Dopamine dysregulation syndrome in Parkinson's disease: from clinical and neuropsychological characterisation to management and long-term outcome

Management of Impulse Control and Related Disorders in Parkinson's Disease: An Expert Consensus

BACKGROUND

Impulse-control and related behavioral disorders (ICBDs) significantly impact the lives of Parkinson's disease (PD) patients and caregivers, with lasting consequences if undiagnosed and untreated. While ICBD pathophysiology and risk factors are well-studied, a standardized severity definition and treatment evidence remain elusive.

OBJECTIVE

This work aimed to establish international expert consensus on ICBD treatment strategies. To comprehensively address diverse treatment availabilities, experts from various continents were included.

METHODS

From 2021 to 2023, global movement disorders specialists engaged in a Delphi process. A core expert group initiated surveys, involving a larger panel in three iterations, leading to refined severity definitions and treatment pathways.

RESULTS

Experts achieved consensus on defining ICBD severity, emphasizing regular PD patient screenings for early detection. General treatment recommendations focused on continuous monitoring, collaboration with significant others, and seeking specialist advice for legal or financial challenges. For mild to severe ICBDs, gradual reduction in dopamine agonists was endorsed, followed by reductions in other PD medications. Second-line treatment strategies included diverse approaches like reversing the last medication change, cognitive behavior therapy, subthalamic nucleus deep brain stimulation, and specific medications like quetiapine, clozapine, and antidepressants. The panel reached consensus on distinct treatment pathways for punding and dopamine dysregulation syndrome, formulating therapy recommendations. Comprehensive discussions addressed management strategies for the exacerbation of either motor or non-motor symptoms following the proposed treatments.

CONCLUSION

The consensus offers in-depth insights into ICBD management, presenting clear severity criteria and expert consensus treatment recommendations. The study highlights the critical need for further research to enhance ICBD management. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Predictors of dopamine dysregulation syndrome in patients with early Parkinson's disease

BACKGROUND

Dopamine dysregulation syndrome (DDS) is a complication of Parkinson's disease (PD) that seriously affects the quality of life of PD patients. Currently, the risk factors for DDS are poorly known, and it is critical to identify them in the early stages of PD.

OBJECTIVE

To explore the incidence of and risk factors for DDS in patients with early PD.

METHODS

A retrospective cohort study was conducted on the general data, clinical features, and imaging data of patients with early PD in the PPMI database. Multivariate Cox regression analysis was performed to analyze the risk factors for the development of DDS in patients with early PD, and Kaplan‒Meier curves examined the frequency and predictors of incident DDS symptoms.

RESULTS

At baseline, 2.2% (n = 6) of patients with early PD developed DDS, and the cumulative incidence rates of DDS during the 5-year follow-up period were 2.8%, 6.4%, 10.8%, 15.5%, and 18.7%, respectively. In the multivariate Cox regression model controlling for age, sex, and drug use, hypersexuality (HR = 3.088; 95% CI: 1.416~6.732; P = 0.005), compulsive eating (HR = 3.299; 95% CI: 1.665~6.534; P = 0.001), compulsive shopping (HR = 3.899; 95% CI: 1.769~8.593; P = 0.001), anxiety (HR = 4.018; 95% CI: 2.136~7.599; P < 0.01), and lower Hoehn-Yahr (H-Y) stage (HR = 0.278; 95% CI: 0.152~0.509; P < 0.01) were independent risk factors for DDS in patients with early PD. PD patients with DDS had lower DAT uptake values than those patients without DDS.

CONCLUSION

Early PD patients with hypersexuality, compulsive eating, compulsive shopping, anxiety, and lower H-Y stage were at increased risk for DDS. The occurrence of DDS may be related to the decrease in the average DAT uptake of the caudate and putamen.

Case report: Dopamine Dysregulation Syndrome, mania, and compulsive buying in a patient with Parkinson's disease

Neuropsychiatric symptoms and syndromes are among the most common non-motor symptoms of Parkinson's Disease but they are frequently unrecognized and untreated. Dopamine Dysregulation Syndrome is an uncommon complication of the treatment of Parkinson's disease, characterized by an addictive use of dopamine far more than the dosage required for treatment of objective motor impairment, leading to severe dyskinesia, euphoria, aggressivity, or psychosis. We present a paradigmatic case of Dopamine Dysregulation Syndrome, Mania, and Compulsive Buying in a 55-year-old male with Parkinson's Disease. We also reviewed the risk factors and the therapeutic management of Dopamine Dysregulation Syndrome in Parkinson's Disease.

Continuous Subcutaneous Infusion Delivery of Apomorphine in Parkinson's Disease: A Systematic Review

Background

Continuous subcutaneous apomorphine infusion (CSAI) is one of the advanced therapies for Parkinson's disease (PD).

Methods

A systematic review of all published articles in English on CSAI for PD till January 30, 2022 was conducted.

Results

A total of 82 articles met the search criteria. Publications included retrospective or prospective open-label observational studies, with a limited number of randomized control trials (RCT). Publications were highly heterogeneous and focused on different aspects of CSAI and included clinical audits, effects on cognition/behavior, axial symptoms, nocturnal issues, adverse events/reasons for discontinuation and comparison with other continuous dopaminergic therapies. CSAI was used in patients who presented severe motor fluctuations not resolved by oral therapy, poor candidates for deep brain stimulation (DBS) due to cognitive/behavioral issues or in those with DBS weaning effect. Recent studies have also shown that CSAI was useful for nocturnal usage in advanced PD, in addition to daytime utilization. Adverse effects were common and include skin lesions, sedation and nausea. Pump management difficulties and patient decisions were common reasons for therapy dropout, predominantly during the initial stages of the CSAI.

Conclusion

There is consistent agreement on the benefits of CSAI in reducing OFF periods and improving ON periods without troublesome dyskinesia and specific motor and non-motor symptoms. Although there is a paucity of RCTs, current data from almost 30 years of use suggests CSAI to be beneficial in advanced cases of PD.

