Impulse control disorders in Parkinson's disease: clinical characteristics and implications

Inhibition of Indirect Pathway Activity Causes Abnormal Decision-Making In a Mouse Model of Impulse Control Disorder in Parkinson's Disease

Healthy action selection relies on the coordinated activity of striatal direct and indirect pathway neurons. In Parkinson's disease (PD), in which loss of midbrain dopamine neurons is associated with progressive motor and cognitive deficits, this coordination is disrupted. Dopamine replacement therapy can remediate motor symptoms, but can also cause impulse control disorder (ICD), which is characterized by pathological gambling, hypersexuality, and/or compulsive shopping. The cellular and circuit mechanisms of ICD remain unknown. Here we developed a mouse model of PD/ICD, in which ICD-like behavior was assayed with a delay discounting task. We found that in parkinsonian mice, the dopamine agonist pramipexole drove more pronounced delay discounting, as well as disrupted firing in both direct and indirect pathway neurons. We found that chemogenetic inhibition of indirect pathway neurons in parkinsonian mice drove similar phenotypes. Together, these findings provide a new mouse model and insights into ICD pathophysiology.

Performance on the balloon analogue risk task and anticipatory response inhibition task is associated with severity of impulse control behaviours in people with Parkinson's disease

Dopamine agonist medication is one of the largest risk factors for development of problematic impulse control behaviours (ICBs) in people with Parkinson's disease. The present study investigated the potential of dopamine gene profiling and individual performance on impulse control tasks to explain ICB severity. Clinical, genetic and task performance data were entered into a mixed-effects linear regression model for people with Parkinson's disease taking (n = 50) or not taking (n = 25) dopamine agonist medication. Severity of ICBs was captured via the Questionnaire for Impulsive-compulsive disorders in Parkinson's disease Rating Scale. A cumulative dopamine genetic risk score (DGRS) was calculated for each participant from variance in five dopamine-regulating genes. Objective measures of impulsive action and impulsive choice were measured on the Anticipatory Response Inhibition Task and Balloon Analogue Risk Task, respectively. For participants on dopamine agonist medication, task performance reflecting greater impulsive choice (p = 0.014), and to a trend level greater impulsive action (p = 0.056), as well as a longer history of DA medication (p < 0.001) all predicted increased ICB severity. DGRS however, did not predict ICB severity (p = 0.708). No variables could explain ICB severity in the non-agonist group. Our task-derived measures of impulse control have the potential to predict ICB severity in people with Parkinson's and warrant further investigation to determine whether they can be used to monitor ICB changes over time. The DGRS appears better suited to predicting the incidence, rather than severity, of ICBs on agonist medication.

Assessment of therapeutic strategies for management of impulse control disorder in Parkinson's disease

BACKGROUND

Impulse control disorders (ICD) occur frequently in individuals with Parkinson's disease. So far, prevention is the best treatment. Several strategies for its treatment have been suggested, but their frequency of use and benefit have scarcely been explored.

OBJECTIVE

To investigate which strategy is the most commonly used in a real-life setting and its rate of response.

METHODS

A longitudinal study was conducted. At the baseline evaluation, data on current treatment and ICD status according to QUIP-RS were collected. The treatment strategies were categorized as "no-change", dopamine agonist (DA) dose lowering, DA removal, DA switch or add-on therapy. At the six-month follow-up visit, the same tools were applied.

RESULTS

A total of 132 individuals (58.3% men) were included; 18.2% had at least one ICD at baseline. The therapeutic strategy most used in the ICD group was no-change (37.5%), followed by DA removal (16.7%), DA switch (12.5%) and DA lowering (8.3%). Unexpectedly, in 20.8% of the ICD subjects the DA dose was increased. Overall, nearly 80% of the subjects showed remission of their ICD at follow-up.

CONCLUSIONS

Regardless of the therapy used, most of the subjects presented remission of their ICD at follow-up Further research with a longer follow-up in a larger sample, with assessment of decision-making processes, is required in order to better understand the efficacy of strategies for ICD treatment.

Neuropsychiatric Aspects of Impulse Control Disorders

Impulse control disorders (ICDs) are neuropsychiatric conditions characterized by the repeated inability to resist an impulse, drive, or temptation to perform an act that is harmful to the person or others. Although classification approaches to ICDs vary both diachronically and synchronically, this group of conditions encompasses a wide range of syndromes, including pathologic gambling, kleptomania, trichotillomania, excoriation (skin picking) disorder, intermittent explosive disorder, pyromania, oppositional defiant, conduct, and antisocial personality disorders. ICDs can play a significant role as comorbidities in both neurodevelopmental (eg, attention-deficit/hyperactivity disorder, Tourette syndrome) and neurodegenerative (eg, Parkinson disease) disorders.

