Impulse control disorders and levodopa-induced dyskinesias in Parkinson's disease: an update

Cinnamoyl-N-Acylhydrazone-Donepezil Hybrids: Synthesis and Evaluation of Novel Multifunctional Ligands Against Neurodegenerative Diseases

A new series of ten multifunctional Cinnamoyl-N-acylhydrazone-donepezil hybrids was synthesized and evaluated as multifunctional ligands against neurodegenerative diseases. The molecular hybridization approach was based on the combination of 1-benzyl-4-piperidine fragment from the anti-Alzheimer AChE inhibitor donepezil (1) and the cinnamoyl subunit from curcumin (2), a natural product with remarkable antioxidant, neuroprotective and anti-inflammatory properties, using a N-acylhydrazone fragment as a spacer subunit. Compounds 4a and 4d showed moderate inhibitory activity towards AChE with IC₅₀ values of 13.04 and 9.1 µM, respectively. In addition, compound 4a and 4d showed a similar predicted binding mode to that observed for donepezil in the molecular docking studies. On the other hand, compounds 4a and 4c exhibited significant radical scavenging activity, showing the best effects on the DPPH test and also exhibited a significant protective neuronal cell viability exposed to t-BuOOH and against 6-OHDA insult to prevent the oxidative stress in Parkinson's disease. Similarly, compound 4c was capable to prevent the ROS formation, with indirect antioxidant activity increasing intracellular GSH levels and the ability to counteract the neurotoxicity induced by both OAβ1-42 and 3-NP. In addition, ADMET in silico prediction indicated that both compounds 4a and 4c did not show relevant toxic effects. Due to their above-mentioned biological properties, compounds 4a and 4c could be explored as lead compounds in search of more effective and low toxic small molecules with multiple neuroprotective effects for neurodegenerative diseases.

Longitudinal association between dopamine agonists and weight in Parkinson's disease

OBJECTIVE

To examine the longitudinal relation of dopamine agonists (DA) use with body mass index (BMI) change and weight gain in Parkinson's disease (PD).

METHODS

In a cohort of 356 patients with PD annually followed up to 6 years, BMI, antiparkinsonian drugs use, and impulse control disorders (ICDs) were assessed at each visit. DA dose trajectories were estimated using latent class mixed models. The association of DA use with BMI change and weight gain was examined using latent-process mixed models and time-dependent Cox models respectively, while adjusting for disease severity and levodopa (LD) use.

RESULTS

In the mixed model, BMI (kg/m²) increased over the follow-up in DA users (beta_DA×time = 0.13, 95% CI = 0.02, 0.24) compared to non-users, while it decreased in LD users (beta_LD×time = -0.26, 95% CI = -0.38, -0.13). We identified three trajectories of average daily DA dose over the follow-up. Patients in the high trajectory gained more weight than patients who never used DA (P = .001) and in the low (P = .02) or moderate (P = .04) trajectories. The incidence of weight gain of ≥6 kg was 2.10-fold (95% CI = 1.03, 4.28) higher in DA users compared to non-users, while LD users were less likely to gain weight (HR = 0.60, 95% CI = 0.33, 1.11). Associations decreased in analyses adjusted for compulsive eating or ICDs.

CONCLUSION

Weight increased in DA users over 6 years, and DA use was associated with increased incidence of weight gain. These associations were partially explained by compulsive eating. Alternatively, weight decreased in LD users. These findings warrant careful monitoring of compulsive eating and weight in PD patients.

Suicide in Parkinson's Disease: A Systematic Review

Psychiatric disorders and suicide have been reported in patients suffering from Parkinson's disease. The aims of the present paper were to determine whether patients with Parkinson's disease have an increased rate of suicide and to identify the clinical features possibly associated with suicide risk in Parkinson's disease. We also reviewed the studies on suicide risk in Parkinson's disease in patients after deep brain stimulation. We performed a Medline, Excerpta Medica, PsycLit, PsycInfo and Index Medicus search to identify all articles published on this topic from 1970 to 2019. The following search terms were used: suicide OR suicide attempt OR suicidal ideation OR suicide risk AND Parkinson's disease AND Parkinson's disease and deep brain stimulation. The studies we identified that assessed the suicide rate associated with Parkinson's disease yielded contrasting results, although an increase in suicidal ideation did emerge. The studies on the effect of deep brain stimulation on suicide risk in Parkinson's disease also reported mixed findings. Psychiatric symptoms, including depression, appear to be associated with suicide risk in patients with Parkinson's disease undergoing medical and after surgical treatment. The studies reviewed suggest that suicidal ideation is increased in Parkinson's disease. Further longitudinal studies designed to assess suicidality in this condition are still needed.

[Problematic gambling and criminal responsibility]

OBJECTIVES

In total, 14% to 30 % of individuals with gambling disorder engage in illegal acts to finance such behavior. This clinical situation could be explained by higher gambling severity, associated substance use disorder, antisocial personality disorder and economic factors (debts, financial problems). The present work focuses, more broadly, on criminal responsibility of problematic gamblers.

METHODS

We will discuss this question through different typical situations that medical experts of criminal responsibility may have to face. We will address each of the following cases: 1) isolated problematic gambling; 2) problematic gambling associated with antisocial personality disorder; 3) problematic gambling associated with a manic episode; 4) problematic gambling associated with substance use disorders; and 5) problematic gambling associated wiht dopamine agonist treatment.

RESULTS

Isolated problematic gambling, (not associated with any psychiatric or addictive disorder): it seems consensual that individuals committing infractions in this case are criminally responsible. However, impeded ability to action control and possible sentence attenuation could be discussed in case of severe gambling disorder. Problematic gambling associated with antisocial personality disorder: if the penal offence reports solely to personality disorder, criminal responsibility would be attributed. However, if illegal or violent acting is directly linked to co-cocurrent delusional symptoms, it could be a cause of criminal non-responsibility. Problematic gambling associated with manic episode: manic episode related offence could lead to negation of criminal responsibility, while a hypomanic episode may provide grounds for sentence reduction. Problematic gambling associated with substance use disorders: in France, addiction is not considered to remove nor to impede a person's ability to understand or control his actions and is excluded from criminal non-responsibility causes. However, substance induced delusional or confusional episodes could abolish a subject's discernment or his ability to control his actions yielding to penal non-responsibility. Problematic gambling associated with dopamine agonist treatment: Criminal responsibility for dopamine agonist induced gambling related illegal acts is still controversial. Nevertheless, people committing an infraction linked to associated dementia or dopamine agonist induced mania should be considered as criminally non-responsible.

CONCLUSIONS

Some clinical dimensions such as craving intensity, compulsivity, disorder's severity, volitional control might be forensic targets to assess criminal responsibility.

Clinical Approach to Personality Change Due to Another Medical Condition

BACKGROUND

Medical personality change (MPC) is a codable diagnosis (i.e., F07.0) that deserves consideration when a patient is inexplicably no longer "acting like him/herself." Its presentation ranges from subtle to severe and is often characterized by bafflingly poor judgment and impairment in several aspects of a person's life. Despite the global impact that MPC can have on a patient's functioning, occupation, and relationships, this condition receives far less clinical consideration than better known syndromes such as depression or anxiety and is often likely incorrectly formulated as such.

OBJECTIVE/METHODS

This article provides a clinically focused review of MPC. We review its clinical assessment followed by a review of its subtypes, which we have categorized to reflect the behavioral correlates of known frontotemporal-subcortical circuits. These include the apathetic type (ventromedial prefrontal cortex), the labile and disinhibited types (orbitofrontal cortex), and the aggressive and paranoid types (medial temporal lobes).

RESULTS

For each of these 3 categories, we describe the clinical presentation and review management strategies. For each category, we focus on 3 common causes for MPC-traumatic brain injury, Huntington disease, and brain tumors-which we have selected because clinical features of MPC due to these conditions generalize to many other etiologies of MPC.

CONCLUSIONS

MPC warrants clinical attention for the range of dysfunction and distress it can cause. It also deserves further scientific study to better characterize its phenotypes, to tailor instruments for its clinical assessment, and to identify effective treatments.

