Long-Term Follow-Up of the LEAP Study: Early Versus Delayed Levodopa in Early Parkinson's Disease.

BACKGROUND AND OBJECTIVE: The Levodopa in EArly Parkinson's disease study showed no effect of earlier versus later levodopa initiation on Parkinson's disease (PD) progression over 80 weeks. We now report the effects over 5 years. METHODS: The Levodopa in EArly Parkinson's disease study randomly assigned patients to levodopa/carbidopa 300/75 mg daily for 80 weeks (early start) or to placebo for 40 weeks followed by levodopa/carbidopa 300/75 mg daily for 40 weeks (delayed start). Follow-up visits were performed 3 and 5 years after baseline. We assessed the between-group differences in terms of square root transformed total Unified Parkinson's Disease Rating Scale score at 3 and 5 years with linear regression. We compared the prevalence of dyskinesia, prevalence of wearing off, and the levodopa equivalent daily dose. RESULTS: A total of 321 patients completed the 5-year visit. The adjusted square root transformed total Unified Parkinson's Disease Rating Scale did not differ between treatment groups at 3 (estimated difference, 0.17; standard error, 0.13; P = 0.18) and 5 years (estimated difference, 0.24; standard error, 0.13; P = 0.07). At 5 years, 46 of 160 patients in the early-start group and 62 of 161 patients in the delayed-start group experienced dyskinesia (P = 0.06). The prevalence of wearing off and the levodopa equivalent daily dose were not significantly different between groups. CONCLUSIONS: We did not find a difference in disease progression or in prevalence of motor complications between patients with early PD starting treatment with a low dose of levodopa 40 weeks earlier versus 40 weeks later over the subsequent 5 years. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Randomized Delayed-Start Trial of Levodopa in Parkinson's Disease.

BACKGROUND: Levodopa is the main treatment for symptoms of Parkinson's disease. Determining whether levodopa also has a disease-modifying effect could provide guidance as to when in the course of the disease the treatment with this drug should be initiated. METHODS: In a multicenter, double-blind, placebo-controlled, delayed-start trial, we randomly assigned patients with early Parkinson's disease to receive levodopa (100 mg three times per day) in combination with carbidopa (25 mg three times per day) for 80 weeks (early-start group) or placebo for 40 weeks followed by levodopa in combination with carbidopa for 40 weeks (delayed-start group). The primary outcome was the between-group difference in the mean change from baseline to week 80 in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS; scores range from 0 to 176, with higher scores signifying more severe disease). Secondary analyses included the progression of symptoms, as measured by the UPDRS score, between weeks 4 and 40 and the noninferiority of early initiation of treatment to delayed initiation between weeks 44 and 80, with a noninferiority margin of 0.055 points per week. RESULTS: A total of 445 patients were randomly assigned: 222 to the early-start group and 223 to the delayed-start group. The mean (±SD) UPDRS score at baseline was 28.1±11.4 points in the early-start group and 29.3±12.1 points in the delayed-start group. The change in UPDRS score from baseline to week 80 was -1.0±13.1 points and -2.0±13.0 points, respectively (difference, 1.0 point; 95% confidence interval [CI], -1.5 to 3.5; P=0.44); this finding of no significant between-group difference at week 80 implies that levodopa had no disease-modifying effect. Between weeks 4 and 40, the rate of progression of symptoms, as measured in UPDRS points per week, was 0.04±0.23 in the early-start group and 0.06±0.34 in the delayed-start group (difference, -0.02; 95% CI, -0.07 to 0.03). The corresponding rates between weeks 44 and 80 were 0.10±0.25 and 0.03±0.28 (difference, 0.07; two-sided 90% CI, 0.03 to 0.10); the difference in the rate of progression between weeks 44 and 80 did not meet the criterion for noninferiority of early receipt of levodopa to delayed receipt. The rates of dyskinesia and levodopa-related fluctuations in motor response did not differ significantly between the two groups. CONCLUSIONS: Among patients with early Parkinson's disease who were evaluated over the course of 80 weeks, treatment with levodopa in combination with carbidopa had no disease-modifying effect. (Funded by the Netherlands Organization for Health Research and Development and others; LEAP Current Controlled Trials number, ISRCTN30518857 .).

Feasibility of a Cognitive Training Game in Parkinson's Disease: The Randomized Parkin'Play Study.

