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1.  Dopamine and Impulse Control Disorders in Parkinson’s Disease 
Annals of neurology  2008;64(Suppl 2):S93-100.
There is an increasing awareness that impulse control disorders (ICDs), including compulsive gambling, buying, sexual behavior, and eating, can occur as a complication of Parkinson’s disease (PD). In addition, other impulsive or compulsive disorders have been reported to occur, including dopamine dysregulation syndrome (DDS) and punding. Case reporting and prospective studies have reported an association between ICDs and the use of dopamine agonists (DAs), particularly at greater dosages, whereas dopamine dysregulation syndrome has been associated with greater dosages of levodopa or short-acting DAs. Data suggest that risk factors for an ICD may include male sex, younger age or younger age at PD onset, a pre-PD history of ICD symptoms, personal or family history of substance abuse or bipolar disorder, and a personality style characterized by impulsiveness. Although psychiatric medications are used clinically in the treatment of ICDs, there is no empiric evidence supporting their use in PD. Therefore, management for clinically significant ICD symptoms should consist of modifications to dopamine replacement therapy, particularly DAs, and there is emerging evidence that such management is associated with an overall improvement in ICD symptomatology. It is important that PD patients be aware that DA use may lead to the development of an ICD, and that clinicians monitor patients as part of routine clinical care. As empirically validated treatments for ICDs are emerging, it will be important to examine their efficacy and tolerability in individuals with cooccurring PD and ICDs.
doi:10.1002/ana.21454
PMCID: PMC3530139  PMID: 19127573
2.  Long-Term Follow-Up of Impulse Control Disorders in Parkinson’s Disease 
Recent studies have linked dopamine agonist (DA) usage with the development of impulse control disorders (ICDs) in Parkinson’s disease (PD). Little is known about optimal management strategies or the long-term outcomes of affected patients. To report on the clinical interventions and long-term outcomes of PD patients who developed an ICD after DA initiation. Subjects contacted by telephone for a follow-up interview after a mean time period of 29.2 months. They were administered a modified Minnesota Impulse Disorder Interview for compulsive buying, gambling, and sexuality, and also self-rated changes in their ICD symptomatology. Baseline and follow-up dopamine replacement therapy use was recorded and verified by chart review. Of 18 subjects, 15 (83.3%) participated in the follow-up interview. At follow-up, patients were receiving a significantly lower DA levodopa equivalent daily dosage (LEDD) (Z = -3.1, P = 0.002) and a higher daily levodopa dosage (Z = -1.9, P = 0.05), but a similar total LEDD dosage (Z = -0.47, P = 0.64) with no changes in Unified Parkinson’s Disease Rating Scale motor score (Z = -1.3, P = 0.19). As part of ICD management, 12 (80.0%) patients discontinued or significantly decreased DA treatment, all of whom experienced full or partial remission of ICD symptoms by self-report, and 10 (83.3%) of whom no longer met diagnostic criteria for an ICD. For PD patients who develop an ICD in the context of DA treatment, discontinuing or significantly decreasing DA exposure, even when offset by an increase in levodopa treatment, is associated with remission of or significant reduction in ICD behaviors without worsening in motor symptoms.
doi:10.1002/mds.21770
PMCID: PMC2651355  PMID: 17960796
dopamine agonist; gambling; impulse control disorders; Parkinson’s disease
3.  Validation of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) 
Objective
As no comprehensive assessment instrument for impulse control disorders (ICDs) in Parkinson’s disease (PD) exists, the aim of this study was to design and assess the psychometric properties of a self-administered screening questionnaire for ICDs and other compulsive behaviors in PD.
Methods
The Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) has 3 sections: Section 1 assesses four ICDs (involving gambling, sexual, buying, and eating behaviors), Section 2 other compulsive behaviors (punding, hobbyism and walkabout), and Section 3 compulsive medication use. For validation, a convenience sample of 157 PD patients at 4 movement disorders centers first completed the QUIP, and then was administered a diagnostic interview by a trained rater blinded to the QUIP results. A shortened instrument (QUIP-S) was then explored.
Results
The discriminant validity of the QUIP was high for each disorder or behavior (receiver operating characteristic area under the curve [ROC AUC]: gambling=0.95, sexual behavior=0.97, buying=0.87, eating=0.88, punding=0.78, hobbyism=0.93, walkabout=0.79). On post hoc analysis, the QUIP-S ICD section had similar properties (ROC AUC: gambling=0.95, sexual behavior=0.96, buying=0.87, eating=0.88). When disorders/behaviors were combined, the sensitivity of the QUIP and QUIP-S to detect an individual with any disorder was 96% and 94%, respectively.
Conclusions
Scores on the QUIP appear to be valid as a self-assessment screening instrument for a range of ICDs and other compulsive behaviors that occur in PD, and a shortened version may perform as well as the full version. A positive screen should be followed by a comprehensive, clinical interview to determine the range and severity of symptoms, as well as need for clinical management.
doi:10.1002/mds.22571
PMCID: PMC2848971  PMID: 19452562
Parkinson’s disease; impulse control disorders; dopamine dysregulation syndrome; punding; pathological gambling
4.  Impulse control disorders and compulsive behaviors associated with dopaminergic therapies in Parkinson disease 
Neurology. Clinical Practice  2012;2(4):267-274.
