern when watching a video recording of themselves. CD patients also displayed a preserved awareness of their head tremor. We did not find any associations between dystonic pattern awareness and clinical or demographic features.

Conclusion

Contrary to our hypothesis, the majority of CD patients have a preserved awareness of their dystonic pattern and tremor.

High levodopa plasma concentration after oral administration predicts levodopa-induced dyskinesia in Parkinson's disease

INTRODUCTION

In patients with Parkinson's disease (PD), pulsatile dopaminergic stimulation may be a primary cause of levodopa-induced dyskinesia (LID). We aimed to investigate the correlation between levodopa pharmacokinetics (PK) and LID in PD.

METHODS

We retrospectively reviewed the consecutive series of 255 PD patients without LID who underwent PK assessments with 100 mg levodopa. The type of peripheral decarboxylase inhibitor used in the PK assessments was determined by the usual prescription of the formulations of levodopa (10 mg carbidopa [n = 185] and 25 mg benserazide [n = 70]).

RESULTS

During a median follow-up of 32 months (IQR, 16-49 months), 73 patients (29%) developed LID. Compared with patients who did not develop LID (PD-LID-), those who developed LID (PD-LID+) were younger (p = 0.003) and had significantly higher maximum levodopa concentration (Cmax) (p = 0.002) and area under the curve (p < 0.001), LEDD (p < 0.001), and improvement of motor symptoms (p = 0.009). In the multivariate Cox proportional hazards models, Cmax and AUC were associated with incident LID (Hazard Ratio [HR] 1.11, 95% confidence interval [CI] 1.03-1.19 and HR 1.13, 95% CI 1.03-1.24, respectively). In addition, younger age, benserazide use, LEDD, and MAOBI use were associated with incident LID.

CONCLUSION

High levodopa plasma concentration after oral administration was associated with incident LID in patients with PD.

Objective measurement in Parkinson's disease: a descriptive analysis of Parkinson's symptom scores from a large population of patients across the world using the Personal KinetiGraph®

Background

The Personal KinetiGraph® (PKG®) Movement Recording System provides continuous, objective, ambulatory movement data during routine daily activities and provides information on medication compliance, motor fluctuations, immobility, and tremor for patients with Parkinson’s disease (PD). Recent evidence has proposed targets for treatable symptoms. Indications for PKG vary by country and patient selection varies by physician.

Methods

The analyses were based upon 27,834 complete and de-identified PKGs from January 2012 to August 2018 used globally for routine clinical care. Median scores for bradykinesia (BKS) and dyskinesia (DKS) as well as percent time with tremor (PTT) and percent time immobile (PTI) were included as well as proportions of PKGs above published PKG summary score target values (BKS > 25, DKS > 9, PTT > 1%, PTI > 10%). Two sub-analyses included subjects who had 2+ PKG records and scores above proposed BKS and DKS targets, respectively, on their first PKG. Median BKS and DKS scores for subsequent PKGs (1st, 2nd, etc.) were summarized and limited to those with 100+ subsequent PKGs for each data point.

Results

Significant differences between countries were found for all 4 PKG parameter median scores (all p < 0.0001). Overall, 54% of BKS scores were > 25 and ranged from 46 to 61% by country. 10% of all DKS scores were > 9 and ranged from 5 to 15% by country. Sub-analysis for BKS showed global median BKS and DKS scores across subsequent PKGs for subjects who had 2+ PKGs and had BKS > 25 on their first PKG. There were significant changes in BKS from 1st to 2nd-6th PKGs (all p < 0.0001). Sub-analysis for DKS showed global median BKS & DKS scores across subsequent PKGs for subjects who had 2+ PKGs and had DKS > 9 on their first PKG. There were significant changes in DKS from 1st to 2nd and 3rd PKGs (both p < 0.0001).

Conclusions

This analysis shows that in every country evaluated a meaningful proportion of patients have sub-optimal PD motor symptoms and substantial variations exist across countries. Continuous objective measurement (COM) in routine care of PD enables identification and quantification of PD motor symptoms, which can be used to enhance clinical decision making, track symptoms over time and improve PD symptom scores. Thus, clinicians can use these PKG scores during routine clinical management to identify PD symptoms and work to move patients into a target range or a more controlled symptom state.