Cognitive training (CT) shows modest positive effects on cognitive function in patients with Parkinson's disease (PD). Gamification may enhance adherence to traditional CT, but this has not been studied yet. Here, we investigated the feasibility of a gamified CT. We performed a randomized controlled trial including PD patients with mild cognitive impairment. Participants were randomly allocated to a 12-week home-based gamified CT intervention or waiting-list control group. Assessments were performed at baseline and at weeks 12 and 24. Forty-one patients were included (21 intervention and 20 waiting-list controls). Sixty-three percent of the intervention group trained >50% of the recommended sessions, while 81% voluntarily continued training after 12 weeks. After 24 weeks, 87.5% graded the game to be satisfactory. Global cognition scores improved after 24 weeks. Home-based gamified CT shows acceptable feasibility in patients with PD, and we observed preliminary indications for efficacy. Larger trials are needed to establish this efficacy.

The Parkin'Play study: protocol of a phase II randomized controlled trial to assess the effects of a health game on cognition in Parkinson's disease.

BACKGROUND: In Parkinson's disease (PD), cognitive impairment is an important non-motor symptom heralding the development of dementia. Effective treatments to slow down the rate of cognitive decline in PD patients with mild cognitive impairment are lacking. Here, we describe the design of the Parkin'Play study, which assesses the effects of a cognitive health game intervention on cognition in PD. METHODS/DESIGN: This study is a multicentre, phase-II, open-randomized clinical trial that aims to recruit 222 PD patients with mild cognitive impairment. Eligible patients have PD, Hoehn & Yahr stages I-III, are aged between 40 and 75 years, and have cognitive impairment but no dementia. The intervention group (n = 111) will be trained using a web-based health game targeting multiple cognitive domains. The control group (n = 111) will be placed on a waiting list. In order to increase compliance the health game adapts to the subjects' performance, is enjoyable, and can be played at home. From each group, 20 patients will undergo fMRI to test for potential functional brain changes underlying treatment. The primary outcome after 12 weeks of training is cognitive function, as assessed by a standard neuropsychological assessment battery and an online cognitive assessment. The neuropsychological assessment battery covers the following domains: executive function, memory, visual perception, visuoconstruction and language. A compound score for overall cognitive function will be calculated as the mean score of all test Z-scores based on the distribution of scores for both groups taken together. Secondary outcomes at follow-up visits up to 24 weeks include various motor and non-motor symptoms, compliance, and biological endpoints (fMRI). DISCUSSION: This study aims at evaluating whether a cognitive intervention among PD patients leads to an increased cognitive performance on targeted domains. Strengths of this study are a unique web-based health game intervention, the large sample size, a control group without intervention and innovations designed to increase compliance. TRIAL REGISTRATION: NTR5637 on 7-jan-2016.

Levodopa Response in Patients With Early Parkinson Disease: Further Observations of the LEAP Study.

BACKGROUND AND OBJECTIVES: The Levodopa in EArly Parkinson's Disease (LEAP) study enabled us to conduct post hoc analyses concerning the effects of levodopa in patients with early Parkinson disease. METHODS: The LEAP study was a double-blind, placebo-controlled, randomized, delayed-start trial in which patients with early Parkinson disease were randomized to receive levodopa/carbidopa 300/75 mg daily for 80 weeks (early-start group) or to placebo for 40 weeks followed by levodopa/carbidopa 300/75 mg daily for 40 weeks (delayed-start group). We analyzed the effect of levodopa with the Unified Parkinson's Disease Rating Scale on bradykinesia, rigidity, and tremor. At week 80, participants answered 3 questions regarding motor response fluctuations. RESULTS: A total of 222 patients were randomized to the early-start group (mean ± SD age at baseline 64.8 ± 8.7 years; 71% male) and 223 to the delayed-start group (mean ± SD age at baseline 65.5 ± 8.8 years; 69% male). The difference between the early- and delayed-start groups in mean change from baseline to week 4, expressed as Hedges g effect size, was -0.33 for bradykinesia, -0.29 for rigidity, and -0.25 for tremor (for all symptoms indicating a small effect in favor of the early-start group); from baseline to week 22, respectively, -0.49, -0.36, and -0.44 (small to medium effect); and from baseline to week 40, respectively, -0.32, -0.19, and -0.27 (small effect). At 80 weeks, fewer patients in the early-start group (46 of 205 patients, 23%) experienced motor response fluctuations than patients in the delayed-start group (81 of 211, 38%; p < 0.01). DISCUSSION: In patients with early Parkinson disease, levodopa improves bradykinesia, rigidity, and tremor to the same order of magnitude. For all 3 symptoms, effects were larger at 22 weeks compared with 4 weeks. At 80 weeks, there were fewer patients with motor response fluctuations in the group that had started levodopa earlier. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that the effect of levodopa on bradykinesia, rigidity, and tremor is larger after 22 weeks compared with 4 weeks of treatment. TRIAL REGISTRATION INFORMATION: ISRCTN30518857, EudraCT number 2011-000678-72.

