Impulsive and compulsive behaviors in Parkinson's disease: A one-year follow-up study

Burden of non-motor symptoms of Parkinson's disease: cost-of-illness and quality-of-life estimates through a scoping review

INTRODUCTION

Parkinson's Disease (PD) is a progressive, chronic neurodegenerative disease, representing significant economic and social burdens. It is typically defined by motor symptoms (MSs), however, this does not reflect the full patient burden. Non-motor symptoms (NMSs) are increasingly recognized as central characteristics of PD. However, they still lack recognition in research. Therefore, this study aims to identify relevant NMSs, their prevalence, and the effect they have on Quality-of-Life (QoL) and Cost-of-Illness (COI). Secondly, it aims to identify gaps in the current body of knowledge and propose possible ways future research could bridge those gaps.

METHODS

The study employed a scoping review, identifying 60 records for inclusion, using PubMed and Web of Science. It included studies from Spain or Italy, including data on People with Parkinson's Disease. A comparative analysis was performed using Microsoft Excel.

RESULTS

It showed that the body of evidence relevant to NMSs, their prevalence, QoL, and COI is limited, or that estimates vary to an extent where interpretation is difficult.

CONCLUSION

Most studies suffer from generalization, representation, and standardization issues, stemming from their designs and methodological decisions. Although the findings of this study should be interpreted with caution, several recommendations are made for future research.

Hypersexuality in neurological disorders: A systematic review

BACKGROUND

Hypersexuality (HS) accompanying neurological conditions remains poorly characterized despite profound psychosocial impacts. Objective We aimed to systematically review the literature on HS in patients with neurological disorders. Study selection and analysis We conducted a systematic review to identify studies that reported HS in neurological disorders. HS was defined as a condition characterized by excessive and persistent preoccupation with sexual thoughts, urges, and behaviors that cause significant distress or impairment in personal, social, or occupational functioning. Data on demographics, assessment techniques, associated elements, phenotypic manifestations, and management strategies were also extracted. Findings The final analysis included 79 studies on HS, encompassing 32 662 patients across 81 cohorts with neurological disorders. Parkinson's disease was the most frequently studied condition (55.6%), followed by various types of dementia (12.7%). Questionnaires were the most common assessment approach for evaluating HS, although the techniques varied substantially. Alterations in the dopaminergic pathways have emerged as contributing mechanisms based on the effects of medication cessation. However, standardized treatment protocols still need to be improved, with significant heterogeneity in documented approaches. Critical deficiencies include risks of selection bias in participant sampling, uncontrolled residual confounding factors, and lack of blinded evaluations of reported outcomes. Conclusions and clinical implications Despite growth in the last decade, research on HS remains limited across neurological conditions, with lingering quality and methodological standardization deficits. Key priorities include advancing assessment tools, elucidating the underlying neurobiology, and formulating management guidelines.

PROSPERO REGISTRATION NUMBER

CRD42017036478.

Punding in Parkinson's Disease: An Update

Background

Punding is a stereotyped behavior characterized by an intense fascination with a complex, excessive, non-goal oriented, repetitive activity affecting individuals with Parkinson's disease (PD) on dopamine replacement therapy (DRT).

Objectives

In 2010, we published the first review focused on the pathophysiology of punding. This study aims to systematically review the literature of the past decade on punding in PD, particularly focusing on the clinical features, underlying pathophysiological mechanisms, and treatment.

Methods

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we searched PubMed, Embase, and APA PsycInfo for articles published between July 1, 2010 and March 19, 2022. The search strategy included: (punding) AND (parkinson*).

Results

Of 256 studies identified, 29 were eligible for inclusion with 19 original research articles and 10 case reports. This review confirmed that predictors of punding in PD are higher doses of DRT, younger age, male sex, and increasing disease severity. We also found an association between punding and psychiatric and/or cognitive symptoms. Neuroimaging studies have showed that punding in PD is associated with a disconnection between midbrain, limbic and white matter tracts projecting to the frontal cortices and a breakdown of the connectivity among the crucial nodes of the reward circuit. Low-frequency repetitive transcranial magnetic stimulation on the dorsolateral prefrontal cortex has been shown to produce a transient beneficial effect in PD patients with punding.

Conclusion

In conclusion, although the clinical features of punding have been established, in the past 12 years, we gained a better understanding of the pathophysiological mechanisms of punding, mainly thanks to magnetic resonance imaging techniques.

