Sleep and REM sleep behaviour disorder in Parkinson's disease with impulse control disorder

Impulse Control Disorders in Parkinson's Disease and Atypical Parkinsonian Syndromes-Is There a Difference?

BACKGROUND AND OBJECTIVES

Impulse control disorders (ICDs) are characterized by potentially harmful actions resulting from disturbances in the self-control of emotions and behavior. ICDs include disorders such as gambling, hypersexuality, binge eating, and compulsive buying. ICDs are known non-motor symptoms in Parkinson's disease (PD) and are associated primarily with the use of dopaminergic treatment (DRT) and especially dopamine agonists (DA). However, in atypical parkinsonism (APS), such as progressive supranuclear palsy (PSP) or multiple system atrophy (MSA), there are only single case reports of ICDs without attempts to determine the risk factors for their occurrence. Moreover, numerous reports in the literature indicate increased impulsivity in PSP. Our study aimed to determine the frequency of individual ICDs in APS compared to PD and identify potential factors for developing ICDs in APS.

MATERIALS AND METHODS

Our prospective study included 185 patients with PD and 35 with APS (27 patients with PSP and 9 with MSA) hospitalized between 2020 and 2023 at the Neurological Department of University Central Hospital in Katowice. Each patient was examined using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP) to assess ICDs. Additionally, other scales were used to assess the advancement of the disease, the severity of depression, and cognitive impairment. Information on age, gender, age of onset, disease duration, and treatment used were collected from medical records and patient interviews.

RESULTS

ICDs were detected in 23.39% of patients with PD (including binge eating in 11.54%, compulsive buying in 10.44%, hypersexuality in 8.79%, and pathological gambling in 4.40%), in one patient with MSA (hypersexuality and pathological gambling), and in 18.52% of patients with PSP (binge eating in 3.70%, compulsive buying in 7.41%, and hypersexuality in 11.11%). We found no differences in the frequency of ICDs between individual diseases (p = 0.4696). We confirmed that the use of higher doses of DA and L-dopa in patients with PD, as well as a longer disease duration and the presence of motor complications, were associated with a higher incidence of ICDs. However, we did not find any treatment effect on the incidence of ICDs in APS.

CONCLUSIONS

ICDs are common and occur with a similar frequency in PD and APS. Well-described risk factors for ICDs in PD, such as the use of DRT or longer disease duration, are not fully reflected in the risk factors for ICDs in APS. This applies especially to PSP, which, unlike PD and MSA, is a tauopathy in which, in addition to the use of DRT, other mechanisms related to the disease, such as disorders in neuronal loops and neurotransmitter deficits, may influence the development of ICDs. Further prospective multicenter studies recruiting larger groups of patients are needed to fully determine the risk factors and mechanisms of ICD development in APS.

Associations between Sleep Disorders and Impulsive-Compulsive Behaviors in Parkinson's Disease: A Prospective Cohort Study

OBJECTIVE

To examine the associations of excessive daytime sleepiness (EDS) and probable rapid eye movement sleep behavior disorder (pRBD), respectively, with impulsive-compulsive behaviors (ICBs) over a 5-year follow-up in patients with early Parkinson's disease (PD).

METHODS

The Parkinson's Progression Markers Initiative is a multicenter cohort study based on an ongoing and open-ended registry. Longitudinal associations of sleep disorders with ICB over 5-year follow-up visits were estimated using generalized linear mixed-effects models among PD participants.

RESULTS

A total of 825 PD participants were enrolled at baseline. The study sample had a median baseline age of 63.1 (interquartile range: 55.6-69.3) years and comprised 496 (61.5%) men. Among them, 201 (24.9%) had ICB at baseline. In the generalized mixed-effects models, EDS (odds ratio [OR] = 1.09, 95% confidence interval [CI] 1.05, 1.12) and RBD (OR = 1.07, 95% CI 1.03, 1.12) were substantially associated with higher odds of developing ICB over time in PD patients, after multivariate adjustment including age, gender, family history, GDS score, STAI-Y score, MDS-UPDRS part III score, LEDD, and disease duration. Consistent results were observed when stratifying by age at baseline, gender, and PD family history.