Cost-Effectiveness and Cost-Utility of Early Levodopa in Parkinson's Disease.

BACKGROUND: In the Levodopa in EArly Parkinson's disease (LEAP) study, 445 patients were randomized to levodopa/carbidopa 100/25 mg three times per day for 80 weeks (early-start) or placebo for 40 weeks followed by levodopa/carbidopa 100/25 mg three times per day for 40 weeks (delayed-start). OBJECTIVE: This paper reports the results of the economic evaluation performed alongside the LEAP-study. METHODS: Early-start treatment was evaluated versus delayed-start treatment, in which the cost-effectiveness analysis (CEA) and the cost-utility analysis (CUA) were performed from the societal perspective, including health care costs among providers, non-reimbursable out-of-pocket expenses of patients, employer costs of sick leave, and lowered productivity while at work. The outcome measure for the CEA was the extra cost per unit decrease on the Unified Parkinson's Disease Rating Scale 80 weeks after baseline. The outcome measure for the CUA was the extra costs per additional quality adjusted life year (QALY) during follow-up. RESULTS: 212 patients in the early-start and 219 patients in the delayed-start group reported use of health care resources. With savings of € 59 per patient (BCa 95% CI: -829, 788) in the early-start compared to the delayed-start group, societal costs were balanced. The early-start group showed a mean of 1.30 QALYs (BCa 95% CI: 1.26, 1.33) versus 1.30 QALYs (BCa 95% CI: 1.27, 1.33) for the delayed-start group. Because of this negligible difference, incremental cost-effectiveness and cost-utility ratios were not calculated. CONCLUSION: From an economic point of view, this study suggests that early treatment with levodopa is not more expensive than delayed treatment with levodopa.

Telemonitoring via Questionnaires Reduces Outpatient Healthcare Consumption in Parkinson's Disease.

BACKGROUND: Parkinson's disease (PD) is best managed by neurologists, traditionally including frequent doctor-patient contact. Because of a rise in PD prevalence and associated healthcare costs, this personnel-intensive care may not be future proof. Telemedicine tools for home monitoring have shown to reduce healthcare consumption in several chronic diseases and also seem promising for PD. OBJECTIVE: To explore whether telemonitoring can reduce outpatient healthcare consumption in PD. METHODS: We conducted a cohort study with 116 outpatients with PD who used the telemedicine tool "myParkinsoncoach." The tool involved periodic monitoring, feedback, knowledge modules, and text message functionality. Retrospective data about PD-related healthcare consumption in the year before and after introduction of the tool were retrieved from the hospital information system. Additional data about tool-related activities performed by nursing staff were logged prospectively for 3 months. RESULTS: There was a 29% reduction in the number of outpatient visits (P < 0.001) in the year after introduction of the tool compared with the year before. A 39% reduction was seen in overall PD-related healthcare costs (P = 0.001). Similar results were found for patients ≥70 years old. Nursing staff spent on average 15.5 minutes per patient a month on monitoring the tool and follow-up activities. CONCLUSIONS: Study results demonstrate a significant reduction in PD-related healthcare consumption using telemonitoring. Notably, these results were also found in elderly patients. Further research is needed to confirm these findings, preferably taking a broader perspective on healthcare consumption and within a larger, multicenter and prospective setup.

Rivastigmine for minor visual hallucinations in Parkinson's disease: A randomized controlled trial with 24 months follow-up.