A single-arm open-label pilot study of brief mindfulness meditation to control impulsivity in Parkinson’s disease

Background

Impulse control disorders are detrimental neuropsychiatric symptoms of Parkinson’s disease. Increased impulsivity is a predisposing factor for impulse control disorders and should therefore be controlled. Recently, mindfulness meditation as a non-drug therapy has been reported to be useful in improving neuropsychiatric symptoms, such as impulsivity.

Methods

We performed a prospective single-arm, open-label pilot trial to investigate the effectiveness of mindfulness meditation to control impulsivity in patients with Parkinson’s disease (UMIN clinical trials registry: UMIN000037779).

Results

Twenty patients with Parkinson’s disease were enrolled in an 8-week mindfulness meditation program. As a primary outcome, we investigated whether the score of the Barratt Impulsiveness Scale (BIS-11) was significantly reduced after the intervention. As an exploratory examination, functional connectivity changes were also assessed by resting-state functional magnetic resonance imaging. After the intervention, the BIS-11 score was decreased from 59.5 [55.6, 63.3] (mean [95% confidence interval]) to 55.2 [50.3, 60.1] (ΔBIS-11: -4.2, [-7.5, -0.9]). Functional connectivity was increased in the default mode network (DMN) at a cluster including the precuneus, posterior cingulate gyrus, and left posterior lobe (false discovery rate-adjusted p [FDR-p] = 0.046) and in the right frontoparietal network (FPN) at the medial frontal lobe (FDR-p = 0.039).

Conclusions

This open-label, single-arm pilot study provided preliminary data for mindfulness meditation to control the impulsivity of patients with PD. A brief mindfulness meditation program may be effective in controlling impulsivity in PD and may change the functional connectivity of the DMN and right FPN.

Impulse control disorders and related behaviors in Parkinson's disease: risk factors, clinical and genetic aspects, and management

PURPOSE OF REVIEW

To review recent findings and research directions on impulse control disorders and related behaviors (ICDRBs) in Parkinson's disease (PD).

RECENT FINDINGS

Longitudinal studies found that prevalence increases during PD progression, incident ICDRBs being around 10% per year in patients treated with dopaminergic therapies. Screening tools and severity scales already developed have been validated and are available in several countries and languages. The main clinical risk factors include young age, male gender, type, doses and duration of dopaminergic therapy, PD motor severity and dyskinesia, depression, anxiety, apathy, sleep disorders, and impulsivity traits. Genetic factors are suspected by a high estimated heritability, but individual genes and variants remain to be replicated. Management of ICDRBs is centered on dopamine agonist decrease, with the risk to develop withdrawal symptoms. Cognitive behavioral therapy and subthalamic nucleus deep brain stimulation also improve ICDRBs. In the perspective of precision medicine, new individual prediction models of these disorders have been proposed, but they need further independent replication.

SUMMARY

Regular monitoring of ICDRB during the course of PD is needed, particularly in the subject at high risk of developing these complications. Precision medicine will require the appropriate use of machine learning to be reached in the clinical setting.

Pathological gambling in a patient on piribedil: A case report

RATIONALE

Piribedil is an orally active dopamine agonist that has been widely used for Parkinson disease (PD), with its partial D2/D3 agonistic functions and alpha2-adrenoreceptor antagonistic effects, piribedil has been proved to be efficacious in the relief of motor symptoms in PD, while it can also lead to impulse control disorders such as pathological gambling due to its dopamine agonistic effects.

PATIENT CONCERNS

A 28-year-old Chinese female patient with Parkinson disease and a history of taking piribedil finally developed pathological gambling and depressive episode.

DIAGNOSES

After a careful clinical observation and evaluation, the patient met the criteria of severe depressive episode and pathological gambling due to antiparkinson therapy.

INTERVENTIONS

We discontinued piribedil and picked bupropion, a dopamine reuptake inhibitor, to alleviate the depressive symptom. Benzhexol and selegiline were also added for the control of motor fluctuations.

OUTCOMES

After 3 weeks' treatment, the patient's depressive mood was significantly alleviated and her recurring PD symptoms were also relieved. She was no more addicted to network gambling, and there was no recurrence during the 1-year follow-up.

LESSONS

Piribedil-induced problem gambling and impulse control disorders are side effects needed to be evaluated when commencing a patient on piribedil. This case further emphasizes the importance of monitoring and controlling Parkinson symptoms after drug reduction or withdrawal. Anticipation of this risk strengthens the significance of detailed medical history-taking and targeted clinical management.