A single centre prospective study of three device-assisted therapies for Parkinson's disease

Comparative studies assessing outcomes with the three device-assisted therapies could help to individualise treatment for patients living with Parkinson's disease. We designed a single-centre non-randomised prospective observational study assessing the quality of life (QoL), motor and non-motor outcomes at 6 and 12-months in patients treated with subcutaneous apomorphine continuous 16-hours infusion (APO), levodopa-carbidopa intestinal gel (LCIG) or subthalamic nucleus deep brain stimulation (STN-DBS). In this study, 66 patients were included (13 APO; 19 LCIG; 34 STN-DBS). At baseline, cognitive, non-motor and motor scores were significantly less severe in the STN-DBS group, whereas the LCIG group had a longer disease duration and higher non-motor scores. In the APO group, there were no statistically significant changes in non-motor, motor and QoL scales. The LCIG group had significant changes in QoL and motor scales that were significant after multiple comparison analysis at 6 and 12-months. The STN-DBS group showed improvement in QoL scores and non-motor and motor scores at 6 and 12-months after multiple comparison analysis. In this real-life prospective study, device-assisted therapies showed differences in their effects on QoL and motor and non-motor function at 12-months. However, there were also differences in baseline characteristics of the patient groups that were not based on pre-determined selection criteria. Differences in characteristics of patients offered and/or treatment with different device-assisted therapies may reflect within-centre biases that may, in turn, influence perceptions of treatment efficacy or outcomes. Treatment centres should be aware of this potential confounder when assessing and offering device-assisted treatment options to their patients and potential baseline differences need to be taken into consideration when comparing the results of non-randomised studies.

Subthalamic Oscillatory Activity of Reward and Loss Processing Using the Monetary Incentive Delay Task in Parkinson Disease

BACKGROUND

The subthalamic nucleus (STN) is an effective deep brain stimulation target for Parkinson disease (PD) and obsessive-compulsive disorder and has been implicated in reward and motivational processing. In this study, we assessed the STN and prefrontal oscillatory dynamics in the anticipation and receipt of reward and loss using a task commonly used in imaging.

MATERIALS AND METHODS

We recorded intracranial left subthalamic local field potentials from deep brain stimulation electrodes and prefrontal scalp electroencephalography in 17 patients with PD while they performed a monetary incentive delay task.

RESULTS

During the expectation phase, enhanced left STN delta-theta activity was observed in both reward and loss vs neutral anticipation, with greater STN delta-theta activity associated with greater motivation specifically to reward. In the consummatory outcome phase, greater left STN delta activity was associated with a rewarding vs neutral outcome, particularly with more ventral contacts along with greater delta-theta coherence with the prefrontal cortex. We highlight a differential activity in the left STN to loss vs reward anticipation, demonstrating a distinct STN high gamma activity. Patients with addiction-like behaviors show lower left STN delta-theta activity to loss vs neutral outcomes, emphasizing impaired sensitivity to negative outcomes.

CONCLUSIONS

Together, our findings highlight a role for the left STN in reward and loss processing and a potential role in addictive behaviors. These findings emphasize the cognitive-limbic function of the STN and its role as a physiologic target for neuropsychiatric disorders.

Dementia-Associated Compulsive Singing (DACS): Presentation of Unpublished Clinical Cases Miniseries

Dementia-associated compulsive singing (DACS) is a neurotransmettitorial-based behavioral disturbance, characterized by an unabating melodic expression, occurring in patients that suffer from evolved dementia. Previously described only as a "punding" aspect of the dopamine dysregulation syndrome (DDS) in the Parkinson's disease (PD), compulsive singing has now been described, for the first time, in four non-PD patients effectively treated with Haloperidol or Quetiapine. Unlike the DDS-associated conditions, in our cases DACS is not pharmacologically induced, being that all patients were L-dopa-free. We detected a diffuse hyperintensity of the white matter and brain atrophy, with insular shrinkage as well as ventricular system and/or sub-arachnoid space enlargement in our DACS patients. Furthermore, similarly to the other behavioral symptoms of dementia, DACS also seems to be correlated to the degree of cognitive and functional impairment, rather than its subtype. In conclusion, DACS is a non-cognitive, unpublished clinical aspect of evolved dementia, which is interesting due to the involvement of the extra-nigral dopaminergic system, resulting in an unabating altered behavior, but also to the enrichment of our knowledge in the involutional diseases of the central nervous system and their physiopathological manifestations.

Abuse/Misuse of Prescription Medications in Older Adults

The world population is aging due to increasing life expectancy. The rate of drug use increases, and inappropriate prescribing is frequently encountered with advancing age. In addition, misuse and abuse of prescription drugs is a serious problem in older adults. It is challenging to detect substance and drug abuse in older patients because it may have fewer consequences in social, legal, and occupational fields. However, there is not enough information about the screening, evaluation, diagnosis, and treatment of abuse. Therefore, the awareness of health care professionals and others involved in older patients' care should be raised about the misuse and abuse of drugs.

Impulse Control Disorders and Levodopa-Induced Dyskinesias in Parkinson's Disease: Pulsatile versus Continuous Dopaminergic Stimulation

BACKGROUND

Dopaminergic medications in Parkinson's disease (PD) are usually associated with the development of both levodopa-induced dyskinesias (LID) and impulse control and repetitive behavior disorders (ICRB).

OBJECTIVE

To assess the prevalence and the severity of ICRB in a cohort of moderate and advanced PD patients and to investigate the potential interplay between ICRB, LID and dopaminergic therapies.

METHODS

117 PD patients were consecutively recruited. LID were assessed by using the Rush Dyskinesia Rating Scale (RDRS). ICRB were tested by means of Questionnaire for Impulsive Compulsive Disorders in Parkinson's Disease Rating Scale (QUIP-RS).