Improving Self-Awareness of Motor Symptoms in Patients With Parkinson's Disease by Using Mindfulness - A Study Protocol for a Randomized Controlled Trial

Objective

This study aims to increase self-awareness in patients with Parkinson’s disease (PD) using a newly developed mindfulness-based intervention, tailored for the specific needs of PD patients. Its impact on self-awareness and patients’ daily lives is currently being evaluated.

Background

Recently, the phenomenon of impaired self-awareness for motor symptoms (ISAm) and some non-motor symptoms has been described in PD. ISAm can negatively influence patients’ daily lives, e.g., by affecting therapy adherence, and is therefore the main focus of this study. The main goal is the development of IPSUM (“Insight into Parkinson’s Disease Symptoms by using Mindfulness”), a PD-specific intervention for increasing patients’ mindfulness and thereby reducing ISAm.

Methods

The effectiveness of IPSUM is evaluated by comparison of an intervention group with a waitlist-control group. A pre-post design with an additional 8-week follow-up measurement is applied, resulting in three measurement points: before, directly after and 8 weeks after completing the intervention protocol. In total, up to 180 non-depressed PD patients without severe cognitive impairment (non-demented) will be included. The primary outcome is a quantitative score for measuring ISAm. Secondary outcome measures are affective changes, neuropsychological performance and self-awareness of cognition. At pre- and post-measurement an fMRI scan is performed to connect behavioral and neurobiological findings. At post- and follow-up-measurement each patient will take part in a semi-structured interview to explore IPSUM’s impact on self-awareness and patients’ everyday lives.

Results

The conception of the intervention protocol is finished, the resulting 8-week program is presented in detail. It has successfully been tested in the first group of patients, their feedback so far was quite promising. Recruitment is ongoing and a first interim analysis will be performed once 30 patients have completed IPSUM.

Conclusion

For the first time, the intervention protocol of IPSUM has successfully been tested in a group of PD patients. As the study goes on, more quantitative data is collected for statistical analyses to evaluate its effectiveness. More qualitative data is collected to evaluate feasibility and effectiveness. We hope for this intervention to be capable of reducing the patients’ ISAm and improving their quality of life on many levels.

Dyskinesia matters

Levodopa-induced dyskinesia (LID) represents a significant source of discomfort for people with Parkinson's disease (PD). It negatively affects quality of life, it is associated with both motor and nonmotor fluctuations, and it brings an increased risk of disability, balance problems, and falls. Although the prevalence of severe LID appears to be lower than in previous eras (likely owing to a more conservative use of oral levodopa), we have not yet found a way to prevent the development of this complication. Advanced surgical therapies, such as deep brain stimulation, ameliorate LID, but only a minority of PD patients qualify for these interventions. Although some have argued that PD patients would rather be ON with dyskinesia than OFF, the deeper truth is that patients would very much prefer to be ON without dyskinesia. As researchers and clinicians, we should aspire to make that goal a reality. To this end, translational research on LID is to be encouraged and persistently pursued. © 2019 International Parkinson and Movement Disorder Society.

Complex dyskinesias in Parkinson patients on levodopa/carbidopa intestinal gel

BACKGROUND

Levodopa-carbidopa intestinal infusion is an effective treatment for motor fluctuations in Parkinson's disease. However, it has been recently associated with emergent complex/atypical dyskinesias. We sought to characterize patients who developed these dyskinesias after levodopa infusion initiation, and to compare these patients to a control population with conventional motor fluctuations.

METHODS

208 Parkinson's disease patients, treated with levodopa intestinal infusion due to motor fluctuations, were screened for onset and/or worsening of dyskinesias after initiation of levodopa infusion, resistant to the routine titration, and presenting with atypical or unexpected patterns. Patients with extensive follow-up data were enrolled for a longitudinal analysis. Cases were compared to a control sample with conventional motor fluctuations in order to investigate predisposing factors, difference in dyskinesia phenotype, management strategies and dropouts.

RESULTS

Thirty patients out of 208 (14.4%) reported atypical (i.e. long-lasting) biphasic, biphasic-like (i.e. continuous) or mixed (peak-dose and continuous biphasic) dyskinesias after levodopa infusion. They were compared at baseline and follow-up to a sample of 49 patients with conventional motor fluctuations on levodopa infusion. Both groups had similar demographic and clinical features, except the former having higher prevalence of biphasic dyskinesias while on oral therapy. Biphasic-like dyskinesias in nearly half the number of cases improved with increasing the dopaminergic load, while mixed dyskinesias had the worst outcome and highest dropout rate (58%).

