Behavioural adverse effects of dopaminergic treatments in Parkinson's disease: incidence, neurobiological basis, management and prevention

Investigating the Brain Mechanisms of Externally Cued Sit-to-Stand Movement in Parkinson's Disease

BACKGROUND

One of the more challenging daily-life actions for Parkinson's disease patients is starting to stand from a sitting position. Parkinson's disease patients are known to have difficulty with self-initiated movements and benefit from external cues. However, the brain processes underlying external cueing as an aid remain unknown. The advent of mobile electroencephalography (EEG) now enables the investigation of these processes in dynamic sit-to-stand movements.

OBJECTIVE

To identify cortical correlates of the mechanisms underlying auditory cued sit-to-stand movement in Parkinson's disease.

METHODS

Twenty-two Parkinson's disease patients and 24 healthy age-matched participants performed self-initiated and externally cued sit-to-stand movements while cortical activity was recorded through 32-channel mobile EEG.

RESULTS

Overall impaired integration of sensory and motor information can be seen in the Parkinson's disease patients exhibiting less modulation in the θ band during movement compared to healthy age-matched controls. How Parkinson's disease patients use external cueing of sit-to-stand movements can be seen in larger high β power over sensorimotor brain areas compared to healthy controls, signaling sensory integration supporting the maintenance of motor output. This appears to require changes in cognitive processing to update the motor plan, reflected in frontal θ power increases in Parkinson's disease patients when cued.

CONCLUSION

These findings provide the first neural evidence for why and how cueing improves motor function in sit-to-stand movement in Parkinson's disease. The Parkinson's disease patients' neural correlates indicate that cueing induces greater activation of motor cortical areas supporting the maintenance of a more stable motor output, but involves the use of cognitive resources to update the motor plan. © 2024 International Parkinson and Movement Disorder Society.

Cognitive disorders in advanced Parkinson's disease: challenges in the diagnosis of delirium

Parkinson's disease (PD) is a neurodegenerative condition that is frequently associated with cognitive disorders. These can arise directly from the primary disease, or be triggered by external factors in susceptible individuals due to PD or other predisposing factors. The cognitive disorders encompass PD-associated cognitive impairment (PD-CI), delirium, PD treatment-associated cognitive side effects, cognitive non-motor fluctuations, and PD-associated psychosis. Accurate diagnosis of delirium is crucial because it often stems from an underlying disease that may be severe and require specific treatment. However, overlapping molecular mechanisms are thought to be involved in both delirium and PD, leading to similar clinical symptoms. Additionally, there is a bidirectional interaction between delirium and PD-CI, resulting in frequent concurrent processes that further complicate diagnosis. No reliable biomarker is currently available for delirium, and the diagnosis is primarily based on clinical criteria. However, the screening tools validated for diagnosing delirium in the general population have not been specifically validated for PD. Our review addresses the current challenges in the diagnosis of these cognitive disorders and highlights existing gaps within this field.

The pharmacological management of the behavioral aspects of Parkinson's disease: an update

INTRODUCTION

Behavioural symptoms are common manifestations of Parkinson's disease and include depression, anxiety, impulse control disorders, hallucinations, psychosis, and cognitive dysfunction. They remain inadequately addressed in many patients despite their relevance for quality of life and disability. This applies also to impulse control disorders where the most common approach in recent literature is to refrain from using dopamine agonists without consideration about their potential benefit on motor complications.

AREAS COVERED

We conducted a narrative review searching for articles on behavioral symptoms in Parkinson disease and selected those which included involved neurotransmitters such as dopamine, noradrenaline, serotonin, acetylcholine. We specifically focused our search on open-label and randomized double-blind studies and biomarkers which could best characterize these clinical manifestations.

EXPERT OPINION

Management of Parkinson disease behavioural manifestations lacks clear guidelines and standardized protocols beside general suggestions of dose adjustments in dopamine replacement therapy and use of antidepressants or antipsychotic drugs with little consideration of patients' age, sex, comorbidities, and motor status. We suggest a pragmatic approach which includes education of affected patients and caring people, dealing with complex cases by experienced multidisciplinary teams, use of cognitive behavioural therapy, and psychological counselling to complement drug treatment.

Magnetic Resonance-Guided Focused Ultrasound Thalamotomy May Spare Dopaminergic Therapy in Early-Stage Tremor-Dominant Parkinson's Disease: A Pilot Study

BACKGROUND

Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy is a safe and effective procedure for drug-resistant tremor in Parkinson's disease (PD).

OBJECTIVE

The aim of this study was to demonstrate that MRgFUS ventralis intermedius thalamotomy in early-stage tremor-dominant PD may prevent an increase in dopaminergic medication 6 months after treatment compared with matched PD control subjects on standard medical therapy.

METHODS

We prospectively enrolled patients with early-stage PD who underwent MRgFUS ventralis intermedius thalamotomy (PD-FUS) and patients treated with oral dopaminergic therapy (PD-ODT) with a 1:2 ratio. We collected demographic and clinical data at baseline and 6 and 12 months after thalamotomy.

RESULTS

We included 10 patients in the PD-FUS group and 20 patients in the PD-ODT group. We found a significant increase in total levodopa equivalent daily dose and levodopa plus monoamine oxidase B inhibitors dose in the PD-ODT group 6 months after thalamotomy.