Ropinirole, a dopamine agonist with high D3 affinity, reduces proactive inhibition: A double-blind, placebo-controlled study in healthy adults

Response inhibition describes the cognitive processes mediating the suppression of unwanted actions. A network involving the basal ganglia mediates two forms of response inhibition: reactive and proactive inhibition. Reactive inhibition serves to abruptly stop motor activity, whereas proactive inhibition is goal-orientated and results in slowing of motor activity in anticipation of stopping. Due to its impairment in several psychiatric disorders, the neurochemistry of response inhibition has become of recent interest. Dopamine has been posed as a candidate mediator of response inhibition due to its role in functioning of the basal ganglia and the observation that patients with Parkinson's disease on dopamine agonists develop impulse control disorders. Although the effects of dopamine on reactive inhibition have been studied, substantial literature on the role of dopamine on proactive inhibition is lacking. To fill this gap, we devised a double-blind, placebo-controlled study of 1 mg ropinirole (a dopamine agonist) on response inhibition in healthy volunteers. We found that whilst reactive inhibition was unchanged, proactive inhibition was impaired when participants were on ropinirole relative to when on placebo. To investigate how ropinirole mediated this effect on proactive inhibition, we used hierarchical drift-diffusion modelling. We found that ropinirole impaired the ability to raise the decision threshold when proactive inhibition was called upon. Our results provide novel evidence that an acute dose of ropinirole selectively reduces proactive inhibition in healthy participants. These results may help explain how ropinirole induces impulse control disorders in susceptible patients with Parkinson's disease.

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Proactive but not reactive inhibition is impaired under the influence of ropinirole vs placebo.

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Ropinirole impairs the ability to raise the decision threshold when proactive inhibition is called upon.

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We provide novel evidence that an acute dose of ropinirole selectively reduces proactive inhibition in healthy participants.

An update on the use of non-ergot dopamine agonists for the treatment of Parkinson's disease

INTRODUCTION

Long-term treatment of Parkinson's disease (PD) with levodopa is hampered by motor complications related to the inability of residual nigrostriatal neurons to convert levodopa to dopamine (DA) and use it appropriately. This generated a tendency to postpone levodopa, favoring the initial use of DA agonists, which directly stimulate striatal dopaminergic receptors. Use of DA agonists, however, is associated with multiple side effects and their efficacy is limited by suboptimal bioavailability.

AREAS COVERED

This paper reviewed the latest preclinical and clinical findings on the efficacy and adverse effects of non-ergot DA agonists, discussing the present and future of this class of compounds in PD therapy.

EXPERT OPINION

The latest findings confirm the effectiveness of DA agonists as initial treatment or adjunctive therapy to levodopa in advanced PD, but a more conservative approach to their use is emerging, due to the complexity and repercussions of their side effects. As various factors may increase the individual risk to side effects, assessing such risk and calibrating the use of DA agonists accordingly may become extremely important in the clinical management of PD, as well as the availability of new DA agonists with better profiles of safety and efficacy.

Dopamine agonist treatment increases sensitivity to gamble outcomes in the hippocampus in de novo Parkinson's disease

BACKGROUND

Parkinson's disease is associated with severe nigro-striatal dopamine depletion, leading to motor dysfunction and altered reward processing. We previously showed that drug-naïve patients with Parkinson's disease had a consistent attenuation of reward signalling in the mesolimbic and mesocortical system. Here, we address the neurobiological effects of dopaminergic therapy on reward sensitivity in the mesolimbic circuitry, and how this may contribute to neuropsychiatric symptoms.

OBJECTIVES

We tested the hypothesis that (1) dopaminergic treatment would restore the attenuated, mesolimbic and mesocortical responses to reward; and (2) restoration of reward responsivity by dopaminergic treatment would predict motor performance and the emergence of impulse control symptoms.

METHODS

In 11 drug-naïve Parkinson patients, we prospectively assessed treatment-induced changes in reward processing before, and eight weeks after initiation of monotherapy with dopamine agonists. They were compared to 10 non-medicated healthy controls who were also measured longitudinally. We used whole-brain functional magnetic resonance imaging at 3 Tesla to assess the reward responsivity of the brain to monetary gains and losses, while participants performed a simple consequential gambling task.

RESULTS

In patients, dopaminergic treatment improved clinical motor symptoms without significantly changing task performance. Dopamine agonist therapy induced a stronger reward responsivity in the right hippocampus with higher doses being less effective. None of the patients developed impulse control disorders in the follow-up period of four years.

CONCLUSIONS

Short-term treatment with first-ever dopaminergic medication partially restores deficient reward-related processing in the hippocampus in de novo Parkinson's disease.

The effect on deep brain stimulation of subthalamic nucleus and dopaminergic treatment in Parkinson disease

Impulsivity is a frequent non-motor symptom in Parkinson disease (PD). It comprises psycho-behavioral alterations that negatively impact quality of life. Dopaminergic treatments underpin many impulsive controls disorders however, side effects, such as increased impulsivity, are described also after neurosurgical procedure of deep brain stimulation (DBS). We investigated the effect of deep brain stimulation on psycho-behavioral alterations and quality of life (QoL) in PD patients, analyzing, also, the role of dopaminergic therapies.Twenty idiopathic PD patients with and 20 idiopathic PD patients without DBS were included in the study. All patient underwent to neuropsychological assessment for a screening of executive functions, impulsivity, anxiety and depressive symptoms and QoL.Differences were found between DBS and no DBS groups and in term of dopaminergic therapies. The comparison between 2 groups showed a greater motor and attentional impulsivity in DBS patients. Moreover, this impulsivity worse QoL and interpersonal relationships. The combination of Levodopa and dopamine agonists exerted a great impact on impulsivity behavior.The emergence of postoperative impulsivity seems to be a neurostimulator phenomenon related to the computational role of the subthalamic nucleus in modulation of behavior.

Lack of correlation between dyskinesia and pallidal serotonin transporter expression-induced by L-Dopa and Pramipexole in hemiparkinsonian rats

The role of pallidal serotonergic terminals in the development of L-Dopa-induced dyskinesias (LIDs) in Parkinson's disease (PD) has been recently highlighted correlating pallidal serotonin transporter (SERT) expression levels with dyskinesias severity. However, the role of external globus pallidus (GPe, GP in rodents) serotonergic function in LIDs is still controversial since several studies have shown no differences in GPe serotonin (SER) and SERT levels between dyskinetic and non-dyskinetic PD patients. In addition, the increase in pallidal SERT/dopamine transporter (DAT) binding ratio obtained in positron emission tomography studies has been shown similar in both subtypes of PD patients. Based on these controversial results, further studies are required to clarify the possible involvement of GPe serotonergic activity in LIDs expression. We investigated the pallidal SER and SERT expression changes and the abnormal involuntary movements (AIMs) induced by L-Dopa or the D3/D2 dopamine (DA) agonist, Pramipexole, in partial unilateral 6-hydroxydopamine (6-OHDA)-lesioned rats. L-Dopa treatment led to an increment of axial (p < 0.01), limb (p < 0.01), and orolingual (p < 0.01) AIMs. However, Pramipexole treatment did not induce AIMs. The number of GP SERT-positive axon varicosities was increased in L-Dopa (p < 0.05) and Pramipexole (p < 0.01) treated rats. No differences were observed in the number of GP SERT-positive varicosities between L-Dopa and Pramipexole treatments. Our results indicate a lack of correlation between GP SERT expression levels and the development of AIMs suggesting that pallidal serotonergic fibers are not responsible for LIDs. The possible involvement of the SER system in dyskinesia may include other mechanisms.