The role of dopamine pharmacotherapy and addiction-like behaviors in Parkinson's disease

Addictions involve a spectrum of behaviors that encompass features of impulsivity and compulsivity, herein referred to as impulsive-compulsive spectrum disorders (ICSDs). The etiology of ICSDs likely involves a complex interplay among neurobiological, psychological and social risk factors. Neurobiological risk factors include the status of the neuroanatomical circuits that govern ICSDs. These circuits can be altered by disease, as well as exogenous influences such as centrally-acting pharmacologics. The 'poster child' for this scenario is Parkinson's disease (PD) medically managed by pharmacological treatments. PD is a progressive neurodegenerative disease that involves a gradual loss of dopaminergic neurons largely within nigrostriatal projections. Replacement therapy includes dopamine receptor agonists that directly activate postsynaptic dopamine receptors (bypassing the requirement for functioning presynaptic terminals). Some clinically useful dopamine agonists, e.g., pramipexole and ropinirole, exhibit high affinity for the D2/D3 receptor subtypes. These agonists provide excellent relief from PD motor symptoms, but some patients exhibit debilitating ICSD. Teasing out the neuropsychiatric contribution of PD-associated pathology from the drugs used to treat PD motor symptoms is challenging. In this review, we posit that modern clinical and preclinical research converge on the conclusion that dopamine replacement therapy can mediate addictions in PD and other neurological disorders. We provide five categories of evidences that align with this position: (i) ICSD prevalence is greater with D2/D3 receptor agonist therapy vs PD alone. (ii) Capacity of dopamine replacement therapy to produce addiction-like behaviors is independent of disease for which the therapy is being provided. (iii) ICSD-like behaviors are recapitulated in laboratory rats with and without PD-like pathology. (iv) Behavioral pathology co-varies with drug exposure. (v) ICSD Features of ICSDs are consistent with agonist pharmacology and neuroanatomical substrates of addictions. Considering the underpinnings of ICSDs in PD should not only help therapeutic decision-making in neurological disorders, but also apprise ICSDs in general.

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.

Dopamine Agonists and Impulse Control Disorders: A Complex Association

Impulse control disorders (ICDs) are a well-known adverse effect of dopamine agonists (DAAs). This critical review aims to summarize data on the prevalence and factors associated with the development of an ICD simultaneous to DAA use. A search of two electronic databases was completed from inception to July 2017. The search terms were medical subject headings (MeSH) terms including “dopamine agonists” AND “disruptive disorders”, “impulse control disorders”, or “conduct disorders”. Articles had to fulfill the following criteria to be included: (i) the target problem was an ICD; (ii) the medication was a dopaminergic drug; and (iii) the article was an original article. Of the potential 584 articles, 90 met the criteria for inclusion. DAAs were used in Parkinson’s disease (PD), restless legs syndrome (RLS) or prolactinoma. The prevalence of ICDs ranged from 2.6 to 34.8% in PD patients, reaching higher rates in specific PD populations; a lower prevalence was found in RLS patients. We found only two studies about prolactinoma. The most robust findings relative to the factors associated with the development of an ICD included the type of DAA, the dosage, male gender, a younger age, a history of psychiatric symptoms, an earlier onset of disease, a longer disease duration, and motor complications in PD. This review suggests that DAA use is associated with an increased risk in the occurrence of an ICD, under the combined influence of various factors. Guidelines to help prevent and to treat ICDs when required do exist, although further studies are required to better identify patients with a predisposition.

The factors associated with impulse control behaviors in Parkinson's disease: A 2-year longitudinal retrospective cohort study

INTRODUCTION

Impulse control behaviors (ICBs) are impulsive-compulsive behaviors often associated with dopamine replacement therapy in Parkinson's disease (PD). Although remission can occur in ICB, only four reports on the ratio of remission and the persistence of ICB have been published, and the associated factors with ICB remission or persistence have been little known. Therefore, we conducted a longitudinal assessment of the remission, persistence, and development of ICB and those associated factors in patients with PD.