RESULTS

55 patients were affected by LID. Among them, 37 were treated only by oral therapy, OT (LID/OT), while 18 were on treatment with jejunal levodopa infusion, JLI (LID/JLI). 62 patients were not affected by LID (NLID) and all of them were on therapy only with oral drugs. The overall prevalence of clinically significant ICRB was 34% (95% CI = 26% to 43%) and the mean value (±SD) of QUIP-RS total score was 5.4±8.5. Prevalence of clinically significant ICRB, as well as severity of ICRB, was higher in patients with LID compared to NLID patients (p = 0.016 and p < 0.001, respectively). When considering LID/JLI, LID/OT and NLID groups, QUIP-RS total score was significantly higher in LID/OT patients compared to LID/JLI (10.4±11.8 vs. 4.9±6.0, p = 0.019) and NLID (10.4±11.8 vs. 2.5±4.8, p < 0.001) groups.

CONCLUSION

PD patients with LID show ICRB more frequently and more severely than patients without LID. Among LID patients, those treated by JLI showed a lower severity of ICRB than those on OT, suggesting a potential protective effect of JLI on ICRB.

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.

New pharmacological and neuromodulation approaches for impulsive-compulsive behaviors in Parkinson's disease

INTRODUCTION

A significant proportion of patients with Parkinson's disease (PD) display a set of impulsive-compulsive behaviors at some point during the course of illness. These behaviors range from the so-called behavioral addictions to dopamine dysregulation syndrome, punding and hoarding disorders. These behaviors have been consistently linked to the use of dopaminergic medications used to treat PD motor symptoms (dopamine agonists, levodopa, and other agents) and less consistently to neuromodulation techniques such as deep brain stimulation (DBS). Since there are still no approved treatments for these conditions, their pharmacological management is still a big challenge for clinicians.

METHODS

We conducted an extensive review of current pharmacological and neuromodulation literature for the management of impulsive-compulsive disorders in PD patients.

RESULTS

Pharmacological treatment approaches for impulsive-compulsive behaviors and DDS in PD patients include reduction of levodopa (LD), reduction/cessation of dopamine agonist (DA), and initiation of infusion therapies (apomorphine infusion and duodopa). Also, atomoxetine, a noradrenergic agent approved for the treatment of attention deficit hyperactivity disorder, showed some interesting preliminary results but there is still a lack of controlled longitudinal studies. Finally, while DBS effects on impulsive-compulsive disorders are still controversial, non-invasive techniques (such as transcranial magnetic stimulation and transcranial direct current stimulation) could have a potential positive effect but, again, there is still a lack of controlled trials.

CONCLUSION

Managing impulsivity and compulsivity in PD patients is still a non-evidence-based challenge for clinicians. Controlled trials on promising approaches such as atomoxetine and non-invasive neuromodulation techniques are needed.

Hypomania, Depression, Euthymia: New Evidence in Parkinson's Disease

The field related to mood disorders in Parkinson's disease (PD) is fragmented. The aim of this cohort observational study was to evaluate whether the episodes of mood alteration could appear in different disease stages and to verify how nonmotor symptoms were led off into different stages. We enrolled 93 PD outpatients (three groups: drug naive—DN; not exhibiting motor fluctuations—n-MF; and exhibiting motor fluctuations—MF) and 50 healthy controls. Mood state was assessed through the Internal State Scale (ISS) while depressive symptoms were evaluated through the Beck Depression Inventory-II (BDI-II), nonmotor symptoms by means of the Non-Motor Symptoms Scale (NMSS), and the presence of impulse control disorders (ICDs) with the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP). Clinical and pharmacological data have also been recorded. No significant differences in mood state distribution between groups were observed. Nevertheless, as regards the mood state distribution within groups, in n-MF (47.6%) and MF patients (50%), (hypo)mania presence was significantly higher than other symptoms. In DN patients, hypomania showed a prevalence of 38.1% although it was not significant. At least one ICD was reported in 29.3% of n-MF and 50% of MF patients. In the MF group, a moderate positive correlation between ISS ACTivation subscale scores and the presence of ICDs and compulsive medication use emerged. Finally, MF patients reported higher BDI-II total scores than DN. Our results show that mood alterations in PD, considering both depressive symptoms and mood elevation, are related to the advanced stages of the disease as well as the presence of ICDs, and dopaminergic therapy would not always be able to restore a normal mood condition.

Contributing Factors and Evolution of Impulse Control Disorder in the Luxembourg Parkinson Cohort

Background: To establish the frequency of impulse control disorder (ICD) in Parkinson's disease (PD).

Methods: Within the Luxembourg Parkinson's Study, PD patients were evaluated for ICD presence (score ≥ 1 on MDS-UPDRS I item 1.6), use of dopamine agonists (DA) and other medications.

Results: 470 patients were enrolled. Among 217 patients without DA use, 6.9% scored positive for ICD, vs. 15.4% among 253 patients with DA use (p = 0.005). The regression analysis showed that age at PD diagnosis had only a minor impact on ICD occurrence, while there was no influence by gender or co-medications. The longitudinal study over 2 years in 156 patients demonstrated increasing ICD frequency in DA users (p = 0.005).

Conclusion: This large and non-interventional study confirms that PD patients with DA treatment show higher frequency of ICD than patients without DA use. It newly demonstrates that ICD can develop independently from age, gender, or co-medications.

Relationship of Movement Disorders Society-Unified Parkinson's Disease Rating Scale Nonmotor Symptoms to Cognitive Functioning in Patients with Parkinson's Disease

Background

Few studies assess the relationships between nonmotor aspects of experiences of daily living and cognitive functioning in Parkinson's disease (PD).

Objective

To evaluate the relationships among the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part I items and neuropsychological tests in PD.Methods: We assessed 151 PD patients with the MDS-UPDRS part I and a battery of cognitive tests focused on the following 5 cognitive domains: attention/working memory, executive functioning, recent memory, language, visuoperception. Raw scores for individual cognitive tests were transformed to z scores, and cognitive domain scores were calculated by averaging z scores within each domain. Individual items from the MDS-UPDRS part I were entered in a stepwise linear regression analysis assessing item contribution to cognitive domain scores.