Dopamine and reward hypersensitivity in Parkinson's disease with impulse control disorder

Impulse control disorders in Parkinson's disease are common neuropsychiatric complications associated with dopamine replacement therapy. Some patients treated with dopamine agonists develop pathological behaviours, such as gambling, compulsive eating, shopping, or disinhibited sexual behaviours, which can have a severe impact on their lives and that of their families. In this study we investigated whether hypersensitivity to reward might contribute to these pathological behaviours and how this is influenced by dopaminergic medication. We asked participants to shift their gaze to a visual target as quickly as possible, in order to obtain reward. Critically, the reward incentive on offer varied over trials. Motivational effects were indexed by pupillometry and saccadic velocity, and patients were tested ON and OFF dopaminergic medication, allowing us to measure the effect of dopaminergic medication changes on reward sensitivity. Twenty-three Parkinson's disease patients with a history of impulse control disorders were compared to 26 patients without such behaviours, and 31 elderly healthy controls. Intriguingly, behavioural apathy was reported alongside impulsivity in the majority of patients with impulse control disorders. Individuals with impulse control disorders also exhibited heightened sensitivity to exogenous monetary rewards cues both ON and OFF (overnight withdrawal) dopamine medication, as indexed by pupillary dilation in anticipation of reward. Being OFF dopaminergic medication overnight did not modulate pupillary reward sensitivity in impulse control disorder patients, whereas in control patients reward sensitivity was significantly reduced when OFF dopamine. These effects were independent of cognitive impairment or total levodopa equivalent dose. Although dopamine agonist dose did modulate pupillary responses to reward, the pattern of results was replicated even when patients with impulse control disorders on dopamine agonists were excluded from the analysis. The findings suggest that hypersensitivity to rewards might be a contributing factor to the development of impulse control disorders in Parkinson's disease. However, there was no difference in reward sensitivity between patient groups when ON dopamine medication, suggesting that impulse control disorders may not emerge simply because of a direct effect of dopaminergic drug level on reward sensitivity. The pupillary reward sensitivity measure described here provides a means to differentiate, using a physiological measure, Parkinson's disease patients with impulse control disorder from those who do not experience such symptoms. Moreover, follow-up of control patients indicated that increased pupillary modulation by reward can be predictive of the risk of future emergence of impulse control disorders and may thereby provide the potential for early identification of patients who are more likely to develop these symptoms.

Motor impulsivity and delay intolerance are elicited in a dose-dependent manner with a dopaminergic agonist in parkinsonian rats

RATIONALE

Impulse control disorders (ICD) and other impulsive-compulsive behaviours are frequently found in Parkinson's disease (PD) patients treated with dopaminergic agonists. To date, there are no available animal models to investigate their pathophysiology and determine whether they can be elicited by varying doses of dopaminergic drugs. In addition, there is some controversy regarding the predispositional pattern of striatal dopaminergic depletion.

OBJECTIVES

To study the effect of two doses of pramipexole (PPX) on motor impulsivity, delay intolerance and compulsive-like behaviour.

METHODS

Male rats with mild dopaminergic denervation in the dorsolateral striatum (bilateral injections of 6-hydroxidopamine (6-OHDA)) treated with two doses of PPX (0.25 mg/kg and 3 mg/kg) and tested in the variable delay-to-signal paradigm.

RESULTS

Partial (50%) dopaminergic depletion did not induce significant changes in motor impulsivity or delay intolerance. However, 0.25 mg/kg of PPX increased motor impulsivity, while 3 mg/kg of PPX increased both motor impulsivity and delay intolerance. These effects were independent of the drug's antiparkinsonian effects. Importantly, impulsivity scores before and after dopaminergic lesion were positively associated with the impulsivity observed after administering 3 mg/kg of PPX. No compulsive-like behaviour was induced by PPX administration.

CONCLUSIONS

We described a rat model, with a moderate dorsolateral dopaminergic lesion resembling that suffered by patients with early PD, that develops different types of impulsivity in a dose-dependent manner dissociated from motor benefits when treated with PPX. This model recapitulates key features of abnormal impulsivity in PD and may be useful for deepening our understanding of the pathophysiology of ICD.

The role of dopaminergic and serotonergic transmission in the processing of primary and monetary reward

Natural rewards such as erotic stimuli activate common neural pathways with monetary rewards. In human studies, the manipulation of dopamine and serotonin play an important role in the processing of monetary rewards with less understood on its role on erotic stimuli. In this study, we investigate the neuromodulatory effects of dopaminergic and serotonergic transmission in the processing of erotic versus monetary visual stimuli. We scanned one hundred and two (N = 102) healthy volunteers using functional magnetic resonance imaging while performing a modified version of the well-validated monetary incentive delay task consisting of erotic, monetary and neutral visual stimuli. We show a role for enhanced central dopamine and lowered central serotonin levels in increasing activity in the right caudate and left anterior insula during anticipation of erotic relative to monetary rewards in healthy controls. We further show differential activation in the anticipation of natural versus monetary rewards with the former associated with ventromesial and dorsomesial activity and the latter with dorsal cingulate, striatal and anterior insular activity. These findings are consistent with preclinical and clinical findings of a role for dopaminergic and serotonergic mechanisms in the processing of natural rewards. Our study provides further insights into the neural substrates underlying reward processing for natural primary erotic rewards and yields importance for the neurochemical systems of addictive disorders including gambling disorder.

From apathy to addiction: Insights from neurology and psychiatry

The tendency to engage in addictive behaviors has long been tied to the actions of the dopamine system. Early theories were based on the fact that all addictive drugs and behaviors (such as gambling) increase dopamine levels in the striatum, and the evidence that dopamine signaled reward or reward prediction error. However, with a changing emphasis of addiction away from purely pharmacological models that emphasize tolerance and withdrawal, towards one of behavioral dyscontrol, is there still a place for abnormal dopamine signaling in addiction? Here we recast the dopamine theory of addiction based on the idea that tonic dopamine may index a continuous phenotype that goes from apathy to impulsivity and compulsivity. Higher tonic dopamine signaling would make individuals vulnerable to drug reinforcement and cue-induced craving. We relate this to computational models of dopamine signaling, and review clinical and neuroimaging evidence from Parkinson's Disease, schizophrenia and bipolar disorder in support of this model.

Spectrum of impulse control behaviours in Parkinson's disease: pathophysiology and management

Impulse control behaviours (ICBs) are a range of behaviours linked by their reward-based, repetitive natures. They can be precipitated in Parkinson's disease (PD) by dopamine replacement therapy, often with detrimental consequences for patients and caregivers. While now a well-recognised non-motor feature of treated PD, much remains unknown about the influence of risk factors, pathophysiological mechanisms, vulnerability factors for specific types of behaviour and the optimal management strategies. Imaging studies have identified structural and functional changes in striatal and prefrontal brain regions, among others. Gene association studies indicate a role for genetic predisposition to PD-ICB. Clinical observational studies have identified potential modifiable and non-modifiable risk factors. Psychological studies shed light on the neurocognitive domains implicated in PD-ICBs and identify psychosocial determinants that may perpetuate the cycle of impulsive and harm-avoidance behaviours. Based on these results, a range of pharmacological and non-pharmacological management strategies have been trialled in PD-ICBs with varying success. The purpose of this review is to update clinicians on the evidence around the pathophysiology of PD-ICB. We aim to translate our findings into an interpretable biopsychosocial model that can be applied to the clinical assessment and management of individual cases of PD-ICB.

Neuropsychiatric Traits Associated with Refractory Impulse Control Disorder in Parkinson's Disease

INTRODUCTION

Impulse control disorder (ICD) in Parkinson's disease (PD) is a critical nonmotor symptom with personality or neuropsychiatric traits contributing to ICD.

OBJECTIVE

This study aimed to identify predictive traits for persistent or paradoxical aggravation of ICD after dopamine agonist substitution therapy for ICD in PD.

METHODS

We conducted a case-control study using a database of a multicenter intervention trial for ICD in PD. The poor-outcome group was defined by showing paradoxical increases in ICD behaviors after the substitution of dopamine agonists with levodopa. We analyzed the pre-intervention personality traits associated with the poor outcome and also evaluated the risk traits for refractory ICD using a receiver-operating characteristic (ROC) curve analysis.

RESULTS

The poor-outcome group showed higher levels of anger expression (p =0.007) and obsessive-compulsive traits (p =0.009) compared with the good-outcome group at the pre-intervention state. In the ROC curve analysis, the Obsessive-Compulsive Inventory showed the highest area under the curve with 80.0% sensitivity and 74.3% specificity in discriminating against the poor-outcome group.

CONCLUSIONS

Our results suggest that assessment of obsessive compulsiveness may be useful for predicting the refractoriness of ICD behaviors in planning an interventional treatment for ICD in PD.