METHODS

We retrospectively investigated a PD database at Aomori Prefectural Central Hospital, Japan. One hundred and forty-eight patients with PD who could be followed up for 2 years were enrolled. ICB was assessed using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's disease. Motor severity (Hoehn and Yahr scale and United Parkinson's Disease Rating Scale), cognitive function (Mini-Mental State Examination), and other clinical variables (sex, age, onset age, disease duration, olfactory dysfunction, and dyskinesia) and medications used to treat PD were assessed. Univariate analyses were performed.

RESULTS

Seven patients were excluded because of the exclusion criteria, and 141 patients were analyzed. Thirty patients (21.3%) had ICB at baseline, and these patients also had significantly higher use of pergolide. The ICB remission rate was 60%, the ICB persistence ratio was 40%, and the ICB development ratio was 12.6% over 2 years. Statistically, younger age and pergolide use were associated with ICB persistence. Being male, having dyskinesia, and rotigotine, entacapone, zonisamide, and istradefylline use were associated with ICB development.

CONCLUSION

This study suggests that younger age and pergolide use may be the new associated factors with ICB persistence and that entacapone, zonisamide, and istradefylline use may be associated with the development of ICB. Drug profiles and medication practices in Japan may explain the association of these factors with ICB.

Psychiatric Conditions in Parkinson Disease: A Comparison With Classical Psychiatric Disorders

Psychiatric conditions often complicate the outcome of patients affected by Parkinson disease (PD), but they differ from classical psychiatric disorders in terms of underlying biological mechanisms, clinical presentation, and treatment response. The purpose of the present review is to illustrate the biological and clinical aspects of psychiatric conditions associated with PD, with particular reference to the differences with respect to classical psychiatric disorders. A careful search of articles on main databases was performed in order to obtain a comprehensive review about the main psychiatric conditions associated with PD. A manual selection of the articles was then performed in order to consider only those articles that concerned with the topic of the review. Psychiatric conditions in patients with PD present substantial differences with respect to classical psychiatric disorders. Their clinical presentation does not align with the symptom profiles represented by Diagnostic and Statistical Manual for Mental Disorders and International Classification of Diseases. Furthermore, psychiatry treatment guidelines are of poor help in managing psychiatric symptoms of patients with PD. Specific diagnostic tools and treatment guidelines are needed to allow early diagnosis and adequate treatment of psychiatric conditions in comorbidity with PD.

Piribedil and pathological gambling in six parkinsonian patients

Impulse control disorders (ICD) in Parkinson's disease (PD) have attracted increasing interest. They are characterized by the inability to control the impulse to perform an act that can be detrimental to them or to others. Although dopamine agonists (DA), as a group, have been associated with impulse control disorders (ICD), piribedil has rarely been reported to cause them.

METHOD

Case reports of six parkinsonian patients on piribedil presenting pathological gambling (PG).

RESULTS

All of the patients presented ICD associated with piribedil use. Two of them received this medication as first treatment and four of them who had developed ICDs secondary to other DA that reappeared with piribedil.

CONCLUSION

Despite piribedil is commercially available in only a few countries, it should be considered in the differential diagnosis of PG in patients with PD.

Long-term cognitive follow-up of Parkinson's disease patients with impulse control disorders

This study investigated cognitive functions in Parkinson's disease (PD) patients with impulse control disorders (ICDs) and aimed to identify possible predictors of behavioral outcome. In this longitudinal cohort study, 40 PD outpatients with ICDs and 40 without, were matched for sex, age at PD onset, age and disease duration at cognitive assessment. All patients had two neuropsychological assessments at least 2 years apart (mean, 3.5 years). Multivariate logistic regression analysis was performed to identify predictors of ICDs remission at follow-up. The PD patients with and without ICDs had overall comparable cognitive performance at baseline. When evaluating changes between baseline and follow-up, we found significant group × time interactions in several frontal lobe-related tests, with the ICDs group showing a less pronounced worsening over time. ICDs remission was associated with better performance at baseline in working memory-related tasks, such as digit span (odds ratio [OR] = 2.69 [95% confidence interval (CI), 1.09-6.66]) and attentive matrices (OR=1.19 [95%CI, 1.03-1.37]). ICDs remitters and non-remitters had no remarkable differences in baseline PD-related features and therapy management strategies (including the extent of dopamine agonist dose reduction). In conclusion, ICDs in PD patients are not related to greater cognitive impairment or executive dysfunction, but rather show relatively lower cognitive decline over time. The impaired top-down inhibitory control characterizing ICDs is likely attributable to a drug-induced overstimulation of relatively preserved prefrontal cognitive functions. Full behavioral remission in the long term was predicted by better working memory abilities. © 2015 International Parkinson and Movement Disorder Society.