CONCLUSIONS

Atypical biphasic, biphasic-like and complex dyskinesias could hinder the course of patients treated with levodopa infusion. This study further informs the selection process of advanced therapies, particularly in dyskinetic patients.

Viewpoint: Developing drugs for levodopa-induced dyskinesia in PD: Lessons learnt, what does the future hold?

The drive to develop drugs to treat PD starts and ends with the patient. Herein, we discuss how the experience with drug development for LID has led the field in translational studies in PD with advancing ground-breaking science via rigorous clinical trial design, to deliver clinical proof-of-concepts across multiple therapeutic targets. However, issues remain in advancing drugs efficacious preclinically to the clinic, and future studies need to learn from past successes and failures. Such lessons include implementing better early indicators of tolerability, for instance evaluating non-motor symptoms in preclinical models; improving patient-related outcome measures in clinical trials, as well as considering the unique nature of dyskinesia in an individual patient. The field of translational studies needs to become more patient focused to improve successful outcomes.

Role of the Cingulate Cortex in Dyskinesias-Reduced-Self-Awareness: An fMRI Study on Parkinson's Disease Patients

Objectives: The detection of dyskinesias-reduced-self-awareness (DRSA), in Parkinson’s disease (PD), was previously associated to executive and metacognitive deficits mainly due to dopaminergic overstimulation of mesocorticolimbic circuits. Response-inhibition dysfunction is often observed in PD. Apart from being engaged in response-inhibition tasks, the anterior cingulate cortex (ACC), is part of a functional system based on self-awareness and engaged across cognitive, affective and behavioural contexts. The purpose of the study was to examine the relationship between response-inhibition disabilities and DRSA using whole-brain event-related functional magnetic resonance imaging (fMRI), over the course of a specific executive task.

Methods: Twenty-seven cognitively preserved idiopathic PD patients – presenting motor fluctuations and dyskinesias – were studied. They underwent a neurological and neuropsychological evaluation. The presence of DRSA was assessed using the Dyskinesias Subtracted-Index (DS-I). Cingulate functionality was evaluated with fMRI, while patients performed an ACC-sensitive GO-NoGO task. Association between blood oxygenation level dependent response over the whole-brain during the response-inhibition task and DS-I scores was investigated by regression analysis.

Results: The presence of DRSA was associated with reduced functional recruitment in the bilateral ACC, bilateral anterior insular cortex and right dorsolateral prefrontal cortex (p_FWE<0.05). Moreover, DS-I scores significantly correlated with percent errors on the NoGO condition (r = 0.491, p_FWE = 0.009).

Discussion: These preliminary findings add evidence to the relevant role of executive dysfunctions in DRSA pathogenesis beyond the effects of chronic dopaminergic treatment, with a key leading role played by ACC as part of a functionally impaired response-inhibition network. Imaging biomarkers for DRSA are important to be studied, especially when the neuropsychological assessment seems to be normal.

Levodopa-induced dyskinesia: clinical features, incidence, and risk factors

Symptoms of Parkinson's disease have been controlled with levodopa for many years; however, motor complications consisting of wearing off of medication effect and dyskinesias tend to occur within a few years of starting levodopa. Motor complications can begin a few months after taking levodopa, with the average time to onset estimated to be 6.5 years. Dyskinesias can be troublesome and require intervention. Levodopa-induced dyskinesia can be composed of a variety of movement disorders including chorea, dystonia, ballism, myoclonus, and akathisia. Based on the clinical pattern, the most common dyskinesia is chorea and choreoathetosis. The clinical manifestations can be divided into three main categories based on their clinical movement patterns and the temporal correlation between the occurrence of dyskinesia and the levodopa dosing: on or peak-dose dyskinesias, biphasic dyskinesias, and Off dyskinesias. Severe cases of dyskinesia have been reported, with the extreme being dyskinesia-hyperpyrexia syndrome. The prevalence of LID has been reported in many studies, but the reported incidence varies. The rate of LID development is from 3 to 94%. The prevalence of LID mainly depends on age at onset, disease duration, and severity, and duration of levodopa therapy. Some of the risk factors for the development of dyskinesia are modifiable. Modifiable risk factors include levodopa dose and body weight. Non-modifiable risk factors include age, gender, duration of disease, clinical subtype, disease progression, disease severity, and genetic factors.