CONCLUSIONS

The study findings suggest a longitudinal association between EDS and pRBD with an increased risk of developing ICB in patients with PD. The findings emphasize the significance of evaluating and addressing sleep disorders in PD patients as a potential approach to managing ICB.

Altered connectivity in the cognitive control-related prefrontal cortex in Parkinson's disease with rapid eye movement sleep behavior disorder

Rapid eye movement sleep behavior disorder (RBD) frequently occurs in Parkinson's disease (PD), however, the exact pathophysiological mechanism is not clear. The prefrontal cortex (PFC), especially ventrolateral prefrontal cortex (VLPFC), dorsolateral prefrontal cortex (DLPFC), and inferior frontal gyrus (IFG) which may play roles by regulating cognitive control processes. The purpose of this study was to investigate whether there is abnormal functional connectivity (FC) maps and volume changes in PD with RBD(PD-RBD). We recruited 20 PD-RBD, 20 PD without RBD (PD-nRBD), and 20 normal controls (NC). We utilized resting-state functional Magnetic Resonance Imaging (rs-MRI) to explore FC changes based on regions of interest (VLPFC, DLPFC, and IFG), and used voxel-based morphology technology to analyze whole-brain volumes by 3D-T1 structural MRI. Except the REM sleep behavioral disorders questionnaire (RBDSQ), the PD-RBD showed lower visuospatial/executive and attention scores than the NC group. The RBDSQ scores were significantly positively correlated with zFC of right DLPFC to bilateral posterior cingulate cortex (PCC) (P = 0.0362, R = 0.4708, AlphaSim corrected) and also significantly positively correlated with zFC of left VLPFC to right inferior temporal (P = 0.0157, R = 0.5323, AlphaSim corrected) in PD-RBD group. Furthermore, abnormal correlations with zFC values were also found in some cognitive subdomains in PD-RBD group. The study may suggest that in PD-RBD patients, the presence of RBD may be related to the abnormal FC of VLPFC and DLPFC, meanwhile, the abnormal FC of DLPFC and IFG may be related to the mechanisms of cognitive impairment.

Rapid Eye Movement Sleep Behavior Disorder in Parkinson's Disease: A Survey-Based Study

OBJECTIVE

To characterize Parkinson's disease (PD) symptoms based on the presence, onset time, and severity of rapid eye movement sleep behavior disorder (RBD) and their association with impulse control disorders (ICD).

BACKGROUND

RBD is a frequent non-motor symptom in PD, usually described as prodromal. The severity of RBD according to the start time and its relationship with ICD in PD needs further clarification.

METHODS

A survey-based study was performed to determine the presence of RBD symptoms, their severity, and the temporal relationship with the PD onset. The survey included RBD1Q, the Mayo Sleep, and the RBDQ-HK questionnaires and questions about clinical characteristics, including ICD. Only PD patients with care partners spending night hours in the same room were included.

RESULTS

410 PD patients were included: 206 with RBD (50.2%) and 204 non-RBD (49.8%). The PD-RBD patients were younger and their daily levodopa dose was higher than the non-RBD group. Most of these patients developed RBD symptoms after the onset of clinical PD were younger at motor symptom onset and had higher scores in the hallucinations and psychosis subsection of MDS-UPDRS-I. RBD group had a more severe non-motor phenotype, including more ICD than those without RBD, mainly due to higher compulsive eating.

CONCLUSIONS

In our study, most patients recognized RBD symptoms after the onset of the PD motor symptoms and the clinical features of PD with and without RBD were distinctive, supporting the hypothesis that PD-RBD might represent a variant pattern of neurodegeneration.

Genetic prediction of impulse control disorders in Parkinson's disease

OBJECTIVE

To develop a clinico-genetic predictor of impulse control disorder (ICD) risk in Parkinson's disease (PD).