CONCLUSIONS

In early-stage tremor-dominant PD, MRgFUS thalamotomy may be useful to reduce tremor and avoid the need to increase dopaminergic medications. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Analysis of Impulse Control Disorders (ICDs) and Factors Associated with Their Development in a Parkinson's Disease Population

Parkinson's Disease (PD) is a neurodegenerative disease in which non-motor symptoms may appear before motor phenomena, which include Impulse Control Disorders (ICDs). The objective of this study is to identify factors associated with the development of ICDs in PD. An analytical, cross-sectional study was conducted using clinical records from patients diagnosed with PD, both genders, from 40 to 80 years old. Clinical and demographic data were collected: 181 patients were recruited; 80 of them showed PD and ICDs, and they constituted the study group, whereas 101 patients with PD without ICDs constituted the control reference group. The duration of PD was longer in the group with ICDs (p < 0.008), and all patients showed at least one ICD: binge eating (61.29%), compulsive shopping (48.75%), hypersexuality (23.75%), gambling behavior (8.75%), and punding (3.75%). After logistic regression analysis, only the use of dopamine agonists remained associated with ICDs (p < 0.001), and the tremorgenic form was suggested to be a protective factor (p < 0.001). Positive associations were observed between the rigid-akinetic form and compulsive shopping (p < 0.007), between male and hypersexuality (p < 0.018), and between dopamine agonists and compulsive shopping (p < 0.004), and negative associations were observed between motor fluctuations and compulsive shopping (p < 0.031), between Deep Brain Stimulation and binge eating (p < 0.046), and between levodopa consumption and binge eating (p < 0.045). Binge eating, compulsive shopping, and hypersexuality were the most frequent ICDs. Complex forms and motor complications of PD were associated with the development of ICDs.

The Effect of Dopaminergic Replacement Therapy on Creative Thinking and Insight Problem-Solving in Parkinson's Disease Patients

Parkinson's disease (PD) patients receiving dopaminergic treatment may experience bursts of creativity. Although this phenomenon is sometimes recognized among patients and their clinicians, the association between dopamine replacement therapy (DRT) in PD patients and creativity remains underexplored. It is unclear, for instance, whether DRT affects creativity through convergent or divergent thinking, idea generation, or a general lack of inhibition. It is also unclear whether DRT only augments pre-existing creative attributes or generates creativity de novo. Here, we tested a group of PD patients when “on” and “off” dopaminergic treatment on a series of tests of creative problem-solving (Alternative Uses Task, Compound Remote Associates, Rebus Puzzles), and related their performance to a group of matched healthy controls as well as to their pre-PD creative skills and measures of inhibition/impulsivity. Results did not provide strong evidence that DRT improved creative thinking in PD patients. Rather, PD patients “on” medication showed less flexibility in divergent thinking, generated fewer ideas via insight, and showed worse performance in convergent thinking overall (by making more errors) than healthy controls. Pre-PD creative skills predicted enhanced flexibility and fluency in divergent thinking when PD patients were “on” medication. However, results on convergent thinking were mixed. Finally, PD patients who exhibited deficits in a measure of inhibitory control showed weaker convergent thinking while “on” medication, supporting previous evidence on the importance of inhibitory control in creative problem-solving. Altogether, results do not support the hypothesis that DRT promotes creative thinking in PD. We speculate that bursts of artistic production in PD are perhaps conflated with creativity due to lay conceptions of creativity (i.e., an art-bias).

Pharmacological interventions in corticobasal degeneration: a review

Corticobasal degeneration (CBD) is a sporadic tauopathy that presents with a varied combination of motor, cognitive, and behavioral features, making its diagnosis difficult. CBD has high morbidity and poor prognosis, with no effective therapy at present. We searched the PubMed/MEDLINE database for articles published from 1990 to 2019, using the keywords “corticobasal degeneration” AND “treatment.” The PRISMA method was adopted. Retrieved articles were characterized as having one of two methodological approaches: (1) studies aimed at primary tauopathy treatment and (2) symptomatic management. Review articles (based on CBD expert groups), case reports, case series, and pilot clinical trials were selected. Few attempts have been made to study drug options and drug efficacy in CBD systematically, and an effective treatment is not yet available. Treatment is symptomatic and based on similarity with other diseases due to the scarcity of studies specifically addressing CBD. CBD seems not to spark interest in more clinical trials for its low prevalence and reliability in clinical diagnosis.

Dopamine dysregulation syndrome in non-Parkinson's disease patients: a systematic review

OBJECTIVES

To explore the presence of dopamine dysregulation syndrome in non-Parkinson's disease patients receiving dopamine replacement therapy.

METHODS

Electronic searches were conducted of Medline, Embase, PsycINFO and PreMedline to capture articles related to dopamine misuse or factitious disorder combined with the presence of dopamine replacement therapy or a non-Parkinson's disease population. In total, 430 articles were reviewed and studies that addressed dopamine dysregulation syndrome in non-Parkinson's disease patients were included.

RESULTS

Nine case reports were identified.

CONCLUSIONS

The pathophysiology underlying dopamine dysregulation syndrome has been thoroughly explored with numerous mechanisms posited. What remains unclear is whether dopamine dysregulation syndrome is a phenomenon specific to Parkinson's disease, as indicated in the proposed diagnostic criteria. A more useful predictor of susceptibility to dopamine dysregulation syndrome may be temperamental traits such as novelty seeking and impulsivity, which overlap with predisposing factors for an addiction disorder.

Review: Non-Invasive Brain Stimulation in Behavioral Addictions: Insights from Direct Comparisons With Substance Use Disorders

BACKGROUND AND OBJECTIVES

Treatment models developed for substance use disorders (SUDs) are often applied to behavioral addictions (BAs), even though the correspondence between these forms of addiction is unclear. This is also the case for noninvasive brain stimulation (NIBS) techniques being investigated as potential treatment interventions for SUDs and BAs.

OBJECTIVES

to contribute to the development of more effective NIBS protocols for BAs.

METHODS

Two literature searches using PubMed and Google Scholar were conducted identifying a total of 35 studies. The first search identified 25 studies examining the cognitive and neurophysiological overlap between BAs and SUDs. The second search yielded 10 studies examining the effects of NIBS in BAs.