Impaired Self-Awareness of Motor Disturbances in Parkinson's Disease

Traditionally, anosognosia for cognitive or motor impairments in patients with Parkinson's disease (PD) was viewed as unlikely unless the patient was demented. More recent research has suggested that a portion of non-demented PD patients (30%-50%) in fact have impaired subjective awareness (ISA) of their motor impairments (ISAm). This empirical finding has implications for the clinical neuropsychological examination of PD patients and raises theoretical questions relevant to the broader study of anosognosia seen in other patient groups. The purpose of this paper is to primarily review our own research in this area and to summarize research findings of other investigators who have examined ISA in PD patients. Our secondary goal is to demonstrate the relevance of assessing ISA when conducting a neuropsychological examination of PD patients. Our findings suggest ISAm in PD patients is related to motor signs of right hemispheric dysfunction, but the brain imaging correlates of ISA for hypokinesias appear different than those obtained for ISA for dyskinesia in this patient group.

Subjective Perceived Motor Improvement after Acute Levodopa Challenge in Parkinson's Disease

BACKGROUND

Previous studies found a poor association between parkinsonian patient's reported subjective improvement after commencing dopaminergic treatment and improvements in objective measures of motor impairment by clinician.

OBJECTIVE

To compare PD patient's subjective perceived motor improvement after acute levodopa challenge test with objective motor improvement assessed by the clinician using the UPDRS part III. To analyze clinical characteristics, i.e. age, disease duration, cognitive performance or severity of axial features, that may have influenced patient's perception.

METHODS

Fifty-seven consecutive PD patients (23 women, 34 men; mean age, 63.4±7.7 years) (Hoehn and Yahr off score, 2.5±0.7; mean disease duration, 11.4±4.1 years) completed the acute levodopa challenge. The percentage of improvement in motor disability, i.e. objective motor improvement, was determined with respect to the off-drug condition.

RESULTS

Bland & Altman visual analysis reveals a high degree of correlation between objective and subjective perceived motor improvement. Both the axial sub-scores in the off- and on-state (respectively, P = 0.006 and P = 0.024) and the presence of peak-dose dyskinesia (P = 0.043) significantly influence the difference between objective and subjective perceived motor improvement.

CONCLUSIONS

This is the first study reporting on how PD patients assessed their motor improvement after acute levodopa challenge. These findings suggest a strong correlation between objective motor improvement assessed by the clinician using the UPDRS part III and subjective perceived motor improvement reported by the patient.

Impulse control disorders in advanced Parkinson's disease with dyskinesia: The ALTHEA study

BACKGROUND

Impulse control disorders and dyskinesia are common and disabling complications of dopaminergic treatment in Parkinson's disease. They may coexist and are possibly related. The objectives of this study were to assess the frequency and severity of impulse control disorders in Parkinson's disease patients with dyskinesia.

METHODS

The ALTHEA study enrolled 251 Parkinson's disease patients with various degrees of dyskinesia severity from 11 movement disorders centers in Italy. Each patient underwent a comprehensive assessment including Unified Dyskinesia Rating Scale and the Questionnaire for Impulsive Compulsive Disorders in Parkinson Disease-Rating Scale.

RESULTS

There was an overall 55% frequency of impulse control disorder and related behaviors (36% were clinically significant). The positive patients were younger at disease diagnosis and onset and had higher Unified Dyskinesia Rating Scale historical and total score (P = 0.001 and P = 0.02, respectively, vs negative). There was an increased frequency of clinically significant impulse control disorders in patients with severe dyskinesia (P = 0.013), a positive correlation between the questionnaire total score and dopamine agonist dose (P = 0.018), and a trend with levodopa dose.

CONCLUSIONS

More than half of Parkinson's disease patients with dyskinesia have impulse control disorders and related behaviors, which are frequently clinically significant. Dopaminergic therapy total dose is associated with their severity. Clinicians should carefully assess patients with maladaptive behaviors and dyskinesia because they do not properly evaluate their motor and nonmotor status. © 2017 International Parkinson and Movement Disorder Society.