Naltrexone Use in Treating Hypersexuality Induced by Dopamine Replacement Therapy: Impact of OPRM1 A/G Polymorphism on Its Effectiveness

Hypersexuality is a well-known adverse side effect of dopamine replacement therapy (DRT), and anti-craving drugs could be an effective therapeutic option. Our aim was to update the knowledge on this issue, particularly on the influence of an Opioid Receptor Mu 1 (OPRM1) genetic polymorphism. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We also analyzed a case of iatrogenic hypersexuality that occurred in a patient treated with DRT. An analysis of the OPRM1 gene was performed on said patient. Our search identified 597 publications, of which only 7 were included in the final data synthesis. All seven publications involved naltrexone use. Five of them were case reports. None of the publications mentioned DRT side effects, nor did they report genetic data. Regarding our case report, the introduction of naltrexone corresponded with the resolution of the patient’s hypersexuality. Moreover, the patient carried the A/G genotype, which has been reported to be associated with a stronger response to naltrexone for patients with an alcohol use disorder. Although studies are inconclusive so far, naltrexone could be an interesting therapeutic option for resistant hypersexuality due to DRT. Carrying the A/G genotype could help explain a good response to treatment.

Non-motor symptom burden is strongly correlated to motor complications in patients with Parkinson's disease

BACKGROUND AND PURPOSE

The objective of this study was to analyze the relationship between motor complications and non-motor symptom (NMS) burden in a population of patients with Parkinson's disease (PD) and also in a subgroup of patients with early PD.

METHODS

Patients with PD from the COPPADIS cohort were included in this cross-sectional study. NMS burden was defined according to the Non-Motor Symptoms Scale (NMSS) total score. Unified Parkinson's Disease Rating Scale (UPDRS) part IV was used to establish motor complication types and their severity. Patients with ≤5 years of symptoms from onset were included as patients with early PD.

RESULTS

Of 690 patients with PD (62.6 ± 8.9 years old, 60.1% males), 33.9% and 18.1% presented motor fluctuations and dyskinesia, respectively. The NMS total score was higher in patients with motor fluctuations (59.2 ± 43.1 vs. 38.3 ± 33.1; P < 0.0001) and dyskinesia (63.5 ± 40.7 vs. 41.4 ± 36.3; P < 0.0001). In a multiple linear regression model and after adjustment for age, sex, disease duration, Hoehn & Yahr stage, UPDRS-III score and levodopa equivalent daily dose, UPDRS-IV score was significantly related to a higher NMSS total score (β = 0.27; 95% confidence intervals, 2.81-5.61; P < 0.0001), as it was in a logistic regression model on dichotomous NMSS total score (≤40, mild or moderate vs. >40, severe or very severe) (odds ratio, 1.31; 95% confidence intervals, 1.17-1.47; P < 0.0001). In the subgroup of patients with early PD (n = 396; mean disease duration 2.7 ± 1.5 years), motor fluctuations were frequent (18.1%) and similar results were obtained.

CONCLUSIONS

Motor complications were frequent and were associated with a greater NMS burden in patients with PD even during the first 5 years of disease duration.

Update on the Management of Parkinson's Disease for General Neurologists

Management of Parkinson's disease (PD) is complicated due to its progressive nature, the individual patient heterogeneity, and the wide range of signs, symptoms, and daily activities that are increasingly affected over its course. The last 10–15 years have seen great progress in the identification, evaluation, and management of PD, particularly in the advanced stages. Highly specialized information can be found in the scientific literature, but updates do not always reach general neurologists in a practical and useful way, potentially creating gaps in knowledge of PD between them and neurologists subspecialized in movement disorders, resulting in several unmet patient needs. However, general neurologists remain instrumental in diagnosis and routine management of PD. This review provides updated practical information to identify problems and resolve common issues, particularly when the advanced stage is suspected. Some tips are provided for efficient communication with the members of a healthcare team specialized in movement disorders, in order to find support at any stage of the disease in a given patient, and especially for a well-timed decision on referral.

Initiation of pharmacological therapy in Parkinson's disease: when, why, and how

Debate is ongoing regarding when, why, and how to initiate pharmacotherapy for Parkinson's disease. Early initiation of dopaminergic therapies does not convey disease-modifying effects but does reduce disability. Concerns about the development of motor complications arising from the early initiation of levodopa, which led to misconceived levodopa-sparing strategies, have been largely mitigated by the outcomes of the PD MED and Levodopa in Early Parkinson's Disease (LEAP) studies. The LEAP study also showed the potential for early improvement in quality of life, even when disability is negligible. Until more effective methods of providing stable dopamine concentrations are developed, current evidence supports the use of levodopa as initial symptomatic treatment in most patients with Parkinson's disease, starting with low doses and titrating to therapeutic threshold. Monoamine oxidase-B inhibitors and dopamine agonists can be reserved as potential adjunct treatments later in the disease course. Future research will need to establish effective disease-modifying treatments, address whether patients' quality of life is substantially improved with early initiation of treatment rather than a wait and watch strategy, and establish whether new levodopa formulations will delay onset of dyskinesia.

Comparison of long-term use of prolonged-release ropinirole and immediate-release dopamine agonists in an observational study in patients with Parkinson's disease

Purpose

To estimate the risk of dyskinesia and impulse control disorders (ICDs) in patients with Parkinson's disease (PD) prescribed ropinirole prolonged‐release (R‐PR) compared to those prescribed immediate‐release dopamine agonists (IR‐DA) as monotherapy.

Methods

PD patients initiating R‐PR or IR‐DA as monotherapy between 2008 and 2013 were identified on the Clinical Practice Research Datalink. The cohorts were propensity score matched on a 1:1 basis. The incidence of dyskinesia and ICD in each treatment cohort and the incidence rate ratios were calculated. Adherence to medication and time to levodopa initiation were also evaluated.

Results

We identified 341 patients in each treatment cohort after propensity score matching. The baseline characteristics were generally comparable. Dyskinesia incidence in R‐PR and IR‐DA cohorts was 2.98 (95% CI: 0.74‐11.9) and 3.93 (95% CI: 0.98‐15.7) per 1000 person‐years, respectively (incidence rate ratio of R‐PR vs ID‐DA: 0.76, 95% CI: 0.11‐5.38). Less than five cases of ICD were identified and all occurred in the IR‐DA cohort. The patients in the R‐PR cohort remained on treatment for a significantly longer duration than those in the IR‐DA cohort (682 days vs 444 days; P < .0001) and had greater adherence to the medication. The median time to levodopa initiation was 417 days (IQR: 205‐736) in R‐PR vs 297 days (IQR: 111‐552) in IR‐DA cohort.

Conclusions

The number of dyskinesia and ICD events was lower than expected, resulting in an underpowered study. A significantly longer persistence and greater adherence to medication was observed in patients receiving R‐PR compared to IR‐DA.

Aromatic L-Amino Acid Decarboxylase Gene Therapy Enhances Levodopa Response in Parkinson's Disease

BACKGROUND

As Parkinson's disease progresses, levodopa treatment loses efficacy, partly through the loss of the endogenous dopamine-synthesizing enzyme L-amino acid decarboxylase (AADC). In the phase I PD-1101 study, putaminal administration of VY-AADC01, an investigational adeno-associated virus serotype-2 vector for delivery of the AADC gene in patients with advanced Parkinson's disease, was well tolerated, improved motor function, and reduced antiparkinsonian medication requirements.

OBJECTIVES

This substudy aimed to determine whether the timing and magnitude of motor response to intravenous levodopa changed in PD-1101 patients after VY-AADC01 administration.

METHODS

Participants received 2-hour threshold (0.6 mg/kg/h) and suprathreshold (1.2 mg/kg/h) levodopa infusions on each of 2 days, both before and approximately 6 months after VY-AADC01. Infusion order was randomized and double blinded. Unified Parkinson's Disease Rating Scale motor scores, finger-tapping speeds, and dyskinesia rating scores were assessed every 30 minutes for 1 hour before and ≥3 hours after start of levodopa infusion.

RESULTS

Of 15 PD-1101 patients, 13 participated in the substudy. Unified Parkinson's Disease Rating Scale motor score area under the curve responses to threshold and suprathreshold levodopa infusions increased by 168% and 67%, respectively, after VY-AADC01; finger-tapping speeds improved by 162% and 113%, and dyskinesia scores increased by 208% and 72%, respectively, after VY-AADC01. Adverse events (mild/moderate severity) were reported in 5 participants during levodopa infusions pre-VY-AADC01 and 2 participants post-VY-AADC01 administration.