Summary
Impulse control disorders (ICD) (most commonly pathologic gambling, hypersexuality, and uncontrollable spending) and compulsive behaviors can be triggered by dopaminergic therapies in Parkinson disease (PD). ICD are especially prevalent in patients receiving a dopamine agonist as part of their treatment regimen for PD, and have also been reported when dopamine agonists are used for other indications (e.g., restless legs syndrome). Although these iatrogenic disorders are common, affecting 1 in 7 patients with PD on dopamine agonists, they often elude detection by the treating physician. ICD lead to serious consequences, causing significant financial loss and psychosocial morbidity for many patients and families. ICD can appear at any time during treatment with dopamine agonists, sometimes within the first few months, but most often after years of treatment, particularly when patients receive dopamine agonists and levodopa together. In most cases ICD resolve if the dopamine agonist is withdrawn, and PD motor symptoms are managed with levodopa monotherapy. Familiarity with the clinical aspects, risk factors, pathophysiology, and management of ICD is essential for physicians using dopaminergic therapies to treat PD and other disorders.
doi:10.1212/CPJ.0b013e318278be9b
PMCID: PMC3613210  PMID: 23634371
5.  The Risky Business of Dopamine Agonists in Parkinson Disease and Impulse Control Disorders 
Behavioral neuroscience  2011;125(4):492-500.
Risk-taking behavior is characterized by pursuit of reward in spite of potential negative consequences. Dopamine neurotransmission along the mesocorticolimbic pathway is a potential modulator of risk behavior. In patients with Parkinson's Disease (PD), impulse control disorder (ICD) can result from dopaminergic medication use, particularly Dopamine Agonists (DAA). Behaviors associated with ICD include hypersexuality as well as compulsive gambling, shopping, and eating, and are potentially linked to alterations to risk processing. Using the Balloon Analogue Risk task, we assessed the role of agonist therapy on risk-taking behavior in PD patients with (n=22) and without (n=19) active ICD symptoms. Patients performed the task both ‘on’ and ‘off’ DAA. DAA increased risk-taking in PD patients with active ICD symptoms, but did not affect risk behavior of PD controls. DAA dose was also important in explaining risk behavior. Both groups similarly reduced their risk-taking in high compared to low risk conditions and following the occurrence of a negative consequence, suggesting that ICD patients do not necessarily differ in their ability to process and adjust to some aspects of negative consequences. Our findings suggest dopaminergic augmentation of risk-taking behavior as a potential contributing mechanism for the emergence of ICD in PD patients.
doi:10.1037/a0023795
PMCID: PMC3144294  PMID: 21604834
Impulse Control Disorders; Dopamine Agonists; Parkinson Disease; Risk behavior
6.  Patient versus informant reporting of ICD symptoms in Parkinson’s disease using the QUIP: Validity and variability☆ 
Parkinsonism & related disorders  2010;17(3):153-155.
Questions exist regarding the validity of patient-reporting of psychiatric symptoms in Parkinson’s disease (PD). We assessed observer variability and validity in reporting of impulse control disorder (ICD) symptoms in PD by using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP). PD patients and their informants (71 pairs) completed the QUIP to assess four ICDs (compulsive gambling, buying, sexual behavior, and eating) in patients. Trained raters then administered a diagnostic interview. Sensitivity of the QUIP for a diagnosed ICD was 100% for both patient- and informant-completed instruments, and specificity was 75% for both raters. Approximately 40% of patients without an ICD diagnosis had a positive QUIP, suggesting that many PD patients experience subsyndromal ICD symptoms that require ongoing monitoring. Agreement between patient- and informant-reporting of any ICD behaviors on the QUIP was moderate (kappa = 0.408), and for individual ICDs was highest for gambling (kappa = 0.550). Overall, a negative QUIP from either the patient or informant rules out the possibility of an ICD, while a positive QUIP requires a follow-up diagnostic interview and ongoing monitoring to determine if symptoms currently are, or in the future become, clinically significant.
doi:10.1016/j.parkreldis.2010.11.015
PMCID: PMC3073062  PMID: 21186135
Impulse control disorders; Parkinson’s disease; QUIP
7.  Impulsive and Compulsive Behaviors in Parkinson’s Disease 
Background: Impulsive and compulsive behaviors (ICBs) are a heterogeneous group of conditions that may be caused by long-term dopaminergic replacement therapy (DRT) of Parkinson’s disease (PD). The spectrum of ICBs includes dopamine dysregulation syndrome (DDS), punding, and impulse control disorders (ICDs).
Contents: We made a detailed review regarding the epidemiology, pathology, clinical characteristics, risk factors, diagnosis as well as treatment of ICBs.
Results: The prevalence of ICBs in PD patients is approximately 3–4% for DDS, 0.34–4.2% for punding, and 6–14% for ICDs, with higher prevalence in Western populations than in Asian. Those who take high dose of levodopa are more prone to have DDS, whereas, ICDs are markedly associated with dopamine agonists. Different subtypes of ICBs share many risk factors such as male gender, higher levodopa equivalent daily dose, younger age at PD onset, history of alcoholism, impulsive, or novelty-seeking personality. The Questionnaire for Impulsive–Compulsive Disorder in Parkinson’s Disease-Rating Scale seems to be a rather efficacious instrument to obtain relevant information from patients and caregivers. Treatment of ICBs is still a great challenge for clinicians. Readjustment of DRT remains the primary method. Atypical antipsychotics, antidepressants, amantadine, and psychosocial interventions are also prescribed in controlling episodes of psychosis caused by compulsive DRT, but attention should be drawn to balance ICBs symptoms and motor disorders. Moreover, deep brain stimulation of the subthalamic nucleus might be a potential method in controlling ICBs.