RESULTS

Impulsivity and cravings show behavioral and neurophysiologic overlaps between BAs and SUDs, however, other outcomes like working-memory abilities or striatal connectivity, differ between BAs and SUDs. The most-employed NIBS target in BAs was dorsolateral prefrontal cortex (DLPFC), which was associated with a decrease in cravings, and less frequently with a reduction of addiction severity.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Direct comparisons between BAs and SUDs revealed discrepancies between behavioral and neurophysiological outcomes, but overall, common and distinctive characteristics underlying each disorder. The lack of complete overlap between BAs and SUDs suggests that investigating the cognitive and neurophysiological features of BAs to create individual NIBS protocols that target risk-factors associated specifically with BAs, might be more effective than transferring protocols from SUDs to BAs. Individualizing NIBS protocols to target specific risk-factors associated with each BA might help to improve treatment interventions for BAs. (Am J Addict 2019;00:1-23).

Available and future treatments for atypical parkinsonism. A systematic review

AIMS

Success in treating patients with atypical parkinsonian syndromes, namely progressive supranuclear palsy (PSP), cortico-basal degeneration (CBD), multiple system atrophy (MSA), Parkinson's disease with dementia (PDD), and Lewy body dementia with (LBD), remains exceedingly low. The present work overviews the most influential research literature collected on MEDLINE, ISI Web of Science, Cochrane Library, and Scopus for available treatment in atypical parkinsonisms without time restriction.

DISCUSSION

Transdermal rotigotine, autologous mesenchymal stem cells, tideglusib, and coenzyme Q10 along with donepezil, rivastigmine, memantine, and the deep brain stimulation have shown some benefits in alleviating symptoms in APS. Moreover, many new clinical trials are ongoing testing microtubule stabilizer, antitau monoclonal antibody, tau acetylation inhibition, cell replacement, selective serotonin reuptake inhibitor, active immunization, inhibition of toxic α-synuclein oligomers formation, and inhibition of microglia.

CONCLUSION

A detailed knowledge of the pathological mechanism underlying the disorders is needed, and disease-modifying therapies are required to offer better therapeutic options to physician and caregivers of APS patients.

An mGlu4-Positive Allosteric Modulator Alleviates Parkinsonism in Primates

BACKGROUND

Levodopa remains the gold-standard treatment for PD. However, it becomes less effective as the disease progresses and produces debilitating side effects, such as motor fluctuations and l-dopa-induced dyskinesia. Modulation of metabotropic glutamate receptor 4 represents a promising antiparkinsonian approach in combination with l-dopa, but it has not been demonstrated in primates.

OBJECTIVE

We studied whether a novel positive allosteric modulator of the metabotropic glutamate receptor 4, PXT002331 (foliglurax), could reduce parkinsonism in primate models.

METHODS

We assessed the therapeutic potential of PXT002331 in three models of MPTP-induced parkinsonism in macaques. These models represent three different stages of disease evolution: early stage and advanced stage with and without l-dopa-induced dyskinesia.

RESULTS

As an adjunct to l-dopa, PXT002331 induced a robust and dose-dependent reversal of parkinsonian motor symptoms in macaques, including bradykinesia, tremor, posture, and mobility. Moreover, PXT002331 strongly decreased dyskinesia severity, thus having therapeutic efficacy on both parkinsonian motor impairment and l-dopa-induced dyskinesia. PXT002331 brain penetration was also assessed using PET imaging in macaques, and pharmacodynamic analyses support target engagement in the therapeutic effects of PXT002331.

CONCLUSIONS

This work provides a demonstration that a positive allosteric modulator of metabotropic glutamate receptor 4 can alleviate the motor symptoms of PD and the motor complications induced by l-dopa in primates. PXT002331 is the first compound of its class to enter phase IIa clinical trials. © 2018 International Parkinson and Movement Disorder Society.

Impulse Control Disorder in Parkinson's Disease: A Meta-Analysis of Cognitive, Affective, and Motivational Correlates

Background: In Parkinson's disease (PD), impulse control disorders (ICDs) develop as side-effect of dopaminergic replacement therapy (DRT). Cognitive, affective, and motivational correlates of ICD in medicated PD patients are debated. Here, we systematically reviewed and meta-analyzed the evidence for an association between ICD in PD and cognitive, affective, and motivational abnormalities. Methods: A systematic review and meta-analysis was performed on PubMed, Science Direct, ISI Web of Science, Cochrane, EBSCO for studies published between 1-1-2000 and 8-3-2017 comparing cognitive, affective, and motivational measures in PD patients with ICD (ICD+) vs. those without ICD (ICD-). Exclusion criteria were conditions other than PD, substance and/or alcohol abuse, dementia, drug naïve patients, cognition assessed by self-report tools. Standardized mean difference (SMD) was used, and random-effect model applied. Results: 10,200 studies were screened (title, abstract), 79 full-texts were assessed, and 25 were included (ICD+: 625 patients; ICD-: 938). Compared to ICD-, ICD+ showed worse performance reward-related decision-making (0.42 [0.02, 0.82], p = 0.04) and set-shifting tasks (SMD = -0.49 [95% CI -0.78, -0.21], p = 0.0008). ICD in PD was also related to higher self-reported rate of depression (0.35 [0.16, 0.54], p = 0.0004), anxiety (0.43 [0.18, 0.68], p = 0.0007), anhedonia (0.26 [0.01, 0.50], p = 0.04), and impulsivity (0.79 [0.50, 1.09], p < 0.00001). Heterogeneity was low to moderate, except for depression (I² = 61%) and anxiety (I² = 58%). Conclusions: ICD in PD is associated with worse set-shifting and reward-related decision-making, and increased depression, anxiety, anhedonia, and impulsivity. This is an important area for further studies as ICDs have negative impact on the quality of life of patients and their caregivers.