METHODS

In 5770 individuals from three PD cohorts (the 23andMe, Inc.; the University of Pennsylvania [UPenn]; and the Parkinson's Progression Markers Initiative [PPMI]), we used a discovery-replication strategy to develop a clinico-genetic predictor for ICD risk. We first performed a Genomewide Association Study (GWAS) for ICDs anytime during PD in 5262 PD individuals from the 23andMe cohort. We then combined newly discovered ICD risk loci with 13 ICD risk loci previously reported in the literature to develop a model predicting ICD in a Training dataset (n = 339, from UPenn and PPMI cohorts). The model was tested in a non-overlapping Test dataset (n = 169, from UPenn and PPMI cohorts) and used to derive a continuous measure, the ICD-risk score (ICD-RS), enriching for PD individuals with ICD (ICD+ PD).

RESULTS

By GWAS, we discovered four new loci associated with ICD at p-values of 4.9e-07 to 1.3e-06_. Our best logistic regression model included seven clinical and two genetic variables, achieving an area under the receiver operating curve for ICD prediction of 0.75 in the Training and 0.72 in the Test dataset. The ICD-RS separated groups of PD individuals with ICD prevalence of nearly 40% (highest risk quartile) versus 7% (lowest risk quartile).

INTERPRETATION

In this multi-cohort, international study, we developed an easily computed clinico-genetic tool, the ICD-RS, that substantially enriches for subgroups of PD at very high versus very low risk for ICD, enabling pharmacogenetic approaches to PD medication selection.

Progressive Prefrontal Cortex Dysfunction in Parkinson's Disease With Probable REM Sleep Behavior Disorder: A 3-Year Longitudinal Study

This study aimed to explore the disrupted prefrontal cortex activity specific to patients with Parkinson's disease (PD) with rapid eye movement sleep behavior disorder (RBD) compared with those without and to further examine the associations between these alterations and neuropsychological measurements. Ninety-six patients with early PD underwent both structural and functional MRI, and also neuropsychological assessments in the Parkinson's Progression Markers Initiative (PPMI) database. Of these, 46 patients who completed 1- and 3-year fMRI follow-up examinations were categorized as PD with probable RBD (PD-pRBD+) and without (PD-pRBD−). The left dorsolateral prefrontal cortex (DLPFC) seed-to-voxel functional connectivity analysis was conducted to evaluate the progressive neural alterations specific to PD-pRBD+ compared with PD-pRBD− over time. Furthermore, relationships between these alterations and neuropsychological performance were examined. Compared with patients with PD-pRBD−, patients with PD-pRBD+ initially exhibited connectivity deficits between the left DLPFC and the medial frontopolar cortex. Moreover, these patients further exhibited disrupted DLPFC connectivity in the lateral frontopolar cortex at the 3-year follow-up evaluation. Correlation analysis revealed that connectivity between the left DLPFC and frontopolar cortex was positively related to executive function in PD-pRBD+ after adjusting for nuisance variables. Progressive prefrontal cortex dysfunction associated with RBD in early PD may provide an effective subtype-specific biomarker of neurodegenerative progression, which may shed light on the neuropathological mechanisms underlying the clinical heterogeneity of this disease.

White matter changes in drug-naïve Parkinson's disease patients with impulse control & probable REM sleep behavior disorders

BACKGROUND

According to epidemiological studies, Parkinson's disease (PD) patients with probable REM sleep behavior disorder (pRBD) are more prone to develop impulse control disorders (ICDs), which is shown to be present in drug-naïve PD patients, and vice versa.

OBJECTIVES

To investigate white-matter integrity differences, with and without comorbid pRBD and ICDs.

METHODS

149 de-novo PD patients and 30 age- and gender-matched controls from the Parkinson's Progression Markers Initiative were studied. PD subjects were categorized into four groups with and without these comorbidities. We investigated the white matter integrity differences between these groups.