CONCLUSIONS

VY-AADC01 improved motor responses to intravenous levodopa given under controlled conditions. These data and findings from the parent study support further clinical development of AADC gene therapy for people with Parkinson's disease. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

The ease and sureness of a decision: evidence accumulation of conflict and uncertainty

The likelihood of an outcome (uncertainty or sureness) and the similarity between choices (conflict or ease of a decision) are often critical to decision-making. We often ask ourselves: how likely are we to win or lose? And how different is this option's likelihood from the other? Uncertainty is a characteristic of the stimulus and conflict between stimuli, but these dissociable processes are often confounded. Here, applying a novel hierarchical drift diffusion approach, we study their interaction using a sequential learning task in healthy volunteers and pathological groups characterized by compulsive behaviours, by posing it as an evidence accumulation problem. The variables, Conflict (difficult or easy; difference between reward probabilities of the stimuli) and Uncertainty (low, medium or high; inverse U-shaped probability-uncertainty function) were then used to extract threshold ('a', amount of evidence accumulated before making a decision) and drift rate ('v', information processing speed) parameters. Critically, when a decision was both difficult (high conflict) and uncertain, relative to other conditions, healthy volunteers unexpectedly accumulated less evidence with lower decision thresholds and accuracy rates at chance levels. In contrast, patients with obsessive-compulsive disorder had slower processing speeds during these difficult uncertain decisions; yet, despite this more cautious approach, performed suboptimally with poorer accuracy relative to healthy volunteers below that of chance level. Thus, faced with a difficult uncertain decision, healthy controls are capable of rapid possibly random decisions, displaying almost a willingness to 'walk away', whereas those with obsessive compulsive disorder become more deliberative and cautious but despite appearing to learn the differential contingencies, still perform poorly. These observations might underlie disordered behaviours characterized by pathological uncertainty or doubt despite compulsive checking with impaired performance. In contrast, alcohol-dependent subjects show a different pattern relative to healthy controls with difficulties in adjusting their behavioural patterns with slower drift rates or processing speed despite decisions being easy or low conflict. We emphasize the multidimensional nature of compulsive behaviours and the utility of computational models in detecting subtle underlying processes relative to behavioural measures. These observations have implications for targeted behavioural interventions for specific cognitive impairments across psychiatric disorders.

Pharmacologic Treatment of Motor Symptoms Associated with Parkinson Disease

The cardinal motor features of Parkinson disease (PD) are driven by striatal dopamine deficiency. Pharmacologic dopamine substitution is the mainstay of drug treatment of PD. Levodopa is still the most efficacious drug to treat PD motor symptoms. MAO-B inhibitors and dopamine agonists are useful options. The main limitation of levodopa is the development of motor response fluctuations and drug-induced dyskinesias. Adjunct MAO-B and COMT inhibitors as well as dopamine agonists and continuous infusions of levodopa intestinal gel or subcutaneous apomorphine are efficacious in reducing motor fluctuations and amantadine is the only drug with established efficacy in reducing dyskinesias.

Neuropsychiatric Disorders in Parkinson's Disease: What Do We Know About the Role of Dopaminergic and Non-dopaminergic Systems?

Besides the hallmark motor symptoms (rest tremor, hypokinesia, rigidity, and postural instability), patients with Parkinson’s disease (PD) have non-motor symptoms, namely neuropsychiatric disorders. They are frequent and may influence the other symptoms of the disease. They have also a negative impact on the quality of life of patients and their caregivers. In this article, we will describe the clinical manifestations of the main PD-related behavioral disorders (depression, anxiety disorders, apathy, psychosis, and impulse control disorders). We will also provide an overview of the clinical and preclinical literature regarding the underlying mechanisms with a focus on the role of the dopaminergic and non-dopaminergic systems.

Emerging regenerative medicine and tissue engineering strategies for Parkinson's disease

Parkinson's disease (PD) is the second most common progressive neurodegenerative disease, affecting 1-2% of people over 65. The classic motor symptoms of PD result from selective degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in a loss of their long axonal projections to the striatum. Current treatment strategies such as dopamine replacement and deep brain stimulation (DBS) can only minimize the symptoms of nigrostriatal degeneration, not directly replace the lost pathway. Regenerative medicine-based solutions are being aggressively pursued with the goal of restoring dopamine levels in the striatum, with several emerging techniques attempting to reconstruct the entire nigrostriatal pathway-a key goal to recreate feedback pathways to ensure proper dopamine regulation. Although many pharmacological, genetic, and optogenetic treatments are being developed, this article focuses on the evolution of transplant therapies for the treatment of PD, including fetal grafts, cell-based implants, and more recent tissue-engineered constructs. Attention is given to cell/tissue sources, efficacy to date, and future challenges that must be overcome to enable robust translation into clinical use. Emerging regenerative medicine therapies are being developed using neurons derived from autologous stem cells, enabling the construction of patient-specific constructs tailored to their particular extent of degeneration. In the upcoming era of restorative neurosurgery, such constructs may directly replace SNpc neurons, restore axon-based dopaminergic inputs to the striatum, and ameliorate motor deficits. These solutions may provide a transformative and scalable solution to permanently replace lost neuroanatomy and improve the lives of millions of people afflicted by PD.

Disrupted salience network dynamics in Parkinson's disease patients with impulse control disorders

BACKGROUND

Dynamic functional network analysis may add relevant information about the temporal nature of the neurocognitive alterations in PD patients with impulse control disorders (PD-ICD). Our aim was to investigate changes in dynamic functional network connectivity (dFNC) in PD-ICD patients, and topological properties of such networks.

METHODS

Resting state fMRI was performed on 16 PD PD-ICD patients, 20 PD patients without ICD and 17 healthy controls, whose demographic, clinical and behavioral scores were assessed. We conducted a group spatial independent component analysis, sliding window and graph-theory analyses.

RESULTS

PD-ICD patients, in contrast to PD-noICD and HC subjects, were engaged across time in a brain configuration pattern characterized by a lack of between-network connections at the expense of strong within-network connections (State III) in temporal, frontoinsular and cingulate cortices, all key nodes of the salience network. Moreover, this increased maintenance of State III in PD-ICD patients was positively correlated with the severity of impulsivity and novelty seeking as measured by specific scales. While in State III, these patients also exhibited increased local efficiency in all the aforementioned areas.

CONCLUSIONS

Our findings show for the first time that PD-ICD patients have a dynamic functional engagement of local connectivity involving the limbic circuit, leading to the inefficient modulation in emotional processing and reward-related decision-making. These results provide new insights into the pathophysiology of ICD in PD patients and indicate that the dFC study of fMRI could be a useful biomarker to identify patients at risk to develop ICD.

The multifaceted nature of impulsivity in Parkinson's disease

This scientific commentary refers to ‘The structural connectivity of discrete networks underlies impulsivity and gambling in Parkinson’s disease’, by Mosley et al. (doi:10.1093/brain/awz327).

Using rodent models to understand interactions between gambling and substance use

Substance use is strongly associated with gambling, but the nature of this association can be difficult to determine. Rodents offer the opportunity to test causal models of these relationships through isolation of individual variables of interest. This review describes recent research in rodents showing: a) predisposing factors for both gambling-like behavior and substance use; b) exposure to drugs of abuse increasing gambling-like behavior; c) experience with gambling-like behavior increasing substance use; and d) links between gambling-like behavior and substance use in models of Parkinson's disease therapies. These findings reveal novel relationships between gambling and substance use, and highlight the utility of rodent models for future work in this area.

Dopamine and Gambling Disorder: Prospects for Personalized Treatment

Purpose of Review

To address variation in the severity of gambling disorder, this review evaluates the contribution of mesocorticolimbic dopamine neurons to potential behavioral endophenotypes, the influence of individual differences in the dopamine system on gambling and related behaviors, and the possible role for dopaminergic medications in the treatment of gambling disorder.

Recent Findings

Newer work has suggested that dopaminergic dysfunction can lead to increased reward anticipation and a greater sensitivity to uncertainty, which in turn may drive addictive gambling behaviors. In addition, increased impulsivity, a well-recognized risk factor for gambling disorder, has been linked to dopaminergic dysfunction. More recently, emerging evidence has suggested that dopaminergic medications can influence the discounting of delayed rewards.