Results

The MDS-UPDRS part I item scores for hallucinations and psychosis and light headedness on standing predicted attention/working memory domain scores (P = 0.004). These same item scores, along with apathy, depressed mood, and dopamine dysregulation syndrome, predicted executive functioning (P = 0.044). The apathy and dopamine dysregulation syndrome items predicted language (P = 0.006). In addition, the cognitive impairment and sleep items were predictors of recent memory (P = 0.031). None of the items were predictors of visuoperception (P = 0.006). Other part I items were not significantly related to cognitive domain scores.

Conclusions

Specific nonmotor MDS-UPDRS part I items, particularly mood, behavior, and autonomic-related items, exhibited significant relationships with cognitive domains. The highest number of items were predictive of the executive functioning domain, which is the hallmark cognitive dysfunction in PD.

Validation of the Korean Version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease Rating Scale

Background and Purpose

Impulse-control disorder is an important nonmotor symptom of Parkinson's disease (PD) that can lead to financial and social problems, and be related to a poor quality of life. A nationwide multicenter prospective study was performed with the aim of validating the Korean Version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease Rating Scale (K-QUIP-RS).

Methods

The K-QUIP-RS was constructed using forward and backward translation, and pretesting of the prefinal version. PD patients on stable medical condition were recruited from 27 movement-disorder clinics. Participants were assessed using the K-QUIP-RS and evaluated for parkinsonian motor and nonmotor statuses and for PD-related quality of life using a predefined evaluation battery. The test–retest reliability of the K-QUIP-RS was assessed over an interval of 10–14 days, and correlations between the KQUIP-RS and other clinical scales were analyzed.

Results

This study enrolled 136 patients. The internal consistency of the K-QUIP-RS was indicated by a Cronbach's α coefficient of 0.846, as was the test–retest reliability by a Guttman split-half coefficient of 0.808. The total K-QUIP-RS score was positively correlated with the scores for depression and motivation items on the Unified PD Rating Scale (UPDRS), Montgomery-Asberg Depression Scale, and Rapid-Eye-Movement Sleep-Behavior-Disorders Questionnaire. The total K-QUIP-RS score was also correlated with the scores on part II of the UPDRS and the PD Quality of Life-39 questionnaire, and the dopaminergic medication dose.

Conclusions

The K-QUIP-RS appears to be a reliable assessment tool for impulse-control and related behavioral disturbances in the Korean PD population.

Systematic Evaluation of Levodopa Effect on Visual Improvement in Amblyopia: A Meta-analysis

PURPOSE

This study aims to evaluate the effectiveness of levodopa as a therapeutic drug in the treatment of children and adults with amblyopia.

METHODS

We performed a systematic review and meta-analysis with randomized controlled trials of levodopa and placebo in the treatment of amblyopia. All data were identified and extracted from the PubMed, EMBASE, Cochrane libraries, and the Chinese knowledge resource integration database.

RESULTS

After screening the literature and evaluating the quality, 11 studies met the criteria from 308 studies. The mean difference of LogMAR visual acuity between levodopa and the placebo group was -0.1031 (95% confidence interval, -0.11 to -0.09; P < 0.0001). The improvement of visual acuities of the subgroup of younger patients with amblyopia was significantly higher than that of the placebo group (P < 0.0001). Increasing the dosage of levodopa and prolonging the treatment can significantly improve the curative effect.

CONCLUSIONS

Levodopa is effective in the treatment of amblyopia by prolonging the treatment, especially for young patients.

Hallucinations, Delusions and Impulse Control Disorders in Parkinson Disease

Psychotic and compulsive symptoms in Parkinson disease are highly prevalent and associated with poor outcomes and greater caregiver burden. When acute, delirium should be ruled out or treated accordingly. When chronic, comorbid systemic illnesses, dementia, and psychiatric disorders should be considered. Reduction and discontinuation of anticholinergics, amantadine, dopamine agonists, and levodopa as tolerated, as well as adjunctive clozapine or quetiapine are frequently effective to manage Parkinson disease psychosis. Pimavanserin appears effective but is not widely available, and more experience is needed. Dopamine agonist discontinuation is usually successful for impulse control disorders, but requires frequent monitoring, documentation, and caregiver involvement.

Deep Brain Stimulation Programming for Movement Disorders: Current Concepts and Evidence-Based Strategies

Deep brain stimulation (DBS) has become the treatment of choice for advanced stages of Parkinson's disease, medically intractable essential tremor, and complicated segmental and generalized dystonia. In addition to accurate electrode placement in the target area, effective programming of DBS devices is considered the most important factor for the individual outcome after DBS. Programming of the implanted pulse generator (IPG) is the only modifiable factor once DBS leads have been implanted and it becomes even more relevant in cases in which the electrodes are located at the border of the intended target structure and when side effects become challenging. At present, adjusting stimulation parameters depends to a large extent on personal experience. Based on a comprehensive literature search, we here summarize previous studies that examined the significance of distinct stimulation strategies for ameliorating disease signs and symptoms. We assess the effect of adjusting the stimulus amplitude (A), frequency (f), and pulse width (pw) on clinical symptoms and examine more recent techniques for modulating neuronal elements by electrical stimulation, such as interleaving (Medtronic®) or directional current steering (Boston Scientific®, Abbott®). We thus provide an evidence-based strategy for achieving the best clinical effect with different disorders and avoiding adverse effects in DBS of the subthalamic nucleus (STN), the ventro-intermedius nucleus (VIM), and the globus pallidus internus (GPi).

Medications, Deep Brain Stimulation, and Other Factors Influencing Impulse Control Disorders in Parkinson's Disease

Impulse control disorders (ICDs) in Parkinson's disease (PD) have a high cumulative incidence and negatively impact quality of life. ICDs are influenced by a complex interaction of multiple factors. Although it is now well-recognized that dopaminergic treatments and especially dopamine agonists underpin many ICDs, medications alone are not the sole cause. Susceptibility to ICD is increased in the setting of PD. While causality can be challenging to ascertain, a wide range of modifiable and non-modifiable risk factors have been linked to ICDs. Common characteristics of PD patients with ICDs have been consistently identified across many studies; for example, males with an early age of PD onset and dopamine agonist use have a higher risk of ICD. However, not all cases of ICDs in PD can be directly attributable to dopamine, and studies have concluded that additional factors such as genetics, smoking, and/or depression may be more predictive. Beyond dopamine, other ICD associations have been described but remain difficult to explain, including deep brain stimulation surgery, especially in the setting of a reduction in dopaminergic medication use. In this review, we will summarize the demographic, genetic, behavioral, and clinical contributions potentially influencing ICD onset in PD. These associations may inspire future preventative or therapeutic strategies.