Behavioral and Neuroanatomical Account of Impulsivity in Parkinson's Disease

Impulse control disorder (ICD) is a major non-motor complication of Parkinson's disease (PD) with often devastating consequences for patients' quality of life. In this study, we aimed to characterize the phenotype of impulsivity in PD and its neuroanatomical correlates.

Methods: Thirty-seven PD patients (15 patients with ICD, 22 patients without ICD) and 36 healthy controls underwent a neuropsychological battery. The test battery consisted of anxiety and depression scales, self-report measures of impulsivity (Barratt scale and UPPS-P), behavioral measures of impulsive action (Go/No-Go task, Stop signal task) and impulsive choice (Delay discounting, Iowa gambling task), and measures of cognitive abilities (working memory, attention, executive function). Patients and controls underwent structural MRI scanning.

Results: Patients with ICD had significantly higher levels of self-reported impulsivity (Barratt scale and Lack of perseverance from UPPS-P) in comparison with healthy controls and non-impulsive PD patients, but they performed similarly in behavioral tasks, except for the Iowa gambling task. In this task, patients with ICD made significantly less risky decisions than patients without ICD and healthy controls. Patients without ICD did not differ from healthy controls in self-reported impulsivity or behavioral measurements. Both patient groups were more anxious and depressive than healthy controls. MRI scanning revealed structural differences in cortical areas related to impulse control in both patient groups. Patients without ICD had lower volumes and cortical thickness of bilateral inferior frontal gyrus. Patients with ICD had higher volumes of right caudal anterior cingulate and rostral middle frontal cortex.

Conclusions: Despite the presence of ICD as confirmed by both clinical follow-up and self-reported impulsivity scales and supported by structural differences in various neural nodes related to inhibitory control and reward processing, patients with ICD performed no worse than healthy controls in various behavioral tasks previously hypothesized as robust impulsivity measures. These results call for caution against impetuous interpretation of behavioral tests, since various factors may and will influence the ultimate outcomes, be it the lack of sensitivity in specific, limited ICD subtypes, excessive caution of ICD patients during testing due to previous negative experience rendering simplistic tasks insufficient, or other, as of now unknown aspects, calling for further research.

Chemogenetic Modulation of Orexin Neurons Reverses Changes in Anxiety and Locomotor Activity in the A53T Mouse Model of Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease. PD symptomology is recognized as heterogeneous and in addition to motor function decline includes cognitive, mood, sleep, and metabolic disorders. Previous studies showed early reductions in anxiety and locomotion in the A53T mice model of PD. Since inflammation and astrogliosis are an integral part of PD pathology and impair proper neuronal function, we were keen to investigate if behavioral changes in A53T mice are accompanied by increased inflammation and astrogliosis in the hippocampus (Hipp) and motor cortex (mCtx) brain regions involved in the regulation of anxiety and locomotion, respectively. To test this, we used 3-, 5-, and 7-month-old A53T mice to examine anxiety-like behavior, locomotion, and expression of inflammation and astrogliosis markers in the Hipp and mCtx. Further, we examined the presence of alpha-synuclein accumulation in orexin neurons and orexin neuronal loss. The data show early reductions in anxiety-like behavior as well as increased locomotor activity, which was accompanied by inflammation and astrogliosis in the Hipp and mCtx. Due to the persistence of the orexin neuron population in A53T mice and the involvement of orexin in anxiety and locomotor regulation, we hypothesized that chemogenetic modulation of orexin neurons would reverse the observed reductions in anxiety-like behavior and the increases in locomotor activity in these animals. We showed that chemogenetic activation of orexin neurons in A53T mice restores anxiety-like behavior back to control levels without affecting locomotor activity, whereas the inhibition of orexin neurons reverses the elevated locomotor activity without any effects on anxiety-like behavior. This study exemplifies the complex role of orexin neurons in this model of PD and demonstrates the novel finding that changes in locomotor and anxiety-like behavior are accompanied by inflammation and astrogliosis. Together, these data suggest that the orexin system may play a significant role in early and late stages of PD.

Impulse control disorders in Parkinson's disease: A systematic review on the psychometric properties of the existing measures

Background

A significant percentage of patients suffering from Parkinson’s Disease (PD) experience Impulse Control Disorders (ICDs), contributing to reduced quality of life. As they can be managed by reducing the dopamine dosage, the detection of their presence is crucial for PD treatment plan. Nevertheless, they tend to be under-recognized in clinical practice, since routine screening is not common–despite existing instruments that may support clinicians. This work presents a systematic review on the psychometric properties of instruments measuring ICDs in PD, to test whether clinicians dispose of valid tools that may help them in clinical assessment.