Discovery of Novel and Selective Adenosine A2A Receptor Antagonists for Treating Parkinson's Disease through Comparative Structure-Based Virtual Screening

Among non-dopaminergic strategies for combating Parkinson's disease (PD), antagonism of the A_2A adenosine receptor (AR) has emerged to show great potential. In this study, on the basis of two crystal structures of the A_2A AR with the best capability to distinguish known antagonists from decoys, docking-based virtual screening (VS) was conducted to identify novel A_2A AR antagonists. A total of 63 structurally diverse compounds identified by VS were submitted to experimental testing, and 11 of them exhibited substantial activity against the A_2A AR (K_i < 10 μM), including two compounds with K_i below 1 μM (compound 43, 0.42 μM; compound 51, 0.27 μM) and good A_2A/A₁ selectivity (fold < 0.1). Compounds 43 and 51 demonstrated antagonistic activity according to the results of cAMP measurements (cAMP IC₅₀ = 1.67 and 1.80 μM, respectively) and showed good efficacy in the haloperidol-induced catalepsy (HIC) rat model for PD at doses of up to 30 mg/kg. Further lead optimization based on a substructure searching strategy led to the discovery of compound 84 as an excellent A_2A AR antagonist (A_2A K_i = 54 nM, A_2A/A₁ fold < 0.1, cAMP IC₅₀ = 0.3 μM) that exhibited significant improvement in anti-PD efficacy in the HIC rat model.

Dopaminergic Medication Modulates Learning from Feedback and Error-Related Negativity in Parkinson's Disease: A Pilot Study

Dopamine systems mediate key aspects of reward learning. Parkinson’s disease (PD) represents a valuable model to study reward mechanisms because both the disease process and the anti-Parkinson medications influence dopamine neurotransmission. The aim of this pilot study was to investigate whether the level of levodopa differently modulates learning from positive and negative feedback and its electrophysiological correlate, the error related negativity (ERN), in PD. Ten PD patients and ten healthy participants performed a two-stage reinforcement learning task. In the Learning Phase, they had to learn the correct stimulus within a stimulus pair on the basis of a probabilistic positive or negative feedback. Three sets of stimulus pairs were used. In the Testing Phase, the participants were tested with novel combinations of the stimuli previously experienced to evaluate whether they learned more from positive or negative feedback. PD patients performed the task both ON- and OFF-levodopa in two separate sessions while they remained on stable therapy with dopamine agonists. The electroencephalogram (EEG) was recorded during the task. PD patients were less accurate in negative than positive learning both OFF- and ON-levodopa. In the OFF-levodopa state they were less accurate than controls in negative learning. PD patients had a smaller ERN amplitude OFF- than ON-levodopa only in negative learning. In the OFF-levodopa state they had a smaller ERN amplitude than controls in negative learning. We hypothesize that high tonic dopaminergic stimulation due to the dopamine agonist medication, combined to the low level of phasic dopamine due to the OFF-levodopa state, could prevent phasic “dopamine dips” indicated by the ERN needed for learning from negative feedback.

Medicinal-Induced Behavior Disorders

Commonly used medications can have neuropsychiatric and behavioral effects that may be idiosyncratic or metabolic in nature, or a function of interactions with other drugs, toxicity, or withdrawal. This article explores an approach to the patient with central nervous system toxicity, depending on presentation of sedation versus agitation and accompanying physical signs and symptoms. The effects of antihypertensives, opioids, antibiotics, antiepileptic agents, steroids, Parkinson's disease medications, antipsychotics, medications for human immunodeficiency virus infection, cancer chemotherapeutics, and immunotherapies are discussed. A look at the prevalence of adverse reactions to medications and the errors underlying such occurrences is included.

Looking for Creativity: Where Do We Look When We Look for New Ideas?

Recent work using the eye movement monitoring technique has demonstrated that when people are engaged in thought they tend to disengage from the external world by blinking or fixating on an empty portion of the visual field, such as a blank wall, or out the window at the sky. This 'looking at nothing' behavior has been observed during thinking that does not explicitly involve visual imagery (mind wandering, insight in problem solving, memory encoding and search) and it is associated with reduced analysis of the external visual environment. Thus, it appears to indicate (and likely facilitate) a shift of attention from external to internal stimuli that benefits creativity and problem solving by reducing the cognitive load and enhancing attention to internally evolving activation. We briefly mention some possible reasons to collect eye movement data in future studies of creativity.

Dopamine Agonists: Time Pattern of Adverse Effects Reporting in Australia

BACKGROUND

In Australia, there is voluntary reporting of suspected adverse events (AEs) of therapeutic medicines. Some dopamine agonists (DAs) have serious AEs.

OBJECTIVE

We aimed to explore the pattern of DA AE reporting over two decades.

METHODS

We analysed AE case line listings obtained from the Australian Committee on the Safety of Medicines (ACSOM) for bromocriptine, cabergoline, pergolide, pramipexole and ropinirole, and related these to drug utilisation data (1992-2012). We noted the AE nature, frequency, onset, novelty, severity and outcome.

RESULTS

The 220 suspected AEs fell into five categories: (i) syncopal/pre-syncopal, (ii) fibrotic, (iii) psychotic, (iv) obsessive-compulsive behaviours (OCB) and (v) increased sleep. There were differential lag times between initial individual drug registration and reporting of suspected AEs, with a lag of at least one year for fibrotic reactions and OCB compared to more contemporaneous reporting of other AEs. Consistent with the published literature, ACSOM data showed that ergot DAs share fibrotic reactions as a class AE, whereas symptomatic hypotensive reactions, psychosis and OCB occurred in both ergot and non-ergot DAs, cabergoline and pramipexole, respectively. Reports of syncopal and pre-syncopal reactions seemed to diminish as ergot-based DA use declined. Levodopa was taken simultaneously with DAs in 87 instances. Of those treated, 92 % were 50 years or older. Parkinson's disease accounted for 89 % of use (119 reports).

CONCLUSIONS

Exploring the temporal relationship between post-marketing AE reporting and utilisation data, as exemplified by DAs, can be a valuable pharmacovigilance tool to encourage targeted adverse event monitoring and reporting.

[Clinical and psychopathological factors associated with impulse control disorders in Parkinson's disease]

INTRODUCTION

Impulse control disorders (ICD) constitute a complication that may arise during the course of Parkinson's disease (PD). Several factors have been linked to the development of these disorders, and their associated severe functional impairment requires specific and multidisciplinary management. The objective of this study was to evaluate the frequency of ICDs and the clinical and psychopathological factors associated with the appearance of these disorders.