A systematic review of treatments for Impulse Control Disorders and related behaviours in Parkinson's disease

Impulse Control Disorders (ICDs) are a set of behaviours characterised by impulsivity despite known harm. Related to ICDs is the dopamine dysregulation syndrome (DDS), which is characterised by an addiction-like consumption of dopaminergic medication and punding. These behaviours all have an increased prevalence in Parkinson׳s disease (PD). The aim of this review is to identify treatments available for patients suffering from ICDs, DDS and punding in PD. Searches of The Cochrane Controlled Trials Register, Embase, Medline and PsychInfo were conducted, using the entire timescale available. Seven out of the 688 papers retrieved met the inclusion criteria and were considered in this systematic review. One class I study, one class II study, and five class IV studies were identified. All studies demonstrated a positive effect on ICDs in PD. Research in this field is still in its early stages. At present, there is insufficient evidence to recommend any treatment over another. There is a need for more methodologically robust research, using larger, more generalisable samples, randomisation and meaningful follow-up periods. In addition, the use of a validated outcome measures should be implemented in future research efforts.

Neuropsychological findings in a case of punding before and after cessation of pramipexole

Clinical neuropsychologists are well trained to recognize neurological and psychiatric conditions that impact behavior, but tend to have less familiarity with iatrogenic consequences of various pharmacological treatments. One such consequence is the development of an impulse control disorder (ICD), which can result from treatment with dopamine agonists. Knowledge of ICDs is important because they can mimic obsessive-compulsive disorder, mania, or the behavioral variant of frontotemporal dementia. The current case examines a patient who developed punding, which is a type of ICD characterized by repetitive behavior, as a result of treatment with pramipexole. Neuropsychological testing was conducted before and after cessation of pramipexole, and showed that the removal of the medication was consistent with improvement in frontal-subcortical-mediated cognitive functions. Findings suggest that neuropsychologists should be familiar with the symptoms of ICDs and incorporate such knowledge into their case conceptualizations.

Sex addiction and gambling disorder: similarities and differences

OBJECTIVE

Recently, the DSM-5 has developed a new diagnostic category named "Substance-related and Addictive Disorders". This category includes gambling disorder (GD) as the sole behavioral addiction, but does not include sex addiction (SA). The aim of this study is to investigate whether SA should be classified more closely to other behavioral addictions, via a comparison of the personality characteristics and comorbid psychopathology of individuals with SA with those of individuals with GD, which comes under the category of addiction and related disorders.

METHOD

The sample included 59 patients diagnosed with SA, who were compared to 2190 individuals diagnosed with GD and to 93 healthy controls. Assessment measures included the Diagnostic Questionnaire for Pathological Gambling, the South Oaks Gambling Screen, the Symptom CheckList-90 Items-Revised and the Temperament and Character Inventory-Revised.

RESULTS

No statistically significant differences were found between the two clinical groups, except for socio-economic status. Although statistically significant differences were found between both clinical groups and controls for all scales on the SCL-90, no differences were found between the two clinical groups. The results were different for personality characteristics: logistic regression models showed that sex addictive behavior was predicted by a higher education level and by lower scores for TCI-R novelty-seeking, harm avoidance, persistence and self-transcendence. Being employed and lower scores in cooperativeness also tended to predict the presence of sex addiction.

CONCLUSIONS

While SA and GD share some psychopathological and personality traits that are not present in healthy controls, there are also some diagnostic-specific characteristics that differentiate between the two clinical groups. These findings may help to increase our knowledge of phenotypes existing in behavioral addictions.

Behavioral effects of levodopa

In recent years, levodopa-induced behavioral changes have received increased attention in the medical literature and in clinical practice. The spectrum of these symptoms includes non-motor fluctuations with neuropsychiatric symptoms, compulsive behaviors such as punding, dopamine dysregulation syndrome, and impulse control disorders, psychosis and hallucinations, as well as hypomania and mania. Despite knowledge of the clinical features associated with these behaviors, many of them are probably underdiagnosed. Although the mechanisms underlying behavioral symptoms are still incompletely understood, recent data from imaging and pathological studies have increased our understanding and guided new treatment strategies. Appropriate management remains challenging, because reduction of levodopa (l-dopa) and dopaminergic treatment is often recommended; however, doses required for control of motor symptoms may still induce behavioral changes. Newer modes of delivery of dopaminergic treatment, deep brain stimulation, and nondopaminergic agents may either provide alternatives for treatment of these behavioral problems or permit treatment of parkinsonism with less risk of these behavioral disorders.