Conclusion: The exact pathophysiological mechanisms of ICBs in PD remains poorly understood. Further researches are needed not only to study the pathogenesis, prevalence, features, and risk factors of ICBs, but to find efficacious therapy for patients with these devastating consequences.
doi:10.3389/fnagi.2014.00318
PMCID: PMC4231987  PMID: 25452726
Parkinson disease; impulsive control disorders; dopamine dysregulation syndrome; review; dopaminergic replacement therapy
8.  Prospective Cohort Study of Impulse Control Disorders in Parkinson’s Disease 
Impulse control disorders (ICDs) are potentially serious side effects of dopamine agonist therapy in Parkinson’s disease (PD), but prospective data are lacking about their incidence, time course, and risk factors. This work was a 4-year, prospective cohort study of outpatients with PD and no previous ICDs (N = 164). All subjects treated with a dopamine agonist during the study were followed longitudinally for new-onset ICDs. Baseline characteristics were compared in groups with (ICD+) and without (ICD−) subsequent ICDs. Forty-six subjects were treated with a dopamine agonist, including 25 who were newly treated and 21 who received ongoing dopamine agonist therapy. Of these 46 subjects, 18 (39.1%) developed new-onset ICDs. The timing of ICD onset varied from 3.0 to 114.0 months (median, 23.0) after initiation of dopamine agonist therapy. Baseline demographic characteristics were similar in ICD+ and ICD− groups. At baseline, ICD+ subjects had a greater prevalence of motor complications (61.1% versus 25.0%; P = 0.01) than ICD− subjects, despite comparable total dopaminergic medication usage in both groups (median, 150.0 versus 150.0 levodopa equivalents; P = 0.61). Compared with ICD− subjects, ICD+ subjects had a greater baseline prevalence of caffeine use (100% versus 66.7%; P = 0.007) and higher lifetime prevalence of cigarette smoking (44.4% versus 14.3%; P = 0.04). Peak dopamine agonist doses were higher in ICD+ than ICD− subjects (median 300.0 versus 165.0 L-dopa equivalents; P = 0.03), but cumulative dopamine agonist exposure was similar in both groups. In summary, the timing of new-onset ICDs in PD is highly variable. Risk factors include cigarette smoking, caffeine use, motor complications, and higher peak dopamine agonist dosage.
doi:10.1002/mds.25291
PMCID: PMC3894820  PMID: 23283708
dopamine agonist; dopamine agonist withdrawal syndrome; impulse control disorder; prospective; Parkinson’s disease
9.  The role of dopamine in risk taking: a specific look at Parkinson’s disease and gambling 
An influential model suggests that dopamine signals the difference between predicted and experienced reward. In this way, dopamine can act as a learning signal that can shape behaviors to maximize rewards and avoid punishments. Dopamine is also thought to invigorate reward seeking behavior. Loss of dopamine signaling is the major abnormality in Parkinson’s disease. Dopamine agonists have been implicated in the occurrence of impulse control disorders in Parkinson’s disease patients, the most common being pathological gambling, compulsive sexual behavior, and compulsive buying. Recently, a number of functional imaging studies investigating impulse control disorders in Parkinson’s disease have been published. Here we review this literature, and attempt to place it within a decision-making framework in which potential gains and losses are evaluated to arrive at optimum choices. We also provide a hypothetical but still incomplete model on the effect of dopamine agonist treatment on these value and risk assessments. Two of the main brain structures thought to be involved in computing aspects of reward and loss are the ventral striatum (VStr) and the insula, both dopamine projection sites. Both structures are consistently implicated in functional brain imaging studies of pathological gambling in Parkinson’s disease.
doi:10.3389/fnbeh.2014.00196
PMCID: PMC4038955  PMID: 24910600
impulse control disorders; impulsivity; reward; loss aversion; insula; ventral striatum
10.  Maladaptive Reward-Learning and Impulse Control Disorders in Patients with Parkinson’s Disease: A Clinical Overview and Pathophysiology Update 
Journal of Movement Disorders  2014;7(2):67-76.
Impulse control disorders (ICD) in Parkinson’s disease (PD) are a disabling non-motor symptom with frequencies of 13–35% among patients receiving dopamine replacement therapy. ICD in PD is strongly associated with dopaminergic drug use, especially non-ergot dopamine agonists (DA). However, individual susceptibility and disease-related neural changes are also important contributors to the development of ICD. Discrepancies between nigrostriatal and mesolimbic dopaminergic degeneration and non-physiological administration of dopaminergic drugs may induce abnormal ’hyperstimulation’ of the mesolimbic system, which alters reward-learning behaviors in PD patients. In addition, DA can make patients more impulsive during decision-making and seek risk-taking behaviors. DA intake is also related to the biased representation of rewards. Ultimately, loss of negative feedback control due to dysfunctional frontostriatal connections is necessary for the establishment of ICD in PD. The subsequent behavioral and neural changes are affected by PD treatment and disease progression; thus, proper treatment guidelines for physicians are needed to prevent the development of ICD. Future studies aimed at producing novel therapeutics to control the risk factors for ICD or treat ICD behaviors in PD are warranted. This review summarizes recent advances from epidemiological and pathophysiological studies on ICD in PD. Management principles and limitations of current therapeutics are briefly discussed.
doi:10.14802/jmd.14010
PMCID: PMC4213534  PMID: 25360230
Impulse control disorder; Parkinson’s disease; Dopamine agonist; Reward-learning; Impulsivity; Addiction
11.  Impulse control disorders in Parkinson’s disease: recent advances 
Current opinion in neurology  2011;24(4):324-330.