The dark side of dopaminergic therapies in Parkinson's disease: shedding light on aberrant salience

Psychotic subjects and patients with Parkinson's disease (PD) "on" dopaminergic drugs, especially on dopamine agonists, present a hyperdopaminergic state that interferes with learning processing. These clinical populations present with distinct alterations of learning that share an increased potential motivational significance of stimuli: psychotic subjects may attribute salience to neutral stimuli, while medicated PD patients may overvalue rewards. Herein is discussed the speculative hypothesis that the hyperdopaminergic state induced by dopaminergic treatments, especially with dopamine agonists, may also facilitate the attribution of salience to neutral stimuli in PD patients, altering the physiological attribution of salience. Preliminary empirical evidence is in agreement with this speculative hypothesis, which needs further empirical investigation. The clinical implications of this hypothesis are discussed in relation to behavioral addictions, psychosis proneness, and enhanced creativity in medicated PD patients.

Impulse control and related disorders in Parkinson's disease

Neuropsychiatric disorders are common among patients with Parkinson's disease and may appear in any stage of the disease. However, these disorders often go undiagnosed and receive insufficient treatment. Observations in recent years have revealed that dopamine replacement therapy may lead to the development or worsening of conditions, such as gambling disorder, compulsive sexual behavior, compulsive buying and binge eating, in addition to punding and dopamine dysregulation syndrome. The pathophysiology of these disorders seems to be related to abnormal dopaminergic stimulation of the basal regions of the basal ganglia, especially via nigro-mesolimbic pathways. The aim of the present study was to perform a literature review on impulsivity, impulse control disorders and related conditions among patients with Parkinson's disease, with emphasis on their epidemiology, clinical characteristics and treatment.

The Outcome of Dopamine Dysregulation Syndrome in Parkinson's Disease: A Retrospective Postmortem Study

Introduction

We have performed a retrospective analysis of the frequency and relation to treatment of dopamine dysregulation syndrome (DDS) using the Queen Square Brain Bank (QSBB) database.

Methods

A search of the QSBB database for consecutive cases donated between 2005 and 2016 with a pathological diagnosis of Parkinson's disease was performed.

Results

DDS was present in 8.8% of cases, was more prevalent in males, and was associated with younger age of onset, longer disease duration, and more dopa-induced dyskinesias. Treatment approaches for DDS included: reduction of levodopa, reduction/cessation of dopamine agonist (DA), and initiation of infusion therapies. DDS had completely resolved in just over half the patients. DA peak l-dopa equivalent daily dose (LEDD) was higher in patients who failed to achieve remission.

Conclusion

This is the first study to provide data on the course of DDS until death. Treatment strategies consisted mainly of reduction of dopaminergic treatment, and, despite the majority of patients showing some improvement, half remained symptomatic. Successful treatment was associated with a lower l-dopa dosage at death.

Delusions in Parkinson's Disease: A Systematic Review of Published Cases

Delusions in Parkinson's disease (PD) are thought to be associated with disease progression and cognitive impairment. However, this symptom description is not consistent in the literature and there is a suggestion that different subgroups of psychotic patients occur in PD, which we aimed to clarify. Case reports were identified through a systematic search of databases (PUBMED, EMBASE, PsychInfo). Cases with isolated delusions were compared to those with both delusions and hallucinations. We identified 184 cases of delusions in PD. Delusions were primarily paranoid in nature (83%) and isolated in 50%. Those with isolated delusions had an earlier onset of PD (46 years vs 55 years), higher rates of impulse control disorders (40.2 vs 10.3%), dopamine dysregulation (29.9 vs 11.3%) and lower rates of cognitive impairment (8.0 vs 26.8%). There is unexpected heterogeneity amongst cases of delusional psychosis, that cannot adequately be explained by existing models of PD psychosis.

Neurocognitive correlates of medication-induced addictive behaviours in Parkinson's disease: A systematic review

Dopaminergic medication can induce severe addictive behaviours (e.g., pathological gambling) in susceptible Parkinson's disease (PD) patients. It is still unknown which particular neurocognitive processes become exacerbated or dysfunctional in PD patients with addictive behaviours. We sought to systematically review the relevant literature to identity potential neurocognitive correlates of medication-induced addictive behaviours in PD. We framed our review around neurocognitive processes central to four dominant accounts of substance addiction: 'aberrant learning', 'incentive sensitization', 'impulsivity to compulsivity' and 'impaired response inhibition and salience attribution'. Searches of the PubMed and Scopus databases were completed on June 23, 2017. To be included, studies were required to involve: (a) medicated PD patients, without a history of deep brain stimulation, with and without addictive behaviours; (b) a reward-related or decision-making task; and (c) statistical comparison of addictive and non-addictive groups' 'on' medication performance on the task(s). Studies were summarised qualitatively with statistically significant (p<.05) group differences and effect sizes (Cohen's d) highlighted. 35 studies were included. Findings showed that the extant literature is highly heterogeneous. The domains of reward and punishment learning, reflection impulsivity and disadvantageous decision-making exemplify this. More homogeneity exists in domains in which (a) neurocognitive dysfunction is not apparent (motor control, cognitive/attentional flexibility and cognitive control) or (b) typical neurocognitive processes appear exacerbated by medication (reward motivation and choice impulsivity). Future large-scale neurocognitive studies are still required to develop our scientific understanding of addictive behaviours in PD and aid their clinical treatment and prediction.

Challenges in PD Patient Management After DBS: A Pragmatic Review

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or internal globus pallidus (GPi) represents an effective and universally applied therapy for Parkinson's disease (PD) motor complications. However, certain procedure-related problems and unrealistic patient expectations may detract specialists from indicating DBS more widely despite significant clinical effects.