METHODS

Cross-sectional, descriptive, and analytical study of a sample of 115 PD patients evaluated to determine the presence of an ICD. Clinical scales were administered to assess disease severity, personality traits, and presence of psychiatric symptoms at the time of evaluation.

RESULTS

Of the 115 patients with PD, 27 (23.48%) displayed some form of ICD; hypersexuality, exhibited by 14 (12.2%), and binge eating, present in 12 (10.1%), were the most common types. Clinical factors associated with ICD were treatment with dopamine agonists (OR: 13.39), earlier age at disease onset (OR: 0.92), and higher score on the UPDRS-I subscale; psychopathological factors with a significant association were trait anxiety (OR: 1.05) and impulsivity (OR: 1.13).

CONCLUSIONS

ICDs are frequent in PD, and treatment with dopamine agonists is the most important risk factor for these disorders. High impulsivity and anxiety levels at time of evaluation, and younger age at disease onset, were also linked to increased risk. However, presence of these personality traits prior to evaluation did not increase risk of ICD.

Effects of simvastatin on the expression of inducible nitric oxide synthase and brain-derived neurotrophic factor in a lipopolysaccharide-induced rat model of Parkinson disease

OBJECTIVE

To investigate the effects of simvastatin on the expression of inducible nitric oxide synthase (iNOS) and brain-derived neurotrophic factor (BDNF) in the substantia nigra in a lipopolysaccharide (LPS)-induced rat model of Parkinson disease (PD), and to study the mechanisms underlying the neuroprotective effects of simvastatin in PD.

METHODS

The LPS-PD model was established by injection of LPS (5 mg/mL, 2.0 μL) into the right substantia nigra compacta (SNC). Rats in the sham-operated group received saline. The simvastatin treatment group was intraperitoneally administered simvastatin (5 mg/kg, 2.0 μL) at 1 h before, and daily for 14 days after surgery, while the sham-operated and LPS-model groups received saline. Iba-1-positive cells and tyrosine hydroxylase (TH), as well as iNOS and BDNF in the SNC were detected by immunohistochemistry and Western blotting, respectively. The effect of simvastatin in the PD model was also examined in behavioral tests.

RESULTS

The LPS-model group exhibited typical animal PD behaviors. Compared with the control group, the LPS-model group exhibited a decreased number of DA neurons (p < 0.01) in the SNC, as well as increases in the Iba-1-positive cell number and iNOS expression (p < 0.05), while BDNF expression was downregulated (p < 0.01). These effects were inhibited by simvastatin treatment (p < 0.05).

CONCLUSION

Simvastatin mediates a protective effect on dopaminergic neurons in the SNC in the LPS-PD model, possibly by promoting neuronal repair and regeneration, and by inhibiting oxidative stress, thus improving substantia nigra function.

A review of current treatment strategies for restless legs syndrome (Willis-Ekbom disease)

Restless legs syndrome (RLS), recently renamed Willis-Ekbom disease (WED), is a common movement disorder. It is characterised by the need to move mainly the legs due to uncomfortable, sometimes painful sensations in the legs, which have a diurnal variation and a release with movement. Management is complex. First, centres should establish the severity of RLS using a simple 10-item RLS severity rating scale (IRLS). They should also exclude secondary causes, in particular ensuring normal iron levels. Mild cases can be managed by lifestyle changes, but patients with a IRLS score above 15 usually require pharmacological treatment. Dopaminergic therapies remain the mainstay of medical therapies, with recent evidence suggesting opioids may be particularly effective. This article focuses on the different treatment strategies in RLS, their associated complications and ways to manage them.

Behavioral and neurophysiological effects of transdermal rotigotine in atypical parkinsonism

Effective therapies for the so-called atypical parkinsonian syndrome (APS) such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), or corticobasal syndrome (CBS) are not available. Dopamine agonists (DA) are not often used in APS because of inefficacy and in a minority of case, their side effects, like dyskinesias, impairment of extrapyramidal symptoms or the appearance of psychosis, and REM sleep behavioral disorders (RBD). Transdermal rotigotine (RTG) is a non-ergot dopamine agonist indicated for use in early and advanced Parkinson’s disease with a good tolerability and safety. Moreover, its action on a wide range of dopamine receptors, D1, D2, D3, unlike other DA, could make it a good option in APS, where a massive dopamine cell loss is documented. In this pilot, observational open-label study we evaluate the efficacy and tolerability of RTG in patients affected by APS. Thirty-two subjects with diagnosis of APS were treated with transdermal RTG. APS diagnosis was: MSA parkinsonian type (MSA-P), MSA cerebellar type (MSA-C), PSP, and CBS. Patients were evaluated by UPDRS-III, neuropsychiatric inventory, mini mental state examination at baseline, and after 6, 12, and 18 months. The titration schedule was maintained very flexible, searching the major clinical effect and the minor possible adverse events (AEs) at each visit. AEs were recorded. APS patients treated with RTG show an overall decrease of UPDRS-III scores without increasing behavioral disturbances. Only three patients were dropped out of the study. Main AEs were hypotension, nausea, vomiting, drowsiness, and tachycardia. The electroencephalographic recording power spectra analysis shows a decrease of theta and an increase of low alpha power. In conclusion, transdermal RTG seems to be effective and well tolerated in APS patients.