Purpose of review
To review the recent advances in the epidemiology and pathophysiology of impulse control disorders (ICD) in Parkinson’s disease (PD).
Recent findings
Large cross-sectional and case-control multicentre studies show that ICDs in PD are common with a frequency of 13.6%. These behaviours are associated with impaired functioning and with depressive, anxiety and obsessive symptoms, novelty seeking and impulsivity. Behavioural subtypes demonstrate differences in novelty seeking and impulsivity suggesting pathophysiological differences. Observational and neurophysiological studies point towards a potential mechanistic overlap between the behavioural (ICDs) and motor (dyskinesias) dopaminergic sequelae. Converging data suggest dopamine agonists in ICDs appear to enhance learning from rewarding outcomes and impulsive choice. ICD patients also have enhanced risk preference and impaired working memory. Neuroimaging data points towards enhanced bottom-up ventral striatal dopamine release to incentive cues, gambling tasks and reward prediction, and possibly inhibition of top-down orbitofrontal influences. Dopamine agonist-related ventral striatal hypoactivity to risk is consistent with impaired risk evaluation.
Summary
Recent large scale studies and converging findings are beginning to provide an understanding of mechanisms underlying ICDs in PD which can guide prevention of these behaviours and optimize therapeutic approaches.
doi:10.1097/WCO.0b013e3283489687
PMCID: PMC3154756  PMID: 21725242
Impulse control disorders; Parkinson’s disease; dopamine agonists; pathological gambling; impulsivity
12.  Frequency of impulse control behaviours associated with dopaminergic therapy in restless legs syndrome 
BMC Neurology  2011;11:117.
Background
Low doses of dopamine agonists (DA) and levodopa are effective in the treatment of restless legs syndrome (RLS). A range of impulse control and compulsive behaviours (ICBs) have been reported following the use of DAs and levodopa in patients with Parkinson's disease. With this study we sought to assess the cross-sectional prevalence of impulse control behaviours (ICBs) in restless legs syndrome (RLS) and to determine factors associated with ICBs in a population cohort in Germany.
Methods
Several questionnaires based on validated and previously used instruments for assessment of ICBs were mailed out to patients being treated for RLS. Final diagnoses of ICBs were based on stringent diagnostic criteria after psychiatric interviews were performed.
Results
10/140 RLS patients of a clinical cohort (7.1%) were finally diagnosed with ICBs, 8 of 10 on dopamine agonist (DA) therapy, 2 of 10 on levodopa. 8 of the 10 affected patients showed more than one type of abnormal behaviour. Among those who responded to the questionnaires 6/140 [4.3%] revealed binge eating, 5/140 [3.6%] compulsive shopping, 3/140 [2.1%] pathological gambling, 3/140 [2.1%] punding, and 2/140 [1.4%] hypersexuality in psychiatric assessments. Among those who did not respond to questionnaires, 32 were randomly selected and interviewed: only 1 patient showed positive criteria of ICBs with compulsive shopping and binge eating. ICBs were associated with higher DA dose (p = 0.001), younger RLS onset (p = 0.04), history of experimental drug use (p = 0.002), female gender (p = 0.04) and a family history of gambling disorders (p = 0.02), which accounted for 52% of the risk variance.
Conclusion
RLS patients treated with dopaminergic agents and dopamine agonists in particular, should be forewarned of potential side effects. A careful history of risk factors should be taken.
doi:10.1186/1471-2377-11-117
PMCID: PMC3195705  PMID: 21955669
Restless legs syndrome; impulse control disorders; dopamine agonist; gambling; levodopa
13.  Impulsive choice and response in dopamine agonist-related impulse control behaviors 
Psychopharmacology  2009;207(4):645-659.
Rationale
Dopaminergic medication-related Impulse Control Disorders (ICDs) such as pathological gambling and compulsive shopping have been reported in Parkinson disease (PD).
Hypothesis
We hypothesized that dopamine agonists (DAs) would be associated with greater impulsive choice, or greater discounting of delayed rewards, in PD patients with ICDs (PDI).
Methods
Fourteen PDI patients, 14 PD controls without ICDs and 16 medication-free matched normal controls were tested on (i) the Experiential Discounting Task (EDT), a feedback-based intertemporal choice task, (ii) spatial working memory and (iii) attentional set shifting. The EDT was used to assess impulsivity choice (hyperbolic K-value), reaction time (RT) and decision conflict RT (the RT difference between high conflict and low conflict choices). PDI patients and PD controls were tested on and off DA.