Impulsive and compulsive behaviors in Parkinson's disease

BACKGROUND

Impulsive and compulsive behaviors (ICBs) are a heterogeneous group of conditions that may be caused by long-term dopaminergic replacement therapy (DRT) of Parkinson's disease (PD). The spectrum of ICBs includes dopamine dysregulation syndrome (DDS), punding, and impulse control disorders (ICDs).

CONTENTS

We made a detailed review regarding the epidemiology, pathology, clinical characteristics, risk factors, diagnosis as well as treatment of ICBs.

RESULTS

The prevalence of ICBs in PD patients is approximately 3-4% for DDS, 0.34-4.2% for punding, and 6-14% for ICDs, with higher prevalence in Western populations than in Asian. Those who take high dose of levodopa are more prone to have DDS, whereas, ICDs are markedly associated with dopamine agonists. Different subtypes of ICBs share many risk factors such as male gender, higher levodopa equivalent daily dose, younger age at PD onset, history of alcoholism, impulsive, or novelty-seeking personality. The Questionnaire for Impulsive-Compulsive Disorder in Parkinson's Disease-Rating Scale seems to be a rather efficacious instrument to obtain relevant information from patients and caregivers. Treatment of ICBs is still a great challenge for clinicians. Readjustment of DRT remains the primary method. Atypical antipsychotics, antidepressants, amantadine, and psychosocial interventions are also prescribed in controlling episodes of psychosis caused by compulsive DRT, but attention should be drawn to balance ICBs symptoms and motor disorders. Moreover, deep brain stimulation of the subthalamic nucleus might be a potential method in controlling ICBs.

CONCLUSION

The exact pathophysiological mechanisms of ICBs in PD remains poorly understood. Further researches are needed not only to study the pathogenesis, prevalence, features, and risk factors of ICBs, but to find efficacious therapy for patients with these devastating consequences.

Diagnosis and treatment of impulse control disorders in patients with movement disorders

Impulse control disorders are a psychiatric condition characterized by the failure to resist an impulsive act or behavior that may be harmful to self or others. In movement disorders, impulse control disorders are associated with dopaminergic treatment, notably dopamine agonists (DAs). Impulse control disorders have been studied extensively in Parkinson's disease, but are also recognized in restless leg syndrome and atypical Parkinsonian syndromes. Epidemiological studies suggest younger age, male sex, greater novelty seeking, impulsivity, depression and premorbid impulse control disorders as the most consistent risk factors. Such patients may warrant special monitoring after starting treatment with a DA. Various individual screening tools are available for people without Parkinson's disease. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease has been developed specifically for Parkinson's disease. The best treatment for impulse control disorders is prevention. However, after the development of impulse control disorders, the mainstay intervention is to reduce or discontinue the offending anti-Parkinsonian medication. In refractory cases, other pharmacological interventions are available, including neuroleptics, antiepileptics, amantadine, antiandrogens, lithium and opioid antagonists. Unfortunately, their use is only supported by case reports, small case series or open-label clinical studies. Prospective, controlled studies are warranted. Ongoing investigations include naltrexone and nicotine.

Uncertainty about mapping future actions into rewards may underlie performance on multiple measures of impulsivity in behavioral addiction: evidence from Parkinson's disease

A subset of patients with Parkinson's disease (PD) develops behavioral addictions, which may be due to their dopamine replacement therapy. Recently, several groups have been comparing PD patients with and without behavioral addictions on tasks that are thought to measure aspects of impulsivity. Several of these experiments, including information sampling, a bias toward novel stimuli and temporal discounting, have shown differences between PD patients with and without behavioral addictions. We have developed a unifying theoretical framework that allows us to model behavior in all three of these tasks. By exploring the performance of the patient groups on the three tasks with a single framework, we can ask questions about common mechanisms that underlie all three. Our results suggest that the effects seen in all three tasks can be accounted for by uncertainty about the ability to map future actions into rewards. More specifically, the modeling is consistent with the hypothesis that the group with behavioral addictions behaves as if they cannot use information provided within the experimental context to improve future reward guided actions. Future studies will be necessary to more firmly establish (or refute) this hypothesis. We discuss this result in light of what is known about the pathology that underlies the behavioral addictions in the PD patients.