RESULTS

PDs with only ICDs manifested greater fractional anisotropy (FA) and lower mean diffusivity (MD) in ipsilateral cerebellar connections when compared to controls and to Parkinson's with both comorbid disorders. In contrast, significantly lower FA and higher MD in the ipsilateral fornix-stria-terminalis was observed in PDs with only pRBD compared to controls and to PDs without either comorbid disorder. Also, PDs with only pRBD manifested greater FA in contralateral putamen when compared to controls.

CONCLUSIONS

Our results suggest the presence of an underlying neural network in PDs with ICDs, particularly involving cerebellar connections, which makes the subjects susceptible to pRBD. Lower white-matter integrity in the fornix of PDs with only pRBD suggests a neuropathological pathway specific to sleep behavior disorder, independent of impulse control disorders. Greater white-matter integrity observed in PDs without comorbid ICDs, regardless of their comorbid pRBD status, might reflect compensatory mechanisms. Targeted therapies for this particular neuropathology may help prevent these comorbidities.

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.

Limbic hypoconnectivity in idiopathic REM sleep behaviour disorder with impulse control disorders

INTRODUCTION

Current neuroimaging research has revealed several brain alterations in idiopathic REM sleep behaviour disorder (iRBD) that mirror and precede those reported in PD. However, none have specifically addressed the presence of changes across the reward system, and their role in the emergence of impulse control disorders (ICDs). We aimed to compare the volumetric and functional connectivity characteristics of the reward system in relation to the psychobehavioral profile of patients with iRBD versus healthy controls and PD patients.

METHODS

Twenty patients with polysomnography confirmed iRBD along with 17 PD patients and 14 healthy controls (HC) underwent structural and functional resting-state brain MRI analysis. Participants completed the questionnaire for impulsive-compulsive disorders in PD (QUIP), the short UPPS-P impulsive behaviour scale, as well as neuropsychological testing of cognitive function.

RESULTS

A higher percentage of iRBD patients reported hypersexuality, compared to HC and PD (p = 0.008). Whole-brain and striatal voxel-based morphometry analyses showed no significant clusters of reduced grey matter volume between groups. However, iRBD compared to HC demonstrated functional hypoconnectivity between the limbic striatum and temporo-occipital regions. Furthermore, the presence of ICDs correlated with hypoconnectivity between the limbic striatum and clusters located in cuneus, lingual and fusiform gyrus.

CONCLUSION

Altered functional connectivity between the limbic striatum and posterior cortical regions was associated with increased hypersexuality in iRBD. It is possible that this change may ultimately predispose individuals to the emergence of ICDs when they receive dopaminergic medications, after transitioning to PD.

Risk stratification for REM sleep behavior disorder in patients with Parkinson's disease: A PRISMA-compliant meta-analysis and systematic review

This study aimed to compare whether the characteristics of Parkinson's disease (PD) patients between probably rapid eye movement sleep behavior disorder (RBD) and confirmed RBD versus non-RBD are differing using a meta-analytic approach. We systematically searched PubMed, EmBase, and the Cochrane library for eligible studies throughout October 2018 in this meta-analysis. The clinical characteristics of PD patients presented with probably RBD, confirmed RBD, or non-RBD were analyzed. The pooled odds ratios and weighted mean differences with corresponding 95 % confidence intervals were calculated for categories and continuous data, respectively. All the pooled analyses were conducted using random-effects model. Forty-seven studies recruited a total of 8019 PD patients were included in the final meta-analysis. The summary results indicated significant differences between probable RBD and non-RBD for PD duration, levodopa dosage daily, Hoehn-Yahr stage, UPDRS-III, UPDRS-motor score, UPDRS activity of daily living, Epworth Sleepiness scale, male percentage, dyskinesia, orthostatic hypotension, constipation, and fluctuations present. Moreover, confirmed RBD versus non-RBD showed significant differences for age, PD duration, levodopa dosage daily, Mini-Mental State Examination, Hoehn-Yahr stage, UPDRS-motor score, Epworth Sleepiness scale, male percentage, dyskinesia, hallucination, insomnia, dementia, orthostatic hypotension, falls, and fluctuations present. Furthermore, the difference of confirmed RBD versus non-RBD was significantly elderly than probable RBD versus non-RBD. Moreover, PD patients with confirmed RBD with lower Mini-Mental State Examination as compared with probable RBD corresponding PD patients without RBD. In addition, PD patients with confirmed RBD versus probable RBD was associated with high Hoehn-Yahr stage as compared with non-RBD. Finally, patients with confirmed RBD with high incidence of insomnia as compared with probable RBD corresponding PD patients without RBD. The results provide the comprehensive differences in the patients' characteristics among probable RBD, confirmed RBD, and non-RBD in PD patients.