Motor Complications of Dopaminergic Medications in Parkinson's Disease

Motor complications are a consequence of the chronic treatment of Parkinson's disease (PD) and include motor fluctuations (wearing-off phenomenon) and levodopa-induced dyskinesia. Both can have a significant impact on functionality and quality of life; thus, proper recognition and management is essential. The phenomenology and temporal relationship of motor complications to the schedule of levodopa dosing can be helpful in characterizing them. There are several therapeutic approaches to motor complications, including pharmacological and surgical options. The authors summarize the different types of motor complications according to phenomenology and the currently available medical treatments, including ongoing trials for the management of this condition.

A novel framework for understanding reduced awareness of dyskinesias in Parkinson's Disease

BACKGROUND

Although dyskinesias-reduced-self-awareness (DRSA) in Parkinson's disease (PD) is related to deficit in metacognition, other factors, such as "Theory of Mind" (ToM), could operate.

METHODS

Forty-one PD patients were assessed using the Global Awareness of Movement Disorders (GAM) and the Dyskinesias Subtracted-Index (DS-I). To study whether GAM and DS-I scores could be influenced by second-type ToM or Reading the Mind in the Eyes (RME) tasks, we conducted two multiple logistic regression analyses.

RESULTS

The association between the GAM, the DS-I and RME task were highly significant. The association between DS-I and Trail Making Test B-A version was also verified.

CONCLUSION

DRSA was related with affective component of ToM and executive functions, thus caused by a complex interplay between specific neuropsychological and motor factors.

Misperceptions and Parkinson's disease

Most of the neurobehavioral aspects of Parkinson's disease have been well established and studied, but many are not well known, and hardly studied. This article focuses on several behavioral abnormalities that are common, and frequently cause difficulty for the patient and family due to lack of recognition as part of the disease. While it is well known that L-Dopa dyskinesias are frequently not recognized or under appreciated by patients, a similar lack of recognition may affect the patient's own speech volume, where their center of gravity is located, whether they are tilted to one side, and their under-recognition of others' emotional displays. In addition, PD patients are often misperceived by others incorrect impression of their emotional and cognitive state based purely on facial expression. These changes and others are briefly reviewed.

Striatal Plasticity in L-DOPA- and Graft-Induced Dyskinesia; The Common Link?

One of the major symptoms of the neurodegenerative condition Parkinson's disease (PD) is a slowness or loss of voluntary movement, yet frustratingly therapeutic strategies designed to restore movement can result in the development of excessive abnormal movements known as dyskinesia. These dyskinesias commonly develop as a result of pharmacotherapy in the form of L-DOPA administration, but have also been identified following deep brain stimulation (DBS) and intrastriatal cell transplantation. In the case of L-DOPA these movements can be treatment limiting, and whilst they are not long lasting or troubling following DBS, recognition of their development had a near devastating effect on the field of cell transplantation for PD.Understanding the relationship between these therapeutic approaches and the development of dyskinesia may improve our ability to restore function without disabling side effects. Interestingly, despite the fact that dopaminergic cell transplantation repairs many of the changes induced by the disease process and through L-DOPA treatment, there appears to be a relationship between the two. In rodent models of the disease, the severity of dyskinesia induced by L-DOPA prior to the transplantation procedure correlated with post-transplantation, graft-induced dyskinesia. A review of clinical data also suggested that the worse preoperational dyskinesia causes worsened graft-induced dyskinesia (GID). Understanding how these aberrant behaviors come about has been of keen interest to open up these therapeutic options more widely and one major underlying theory is the effects of these approaches on the plasticity of synapses within the basal ganglia. This review uniquely brings together developments in understanding the role of striatal synaptic plasticity in both L-DOPA and GID to guide and stimulate further investigations on the important striatal plasticity.