Results
On the EDT, there was a group by medication interaction effect [F(1,26)=5.62; p=0.03] with pairwise analyses demonstrating that DA status was associated with increased impulsive choice in PDI patients (p=0.02) but not in PD controls (p=0.37). PDI patients also had faster RT compared to PD controls F(1,26)=7.51 p=0.01]. DA status was associated with shorter RT [F(3,24)=8.39, p=0.001] and decision conflict RT [F(1,26)=6.16, p=0.02] in PDI patients but not in PD controls. There were no correlations between different measures of impulsivity. PDI patients on DA had greater spatial working memory impairments compared to PD controls on DA (t=2.13, df=26, p=0.04).
Conclusion
Greater impulsive choice, faster RT, faster decision conflict RT and executive dysfunction may contribute to ICDs in PD.
doi:10.1007/s00213-009-1697-y
PMCID: PMC3676926  PMID: 19838863
dopamine agonist; gambling; impulse control; Parkinson disease; delay discounting
14.  Dopamine agonists and risk: impulse control disorders in Parkinson's; disease 
Brain  2011;134(5):1438-1446.
Impulse control disorders are common in Parkinson's; disease, occurring in 13.6% of patients. Using a pharmacological manipulation and a novel risk taking task while performing functional magnetic resonance imaging, we investigated the relationship between dopamine agonists and risk taking in patients with Parkinson's; disease with and without impulse control disorders. During functional magnetic resonance imaging, subjects chose between two choices of equal expected value: a ‘Sure’ choice and a ‘Gamble’ choice of moderate risk. To commence each trial, in the ‘Gain’ condition, individuals started at $0 and in the ‘Loss’ condition individuals started at −$50 below the ‘Sure’ amount. The difference between the maximum and minimum outcomes from each gamble (i.e. range) was used as an index of risk (‘Gamble Risk’). Sixteen healthy volunteers were behaviourally tested. Fourteen impulse control disorder (problem gambling or compulsive shopping) and 14 matched Parkinson's; disease controls were tested ON and OFF dopamine agonists. Patients with impulse control disorder made more risky choices in the ‘Gain’ relative to the ‘Loss’ condition along with decreased orbitofrontal cortex and anterior cingulate activity, with the opposite observed in Parkinson's; disease controls. In patients with impulse control disorder, dopamine agonists were associated with enhanced sensitivity to risk along with decreased ventral striatal activity again with the opposite in Parkinson's; disease controls. Patients with impulse control disorder appear to have a bias towards risky choices independent of the effect of loss aversion. Dopamine agonists enhance sensitivity to risk in patients with impulse control disorder possibly by impairing risk evaluation in the striatum. Our results provide a potential explanation of why dopamine agonists may lead to an unconscious bias towards risk in susceptible individuals.
doi:10.1093/brain/awr080
PMCID: PMC3097893  PMID: 21596771
Parkinson's; disease; dopamine; gambling; decision making; risk
15.  Pramipexole-Induced Increased Probabilistic Discounting: Comparison Between a Rodent Model of Parkinson's Disease and Controls 
Neuropsychopharmacology  2012;37(6):1397-1408.
The dopamine agonist pramipexole (PPX) can increase impulsiveness, and PPX therapy for neurological diseases (Parkinson's disease (PD) and restless leg syndrome) is associated with impulse control disorders (ICDs) in subpopulations of treated patients. A commonly reported ICD is pathological gambling of which risk taking is a prominent feature. Probability discounting is a measurable aspect of risk taking. We recently developed a probability discounting paradigm wherein intracranial self-stimulation (ICSS) serves as the positive reinforcer. Here we used this paradigm to determine the effects of PPX on discounting. We included assessments of a rodent model of PD, wherein 6-OHDA was injected into the dorsolateral striatum of both hemispheres, which produced persistent PD-like deficits in posture adjustment. Rats were trained to perform ICSS-mediated probability discounting, in which PD-like and control groups exhibited similar profiles. Rats were treated twice daily for 2 weeks with 2 mg/kg (±)PPX (ie, 1 mg/kg of the active form), a dose that improved lesion-induced motor deficits. In both groups, (±)PPX increased discounting; preference for the large reinforcer was enhanced 30–45% at the most uncertain probabilities. Tolerance did not develop with repeated treatments. Increased discounting subsided within 2 weeks of (±)PPX cessation, and re-exposure to (±)PPX reinstated heightened discounting. Such findings emulate the clinical scenario; therefore, ICSS for discounting assessments in rats exhibited high face validity. This model should prove useful in medication development where assessment of the propensity of a putative therapy to induce risk-taking behaviors is of interest.
doi:10.1038/npp.2011.325
PMCID: PMC3327845  PMID: 22257895
pramipexole; probability discounting; 6-OHDA; gambling; rat; reward; animal models; dopamine; addiction & substance abuse; movement disorders; pramipexole; probability discounting; 6-OHDA; gambling; rat
16.  Crack cocaine use due to dopamine agonist therapy in Parkinson disease 
Neurology  2013;80(24):2269-2270.