Levodopa-carbidopa intrajejunal infusion in Parkinson's disease: untangling the role of age

OBJECTIVES

Levodopa-Carbidopa Intrajejunal gel (LCIG) infusion is an effective intervention for people with advanced Parkinson's disease (PD). Although age may not be a limiting factor for LCIG implant, no data are available on late elderly PD (LE-PD) subjects. In this cross-sectional, we aimed to demonstrate if older age may impact on quality of life (QoL), motor and non-motor symptoms severity, and profile of side effects in PD treated with LCIG.

METHODS

Out of 512 PD subjects treated with LCIG at 9 Italian PD centers, we selected 25 LE-PD defined as age ≥ 80 years at last follow-up who were available to attend the study visit. Twenty-five PD patients (Control-PD, defined as age < 75 years at last follow-up) matched to LE-PD by disease and LCIG duration served as control group. The following motor and non-motor variables were ascertained: quality of life (PDQ-8), time spent in ON, wearing-off Questionnaire, Unified PD Rating Scale, freezing of gait questionnaire, Parkinson's disease sleep scale-2, Non Motor Symptoms Scale (NMSS), and MOCA.

RESULTS

No statistically significant differences were found between LE-PD and Control-PD on PDQ-8 and several motor and non-motor variables. LE-PD had less frequent and milder impulsive-compulsive behaviors and milder dyskinesia. At multivariable regression, worse quality of life was associated with UPDRS-III and NMSS scores but not to age at study visit and age at LICG implant. Rate of adverse effects was similar in both groups. Drop-out rate calculated in the whole PD cohort was comparable between the two groups.

CONCLUSION

Our data provide evidence that valuable LCIG infusion might be achieved in late elderly PD.

Othello syndrome in Parkinson's disease: A diagnostic emergency of an underestimated condition

Othello syndrome (OS) is a type of delusional jealousy, characterized by the false absolute certainty of the infidelity of a partner. This syndrome is not uncommon in Parkinson's Disease (PD), appearing as side effect of Dopaminergic Agonists (DA) therapy. We analyze the observations of five patients with OS, diagnosed in a series of 250 consecutive PD patients during two years. All patients are men, with a particularly young age at onset of PD. The mean duration of DA therapy at OS onset was 3 years. One patient had hypersexuality and another had punding. Significant cognitive impairment was present in two patients. All patients were treated with DA: two with Pramipexol and three with Piribedil. At the time of the management of the OS, three patients had already divorced their spouse. It is imperative for clinicians to know this underestimated syndrome in order to identify it early and approach it adequately to avoid irreversible negative prejudice.

Diagnosing REM sleep behavior disorder in Parkinson’s disease without a gold standard: a latent-class model study

Study Objectives

To ascertain whether current diagnostic criteria for REM sleep behavior disorder (RBD) are appropriate in patients with Parkinson’s disease (PD) consulting a movement disorder center, to evaluate the accuracy of REM sleep without atonia (RSWA) thresholds and determine the value of screening questionnaires to discriminate PD patients with RBD.