Summary

Dopaminergic drugs that increase the salience of long-term over short-term goals may ameliorate symptoms of impulsive individuals with gambling disorder. More broadly, improved understanding of intermediate behavioral and other phenotypes with a defined neurobiological substrate may allow for personalized treatment of gambling disorder and other psychiatric conditions.

Functional inhibitory control dynamics in impulse control disorders in Parkinson's disease

BACKGROUND

Impulse control disorders related to alterations in the mesocorticolimbic dopamine network occur in Parkinson's disease (PD). Our objective was to investigate the functional neural substrates of reward processing and inhibitory control in these patients.

METHODS

Eighteen PD patients with impulse control disorders, 17 without this complication, and 18 healthy controls performed a version of the Iowa Gambling Task during functional magnetic resonance scanning under 3 conditions: positive, negative, and mixed feedback. Whole-brain contrasts, regions of interest, time courses, functional connectivity analyses, and brain-behavior associations were examined.

RESULTS

PD patients with impulse control disorders exhibited hyperactivation in subcortical and cortical regions typically associated with reward processing and inhibitory control compared with their PD and healthy control counterparts. Time-course analyses revealed that only PD patients with impulse control disorders exhibited stronger signal intensity during the initial versus final periods of the negative-feedback condition in bilateral insula, and right ventral striatum. Interestingly, hyperactivation of all the examined right-lateralized frontostriatal areas during negative feedback was positively associated with impulse control disorder severity. Importantly, positive associations between impulse control disorder severity and regional activations in the right insula and right inferior frontal gyrus, but not the right subthalamic nucleus, were mediated by functional connectivity with the right ventral striatum.

CONCLUSIONS

During a reward-based task, PD patients with impulse control disorders showed hyperactivation in a right-lateralized network of regions including the subthalamic nucleus that was strongly associated with impulse control disorder severity. In these patients, the right ventral striatum in particular played a critical role in modulating the functional dynamics of right-lateralized inhibitory-control frontal regions when facing penalties. © 2019 International Parkinson and Movement Disorder Society.

Knowing Your Beans in Parkinson's Disease: A Critical Assessment of Current Knowledge about Different Beans and Their Compounds in the Treatment of Parkinson's Disease and in Animal Models

This review contains a critical appraisal of current knowledge about the use of beans in both animal models and patients with Parkinson's disease (PD). The potential beneficial effects of beans in PD are increasingly being touted, not only in scientific journals but also by the lay media. While there is a long tradition in Ayurvedic medicine of prescribing extracts from Mucuna pruriens (MP), whose seeds contain 5% L-3,4-dihydroxyphenylalanin (L-DOPA), many other beans also contain L-DOPA (broad beans, common beans, and soybeans) or have other ingredients (coffee and cocoa) that may benefit PD patients. Indeed, bean-derived compounds can elicit neuroprotective effects in animal models of PD, while several studies in human PD patients have shown that motor performance can improve after ingestion of bean extracts. However, there are several arguments countering the view that beans serve as a natural therapy for PD: (i) the results from animal PD models are not necessarily directly applicable to humans; (ii) beans have many bioactive ingredients, some of which can be harmful in large doses; (iii) studies in human PD patients are scarce and only report on the effects of single doses or the administration of bean extract over short periods of time; and (iv) no data on long-term efficacy or side effects of bean therapy are available. Therefore, reservations about the use of beans as a "natural" therapy for PD seem to be justified.

l-DOPA and Its Receptor GPR143: Implications for Pathogenesis and Therapy in Parkinson's Disease

l-3,4-Dihydroxyphenylalanine (l-DOPA) is the most effective therapeutic agent for Parkinson's disease (PD). l-DOPA is traditionally believed to be an inert amino acid that exerts actions and effectiveness in PD through its conversion to dopamine. In contrast to this generally accepted idea, l-DOPA is proposed to be a neurotransmitter. Recently, GPR143 (OA1), the gene product of ocular albinism 1 was identified as a receptor candidate for l-DOPA. GPR143 is widely expressed in the central and peripheral nervous system. GPR143 immunoreactivity was colocalized with phosphorylated α-synuclein in Lewy bodies in PD brains. GPR143 may contribute to the therapeutic effectiveness of l-DOPA and might be related to pathogenesis of PD.

PKG Movement Recording System Use Shows Promise in Routine Clinical Care of Patients With Parkinson's Disease

Parkinson's disease (PD) is a debilitating, neurodegenerative disorder that affects nearly one million people. It's hallmark signs and symptoms include slow movements, rigidity, tremor, and unstable posture. Additionally, non-motor symptoms such as sleeplessness, depression, cognitive impairment, impulse control behaviors (ICB) have been reported. Today, treatment regimens to modify disease progression do not exist and as such, treatment is focused on symptom relief. Additionally, physicians are challenged to base their diagnoses and treatment plans on unreliable self-reported symptoms, even when used in conjunction to validated assessments such as the Unified Parkinson's Disease Rating Scale (UPDRS) and clinical exams. Wearable technology may provide clinicians objective measures of motor problems to supplement current subjective methods. Global Kinetics Corporation (GKC) has developed a watch-device called the Personal KinetiGraph (PKG) that records movements and provides patients medication dosing reminders. A separate clinician-use report supplies longitudinal motor and event data. The PKG was FDA-cleared in September 2016. We studied 63 PD patients during 85 routine care visits in 2 US academic institutions, evaluating the clinical utility of the PKG. Patients wore a PKG for 6 continuous days before their visit. Next, PKG data was uploaded to produce a report. In clinic, physicians discussed PD symptoms with patients and conducted a motor examination prior to reviewing the PKG report and comparing it to their initial assessments. Lastly, patient, caregiver and physician satisfaction surveys were conducted by each user. Across all visits when patients did not report bradykinesia or dyskinesia, the PKG reported these symptoms (50 and 33% of the time, respectively). The PKG provided insights for treatment plans in 50 (79%) patients across 71 (84%) visits. Physicians found improved patient dialogue in 50 (59%) visits, improved ability to assess treatment impact in 32 (38%) visits, and improved motor assessment in 28 (33%) visits. Patients stated in 82% of responses that they agreed or strongly agreed in PKG training, usability, performance, and satisfaction. In 39% of responses, they also reported a very valuable impact on their care. PKG use in 63 PD patients within our clinical practice showed clinically relevant utility in many areas.

Resting state oscillations suggest a motor component of Parkinson's Impulse Control Disorders

OBJECTIVES

Impulse control disorders (ICDs) in Parkinson's disease (PD) have been associated with cognitive impulsivity and dopaminergic dysfunction and treatment. The present study tests the neglected hypothesis that the neurofunctional networks involved in motor impulsivity might also be dysfunctional in PD-ICDs.

METHODS

We performed blind spectral analyses of resting state electroencephalographic (EEG) data in PD patients with and without ICDs to probe the functional integrity of all cortical networks. Analyses were performed directly at the source level after blind source separation. Discrete differences between groups were tested by comparing patients with and without ICDs. Gradual dysfunctions were assessed by means of correlations between power changes and clinical scores reflecting ICD severity (QUIP score).

RESULTS

Spectral signatures of ICDs were found in the medial prefrontal cortex, the dorsal anterior cingulate and the supplementary motor area, in the beta and gamma bands. Beta power changes in the supplementary motor area were found to predict ICDs severity.

CONCLUSION

ICDs are associated with abnormal activity within frequency bands and cortical circuits supporting the control of motor response inhibition.

SIGNIFICANCE

These results bring to the forefront the need to consider, in addition to the classical interpretation based on aberrant mesocorticolimbic reward processing, the issue of motor impulsivity in PD-ICDs and its potential implications for PD therapy.