Pramipexole-induced disruption of behavioral processes fundamental to intertemporal choice

Evaluating the effects of presession drug administration on intertemporal choice in nonhumans is a useful approach for identifying compounds that promote impulsive behavior in clinical populations, such as those prescribed the dopamine agonist pramipexole (PPX). Based on the results of previous studies, it is unclear whether PPX increases rats' impulsive choice or attenuates aspects of stimulus control. The present study was designed to experimentally isolate behavioral processes fundamental to intertemporal choice and challenge them pharmacologically with PPX administration. In Experiment 1, the hypothesis that PPX increases impulsive choice as a result of enhanced sensitivity to reinforcer delays was tested and disconfirmed. That is, acute PPX diminished delay sensitivity in a manner consistent with disruption of stimulus control whereas repeated PPX had no effect on delay sensitivity. Experiments 2 and 3 elaborated upon this finding by examining the effects of repeated PPX on rats' discrimination of response-reinforcer contingencies and reinforcer amounts, respectively. Accuracy of both discriminations was reduced by PPX. Collectively these results provide no support for past studies that have suggested PPX increases impulsive choice. Instead, PPX impairs stimulus control over choice behavior. The behavioral approach adopted herein could be profitably integrated with genetic and other biobehavioral models to advance our understanding of impulsive behavior associated with drug administration.

Prefrontal dopamine signaling and cognitive symptoms of Parkinson's disease

Cognitive dysfunction is a common symptom of Parkinson's disease (PD) that causes significant morbidity and mortality. The severity of these symptoms ranges from minor executive symptoms to frank dementia involving multiple domains. In the present review, we will concentrate on the aspects of cognitive impairment associated with prefrontal dopaminergic dysfunction, seen in non-demented patients with PD. These symptoms include executive dysfunction and disorders of thought, such as hallucinations and psychosis. Such symptoms may go on to predict dementia related to PD, which involves amnestic dysfunction and is typically seen later in the disease. Cognitive symptoms are associated with dysfunction in cholinergic circuits, in addition to the abnormalities in the prefrontal dopaminergic system. These circuits can be carefully studied and evaluated in PD, and could be leveraged to treat difficult clinical problems related to cognitive symptoms of PD.

Psychiatric syndromes in Parkinson's disease

PURPOSE OF REVIEW

To examine progress about relevant behavioural and psychiatric disorders in Parkinson's disease, such as depression, apathy, psychosis, and impulse control disorder.

RECENT FINDINGS

Several recent studies have characterized the phenomenology of depression in Parkinson's disease, and randomized controlled trials have demonstrated the efficacy of tricyclics, selective serotonin reuptake inhibitors and psychotherapy for depression in Parkinson's disease. Apathy is a valid behavioural syndrome in Parkinson's disease and is associated with depression and cognitive deficits. Psychosis is highly prevalent in the late stages of the disease, but there are few effective therapeutic modalities for this psychiatric condition. Impulse control disorders are also relatively frequent in Parkinson's disease, and are associated with comorbid psychiatric disorders.

SUMMARY

Standardized criteria should be used to diagnose depression and apathy in Parkinson's disease. Psychotherapy and pharmacotherapy are useful treatment modalities for affective disorders in Parkinson's disease. Clozapine is still the most effective, albeit rarely used, treatment for psychosis in Parkinson's disease. Impulse control disorders are relatively frequent in Parkinson's disease and all patients should be screened for this complex disorder.

Impulse control disorders in Parkinson's disease: background and update on prevention and management

Given that impulse control disorders (ICDs) have been identified among a considerable minority of Parkinson's disease (PD) patients, these conditions have gained increased clinical and research attention in the past decade. Dopamine-replacement therapies, taken to ameliorate PD symptoms, have been associated with ICDs in PD. Unfortunately, there are relatively sparse empirical data regarding how best to address ICDs in PD patients. Conversely, progress has been made in understanding the clinical, neurobiological and cognitive correlates of ICDs in PD. Some of these findings may inform possible courses of action for care providers working with PD patients with ICDs. The literature on ICDs in non-PD populations may also be informative in this regard. The goals of the present article are to outline important clinical characteristics of ICDs in PD, briefly review relevant neurocognitive and neurobiological studies and discuss possible ways to prevent and manage ICDs in PD.