METHODS

This review provides a pragmatic educational summary of the most conflicting postoperative management issues in patients undergoing DBS for PD.

RESULTS

DBS in PD has been associated with certain complications and post-procedural management issues, which can complicate surgical outcome interpretation. Many PD patients consider DBS outcomes negative due to unfulfilled expectations, even when significant motor symptom improvement is achieved. Speech, gait, postural stability, and cognition may worsen after DBS and body weight may increase. Although DBS may induce impulse control disorders in some cases, in others, it may actually improve them when dopamine agonist dosage is reduced after surgery. However, apathy may also arise, especially when dopaminergic medication tapering is rapid. Gradual loss of response with time suggests disease progression, rather than the wearing off of DBS effects. Furthermore, implantable pulse generator expiration is considered a movement disorder emergency, as it may worsen parkinsonian symptoms or cause life-threatening akinetic crises due to malignant DBS withdrawal syndrome.

CONCLUSION

Major unsolved issues occurring after DBS therapy preclude complete patient satisfaction. Multidisciplinary management at experienced centers, as well as careful and comprehensive delivery of information to patients, should contribute to make DBS outcome expectations more realistic and allow post procedural complications to be better accepted.

Dopamine dysregulation syndrome in Parkinson's disease: a systematic review of published cases

OBJECTIVES

Dopamine dysregulation syndrome (DDS) is an uncommon complication of the treatment of Parkinson's disease, characterised by addictive behaviour and excessive use of dopaminergic medication. DDS may frequently go unrecognised or misdiagnosed. We aimed to clarify current understanding of presentation, risk factors, comorbidities and management of DDS.

METHODS

Case reports were identified through a systematic search of databases (PubMed, Embase) with the following terms: dopaminergic dysregulation syndrome, hedonistic homeostatic dysregulation, dopamine/levodopa addiction.

RESULTS

We reviewed 390 articles, identifying 98 cases of DDS. Early-onset Parkinson's disease (67%) and male gender (83%) were common. DDS presented with significant physical and social impairment, actions to enable or prevent detection of overuse, as well as mood, anxiety and motor fluctuations. All DDS cases met DSM-V (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) substance use disorder criteria. Past substance and psychiatric history was present in 15.3% and 10.2% of cases. Comorbid impulse control disorders (61%), psychosis (32%) and panic attacks (14%) were common. A large variety of management strategies were used; only 56% of cases resolving. Sodium valproate was successful in 5/5 cases. The response to deep brain stimulation varied.

CONCLUSIONS

Given the functional impairment, medical and psychiatric consequences and the difficulties of treatment, early identification of DDS should be a priority.

Creative Thinking, Professional Artists, and Parkinson's Disease

BACKGROUND

An increase in artistic-like production in Parkinson's disease (PD) has been associated with compulsive and repetitive behaviours after the introduction of dopaminergic treatment (DT). Recent data suggest that it could be due to the emergence of artistic-like skills triggered by DT.

OBJECTIVE

In order to evaluate whether artistic production and creative thinking are influenced by DT or linked to artistic-like skills, we characterize creativity features in PD and healthy controls (HC) including professional artists.

METHODS

Three groups of PD out-patients were included consecutively: professional artists (PD-A), patients with (PD-C) and without artistic-like production (PD-NC). Twenty-four gender and age-matched HC were included: professional artists (HC-A) and non-artists (HC-NC). All patients were evaluated by means of a) a battery of neuropsychological tests and a semi-structured interview; b) the Abbreviated Torrance Test for Adults (ATTA) for creative thinking; c) the Minnesota Impulsive Disorders Interview (mMIDI) and a screening for impulse control disorders (ICDs) for compulsive behaviour.

RESULTS

ATTA total score was significantly higher in HC-A and PD-A than in the other groups. Although PD-NC showed the lowest ATTA total score the difference vs HC-NC was not significant. ATTA scores were not significantly correlated with DT dosage and duration. mMIDI tests were positive only in PD. There were no differences in ICDs among PD groups.

CONCLUSIONS

Our results do not support a relationship between DT and the emergence of artistic creativity. We believe that DT may increase the drive to create and that further studies in "on" and "off" medication are needed to clarify this issue.

Neuropsychiatric Complications of Parkinson Disease Treatments: Importance of Multidisciplinary Care

Although Parkinson disease (PD) is defined clinically by its motor symptoms, it is increasingly recognized that much of the disability and worsened quality of life experienced by patients with PD is attributable to psychiatric symptoms. The authors describe a model of multidisciplinary care that enables these symptoms to be effectively managed. They describe neuropsychiatric complications of PD itself and pharmacologic and neurostimulation treatments for parkinsonian motor symptoms and discuss the management of these complications. Specifically, they describe the clinical associations between motor fluctuations and anxiety and depressive symptoms, the compulsive overuse of dopaminergic medications prescribed for motor symptoms (the dopamine dysregulation syndrome), and neuropsychiatric complications of these medications, including impulse control disorders, psychosis, and manic syndromes. Optimal management of these problems requires close collaboration across disciplines because of the potential for interactions among the pathophysiologic process of PD, motor symptoms, dopaminergic drugs, and psychiatric symptoms. The authors emphasize how their model of multidisciplinary care facilitates close collaboration among psychiatrists, other mental health professionals, neurologists, and functional neurosurgeons and how this facilitates effective care for patients who develop the specific neuropsychiatric complications discussed.

Neuropsychiatric Issues in Parkinson's Disease

Cognitive and neuropsychiatric symptoms are common in Parkinson's Disease and may surpass motor symptoms as the major factors impacting patient quality of life. The symptoms may be broadly separated into those associated with the disease process and those that represent adverse effects of treatment. Symptoms attributed to the disease arise from pathologic changes within multiple brain regions and are not restricted to dysfunction in the dopaminergic system. Mood symptoms such as depression, anxiety, and apathy are common and may precede the development of motor symptoms by years, while other neuropsychiatric symptoms such as cognitive impairment, dementia, and psychosis are more common in later stages of the disease. Neuropsychiatric symptoms attributed to treatment include impulse control disorders, pathologic use of dopaminergic medications, and psychosis. This manuscript will review the current understanding of neuropsychiatric symptoms in Parkinson's Disease.