Wait and you shall see: sexual delay discounting in hypersexual Parkinson's disease

Patients with Parkinson's disease may develop impulse control disorders under dopaminergic treatments. Impulse control disorders include a wide spectrum of behaviours, such as hypersexuality, pathological gambling or compulsive shopping. Yet, the neural systems engaged in specific impulse control disorders remain poorly characterized. Here, using model-based functional MRI, we aimed to determine the brain systems involved during delay-discounting of erotic rewards in hypersexual patients with Parkinson's disease (PD+HS), patients with Parkinson's disease without hypersexuality (PD - HS) and controls. Patients with Parkinson's disease were evaluated ON and OFF levodopa (counterbalanced). Participants had to decide between two options: (i) wait for 1.5 s to briefly view an erotic image; or (ii) wait longer to see the erotic image for a longer period of time. At the time of decision-making, we investigated which brain regions were engaged with the subjective valuation of the delayed erotic reward. At the time of the rewarded outcome, we searched for the brain regions responding more robustly after waiting longer to view the erotic image. PD+HS patients showed reduced discounting of erotic delayed rewards, compared to both patients with Parkinson's disease and controls, suggesting that they accepted waiting longer to view erotic images for a longer period of time. Thus, when using erotic stimuli that motivate PD+HS, these patients were less impulsive for the immediate reward. At the brain system level, this effect was paralleled by the fact that PD+HS, as compared to controls and PD - HS, showed a negative correlation between subjective value of the delayed reward and activity of medial prefrontal cortex and ventral striatum. Consistent with the incentive salience hypothesis combining learned cue-reward associations with current relevant physiological state, dopaminergic treatment in PD+HS boosted excessive 'wanting' of rewards and heightened activity in the anterior medial prefrontal cortex and the posterior cingulate cortex, as reflected by higher correlation with subjective value of the option associated to the delayed reward when ON medication as compared to the OFF medication state. At the time of outcome, the anterior medial prefrontal/rostral anterior cingulate cortex showed an interaction between group (PD+HS versus PD - HS) and medication (ON versus OFF), suggesting that dopaminergic treatment boosted activity of this brain region in PD+HS when viewing erotic images after waiting for longer periods of time. Our findings point to reduced delay discounting of erotic rewards in PD+HS, both at the behavioural and brain system levels, and abnormal reinforcing effect of levodopa when PD+HS patients are confronted with erotic stimuli.10.1093/brain/awy298_video1awy298media15983845074001.

Emergencies and critical issues in Parkinson's disease

Complications from Parkinson’s disease may develop over the disease course, sometimes unexpectedly, and require prompt or even urgent medical intervention. The most common are associated with aggravation of motor symptoms; serious non-motor complications, such as psychosis, orthostatic hypotension or sleep attacks, also occur. Here we review such complications, their clinical presentation, precipitating factors and management, including those related to using device-aided therapies. Early recognition and prompt attention to these critical situations is challenging, even for the Parkinson’s disease specialist, but is essential to prevent serious problems.

The Impact of Impulsivity on Quality of Life in Early Drug-Naïve Parkinson's Disease Patients

Objective

Impulse control disorders (ICDs) in Parkinson’s disease (PD) are mostly related to dopamine replacement therapy (DRT); however, drug-naïve PD patients have also frequently experienced impulsivity. This phenomenon makes clinicians hesitate treating patients with DRT. In this study, we assessed the effect of impulsivity on quality of life (QOL) in drug-naïve PD patients.

Methods

Two hundred three newly diagnosed, nonmedicated PD patients were enrolled, and they received structured clinical interviews, physical examinations and validated questionnaires to evaluate motor and nonmotor symptoms and QOL. Impulsivity was evaluated using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease-Rating Scale (QUIP-RS).

Results

Thirty-eight patients (18.7%) had impulsivity with QUIP-RS scores ≥ 1 and 4 patients (2.0%) were diagnosed with combined ICDs. Motor and nonmotor symptoms were significantly correlated with the Parkinson’s Disease Questionnaire-39 summary index. Female sex and QUIP-RS scores were also correlated with QOL in drug-naïve PD patients.

Conclusion

The results of the present study showed that impulsivity negatively influences QOL in early drug-naïve PD patients. In addition, more severe motor and nonmotor symptoms were also associated with lower QOL. Such findings complicate treatment but provide valuable information for managing early PD.

Brain Imaging and Impulse Control Disorders in Parkinson's Disease

Purpose of Review

Parkinson’s disease (PD) has a wide spectrum of symptoms including the presence of psychiatric disease. At present, most treatment plans, comprised of dopaminergic drugs, are chronic and complex. Though dopaminergic agents are quite efficient in managing the motor aspects of the disease, chronic pharmacotherapy specifically with dopamine receptor agonists has been highly linked to the occurrence of Impulse Compulsive disorder (ICD), which can be problematic for individual patients.

Recent Findings

Much of what is known today about PD-related ICD stems from brain imaging studies, however, evidence is not quite conclusive. Research in the field has been focused on identifying the underlying mechanisms of PD-related ICD and understanding the functions of the structures involved in the reward network.

Summary

This article presents an update of recent findings from key neuroimaging studies in PD-related ICD, discusses results from controversial studies, and identifies areas for future research in the field.

Impulse control disorders in Parkinson disease and RBD: A longitudinal study of severity

Objective

To describe the prevalence, natural history, and risk factors for impulse control behaviors (ICBs) among people with Parkinson disease (PD), those with REM sleep behavior disorder (RBD), and controls.

Methods

Participants with early PD (within 3.5 years of diagnosis), those with RBD, and controls were clinically phenotyped and screened for ICBs longitudinally (with the Questionnaire for Impulsivity in Parkinson's Disease). ICB-positive individuals were invited for a semistructured interview, repeated 1 year later. The severity of the ICB was assessed with the Parkinson's Impulse Control Scale. Multiple imputation and regression models were used to estimate ICB prevalence and associations.

Results

Data from 921 cases of PD at baseline, 768 cases at 18 months, and 531 cases at 36 months were included, with 21% to 25% screening positive for ICBs at each visit. Interviews of ICB screen–positive individuals revealed that 10% met formal criteria for impulse control disorders (ICD), while 33% had subsyndromal ICD (ICB symptoms without reaching the formal diagnostic criteria for ICD). When these data were combined through the use of multiple imputation, the prevalence of PD-ICB was estimated at 19.1% (95% confidence interval 10.1–28.2). On follow-up, 24% of cases of subsyndromal ICD had developed full symptoms of an ICD. PD-ICD was associated with dopamine agonist use, motor complications, and apathy but not PD-RBD. ICD prevalence in the RBD group (1%) was similar to that in controls (0.7%).

Conclusions

ICBs occur in 19.1% of patients with early PD, many persisting or worsening over time. RBD is not associated with increased ICD risk. Psychosocial drivers, including mood and support networks, affect severity.

Treatment of psychiatric disturbances in hypokinetic movement disorders

Introduction: We reviewed studies that assessed the treatment of psychiatric disturbances in Parkinson's disease and atypical parkinsonisms. Neuropsychiatric disturbances in these conditions are frequent and have a profound impact on quality of life of patients and of their caregivers. It is therefore important to be familiar with the appropriate pharmacological and non-pharmacological interventions for treating these disorders. Areas covered: The authors searched for papers in English in Pubmed using the following keywords: Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, Lewy body dementia, depression, apathy, anxiety, fatigue, sleep disorders, obsessive compulsive disorders, psychosis, hallucinations, delusions, impulse control disorders. Expert opinion: In Parkinson's disease, depression may benefit from the optimization of dopaminergic therapy, from the use of antidepressants acting on both the serotoninergic and noradrenergic pathways and from cognitive behavioral therapy. Psychosis in Parkinson's disease may improve with the use of clozapine; the serotonin inverse agonist pimavanserin has been shown to be effective. Treatment of impulse control disorders is primarily based on the removal of dopamine agonists. No controlled studies have investigated the treatment of neuropsychiatric disorders in multiple system atrophy, progressive supranuclear palsy or corticobasal degeneration. Acethylcholinesterase inhibitors may be used to treat hallucinations in Lewy body dementia.