Methods

One hundred twenty-eight consecutive PD patients (M = 80; mean age: 65.6 ± 8.3 years) underwent screening questionnaires, followed by a sleep-focused interview and a full-night video-polysomnography (vPSG). Without a gold standard, latent class models (LCMs) were applied to create an unobserved (“latent”) variable. Sensitivity analysis was performed using RSWA cutoff derived from two visual scoring methods. Finally, we assessed the respective diagnostic performance of each diagnostic criterion for RBD and of the screening questionnaires.

Results

According to the best LCM-derived model, patients having either “history” or “video” with RSWA or alternatively showing both “history” and “video” without RSWA were classified as having RBD. Using both SINBAR and Montreal scoring methods, RSWA criterion showed the highest sensitivity while concomitant history of RBD and vPSG-documented behaviors, regardless to presence of RSWA, displayed the highest specificity. Currently recommended diagnostic threshold of RSWA was found to be optimal in our large cohort of PD patients. Both the RBD screening questionnaire (RBDSQ) and the RBD single question (RBD1Q) showed poor sensitivity and specificity.

Conclusions

Results of the best LCM for diagnosis of RBD in PD were consistent with the current diagnostic criteria. Moreover, RBD might be considered in those PD patients with both history and vPSG-documented dream enactment behaviors, but with RSWA values within the normal range.

Does REM sleep behavior disorder change in the progression of Parkinson's disease?

OBJECTIVES/BACKGROUND

Rapid eye movement (REM) Sleep Behavior Disorder (RBD) in Parkinson's disease (PD) may be associated with a malignant phenotype. Despite its prognostic value, little is known about the time course of RBD in PD. In this study, we aimed to ascertain whether or not RBD is a stable feature in PD. In this study, we prospectively evaluated clinical and neurophysiological features of RBD, including REM Sleep Without Atonia (RSWA), in PD patients with RBD at baseline and after three years then assessed whether the changes in measures of RSWA parallel the progression of PD.

PATIENTS/METHODS

In sum, 22 (17M, mean age 64.0 ± 6.9 years) moderate-to-advanced PD patients (mean PD duration at baseline:7.6±4.8 years) with RBD, underwent a video-polysomnography (vPSG) recording and clinical and neuropsychological assessment at baseline and after three years.

RESULTS

At follow-up, the self-assessed frequency of RBD symptoms increased in six patients, decreased in six and remained stable in 10, while RSWA measures significantly increased in all subjects. At follow-up, patients showed worse H&Y stage (p = 0.02), higher dopaminergic doses (p = 0.05) and they performed significantly worse in phonetic and semantic fluency tests (p = 0.02; p = 0.04). Changes in RSWA correlated significantly with the severity in levodopa-induced dyskinesia (r = 0.61,p = 0.05) and motor fluctuation (r = 0.54,p = 0.03) scores, and with the worsening of executive functions (r = 0.78,p = 0.001) and visuo-spatial perception (r = -0.57,p = 0.04).

CONCLUSION

Despite the subjective improvement of RBD symptoms in one-fourth of PD patients, all RSWA measures increased significantly at follow-up, and their changes correlated with the clinical evolution of motor and non-motor symptoms. RBD is a long-lasting feature in PD and RSWA is a marker of the disease's progression.

Association between REM sleep behavior disorder and impulsive-compulsive behaviors in Parkinson's disease: a systematic review and meta-analysis of observational studies

BACKGROUND

Both REM sleep behavior disorder (RBD) and impulsive-compulsive behaviors (ICBs) are well-recognized non-motor features in patients with Parkinson's disease (PD). Studies have given contradictory results about the potential association between RBD and ICBs.

METHODS

PubMed, Embase (via Ovid), and the Cochrane Central Registry of Controlled Trials (CENTRAL) databases were systematically searched till August 20, 2019 to identify studies that explored the possible correlation between RBD and ICBs in patients with PD. Two authors independently screened records, extracted data and evaluated quality of included studies. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated by employing a random or fixed-effects model. We performed subgroup and sensitivity analyses, and we assessed potential publication bias.