BACKGROUND: Visual hallucinations are common in patients with Parkinson's disease and represent probably the major independent predictor for cognitive deterioration and nursing home placement. OBJECTIVE: To investigate if treatment of minor visual hallucinations in Parkinson's disease with rivastigmine delays the progression to psychosis. METHODS: A multicenter, randomized, double-blind, placebo-controlled trial was conducted which aimed to recruit 168 patients with Parkinson's disease reporting minor visual hallucinations 4 weeks before it. Important exclusion criteria were Parkinson's disease dementia, current delirium, and treatment with antipsychotics or drugs that have significant anti-cholinergic side effects. Subjects were randomized to rivastigmine capsules, 3-6 mg twice a day, or placebo for 24 months. The primary outcome was the time to Parkinson's disease psychosis, which was defined as the need to start with antipsychotics. RESULTS: The trial was stopped prematurely because of slow recruitment. Ninety-one patients were randomized: 46 patients were assigned to rivastigmine and 45 patients to placebo. No effect of rivastigmine could be demonstrated on the transition time to psychosis or dementia during the 24-month follow-up period. After 6 months of study treatment, cognition, mood, motor performance, and non-motor performance did not differ significantly between the rivastigmine-group and the placebo-group. CONCLUSIONS: Because the study was terminated early, it was insufficiently powered to properly evaluate the primary outcome. The limited data of the study favor a wait and see approach instead of early treatment with rivastigmine in PD patients with minor VH.

Predictors of Time to Discontinuation of Levodopa-Carbidopa Intestinal Gel Infusion: A Retrospective Cohort Study.

BACKGROUND: Continuous intra-duodenal infusion of levodopa-carbidopa intestinal gel (LCIG) is a well-established therapy for patients with advanced Parkinson's disease (PD) suffering from motor complications despite optimized treatment with oral dopaminomimetics. However, time to discontinuation of treatment with LCIG varies considerably between patients, ranging from a few months to more than ten years. To improve the selection of candidates for LCIG, knowledge of prognostic factors is of paramount importance. OBJECTIVE: To explore baseline predictors of time to discontinuation of LCIG. METHODS: In this two-center retrospective cohort study, we reviewed the medical files of 98 PD patients treated with LCIG between April 2006 and December 2015 (53% male; mean age: 66.2 years; mean disease duration: 12.3 years). Baseline patient characteristics were used as covariates in Cox regression models. RESULTS: During follow-up (mean observation time: 2.6 years; range: 0.1-9.3) eighteen patients discontinued treatment (18.4%), while seven patients died (7.1%). Median duration of treatment with LCIG, estimated with Kaplan-Meier analysis, was 7.8 years (95% CI: 6.7-9.0). Disease duration (in years) at baseline was a statistically significant predictor of time to discontinuation of LCIG (HR: 0.85; 95% CI: 0.75-0.96, p = 0.006). All other characteristics studied, e.g. age >70 years, did not show statistically significant associations with the total duration of treatment with LCIG. CONCLUSION: Our findings show a low overall rate of discontinuation of LCIG infusion, with a median duration of treatment of 7.8 years. Shorter disease duration at baseline appeared to be a predictor of earlier discontinuation of LCIG.

The diagnostic accuracy of dopamine transporter SPECT imaging to detect nigrostriatal cell loss in patients with Parkinson's disease or clinically uncertain parkinsonism: a systematic review.

In specialized movement disorder centers, Parkinson's disease (PD) is wrongly diagnosed in 6 to 25% of cases. To improve the accuracy of the clinical diagnosis, it is necessary to have a reliable and practical reference standard. Dopamine transporter single-photon emission computed tomography (DAT SPECT) imaging might have the potential (high diagnostic accuracy and practical to use) to act as reference standard in detecting nigrostriatal cell loss in patients with (early stage) parkinsonism. We performed a systematic review to evaluate if DAT SPECT imaging can be used as such. Relevant studies were searched in the MEDLINE and EMBASE databases. Studies were selected when they met the following criteria: (1) all patients were adults with a clinical diagnosis of PD or clinically uncertain parkinsonism and (2) the study reported original data. In addition, studies needed to fulfill one of the two following criteria: (1) patients underwent at least one DAT SPECT and had a neuropathological confirmed diagnosis and (2) patients underwent at least two DAT SPECT scans, performed at least 2 years apart. The search identified 1,649 articles. Eight studies fulfilled our selection criteria and were included in this review. There was only one study including patients with diagnostic uncertainty. Sensitivity and specificity of DAT SPECT imaging to detect nigrostriatal cell loss were 98%. The other studies included patients with a diagnosis of PD in whom there was no uncertainty. In these studies, sensitivity was 100%. Our systematic review indicates that DAT SPECT imaging seems to be accurate to detect nigrostriatal cell loss in patients with parkinsonism.