Non-ergot dopamine agonist rotigotine as a promising therapeutic tool in atypical parkinsonism syndromes: a 24 months pilot observational open-label study

Rotigotine (RTG) is a non-ergot dopamine agonist developed as a new transdermal formulation, indicated for use in early and advanced Parkinson's disease (PD). The potential advantages of the RTG patch include immediacy of effect onset, constant drug delivery, better tolerability avoiding drug peaks and easy of use, helping patient's compliance. So, RTG patch appears to be a suitable candidate in the treatment of patients with atypical parkinsonism. The present is an observational study to evaluate the efficacy and tolerability of RTG in patients affected by atypical parkinsonian disorders. 61 subjects with diagnosis of atypical parkinsonian disorders were treated with transdermal RTG. Diagnosis was: Parkinson disease with dementia, multiple system atrophy parkinsonian type, multiple system atrophy cerebellar type, progressive sopranuclear palsy, cortico-basal degeneration, Lewy body dementia and fronto-temporal dementia with parkinsonism. Patients were evaluated by UPDRS-III, NPI, MMSE and adverse events (AEs) were recorded. Patients treated with RTG show an overall decrease of UPDRS III scores without increasing behavioral disturbances. Main adverse events (AE) were hypotension (14 patients), nausea (13), vomiting (5), drowsiness (5), tachycardia (2) dystonia (3 patients, all treated with concomitant l-dopa). On the whole, 16 patients were affected by AE and 7 patients suspended RTG treatment due to AE (vomiting, tachycardia and sleepiness). In our population transdermal RTG seems to be effective and well tolerated. Due to its system of drug delivery, RTG appears to be a suitable therapy in elderly patients as it has a good tolerability profile, improves patient's compliance and helps management of fragile patients.

Rotigotine is safe and efficacious in Atypical Parkinsonism Syndromes induced by both α-synucleinopathy and tauopathy

Transdermal rotigotine (RTG) is a non-ergot dopamine agonist (D3>D2>D1), and is indicated for use in early and advanced Parkinson's disease (PD). RTG patch has many potential advantages due to the immediacy of onset of the therapeutic effect. Of note, intestinal absorption is not necessary and drug delivery is constant, thereby avoiding drug peaks and helping patient compliance. In turn, transdermal RTG seems a suitable candidate in the treatment of atypical Parkinsonian disorders (APS). Fifty-one subjects with a diagnosis of APS were treated with transdermal RTG. The diagnoses were: Parkinson's disease with dementia, multiple system atrophy Parkinsonian type, multiple system atrophy cerebellar type, progressive supranuclear palsy, corticobasal degeneration, Lewy body dementia, and frontotemporal dementia with Parkinsonism. Patients were evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS; part III), Neuropsychiatric Inventory (NPI), and mini-mental state examination (MMSE) and all adverse events (AEs) were recorded. Patients treated with RTG showed an overall decrease of UPDRS III scores without increasing behavioral disturbances. Main AEs were hypotension, nausea, vomiting, drowsiness, tachycardia, and dystonia. On the whole, 15 patients were affected by AEs and seven patients suspended RTG treatment due to AEs. The results show that transdermal RTG is effective with a good tolerability profile. RTG patch could be a good therapeutic tool in patients with APS.

RISC in PD: the impact of microRNAs in Parkinson's disease cellular and molecular pathogenesis

Parkinson's disease (PD) is a debilitating neurodegenerative disease characterized primarily by the selective death of dopaminergic (DA) neurons in the substantia nigra pars compacta of the midbrain. Although several genetic forms of PD have been identified, the precise molecular mechanisms underlying DA neuron loss in PD remain elusive. In recent years, microRNAs (miRNAs) have been recognized as potent post-transcriptional regulators of gene expression with fundamental roles in numerous biological processes. Although their role in PD pathogenesis is still a very active area of investigation, several seminal studies have contributed significantly to our understanding of the roles these small non-coding RNAs play in the disease process. Among these are studies which have demonstrated specific miRNAs that target and down-regulate the expression of PD-related genes as well as those demonstrating a reciprocal relationship in which PD-related genes act to regulate miRNA processing machinery. Concurrently, a wealth of knowledge has become available regarding the molecular mechanisms that unify the underlying etiology of genetic and sporadic PD pathogenesis, including dysregulated protein quality control by the ubiquitin-proteasome system and autophagy pathway, activation of programmed cell death, mitochondrial damage and aberrant DA neurodevelopment and maintenance. Following a discussion of the interactions between PD-related genes and miRNAs, this review highlights those studies which have elucidated the roles of these pathways in PD pathogenesis. We highlight the potential of miRNAs to serve a critical regulatory role in the implicated disease pathways, given their capacity to modulate the expression of entire families of related genes. Although few studies have directly linked miRNA regulation of these pathways to PD, a strong foundation for investigation has been laid and this area holds promise to reveal novel therapeutic targets for PD.

Depression and impulse control disorders in Parkinson's disease: two sides of the same coin?

Depression and impulse control disorders (ICD) are two common neuropsychiatric features in Parkinson's disease (PD). Studies have revealed that both phenomena are associated with aberrations in ventral striatal dopamine signaling and concomitant dysfunction of the reward-related (limbic) cortico-striatal-thalamocortical (CSTC) circuit. Depression in PD seems associated with decreased activity in the limbic CSTC circuit, whereas ICD seem associated with increased limbic CSTC circuit activity, usually after commencing dopamine replacement therapy (DRT). Not all DRT using PD patients, however, develop symptoms of ICD, suggesting an additional underlying neurobiological susceptibility. Furthermore, the symptoms of depression and ICD frequently coincide even though they are related to seemingly contrasting limbic CSTC circuit activation states. The aim of this review is to provide an overview of the currently available literature on the neurobiology of PD-related depression and ICD and discusses possible susceptibility factors. Finally, we propose a neurobiological model that identifies ventral striatal dopaminergic denervation as a common underlying neurobiological substrate of depression and ICD and subsequent dysfunction of reward and motivation-related brain areas.

Understanding cognitive deficits in Parkinson's disease: lessons from preclinical animal models

Parkinson's disease (PD) has been, until recently, mainly defined by the presence of characteristic motor symptoms, such as rigidity, tremor, bradykinesia/akinesia, and postural instability. Accordingly, pharmacological and surgical treatments have so far addressed these motor disturbances, leaving nonmotor, cognitive deficits an unmet clinical condition. At the preclinical level, the large majority of studies aiming at defining mechanisms and testing novel therapies have similarly focused on the motor aspects of PD. Unfortunately, deterioration of the executive functions, such as attention, recognition, working memory, and problem solving, often appear in an early, premotor phase of the disease and progressively increase in intensity, negatively affecting the quality of life of ∼50%-60% of PD patients. At present, the cellular mechanisms underlying cognitive impairments in PD patients are largely unknown and an adequate treatment is still missing. The preclinical research has recently developed new animal models that may open new perspectives for a more integrated approach to the treatment of both motor and cognitive symptoms of the disease. This review will provide an overview on the cognitive symptoms occurring in early PD patients and then focus on the rodent and nonhuman primate models so far available for the study of discriminative and spatial memory attention and learning abilities related to this pathological condition.