Learning More from Finger Tapping in Parkinson's Disease: Up and Down from Dyskinesia to Bradykinesia

The finger tapping test evaluates bradykinesia, focusing on decrement in rate, amplitude, or both with repetitive action. Vertical positioning of the hands during this task may also be clinically relevant. We developed a "TAP score," measuring the vertical level above the lap where the patient performs the finger tapping ranging from 1 (task performed with the hand close to the lap) to 4 (above the head). In this pilot study, we retrospectively applied the TAP score in addition to usual motor scales during acute levodopa challenge in 123 PD patients (of whom 88 presented l-dopa-induced dyskinesia [LID]). TAP ON was higher than TAP OFF. Patients with LID presented higher TAP ON. TAP ON was related to LID severity, whereas TAP OFF was inversely related to the OFF motor symptoms. The TAP score may be a measure of proximal movement amplitude representing an easy method to evaluate defective or excessive motor output in patients with advanced disease.

Symptom severity in patients with functional motor symptoms: Patient's perception and doctor's clinical assessment

BACKGROUND

Beliefs and expectations about symptoms and an abnormal direction of attention towards the body have been proposed as important mechanistic factors in the pathophysiology of functional motor symptoms (FMS). We therefore aimed to evaluate patients' awareness/perception of the presence and severity of their own symptoms before and while watching themselves in a video and to compare this with doctors' assessment of the presence and severity of FMS, based on video evaluation.

METHODS

We evaluated 16 patients affected by FMS. Patients were invited to give a "subjective evaluation" of their symptoms. Afterwards, patients were invited to watch a video of themselves and to judge the presence of symptoms in the different body parts and, if so, to rate the severity. Patients' videos were also assessed by a rater with expertise in FMS.

RESULTS

Patients judged their symptoms to be more severe on subjective evaluation than when viewing a video of themselves (p = 0.002; t = 3.656). Subjective evaluation of symptom severity by patients was higher than that of raters viewing a video of the patient (p < 0.001, t = 4.860), but there was only a trend towards a difference between video ratings of severity by patients and independent raters (p = 0.017, t = 2.962 with p set at 0.016 according to Bonferroni correction).

CONCLUSIONS

Our study shows that patients with FMS tend to overestimate the severity of their symptoms compared independent rating. However, when viewing a video of themselves they rated their symptoms as less severe and closer to those of independent raters.

Development and psychometric evaluation of a scale to measure impaired self-awareness of hyper- and hypokinetic movements in Parkinson's disease

OBJECTIVE

Patients with Parkinson's disease (PD) can show impaired self-awareness of motor deficits (ISAm). We developed a new scale that measures ISAm severity of hyper- and hypokinetic movements in PD during medication on state and defined its psychometric criteria.

METHOD

Included were 104 right-handed, non-depressed, non-demented patients. Concerning ISAm, 38 motor symptoms were assessed using seven tasks, which were performed and self-rated concerning presence of deficit (yes/no) by all patients. The whole procedure was videotaped. Motor symptoms were then evaluated by two independent experts, blinded for patient's ratings, concerning presence, awareness of deficit, and severity. Exploratory principal component analysis (promax rotation) was applied to reduce items. Principal axis factoring was conducted to extract factors. Reliability was examined regarding internal consistency, split-half reliability, and interrater reliability. Validity was verified by applying two additional measures of ISAm.

RESULTS

Of the initial 38 symptoms, 15 remained, assessed in five motor tasks and merged to a total severity score. Factor analysis resulted in a four factor solution (dyskinesia, resting tremor right hand, resting tremor left hand, bradykinesia). For all subscales and the total score, measures of reliability (values 0.64-0.89) and validity (effect sizes>0.3) were satisfactory. Descriptive results showed that 66% of patients had signs of ISAm (median 2, range 0-15), with ISAm being most distinct for dyskinesia.

CONCLUSIONS

We provide the first validation of a test for ISAm in PD. Using this instrument, future studies can further analyze the pathophysiology of ISAm, the psychosocial sequelae, therapeutic strategies and compliance with therapy.

Speech-related fatigue and fatigability in Parkinson's disease

This study tested the assumption that speech is more susceptible to fatigue than normal in persons with dysarthria. After 1 h of speech-like exercises, participants with Parkinson's disease (PD) were expected to report increased perceptions of fatigue and demonstrate fatigability by producing less precise speech with corresponding acoustic changes compared to neurologically normal participants. Twelve adults with idiopathic PD and 13 neurologically normal adults produced sentences with multiple lingual targets before and after six 10-min blocks of fast syllable or word productions. Both groups reported increasing self-perceived fatigue over time, but trained listeners failed to detect systematic differences in articulatory precision or speech naturalness between sentences produced before and after speech-related exercises. Similarly, few systematic acoustic differences occurred. These findings do not support the hypothesis that dysarthric speakers are particularly susceptible to speech-related fatigue; instead, speech articulation generally appears to be resistant to fatigue induced by an hour of moderate functional exercises.