The hidden sister of motor fluctuations in Parkinson's disease: A review on nonmotor fluctuations

Only a few years after the introduction of levodopa, the first descriptions of motor fluctuations and dyskinesia related to dopaminergic therapy appeared. In PD, attention turned to their management, that had dampened the euphoria of the "levodopa miracle." It soon became clear that neuropsychiatric, autonomic, and sensory features also tend to develop fluctuations after chronic exposure to l-dopa. The diversity of fluctuating nonmotor symptoms, their largely subjective nature, coupled with a frequent lack of insight led to difficulties in identification and quantification. This may explain why, despite the high impact of nonmotor symptoms on patient autonomy and quality of life, evaluation of nonmotor fluctuations is not part of clinical routine. In view of the lack of specific validated assessment tools, detailed anamnesis should ideally be coupled with an evaluation in both ON and OFF drug conditions. The mechanisms of nonmotor fluctuations are not well understood. It is thought that they share dopaminergic presynaptic pharmacokinetic and postsynaptic pharmacodynamic mechanisms with the classical motor complications, but involve different neural pathways. Although symptoms fluctuate with dopaminergic treatment, serotonine and norepinephrine denervation, as well as interactions between neurotransmitter systems, probably contribute to their diversity. The lack of validated tools for assessment of these phenomena explains the almost complete absence of treatment studies. Management, largely resulting from expert opinion, includes psychiatric follow-up, nondopaminergic drugs, and advanced dopaminergic treatment, including drug delivery pumps and DBS. This review aims to provide a starting point for the understanding, diagnosis, and management of nonmotor fluctuations. © 2016 International Parkinson and Movement Disorder Society.

Opposing effects of dopamine D1- and D2-like agonists on intracranial self-stimulation in male rats

Dopamine acts through dopamine Type I receptors (comprising D1 and D5 subtypes) and dopamine Type II receptors (comprising D2, D3, and D4 subtypes). Intracranial self-stimulation (ICSS) is 1 experimental procedure that can be used to evaluate abuse-related effects of drugs targeting dopamine receptors. This study evaluated effects of dopamine receptor ligands on ICSS in rats using experimental procedures that have been used previously to examine abused indirect dopamine agonists such as cocaine and amphetamine. Male Sprague-Dawley rats responded under a fixed-ratio 1 schedule for electrical stimulation of the medial forebrain bundle, and frequency of stimulation varied from 56-158 Hz in 0.05 log increments during each experimental session. Drug potency and time course were determined for the D1 ligands A77636, SKF82958, SKF38393, fenoldopam, and SCH39166 and the D2/3 ligands sumanirole, apomorphine, quinpirole, PD128907, pramipexole, aripiprazole, eticlopride, and PG01037. The high-efficacy D1 agonists A77636 and SKF82958 produced dose-dependent, time-dependent, and abuse-related facilitation of ICSS. Lower efficacy D1 ligands and all D2/3 ligands failed to facilitate ICSS at any dose or pretreatment time. A mixture of SKF82958 and quinpirole produced a mixture of effects produced by each drug alone. Quinpirole also failed to facilitate ICSS after regimens of repeated treatment with either quinpirole or cocaine. These studies provide more evidence for divergent effects of dopamine D1- and D2-family agonists on ICSS procedure in rats and suggest that ICSS may be a useful complement to other approaches for preclinical abuse potential assessment, in part because of the reproducibility of results. (PsycINFO Database Record

Tryptophan hydroxylase type 2 variants modulate severity and outcome of addictive behaviors in Parkinson's disease

BACKGROUND

Impulse control disorders and compulsive medication intake may occur in a minority of patients with Parkinson's disease (PD). We hypothesize that genetic polymorphisms associated with addiction in the general population may increase the risk for addictive behaviors also in PD.

METHODS

Sixteen polymorphisms in candidate genes belonging to five neurotransmitter systems (dopaminergic, catecholaminergic, serotonergic, glutamatergic, opioidergic) and the BDNF were screened in 154 PD patients with addictive behaviors and 288 PD control subjects. Multivariate analysis investigated clinical and genetic predictors of outcome (remission vs. persistence/relapse) after 1 year and at the last follow-up (5.1 ± 2.5 years).

RESULTS

Addictive behaviors were associated with tryptophan hydroxylase type 2 (TPH2) and dopamine transporter gene variants. A subsequent analysis within the group of cases showed a robust association between TPH2 genotype and the severity of addictive behaviors, which survived Bonferroni correction for multiple testing. At multivariate analysis, TPH2 genotype resulted the strongest predictor of no remission at the last follow-up (OR[95%CI], 7.4[3.27-16.78] and 13.2[3.89-44.98] in heterozygous and homozygous carriers, respectively, p < 0.001). The extent of medication dose reduction was not a predictor. TPH2 haplotype analysis confirmed the association with more severe symptoms and lower remission rates in the short- and the long-term (p < 0.005 for all analyses).

CONCLUSION

The serotonergic system is likely to be involved in the pathophysiology of addictive behaviors in PD, modulating the severity of symptoms and the rate of remission at follow-up. If confirmed in larger independent cohorts, TPH2 genotype may become a useful biomarker for the identification of at-risk individuals.