Impulse control disorders (ICD)1 and the dopamine dysregulation syndrome (DDS)2 are dopaminergic complications of Parkinson disease (PD) treatment. A large number of ICDs have been associated with dopamine agonists (DAA), such as gambling, hypersexuality, and consumerism, but none, to our knowledge, involved drugs of abuse.1 DDS is a condition in which patients with PD abuse l-dopa, taking it excessively despite the dyskinesias or psychotic symptoms that result.2 DDS produces l-dopa craving, whereas ICDs produce compulsions, and the 2 may coexist.2 DDS has rarely been associated with dopamine agonists other than apomorphine.
doi:10.1212/WNL.0b013e318296e9d5
PMCID: PMC3721099  PMID: 23677745
17.  Prevalence of hypersexual behavior in Parkinson’s disease patients: Not restricted to males and dopamine agonist use 
This study investigates the prevalence and demographic characteristics of hypersexuality in Parkinson’s disease (PD). Impulse control disorders in PD patients have been associated with dopamine agonist therapy. Moreover, hypersexuality and pathological gambling have been associated with males, while females may be inherently thought to be more likely to participate in compulsive shopping and binge-eating behaviors. In this study, a screening mail-in survey was sent to all PD patients at a single Movement Disorders Center. One hundred forty one of 400 (35.3%) research packets were returned completed. Fifteen of 141 patients met initial screening criteria for hypersexual behavior. After detailed interview, only 6/141 (4.3%) of PD patients met criteria for pathologic hypersexual behavior. These behaviors included: compulsive masturbation, prostitution, and paraphilias. Patients with a younger age of PD onset were more likely to exhibit hypersexual behavior. Unlike previous report, no significant association was found between hypersexuality and gender or dopamine agonist use. Rather, this study suggests that physicians should be vigilant for hypersexual behavior in all PD patients, regardless of gender and PD medication regimen. Ultimately, given the innate sensitivity of the topic and survey limitations, it is very likely that hypersexual behavior in our cohort, as it is in the general PD population, has been under-reported.
PMCID: PMC2840579  PMID: 20360887
Parkinson’s disease; hypersexuality; impulsive behavior; dopamine agonists
18.  Whole-Brain Diffusion-Tensor Changes in Parkinsonian Patients with Impulse Control Disorders 
Background and Purpose
The aim of this study was to determine the changes in diffusion-tensor images associated with medication-related impulse control disorder (ICD) in Parkinson's disease (PD) patients undergoing chronic dopamine-replacement therapy.
Methods
Nineteen PD patients, comprising 10 with ICD (PD-ICD) and 9 without ICD (PD-nonICD), and 18 age-matched healthy controls (HCs) with no cognitive or other psychiatric disorders were analyzed. All subjects underwent 3-T magnetic resonance diffusion-tensor imaging. For all PD patients, clinical data on PD duration, antiparkinsonian medication dosages, Unified Parkinson's Disease Rating Scale and Mini-Mental State Examination were collected. Whole-brain voxel-based measures of fractional anisotropy (FA) and mean diffusivity (MD) were analyzed.
Results
In comparison with HCs, the PD-nonICD subjects had low FA at the bilateral orbitofrontal areas. While the PD-ICD subjects exhibited no such difference, their FA was significantly elevated at the anterior corpus callosum. Analysis of FA between the two PD groups revealed that FA in the anterior corpus callosum, right internal capsule posterior limbs, right posterior cingulum, and right thalamic radiations were significantly higher (corrected p<0.05) in the PD-ICD than in the PD-nonICD patients. MD did not differ between the PD-ICD and PD-nonICD groups in any brain regions.
Conclusions
The PD-ICD patients appear to have relatively preserved white-matter integrity in the regions involved in reward-related behaviors compared to PD-nonICD patients. Further investigation is required to determine whether the difference in FA between PD-ICD and PD-nonICD patients reflects microstructural differences in the pathological progression of PD or is secondary to ICD.
doi:10.3988/jcn.2015.11.1.42
PMCID: PMC4302178  PMID: 25628736
impulse control disorders; Parkinson's disease; diffusion-tensor imaging
19.  Impulse control disorders in Parkinson's disease: clinical characteristics and implications 
Neuropsychiatry  2011;1(2):133-147.
SUMMARY
Impulse control disorders (ICDs), specifically those related to excessive gambling, eating, sex and shopping, have been observed in a subset of people with Parkinson's disease (PD). Although some initial case reports claimed that dopamine replacement therapies, particularly dopamine agonists, cause ICDs, more recent, larger and better controlled studies indicate a more complicated picture. While dopamine replacement therapy use is related to ICDs, other vulnerabilities, some related to PD and/or its treatment directly and others seemingly unrelated to PD, have also been associated with ICDs in PD. This suggests a complex etiology with multiple contributing factors. As ICDs occur in a sizable minority of PD patients and can be associated with significant distress and impairment, further investigation is needed to identify factors that can predict who may be more likely to develop ICDs. Clinical implications are discussed and topics for future research are offered.
PMCID: PMC3120055  PMID: 21709778
20.  Ventral Striatal Dopamine Synthesis Capacity Predicts Financial Extravagance in Parkinson’s Disease 
Impulse control disorders (ICDs), including disordered gambling, can occur in a significant number of patients with Parkinson’s disease (PD) receiving dopaminergic therapy. The neurobiology underlying susceptibility to such problems is unclear, but risk likely results from an interaction between dopaminergic medication and a pre-existing trait vulnerability. Impulse control and addictive disorders form part of a broader psychopathological spectrum of disorders, which share a common underlying genetic vulnerability, referred to as externalizing. The broad externalizing risk factor is a continuously varying trait reflecting vulnerability to various impulse control problems, manifested at the overt level by disinhibitory symptoms and at the personality level by antecedent traits such as impulsivity and novelty/sensation seeking. Trait “disinhibition” is thus a core endophenotype of ICDs, and a key target for neurobiological investigation. The ventral striatal dopamine system has been hypothesized to underlie individual variation in behavioral disinhibition. Here, we examined whether individual differences in ventral striatal dopamine synthesis capacity predicted individual variation in disinhibitory temperament traits in individuals with PD. Eighteen early-stage male PD patients underwent 6-[18F]Fluoro-l-DOPA (FDOPA) positron emission tomography scanning to measure striatal dopamine synthesis capacity, and completed a measure of disinhibited personality. Consistent with our predictions, we found that levels of ventral, but not dorsal, striatal dopamine synthesis capacity predicted disinhibited personality, particularly a propensity for financial extravagance. Our results are consistent with recent preclinical models of vulnerability to behavioral disinhibition and addiction proneness, and provide novel insights into the neurobiology of potential vulnerability to impulse control problems in PD and other disorders.