Parkinson disease in long term care facilities: a review of the literature.

Parkinson disease (PD) is common in long term care (LTC) facilities. The number of institutionalized patients with PD will rise sharply in the coming decades because of 2 concurrent phenomena: aging of the population leads to an increased PD prevalence and improved quality of care has led to a prolonged survival in advanced disease stages. Only a few studies have investigated the prevalence and clinical characteristics of patients with PD in LTC facilities. Even fewer studies have addressed the treatment strategies used to support these institutionalized patients, who are mostly in advanced stages of the disease. The available evidence suggests that current management of patients with PD in LTC facilities is less than optimal. In the Netherlands, and we suspect in many other countries, there are no formal guidelines for treating patients with PD who have been admitted to a LTC facility. In this review, we describe the epidemiology, clinical characteristics, and clinical management of patients with PD in LTC settings. We also address potentially modifiable elements of care and provide several recommendations to improve the management of PD in these facilities. We conclude by suggesting a possible guide for future research in this area.

Perspectives on Parkinson disease care in Dutch nursing homes.

INTRODUCTION: Parkinson's disease (PD) is a complex and disabling disorder. Ultimately, 20% to 40% of patients are admitted to a nursing home, and neurologists often lose track of these patients. Care and treatment of these institutionalized patients have not been addressed comprehensively, but anecdotal reports suggest it is suboptimal. We conducted a qualitative study to analyze the quality of PD care in Dutch nursing homes from the perspective of residents, caregivers, and health care workers. METHODS: Experiences and (unmet) needs of 15 nursing home residents with PD and parkinsonism (90% Hoehn and Yahr stage 4 and 5) and 15 informal caregivers were assessed using semistructured interviews. Furthermore, 5 focus group discussions were organized with 13 nurses and 22 other health care professionals to explore the experiences and barriers of PD care. RESULTS: Three core unmet needs were identified: (1) unsatisfactory empathy and emotional support, according to residents and informal caregivers; (2) insufficient staff knowledge on PD-related issues, such as motor fluctuations, leading to poorly timed administration of levodopa; (3) suboptimal organization of care with limited access to neurologists and specialized PD nurses. CONCLUSIONS: PD care in Dutch nursing homes is suboptimal according to residents, informal caregivers, and health care workers. Three core areas for improvement were identified, including greater attention for psychosocial problems, improved PD-specific knowledge among nursing home staff, and better collaboration with hospital staff trained in movement disorders.

Nonmotor symptoms in nursing home residents with Parkinson's disease: prevalence and effect on quality of life.

OBJECTIVES: To determine the prevalence of nonmotor symptoms (NMS) in nursing home (NH) residents with Parkinson's disease (PD) and to establish the association with quality of life. DESIGN: Cross-sectional. SETTING: Nursing homes in the southeast of the Netherlands. PARTICIPANTS: Nursing home residents with PD and a Mini-Mental State Examination score of 18 or greater (N = 73; mean age 78.7, disease duration 10 years, mainly Hoehn and Yahr Stages 4 (38%) and 5 (49%)) underwent detailed examination to determine the prevalence of NMS. MEASUREMENTS: Validated instruments for PD-related NMS were used to examine the NH residents with PD. The overall burden of NMS, and autonomic problems in particular, were measured using the Non-Motor Symptoms Scale (NMSS). Depression, neuropsychiatric symptoms, sleep problems, cognitive dysfunction, and motor impairments were focused on in further detail using established clinimetric tests. Linear regression analysis was used to examine the relationship between these symptoms and quality of life, which was measured using the Parkinson's Disease Questionnaire (PDQ-8). RESULTS: The NMSS revealed a mean of nearly 13 different NMS per resident. Autonomic problems (constipation, urinary urgency) were particularly prevalent (48-75% of residents). Depressive symptoms were present in 45%. The most prevalent neuropsychiatric symptoms other than depression were irritability and apathy. The most common sleep problems were overall poor nighttime sleep quality, daytime sleepiness, and nocturia. Cognitive problems were highly prevalent, and 77% of the residents met the criteria for PD-related dementia. High scores were also obtained for motor impairments. Mean PDQ-8 score was high, indicating poor quality of life. Poor quality of life was most strongly associated with the prevalence and severity of overall NMS burden (coefficient of determination = 0.45). CONCLUSION: Nonmotor symptoms were highly prevalent in NH residents with PD. Quality of life was poor, largely because of NMS. Because many NMS are potentially treatable, diagnosis and treatment of these severely affected individuals deserve more attention.