Dyskinesias and impulse control disorders in Parkinson's disease: From pathogenesis to potential therapeutic approaches

Dopaminergic treatment in Parkinson's disease (PD) reduces the severity of motor symptoms of the disease. However, its chronic use is associated with disabling motor and behavioral side effects, among which levodopa-induced dyskinesias (LID) and impulse control disorders (ICD) are the most common. The underlying mechanisms and pathological substrate of these dopaminergic complications are not fully understood. Recently, the refinement of imaging techniques and the study of the genetics and molecular bases of LID and ICD indicate that, although different, they could share some features. In addition, animal models of parkinsonism with LID have provided important knowledge about mechanisms underlying such complications. In contrast, animal models of parkinsonism and abnormal impulsivity, although useful regarding some aspects of human ICD, do not fully resemble the clinical phenotype of ICD in patients with PD, and until now have provided limited information. Studies on animal models of addiction could complement the previous models and provide some insights into the background of these behavioral complications given that ICD are regarded as behavioral addictions. Here we review the most relevant advances in relation to imaging, genetics, biochemistry and pharmacological interventions to treat LID and ICD in patients with PD and in animal models with a view to better understand the overlapping and unique maladaptations to dopaminergic therapy that are associated with LID and ICD.

Pathophysiology of L-dopa-induced motor and non-motor complications in Parkinson's disease

Involuntary movements, or dyskinesia, represent a debilitating complication of levodopa (L-dopa) therapy for Parkinson's disease (PD). L-dopa-induced dyskinesia (LID) are ultimately experienced by the vast majority of patients. In addition, psychiatric conditions often manifested as compulsive behaviours, are emerging as a serious problem in the management of L-dopa therapy. The present review attempts to provide an overview of our current understanding of dyskinesia and other L-dopa-induced dysfunctions, a field that dramatically evolved in the past twenty years. In view of the extensive literature on LID, there appeared a critical need to re-frame the concepts, to highlight the most suitable models, to review the central nervous system (CNS) circuitry that may be involved, and to propose a pathophysiological framework was timely and necessary. An updated review to clarify our understanding of LID and other L-dopa-related side effects was therefore timely and necessary. This review should help in the development of novel therapeutic strategies aimed at preventing the generation of dyskinetic symptoms.

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.

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.

EuroInf: a multicenter comparative observational study of apomorphine and levodopa infusion in Parkinson's disease

Subcutaneous apomorphine infusion (Apo) and intrajejunal levodopa infusion (IJLI) are two treatment options for patients with advanced Parkinson's disease (PD) and refractory motor complications, with varying cost of treatment. There are no multicenter studies comparing the effects of the two strategies. This open-label, prospective, observational, 6-month, multicenter study compared 43 patients on Apo (48.8% males, age 62.3 ± 10.6 years; disease duration: 14 ± 4.4 years; median H & Y stage 3; interquartile range [IQR]: 3-4) and 44 on IJLI (56.8% males, age 62.7 ± 9.1 years; disease duration: 16.1 ± 6.7 years; median H & Y stage 4; IQR, 3-4). Cohen's effect sizes (≥0.8 considered as large) were "large" with both therapies with respect to total motor, nonmotor, and quality-of-life scores. The Non-Motor Symptoms Scale (NMSS) with Apo showed moderate improvement, whereas sleep/fatigue, gastrointestinal, urinary, and sexual dimensions of the NMSS showed significantly higher improvement with IJLI. Seventy-five percent on IJLI improved in their quality-of-life and nonmotor symptoms (NMS), whereas in the Apo group, a similar proportion improved in quality of life, but 40% in NMS. Adverse effects included peritonitis with IJLI and skin nodules on Apo. Based on this open-label, nonrandomized, comparative study, we report that, in advanced Parkinson's patients, both IJLI and Apo infusion therapy appear to provide a robust improvement in motor symptoms, motor complications, quality-of-life, and some NMS. Controlled, randomized studies are required.

Impulse control disorders in Parkinson's disease: an overview from neurobiology to treatment

Parkinson's disease (PD) is the second most common neurodegenerative brain disorder and is characterized by motor symptoms such as tremor, bradykinesia, rigidity and postural instability. A majority of the patients also develop non-motor symptoms. Impulse control disorders (ICD) are behavioural changes that often fail to be detected in clinical practice. The prevalence of ICD in PD varies widely from 6.1 to 31.2 % and treatment with dopaminergic medication is considered to be the greatest risk factor. Management consists mainly of reducing dopaminergic medication. In our experience, ICD has a tremendous impact on the quality of life of the patients and their families and should therefore not be disregarded. Studies addressing the role of ICD in PD caregiver strain are imperative. We attempt to give a comprehensive overview of the literature on the complicated neurobiology of ICD and discuss risk factors, genetic susceptibility, screening modalities and management.

Hypomania and mania related to dopamine replacement therapy in Parkinson's disease

OBJECTIVES

To investigate hypomania and mania related to dopamine replacement therapy (DRT) in Parkinson's disease (PD).

METHODS

We recruited 108 non-demented PD patients without deep brain stimulation from a movement disorders in and outpatient clinic. Forty-five age- and gender-matched controls were also included. Disease characteristics, cognitive functioning, comorbid psychiatric diseases, dopaminergic and psychiatric medication were evaluated. Diagnosis of DRT-related hypomania and mania was based on DSM-IV-TR criteria with supplementary assessment of two mania self-rating scales. First, patients and controls were compared. Patients with DRT-related hypomania or mania were then compared to the remaining patients. A binary logistic regression analysis was performed to identify correlates of DRT-related hypomania.

RESULTS

Patients scored significantly higher on mania self-rating scales than controls. Twelve patients (11.1%) had DRT-related hypomania and six patients (5.6%) had DRT-related mania. Both groups had significantly higher self-rating mania-scores than patients without these mood states. DRT-related hypomania was significantly related to younger age, younger age at PD onset, dyskinesias, higher levodopa equivalent daily dose, dopamine dysregulation, and amantadine treatment. In contrast, DRT-related mania was significantly associated with hallucinations and delusions, history of levodopa-induced psychosis, quetiapine treatment, higher depression and daily levodopa dose, and cognitive deficits. Regression analysis revealed dopamine dysregulation, dyskinesias, amantadine treatment, and younger age at PD onset as significant correlates of DRT-related hypomania.

CONCLUSION

DRT-related hypomania and mania are relevant comorbidities in PD. DRT-related hypomania may exist as a distinct psychiatric symptom complex in young patients with early disease onset. Different patient profiles likely underlie DRT-related hypomania and mania.