Method

A systematic literature search in three databases (EMBASE, MEDLINE, and PsycINFO) was conducted. Quality of the instruments’ psychometric properties was evaluated with Terwee et al.’s criteria, and methodological quality of the studies was evaluated with the COSMIN Checklist.

Results

Ten studies examining seven instruments were selected. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) and the Ardouin Scale of Behavior in Parkinson’s Disease (ASBPD) resulted to be the best from a psychometric point of view.

Conclusions

Though the gold standard for diagnosis remains a detailed diagnostic interview, this review will encourage clinicians to use validated tools to accurately assess ICDs.

Dopamine manipulations drive changes in information sampling in healthy volunteers

BACKGROUND

Information sampling is the cognitive process of accumulating information before committing to a decision. Patients across numerous disorders show decreased information sampling relative to controls.

AIMS

Here, we used the Beads and the Best Choice Tasks to study the role of dopamine signaling in information sampling.

METHODS

Participants were given placebo, amisulpride, or ropinirole in each session, in a double-blind cross-over design.

RESULTS

We found that ropinirole (agonist) increased the number of beads drawn in the Beads Task specifically when participants faced a loss, and decreased the rank of the chosen option in the Best Choice Task.

CONCLUSIONS

These effects are likely driven by a combination of effects at presynaptic D₂ receptors, which affect dopamine release, and post-synaptic D₂ receptors. Increased D₂ relative to D₁ receptor activation in the striatum leads to increased sampling in the loss condition in the Beads Task. It also leads to choice of a poorer ranked option in the Best Choice Task. Decreased D₂ relative to D₁ receptor activation leads to decreased sampling in the Beads Task in the loss condition.

Daily consumption of methylene blue reduces attentional deficits and dopamine reduction in a 6-OHDA model of Parkinson's disease

Recently, alternative drug therapies for Parkinson's disease (PD) have been investigated as there are many shortcomings of traditional dopamine-based therapies including difficulties in treating cognitive and attentional dysfunction. A promising therapeutic avenue is to target mitochondrial dysfunction and oxidative stress in PD. One option might be the use of methylene blue (MB), an antioxidant and metabolic enhancer. MB has been shown to improve cognitive function in both intact rodents and rodent disease models. Therefore, we investigated whether MB might treat attentional deficits in a rat model of PD induced by 6-hydroxydopamine (6-OHDA). MB also has neuroprotective capabilities against neurotoxic insult, so we also assessed the ability of MB to provide neuroprotection in our PD model. The results show that MB could preserve some dopamine neurons in the substantia nigra par compacta when 6-OHDA was infused into the medial forebrain bundle. This neuroprotection did not yield a significant behavioral improvement when motor functions were measured. However, MB significantly improved attentional performance in the five-choice task designed to measure selective and sustained attention. In conclusion, MB might be useful in improving some attentional function and preserving dopaminergic cells in this model. Future work should continue to study and optimize the abilities of MB for the treatment of PD.

Should compulsive sexual behavior be considered an addiction?

AIMS

To review the evidence base for classifying compulsive sexual behavior (CSB) as a non-substance or 'behavioral' addiction.

METHODS

Data from multiple domains (e.g. epidemiological, phenomenological, clinical, biological) are reviewed and considered with respect to data from substance and gambling addictions.

RESULTS

Overlapping features exist between CSB and substance use disorders. Common neurotransmitter systems may contribute to CSB and substance use disorders, and recent neuroimaging studies highlight similarities relating to craving and attentional biases. Similar pharmacological and psychotherapeutic treatments may be applicable to CSB and substance addictions, although considerable gaps in knowledge currently exist.

CONCLUSIONS

Despite the growing body of research linking compulsive sexual behavior (CSB) to substance addictions, significant gaps in understanding continue to complicate classification of CSB as an addiction.

Imaging the Gambling Brain

Neuroimaging studies examining the neurobiological basis of gambling disorder (GD) have increased over the past decade. Functional magnetic resonance imaging studies during appetitive cue and reward processing tasks demonstrate altered functioning in frontostriatal brain areas, including the ventral striatum and the ventromedial prefrontal cortex. Findings suggest differences in how the anticipation and outcome of rewards are processed in individuals with GD. Future research requires larger sample sizes and should include appropriate clinical reference groups. Overall, studies to date highlight a common pathophysiology between substance-based addictions and GD, the latter offering a unique condition in which to examine nonchemical factors in addiction.