Summary of the recommendations of the EFNS/MDS-ES review on therapeutic management of Parkinson's disease

OBJECTIVE

To summarize the 2010 EFNS/MDS-ES evidence-based treatment recommendations for the management of Parkinson's disease (PD). This summary includes the treatment recommendations for early and late PD.

METHODS

For the 2010 publication, a literature search was undertaken for articles published up to September 2009. For this summary, an additional literature search was undertaken up to December 2010. Classification of scientific evidence and the rating of recommendations were made according to the EFNS guidance. In cases where there was insufficient scientific evidence, a consensus statement ('good practice point') is made.

RESULTS AND CONCLUSIONS

For each clinical indication, a list of therapeutic interventions is provided, including classification of evidence.

Treatment of Parkinson's disease in the advanced stage

Levodopa/Carbidopa, respectively, Levodopa/Benserazide is the most effective treatment for Parkinson’s disease and during the progress of the disease, patients will inevitably need to be treated with it. Nonetheless, after a certain time period most of the patients experience side effects. Mainly disturbing are motor and non-motor fluctuations and dyskinesia. Numerous options from changing the medication regimen, to continuos dopaminergic drug delivery via apomorphine or Duodopa pumps and stereotactical interventions are available. The physician’s responsibility is to choose the right therapeutic procedure for each timepoint of the patient’s disease. In this review, we provide an up to date overview of the available strategies.

Predictors of discrepancies in Parkinson's disease patient and caregiver ratings of apathy, disinhibition, and executive dysfunction before and after diagnosis

Parkinson’s disease (PD) patient and caregiver reports of patient functioning are often used interchangeably in clinical and research settings; however, the consistency of these reports is largely unknown. This study aimed to investigate the consistency and predictors of discrepancy between self- and caregiver reports of patient apathy, disinhibition, and executive dysfunction. Fifty-one pairs of nondemented PD patients and their caregivers completed the frontal systems behavior scale (FrSBe). Patients were administered a neuropsychological battery, and mood and burden were assessed in a subset of caregivers. Patients and caregivers significantly differed in their ratings of all retrospective prediagnosis behaviors and current levels of disinhibition. Current levodopa equivalent dosages predicted patient-caregiver rating differences in prediagnosis and current apathy and current executive dysfunction, while patient motor function, cognition, and mood failed to predict any disparities in ratings. Caregiver burden and depression were associated with apathy rating discrepancies, while burden was associated with discrepancies in ratings of disinhibition. These results suggest that consistency of patient and caregiver behavioral ratings may vary depending on the behavior assessed; and underscore the importance of considering the reporter when using subjective measures, as discrepancies in behavioral reports may be influenced by specific patient and/or caregiver symptoms or factors.

An update on the management of juvenile and young-onset Parkinson’s disease

Early-onset Parkinson’s disease (PD) denotes onset of the disease below the age of 40 years. Patients tend to have a slower disease progression, an increased rate of dystonia, an increased rate of dyskinesias in response to L-3,4-dihydroxyphenylalanine and a lower rate of dementia compared with those in late-onset PD. Early-onset PD patients may experience more social and psychosocial conflict compared with late-onset patients and these factors would contribute to greater impairment of quality of life. Unemployment due to disability or early retirement may be causes for these conflicts. We have to take these factors into account whenever we institute drug therapy in early-onset PD. There is no randomized controlled study on early-onset PD; however, we may make a reasonable decision by considering the data on PD in general and clinical characteristics of early-onset patients. The management of motor and non-motor symptoms of early-onset PD patients is reviewed here.

Comparison of personality characteristics in Parkinson disease patients with and without impulse control disorders and in healthy volunteers

OBJECTIVE

We aimed to assess personality characteristics in patients with Parkinson disease (PD) with and without impulse control disorders (ICD).

METHODS

We tested patients and controls with the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) scales that have expected high sensitivity to apparent addictive behavior. We recorded mean disease duration and mean levodopa dose in the PD groups.

RESULTS

Of the 46 PD patients, 13 had ICD: hypersexuality, binge eating, or dopamine dysregulation. The PD patients with ICD had a longer duration of disease (11 vs. 5 y) and were taking higher doses of levodopa (900 vs. 500 mg/d). They scored above the pathologic threshold in 4 domains of the MMPI-2 Clinical Scales and in 8 Clinical Subscales and Content Scales. The most significant abnormality was Alienation-Self and Others.

CONCLUSIONS

ICDs in the general population have similarities to disorders of substance addiction. In PD patients, some personality profiles could play a role in development of ICDs or dopamine dysregulation syndrome. The MMPI-2 may be a useful test for PD patients in general, and for detecting ICD in particular.

Nonmotor manifestations in Parkinson disease

BACKGROUND

Although the diagnosis of Parkinson disease (PD) still relies mainly on the appearance of its classical motor features of resting tremor, rigidity, bradykinesia, and postural instability, nonmotor manifestations in PD are now recognized as an integral component of this multisystem disorder.

REVIEW SUMMARY

Nonmotor complications in PD occur commonly. The current understanding of cognitive dysfunction; neuropsychiatric manifestations including psychosis, impulsive control, and compulsive disorders, depression, anxiety and apathy; autonomic complications such as hypotension, erectile dysfunction, and urinary complications; sleep disorders and other nonmotor manifestations are summarized in this review.

CONCLUSION

Nonmotor complications often carry a greater impact than motor features in PD. Therefore, heightened awareness and proper recognition of these features are critical in improving a Parkinson patient's quality of life.