Why not try harder? Computational approach to motivation deficits in neuro-psychiatric diseases

Motivation deficits, such as apathy, are pervasive in both neurological and psychiatric diseases. Even when they are not the core symptom, they reduce quality of life, compromise functional outcome and increase the burden for caregivers. They are currently assessed with clinical scales that do not give any mechanistic insight susceptible to guide therapeutic intervention. Here, we present another approach that consists of phenotyping the behaviour of patients in motivation tests, using computational models. These formal models impose a precise and operational definition of motivation that is embedded in decision theory. Motivation can be defined as the function that orients and activates the behaviour according to two attributes: a content (the goal) and a quantity (the goal value). Decision theory offers a way to quantify motivation, as the cost that patients would accept to endure in order to get the benefit of achieving their goal. We then review basic and clinical studies that have investigated the trade-off between the expected cost entailed by potential actions and the expected benefit associated with potential rewards. These studies have shown that the trade-off between effort and reward involves specific cortical, subcortical and neuromodulatory systems, such that it may be shifted in particular clinical conditions, and reinstated by appropriate treatments. Finally, we emphasize the promises of computational phenotyping for clinical purposes. Ideally, there would be a one-to-one mapping between specific neural components and distinct computational variables and processes of the decision model. Thus, fitting computational models to patients' behaviour would allow inferring of the dysfunctional mechanism in both cognitive terms (e.g. hyposensitivity to reward) and neural terms (e.g. lack of dopamine). This computational approach may therefore not only give insight into the motivation deficit but also help personalize treatment.

Impulse control symptoms in patients with Parkinson's disease: The influence of dopaminergic agonist

BACKGROUND

Impulse control disorders and punding are common in Parkinson's disease patients. Cross-sectional studies suggest an association between dopamine replacement therapy, especially dopaminergic agonists, and impulse control and related disorders in Parkinson's disease. However, some surveys suggest that Parkinson's disease itself does not confer an altered risk for impulse control disorders and related behavior, although these disturbances are more frequently reported in Parkinsonian patients than in healthy controls.

OBJECTIVE

To ascertain the frequency of impulse control disorders and punding symptoms in Parkinson's disease patients and healthy controls and to determine the influence of dopamine agonist treatment on the prevalence of these disturbances.

METHODS

A case-control study was conducted on 207 Parkinson's disease patients (79 taking dopamine agonists) and 230 healthy controls. The outcome measures were the presence of current impulse control disorders and punding symptoms, based on clinical criteria after application of the Minnesota Impulsive Disorders Interview for screening.

RESULTS

The frequency of impulse control disorders in Parkinson's disease patients vs. Healthy controls was 16.9% vs. 15.2% (p = 0.631). Punding was more frequent in Parkinson's disease patients (p = 0.028); however, impulse control disorders were more frequent in medicated Parkinson's disease patients taking dopamine agonists than in medicated patients not taking dopamine agonists (p = 0.001) and healthy controls (p = 0.014).

CONCLUSIONS

Parkinson's disease itself does not lead to the development of impulse control disorders. Dopaminergic agonist treatment may trigger the disorder in susceptible individuals. Punding may be more prevalent in Parkinson's disease patients.

Neuropathology and pathogenesis of extrapyramidal movement disorders: a critical update-I. Hypokinetic-rigid movement disorders

Extrapyramidal movement disorders include hypokinetic rigid and hyperkinetic or mixed forms, most of them originating from dysfunction of the basal ganglia (BG) and their information circuits. The functional anatomy of the BG, the cortico-BG-thalamocortical, and BG-cerebellar circuit connections are briefly reviewed. Pathophysiologic classification of extrapyramidal movement disorder mechanisms distinguish (1) parkinsonian syndromes, (2) chorea and related syndromes, (3) dystonias, (4) myoclonic syndromes, (5) ballism, (6) tics, and (7) tremor syndromes. Recent genetic and molecular-biologic classifications distinguish (1) synucleinopathies (Parkinson's disease, dementia with Lewy bodies, Parkinson's disease-dementia, and multiple system atrophy); (2) tauopathies (progressive supranuclear palsy, corticobasal degeneration, FTLD-17; Guamian Parkinson-dementia; Pick's disease, and others); (3) polyglutamine disorders (Huntington's disease and related disorders); (4) pantothenate kinase-associated neurodegeneration; (5) Wilson's disease; and (6) other hereditary neurodegenerations without hitherto detected genetic or specific markers. The diversity of phenotypes is related to the deposition of pathologic proteins in distinct cell populations, causing neurodegeneration due to genetic and environmental factors, but there is frequent overlap between various disorders. Their etiopathogenesis is still poorly understood, but is suggested to result from an interaction between genetic and environmental factors. Multiple etiologies and noxious factors (protein mishandling, mitochondrial dysfunction, oxidative stress, excitotoxicity, energy failure, and chronic neuroinflammation) are more likely than a single factor. Current clinical consensus criteria have increased the diagnostic accuracy of most neurodegenerative movement disorders, but for their definite diagnosis, histopathological confirmation is required. We present a timely overview of the neuropathology and pathogenesis of the major extrapyramidal movement disorders in two parts, the first one dedicated to hypokinetic-rigid forms and the second to hyperkinetic disorders.

Compulsive eating behaviors in Parkinson's disease

PURPOSE

Eating disorders are common in Parkinson's disease (PD) patients and often class in Impulse control disorders, however, little is known about their phenomenology. Specific symptoms and comorbidities were described in a group of PD patients in this preliminary study.

METHODS

Over a period of 6 months, 51 PD patients who experienced significant changes in eating habits following diagnosis of PD and were interviewed during regularly scheduled follow-up visits. We assessed each patient's height and weight, impulsivity, psychological distress, current eating disorder symptoms, food addiction, food habits and craving.

RESULTS

Among the PD patients who experienced modified dietary habits following diagnosis, few exhibited binge eating disorders (BED) full criteria (3.9%). However, 21.6% of patients experienced episodes of out-of-control eating with a large quantity of food in short time and 39.2% satisfied food addiction (FA) criteria without binge eating disorder. Food cravings more than once a week were experienced in approximately half of the population including all FA patients. Regarding comorbidities, FA PD patients present impulsive features and anxiety.

CONCLUSIONS

This study confirms the existence of FA profile in PD patients. Eating disorders even in PD are complex and have a cross-cutting criteria related to out-of-control eating, FA, and BED. The association of anxiety with PD-related food addiction, contrary to L-dopa equivalent daily dose mean score or the presence of dopamine agonists, underline the complex sustainability of the dopaminergic brainstem support. A study on their detailed prevalence in this population could be helpful to better understand unspecified feeding or eating disorder.

CLINICAL TRIAL NUMBER

DR-2012-007.

NAME OF THE REGISTRY

French Committee for the Protection of Persons (CPP) & French National Commission on Computing and Liberty (CNIL).

LEVEL OF EVIDENCE

Level V, descriptive study.

Dopamine drives binge-like consumption of a palatable food in experimental Parkinsonism

BACKGROUND

Prolonged dopaminergic replacement therapy in PD results in pulsatile dopamine receptors stimulation in both dorsal and ventral striatum causing wearing off, motor fluctuations, and nonmotor side effects such as behavioral addictions. Among impulse control disorders, binge eating can be easily modeled in laboratory animals.

OBJECTIVES

We hypothesize that manipulation of dopamine levels in a 6-hydroxydopamine-lesioned rats, as a model of PD characterized by a different extent of dopamine denervation between dorsal and ventral striatum, would influence both synaptic plasticity of the nucleus accumbens and binge-like eating behavior.

METHODS

Food preference, food intake, and weight gain were monitored in sham-operated and unilaterally lesioned rats, subjected to a modified version of Corwin's limited access protocol, modelling binge eating disorder. Electrophysiological properties and long-term potentiation of GABAergic spiny projection neurons of the nucleus accumbens core were studied through ex vivo intracellular and patch-clamp recordings from corticostriatal slices of naïve and l-dopa-treated rats.

RESULTS

Sham-operated animals with intact nucleus accumbens core plasticity reliably developed food-addiction-like behavior when exposed to intermittent access to a highly palatable food. In contrast, parkinsonian rats were unresponsive to such restriction regimens, and also plasticity was lost in ventral spiny neurons. Chronic l-dopa reestablished long-term potentiation and compulsive eating, but with a different temporal dynamic that follows that of drug administration.

CONCLUSIONS

Our data indicate that endogenous and exogenous dopamine drive binge-like consumption of a palatable food in healthy and parkinsonian rats with distinct temporal dynamics, providing new insights into the complexity of l-dopa effects on the mesolimbic dopaminergic system. © 2019 International Parkinson and Movement Disorder Society.