[Non-motor symptoms of Parkinson's disease]. / Niet-motorische symptomen van de ziekte van Parkinson.

Parkinson's disease has traditionally been viewed as a disease with only motor features. Nowadays, a wide variety of non-motor symptoms and signs are also recognised as being characteristic of the disease. Non-motor symptoms, most importantly autonomic dysfunction, neuropsychiatric symptoms and sleep problems, are prevalent in virtually all Parkinson's disease patients and influence the quality of life more than the motor symptoms. Patients may visit a variety of health care professionals, but non-motor symptoms are often missed, because physicians do not explicitly ask patients about them or do not recognise them as being part of the disease. Knowledge of non-motor symptoms is important to avoid unnecessary additional testing. Specific treatment options are available, as described in the Dutch multidisciplinary guidelines on Parkinson's disease.

Motor profile and drug treatment of nursing home residents with Parkinson's disease.

OBJECTIVES: To examine the clinical characteristics, motor impairments, and drug treatments of nursing home residents with Parkinson's disease (PD). DESIGN: Cross-sectional study. SETTING: Nursing homes in the southeast of the Netherlands. PARTICIPANTS: Nursing home residents with PD and a Mini-Mental State Examination score of 18 or greater seen by a physician with experience in movement disorders. MEASUREMENTS: Participant characteristics, motor function, and dopaminergic medications were assessed. The Short Parkinson's Evaluation Scale/SCales for Outcomes in Parkinson's disease (SPES-SCOPA) was used to assess motor impairments and disabilities. RESULTS: Seventy-three nursing home residents with PD (mean age 78.7; 45% male; mean disease duration 10.1 years; Hoehn and Yahr 4 (38%) and 5 (49%)) were included. Most residents were severely disabled, 49% being wheelchair bound. According to the SPES-SCOPA, 44% of residents were "off" (in a motor state in which they are slow and stiff) most of the time. Dyskinesias were encountered infrequently. Most residents were mainly treated with levodopa monotherapy, and daily doses varied widely (20-1,600 mg, mean 673 mg); 25% of residents were treated with less than 400 mg levodopa daily, and 8% received no levodopa at all. The movement disorders specialist considered 32 residents to be possibly undertreated. CONCLUSION: These findings show that PD in nursing home residents is characterized by severe motor impairment and a high proportion of daily "off" time, which underscores the need for better management of PD in nursing homes, for example within specialized institutions or with periodic consultations by a movement disorders expert.

The role of the dopaminergic system in mood, motivation and cognition in Parkinson's disease: a double blind randomized placebo-controlled experimental challenge with pramipexole and methylphenidate.

In Parkinson's disease (PD) reduced dopaminergic activity in the mesocorticolimbic pathway is implied in the pathophysiology of several non-motor symptoms related to mood, motivation and cognition. Insight in the pathophysiology of these syndromes may pave the way for more rational treatments. In a double-blind, randomized, placebo controlled, crossover design with three arms, we studied the effects of a direct dopaminergic challenge with the dopamine 2 receptor agonist pramipexole, an indirect challenge with the dopamine reuptake inhibitor methylphenidate, and placebo on measures of mood, motivation and cognition in 23 agonist-naïve PD patients and 23 healthy controls. Acute challenge with pramipexole had a negative effect on mood and fatigue in both patients and controls. In addition, challenge with pramipexole led to increased anger, fatigue, vigor and tension in healthy control subjects, but not in PD patients. Challenge with methylphenidate had a positive effect on anhedonia and vigor in PD patients. Due to its side effects after a single administration, pramipexole is probably less suitable for acute challenge studies. The acute effects of a methylphenidate challenge on anhedonia and vigor in PD patients make this drug an interesting choice for further studies of the treatment of mood and motivational disorders in this population.