Clinical spectrum of levodopa-induced complications

The first years of Parkinson disease (PD) treatment are marked by good and sustained responses to dopaminergic therapy. With disease progression and longer exposure to levodopa (l-dopa), patients develop a range of l-dopa-induced complications that include motor and non-motor symptoms. Motor complications include motor fluctuations, characterized by periods of reduced benefit from the medication, and l-dopa-induced dyskinesia, characterized by emergence of hyperkinetic involuntary movements. Dyskinesia can occur at peak effect of l-dopa, at the beginning and end of dose, or between doses. These motor complications are often associated with fluctuations in non-motor symptoms, particularly fluctuations in neuropsychiatric, autonomic, and sensory symptoms. Recognizing such complications and understanding their relationship with the timing of l-dopa doses is essential for adequate diagnosis and management. Society.

Pharmacological strategies for the management of levodopa-induced dyskinesia in patients with Parkinson's disease

L-Dopa-induced dyskinesias (LID) are the most common adverse effects of long-term dopaminergic therapy in Parkinson's disease (PD). However, the exact mechanisms underlying dyskinesia are still unclear. For a long time, nigrostriatal degeneration and pulsatile stimulation of striatal postsynaptic receptors have been highlighted as the key factors for the development of LID. In recent years, PD models have revealed a wide range of non-dopaminergic neurotransmitter systems involved in pre- and postsynaptic changes and thereby contributing to the pathophysiology of LID. In the current review, we focus on therapeutic LID targets, mainly based on agents acting on dopaminergic, glutamatergic, serotoninergic, adrenergic, and cholinergic systems. Despite a large number of clinical trials, currently only amantadine and, to a lesser extent, clozapine are being used as effective strategies in the treatment of LID in clinical settings. Thus, in the second part of the article, we review the placebo-controlled trials on LID treatment in order to disentangle the changing scenario of drug development. Promising results include the extension of L-dopa action without inducing LID of the novel monoamine oxidase B- and glutamate-release inhibitor safinamide; however, this had no obvious effect on existing LID. Others, like the metabotropic glutamate-receptor antagonist AFQ056, showed promising results in some of the studies; however, confirmation is still lacking. Thus, to date, strategies of continuous dopaminergic stimulation seem the most promising to prevent or ameliorate LID. The success of future therapeutic strategies once moderate to severe LID occur will depend on the translation from preclinical experimental models into clinical practice in a bidirectional process.

Self-unawareness of levodopa induced dyskinesias in patients with Parkinson's disease

The study analyzes the presence of dyskinesias-reduced-self-awareness in forty-eight patients suffering from Parkinson's disease (PD). As the association with executive dysfunction is a matter of debate and we hypothesize it plays an important role in dyskinesias self-unawareness, we analyzed the role of dopaminergic treatment on the medial-prefrontal-ventral-striatal circuitry using a neurocognitive approach. Special attention was given to metacognitive abilities related to action-monitoring that represent a novel explanation of the phenomenon. PD patients were assessed using different rating scales that we devised to measure movement awareness disorders. In order to ascertain whether each variable measured at a cognitive-clinical level contributes to predicting the scores of the movement-disorder-awareness-scales, we conducted multiple logistic regression models using the latter as binary dependent variables. We used the Wisconsin Card Sorting Test-metacognitive-version to assess the executive functions of the prefrontal-ventral-striatal circuitry. Data showed that a reduction of self-awareness using the Dyskinesia rating scale was associated with global monitoring (p=.04), monitoring resolution (p=.04) and control sensitivity (p=.04). Patients failed to perceive their performance, distinguish between correct and incorrect sorts, be confident in their choice and consequently decide to gamble during the task. We did not find any association with executive functions using the hypo-bradykinesia rating scale. Our findings indicate that when the comparator mechanism for monitoring attentive performance is compromised at a prefrontal striatal level, patients lose the ability to recognize their motor disturbances that do not achieve conscious awareness.