RESULTS

A total of 134 references were screened and 10 studies involving 2781 PD patients were included. Overall, RBD was associated with a more than twofold higher risk of developing ICBs (OR 2.12, 95% CI 1.43-3.14, I² = 56.7%, P < 0.01). Similar results were obtained in sensitivity analyses and in meta-analyses of subgroups stratified based on multivariable adjustment and methods for diagnosing RBD and ICBs. No significant risk of publication bias was found.

CONCLUSION

RBD in PD is confirmed to be a risk factor for ICBs. Clinicians should be aware of this association to help them improve patient management.

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

Objective

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

Methods

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

Results

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

Conclusions

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

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.

Suggestive association between OPRM1 and impulse control disorders in Parkinson's disease

BACKGROUND

Impulse control disorders are frequently associated with dopaminergic therapy in Parkinson's disease. Genetic studies have suggested a high heritability of impulse control disorders in the general population and in PD. The aim of this study was to identify candidate gene variants associated with impulse control disorders and related behaviors in PD.

METHODS

We performed a multicenter case-control study in PD patients with (cases) or without impulse control disorders and related behaviors despite significant dopamine agonist exposure of >300 mg levodopa-equivalent daily dose during 12 months (controls). Behavioral disorders were assessed using the Ardouin scale. We investigated 50 variants in 24 candidate genes by a multivariate logistic regression analysis adjusted for sex and age at PD onset.

RESULTS

The analysis was performed on 172 cases and 132 controls. Cases were younger (60 ± 8 vs 63 ± 8 years; P < 0.001) and had a higher family history of pathological gambling (12% vs 5%, P = 0.03). No variant was significantly associated with impulse control disorders or related behaviors after correction for multiple testing, although the 2 top variants were close to significant (OPRM1 rs179991, OR, 0.49; 95%CI, 0.32-0.76; P = 0.0013; Bonferroni adjusted P = 0.065; DAT1 40-base pair variable number tandem repeat, OR, 1.82; 95%CI, 1.24-2.68; P = 0.0021; Bonferroni adjusted P = 0.105).

CONCLUSIONS

Our results are suggestive of a novel association of the opioid receptor gene OPRM1 with impulse control disorders and related behaviors in PD and confirm a previous association with DAT1. Although replication in independent studies is needed, our results bring potential new insights to the understanding of molecular mechanisms of impulse control disorders. © 2018 International Parkinson and Movement Disorder Society.

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.

Impulse control disorders in Parkinson's disease

Impulse control disorders (ICD) are frequent side effects of dopamine replacement therapy (DRT) used in Parkinson's disease (PD) with devastating consequences on the patients and caregivers. ICD are behavioural addictions including compulsive gambling, shopping, sexual behaviour, and binge eating that are mainly associated with dopamine D2/D3 agonists. Their management is a real clinical challenge due to the lack of therapeutic alternative. Clinical studies have identified demographic and clinical risk factors for ICD such as younger age at disease onset, male gender, prior history of depression or substance abuse, REM sleep behaviour disorders and higher rate of dyskinesia. PD patients with ICD may also have a specific pattern of dopaminergic denervation in the ventral striatum. Specific evaluation tools have now been designed to better evaluate the severity and impact of ICD in PD. Patients with ICD display altered processing of reward and loss, and decisional bias associated with altered activity in cortical and subcortical areas such as the orbitofrontal cortex, amygdala, insula, anterior cingular cortex, and ventral striatum. Preclinical studies have demonstrated that D2/D3 agonists induce impairments in behavioural processes likely relevant to ICD such as risk-taking behaviour, preference for uncertainty, perseverative responding and sustained drive to engage in gambling-like behaviour. Whether interactions between dopamine denervation and DRT significantly contribute to the pathogenesis of ICD remains poorly understood so far, although features unique to PD have been identified in patients with ICD. Large-scale longitudinal studies are needed to better identify subjects with increased risk to develop ICD and develop therapeutic options.