doi:10.3389/fpsyg.2013.00090
PMCID: PMC3583186  PMID: 23450713
dopa decarboxylase; dopamine; disordered gambling; externalizing; impulse control disorders; impulsivity; reward; ventral striatum
21.  Amantadine and cognitive flexibility: decision making in Parkinson’s patients with severe pathological gambling and other impulse control disorders 
Introduction
Dopamine replacement therapy for Parkinson’s disease (PD) was recently linked to the development of impulse control disorders such as pathological gambling (PG), hypersexuality, compulsive shopping, and binge or compulsive eating. Antiglutamatergic agents including amantadine (Ama) reduce these behaviors in PD and non-PD patients. The aim of our study is to evaluate the changes in executive functions, emotions, and reward/loss processing during Ama treatment in PD patients.
Methods
Thirty-three patients affected by idiopathic PD were selected from a cohort of 1,096 PD patients and categorized in three different groups: ten affected by PG (PD-PG); nine PD patients with other impulse control disorder (PD-ICD); and 14 PD patient without any psychiatric disorder (PD-CTR-controls). For the neuropsychological evaluation, the following behavioral tasks where administered: the Stroop, the emotional Stroop, and the monetary reward/loss risk-taking tasks.
Results
During Ama treatment, PD-PGs showed a decrease in risky choices and an increase in non-risky choices (t(9)=−2.40, P<0.05 and t(9)=2,67, P<0.05 uncorrected, respectively). Between-group comparison showed a significant decrease in risky choices for PD-PG with respect to PD-CTR (t(22)=−4.16, P<0.01), and a decreased accuracy for positive words in comparison between PD-PG and PD-ICD (t(17)=−7,49, P<0.01) and PD-PG and PD-CTR (t(22)=−4.29, P<0.01). No within- and between-group differences were observed for Stroop task.
Discussion
Our data showed that Ama add-on therapy reduces hypersensitivity to reward and sustains activation toward uncertainty in PD-PG patients. These finding might explain the behavioral mechanism underlying the effect of antiglutamatergic drugs.
doi:10.2147/NDT.S54423
PMCID: PMC4069151  PMID: 24971012
Parkinson’s disease; executive functions; emotion
22.  Frequency of New-Onset Pathologic Compulsive Gambling or Hypersexuality After Drug Treatment of Idiopathic Parkinson Disease 
Mayo Clinic Proceedings  2009;84(4):310-316.
OBJECTIVE: To determine the frequency of new-onset compulsive gambling or hypersexuality among regional patients with Parkinson disease (PD), ascertaining the relationship of these behaviors to PD drug use.
PATIENTS AND METHODS: We retrospectively reviewed the medical records of patients from 7 rural southeastern Minnesota counties who had at least 1 neurology appointment for PD between July 1, 2004, and June 30, 2006. The main outcome measure was compulsive gambling or hypersexuality developing after parkinsonism onset, including the temporal relationship to PD drug use.
RESULTS: Of 267 patients with PD who met the study inclusion criteria, new-onset gambling or hypersexuality was documented in 7 (2.6%). All were among the 66 patients (10.6%) taking a dopamine agonist. Moreover, all 7 (18.4%) were among 38 patients taking therapeutic doses (defined as ≥2 mg of pramipexole or 6 mg of ropinirole daily). Behaviors were clearly pathologic and disabling in 5: 7.6% of all patients taking an agonist and 13.2% of those taking therapeutic doses. Of the 5 patients, 2 had extensive treatment for what was considered a primary psychiatric problem before the agonist connection was recognized.
CONCLUSION: Among the study patients with PD, new-onset compulsive gambling or hypersexuality was documented in 7 (18.4%) of 38 patients taking therapeutic doses of dopamine agonists but was not found among untreated patients, those taking subtherapeutic agonist doses, or those taking carbidopa/levodopa alone. Behaviors abated with discontinuation of agonist therapy or dose reduction. Because this is a retrospective study, cases may have been missed, and hence this study may reflect an underestimation of the true frequency. Physicians who care for patients taking these drugs should recognize the drug's potential to induce pathologic syndromes that sometimes masquerade as primary psychiatric disease.
In patients with Parkinson disease, new-onset compulsive gambling or hypersexuality was documented in 7 of 38 patients taking therapeutic doses of dopamine agonists but was not found among untreated patients, those taking subtherapeutic agonist doses, or those taking carbidopa/levodopa alone.