Design and characterization of optimized adenosine A₂A/A₁ receptor antagonists for the treatment of Parkinson's disease

The design and characterization of two, dual adenosine A(2A)/A(1) receptor antagonists in several animal models of Parkinson's disease is described. Compound 1 was previously reported as a potential treatment for Parkinson's disease. Further characterization of 1 revealed that it was metabolized to reactive intermediates that caused the genotoxicity of 1 in the Ames and mouse lymphoma L51784 assays. The identification of the metabolites enabled the preparation of two optimized compounds 13 and 14 that were devoid of the metabolic liabilities associated with 1. Compounds 13 and 14 are potent dual A(2A)/A(1) receptor antagonists that have excellent activity, after oral administration, across a number of animal models of Parkinson's disease including mouse and rat models of haloperidol-induced catalepsy, mouse and rat models of reserpine-induced akinesia, and the rat 6-hydroxydopamine (6-OHDA) lesion model of drug-induced rotation.

Adenosine A(2A) Receptor Antagonists and Parkinson's Disease

This Review summarizes and updates the work on adenosine A(2A) receptor antagonists for Parkinson's disease from 2006 to the present. There have been numerous publications, patent applications, and press releases within this time frame that highlight new medicinal chemistry approaches to this attractive and promising target to treat Parkinson's disease. The Review is broken down by scaffold type and will discuss the efforts to optimize particular scaffolds for activity, pharmacokinetics, and other drug discovery parameters. The majority of approaches focus on preparing selective A(2A) antagonists, but a few approaches to dual A(2A)/A(1) antagonists will also be highlighted. The in vivo profiles of compounds will be highlighted and discussed to compare activities across different chemical series. A clinical report and update will be given on compounds that have entered clinical trials.

Pramipexole for the treatment of early Parkinson's disease

Pramipexole is a nonergolinic dopamine agonist, with high affinity for the D2 subfamily of dopamine receptors. Pramipexole is efficacious for the symptomatic treatment of early Parkinson's Disease (PD) and its early use, before that of levodopa can delay the emergence of levodopa-related motor complication. Dosage should be increased gradually from a starting dose of 0.375 mg/day up to a maximum of 4.5 mg/day in equally divided doses taken three times per day with pramipexole immediate-release or equivalent daily dosages once-daily with pramipexole extended-release. Pramipexole can also improve depressive symptoms and possibly health-related quality of life in PD. Nonetheless, its use is not devoid of tolerability problems. While peripheral adverse drug reactions, such as nausea, vomiting or orthostatic hypotension, can be effectively treated and usually pose few problems to most patients, neuropsychiatric events can seriously limit the use of pramipexole in some cases. Indeed, excessive daytime somnolence, impulse-control disorders, hallucinations or delusions can severely affect patients, causing important personal or social handicap. Patients should be informed about the risk of such neuropsychiatric complications and their presence should be actively detected at each consultation. More effort will have to be put into further studying the risk-benefit ratio of pramipexole and other dopamine agonists in the treatment of early PD.

Frequency of impulse control behaviours associated with dopaminergic therapy in restless legs syndrome

Background

Low doses of dopamine agonists (DA) and levodopa are effective in the treatment of restless legs syndrome (RLS). A range of impulse control and compulsive behaviours (ICBs) have been reported following the use of DAs and levodopa in patients with Parkinson's disease. With this study we sought to assess the cross-sectional prevalence of impulse control behaviours (ICBs) in restless legs syndrome (RLS) and to determine factors associated with ICBs in a population cohort in Germany.

Methods

Several questionnaires based on validated and previously used instruments for assessment of ICBs were mailed out to patients being treated for RLS. Final diagnoses of ICBs were based on stringent diagnostic criteria after psychiatric interviews were performed.

Results

10/140 RLS patients of a clinical cohort (7.1%) were finally diagnosed with ICBs, 8 of 10 on dopamine agonist (DA) therapy, 2 of 10 on levodopa. 8 of the 10 affected patients showed more than one type of abnormal behaviour. Among those who responded to the questionnaires 6/140 [4.3%] revealed binge eating, 5/140 [3.6%] compulsive shopping, 3/140 [2.1%] pathological gambling, 3/140 [2.1%] punding, and 2/140 [1.4%] hypersexuality in psychiatric assessments. Among those who did not respond to questionnaires, 32 were randomly selected and interviewed: only 1 patient showed positive criteria of ICBs with compulsive shopping and binge eating. ICBs were associated with higher DA dose (p = 0.001), younger RLS onset (p = 0.04), history of experimental drug use (p = 0.002), female gender (p = 0.04) and a family history of gambling disorders (p = 0.02), which accounted for 52% of the risk variance.

Conclusion

RLS patients treated with dopaminergic agents and dopamine agonists in particular, should be forewarned of potential side effects. A careful history of risk factors should be taken.

Variations in the GRIN2B gene are associated with risky decision-making

The dopaminergic system is known to modulate decision-making. As N-methyl-D-aspartate (NMDA) receptors strongly influence dopaminergic function, it is conceivable that the glutamatergic system is also involved in decision-making. We examined whether polymorphisms in the N-methyl-d-aspartate receptor 2B subunit gene (GRIN2B) influence decision-making using the Iowa Gambling Task (IGT). In total, 245 (n = 245, 127 female) healthy German students were included in the analysis. Two synonymous SNPs in exon 13, rs1806191 (H1178H) and rs1806201 (T888T) showed the strongest association with aspects of IGT performance. Females with a CC allele in rs1806201 made less use both of a win-stay strategy and demonstrated more exploratory behaviour during task execution. For rs1806191, we found a strong additive effect in usage of a win-stay strategy. This, partly sex-dependent, correlation of the win-stay/lose-shift behaviour with GRIN2B genotypes suggests that healthy individuals with certain GRIN2B variations respond differently to ambiguous conditions, possibly by altered perception of wins and losses. These findings underline the necessity to integrate the glutamatergic system when examining decision-making processes.