PMCID: PMC2665974  PMID: 19339647
23.  Effects of STN and GPi Deep Brain Stimulation on Impulse Control Disorders and Dopamine Dysregulation Syndrome 
PLoS ONE  2012;7(1):e29768.
Objective
Impulse control disorders (ICDs) and dopamine dysregulation syndrome (DDS) are important behavioral problems that affect a subpopulation of patients with Parkinson's disease (PD) and typically result in markedly diminished quality of life for patients and their caregivers. We aimed to investigate the effects of subthalamic nucleus (STN) and internal globus pallidus (GPi) deep brain stimulation (DBS) on ICD/DDS frequency and dopaminergic medication usage.
Methods
A retrospective chart review was performed on 159 individuals who underwent unilateral or bilateral PD DBS surgery in either STN or GPi. According to published criteria, pre- and post-operative records were reviewed to categorize patients both pre- and post-operatively as having ICD, DDS, both ICD and DDS, or neither ICD nor DDS. Group differences in patient demographics, clinical presentations, levodopa equivalent dose (LED), and change in diagnosis following unilateral/bilateral by brain target (STN or GPi DBS placement) were examined.
Results
28 patients met diagnostic criteria for ICD or DDS pre- or post-operatively. ICD or DDS classification did not differ by GPi or STN target stimulation. There was no change in DDS diagnosis after unilateral or bilateral stimulation. For ICD, diagnosis resolved in 2 of 7 individuals after unilateral or bilateral DBS. Post-operative development of these syndromes was significant; 17 patients developed ICD diagnoses post-operatively with 2 patients with pre-operative ICD developing DDS post-operatively.
Conclusions
Unilateral or bilateral DBS did not significantly treat DDS or ICD in our sample, even though a few cases of ICD resolved post-operatively. Rather, our study provides preliminary evidence that DDS and ICD diagnoses may emerge following DBS surgery.
doi:10.1371/journal.pone.0029768
PMCID: PMC3266249  PMID: 22295068
24.  Detecting associations between behavioral addictions and dopamine agonists in the Food & Drug Administration’s Adverse Event database 
Background/Aims: Studies have reported higher prevalences of four behavioral addictions (binge eating, compulsive shopping, hypersexuality, and pathological gambling) in dopamine agonist-treated Parkinson’s disease relative to non-dopamine agonist-treated Parkinson’s. However, recent case-control and epidemiological studies suggest that prevalences of behavioral addictions in dopamine agonist-treated Parkinson’s may be similar to background population rates. This study tests that hypothesis by examining the FDA Adverse Event Reporting System (FAERS) for evidence of these associations, taking into account the potential impact of publicity on reporting rates. Methods: FAERS reports in 2004 (pre-publicity for all but pathological gambling) and 2007 (post-publicity for all four behaviors) were analyzed. A threshold consisting of ≥3 cases, proportional reporting ratio ≥2, and χ2 with Yates’ correction ≥4 was used to detect signals (drug-associated adverse reactions) involving any of five dopamine agonists and any of four behavioral addictions. Results: No reports containing compulsive shopping and no signal for binge eating and dopamine agonists were found in either year. A weak signal was found for hypersexuality in 2004, with a stronger signal in 2007. A robust signal was found for pathological gambling in 2004, with a more robust signal in 2007. Discussion/Conclusions: These results suggest that publicity may increase reporting rates in the FAERS. Findings for binge eating, compulsive shopping, and hypersexuality suggest that prevalences of these behaviors among those treated with dopamine agonists may be similar to background population rates and thus may not reflect an adverse safety signal. Further investigation of the relationship between dopamine agonists and behavioral addictions is warranted.
doi:10.1556/JBA.3.2014.1.3
PMCID: PMC4117280  PMID: 25215211
behavioral addictions; impulse control disorders; Parkinson’s disease; dopamine agonists; pharmaco-vigilance; FAERS
25.  Increased striatal dopamine release in Parkinsonian patients with pathological gambling: a [11C] raclopride PET study 
Brain : a journal of neurology  2009;132(Pt 5):1376-1385.
Pathological gambling is an impulse control disorder reported in association with dopamine agonists used to treat Parkinson’s disease. Although impulse control disorders are conceptualized as lying within the spectrum of addictions, little neurobiological evidence exists to support this belief. Functional imaging studies have consistently demonstrated abnormalities of dopaminergic function in patients with drug addictions, but to date no study has specifically evaluated dopaminergic function in Parkinson’s disease patients with impulse control disorders. We describe results of a [11C] raclopride positron emission tomography (PET) study comparing dopaminergic function during gambling in Parkinson’s disease patients, with and without pathological gambling, following dopamine agonists. Patients with pathological gambling demonstrated greater decreases in binding potential in the ventral striatum during gambling (13.9%) than control patients (8.1%), likely reflecting greater dopaminergic release. Ventral striatal bindings at baseline during control task were also lower in patients with pathological gambling. Although prior imaging studies suggest that abnormality in dopaminergic binding and dopamine release may be markers of vulnerability to addiction, this study presents the first evidence of these phenomena in pathological gambling. The emergence of pathological gambling in a number of Parkinson’s disease patients may provide a model into the pathophysiology of this disorder.
doi:10.1093/brain/awp054
PMCID: PMC3479148  PMID: 19346328 CAMSID: cams2369
Parkinson’s disease; dopamine; impulse control disorders; pathological gambling; PET; functional imaging

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