The Influence of Bilateral Subthalamic Nucleus Deep Brain Stimulation on Impulsivity and Prepulse Inhibition in Parkinson's Disease Patients

BACKGROUND

At least 14% of Parkinson disease (PD) patients develop impulse control disorders (ICDs). The pathophysiology behind these behaviors and the impact of deep brain stimulation in a real-life setting remain unclear.

OBJECTIVES

We prospectively examined the impact of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on ICDs in PD patients, as well as the relationship between impaired sensorimotor gaiting and impulsivity.

METHODS

Patients undergoing bilateral STN-DBS were assessed for ICDs preoperatively and 1-year postoperatively using a validated questionnaire (QUIP-RS). A subset of patients completed the Balloon Analogue Risk Task (BART) and auditory prepulse inhibition (PPI) testing.

RESULTS

Analysis revealed 12 patients had an improvement in score assessing ICDs ('good responders'; p = 0.006) while 4 had a worse or stable score ('poor responders'; p > 0.05). Good responders further exemplified a significant decrease in hypersexual behavior (p = 0.005) and binge eating (p = 0.01). Impaired PPI responses also significantly correlated with impulsivity in BART (r = -0.72, p = 0.044).

DISCUSSION

Following bilateral STN-DBS, 75% of our cohort had a reduction in ICDs, thus suggesting deep brain stimulation effectively manages ICDs in PD. The role of impaired PPI in predisposition to ICDs in PD warrants further investigation.

Translational Models of Gambling-Related Decision-Making

Gambling is a harmless, recreational pastime that is ubiquitous across cultures. However, for some, gambling becomes a maladaptive and compulsive, and this syndrome is conceptualized as a behavioural addiction. Laboratory models that capture the key cognitive processes involved in gambling behaviour, and that can be translated across species, have the potential to make an important contribution to both decision neuroscience and the study of addictive disorders. The Iowa gambling task has been widely used to assess human decision-making under uncertainty, and this paradigm can be successfully modelled in rodents. Similar neurobiological processes underpin choice behaviour in humans and rats, and thus, a preference for the disadvantageous "high-risk, high-reward" options may reflect meaningful vulnerability for mental health problems. However, the choice behaviour operationalized by these tasks does not necessarily approximate the vulnerability to gambling disorder (GD) per se. We consider a number of psychological challenges that apply to modelling gambling in a translational way, and evaluate the success of the existing models. Heterogeneity in the structure of gambling games, as well as in the motivations of individuals with GD, is highlighted. The potential issues with extrapolating too directly from established animal models of drug dependency are discussed, as are the inherent difficulties in validating animal models of GD in the absence of any approved treatments for GD. Further advances in modelling the cognitive biases endemic in human decision-making, which appear to be exacerbated in GD, may be a promising line of research.

Sociodemographic, neuropsychiatric and cognitive characteristics of pathological gambling and impulse control disorders NOS in Parkinson's disease

Despite of previous evidence supporting the association between impulse control disorder (ICD) and several demographic, clinical and therapeutic features in Parkinson's disease (PD), the relationships between pathological gambling (PG) or other variants of ICD (ICD-NOS) and specific neuropsychiatric or cognitive domains are not entirely defined. In this study, 155 PD patients without dementia or cognitive impairment underwent: i. the ICD diagnoses, using the Questionnaire for Impulsive-Compulsive Disorders, ii. the mood and anxiety disorders diagnoses, according to the DSM-IV-TR criteria, and iii. a comprehensive battery for measuring severity of psychopathology and neuropsychology domains. Patients were divided in those with pathological gambling (PG), ICDs not otherwise specified (ICD-NOS), or the lack of ICD (No-ICD). There was a progression in age and age at onset from the younger PG subjects throughout ICD-NOS to No-ICD. PG and ICD-NOS subjects had longer disease duration and were taking significantly higher dosages of antiparkinsonian drugs than No-ICD ones. PG subjects had significantly higher severity of depressive and anxious symptoms with respect to the other 2 groups. Both PG and ICD-NOS subjects suffer from increased severity of psychotic symptoms than No-ICD ones. The 3 groups did not differ in any cognitive measure. Our results support the concept that the different sociodemographic and neuropsychiatric profiles of PD patients are associated with different ICDs. Moreover, we clearly demonstrate the lack of relationship between ICD and cognitive performances in undemented PD patients.

Sex differences in addictive disorders

Gender-dependent differences in the rate of initiation and frequency of misuse of addicting drugs have been widely described. Yet, men and women also differ in their propensity to become addicted to other rewarding stimuli (e.g., sex, food) or activities (e.g., gambling, exercising). The goal of the present review is to summarize current evidence for gender differences not only in drug addiction, but also in other forms of addictive behaviours. Thus, we first reviewed studies showing gender-dependent differences in drug addiction, food addiction, compulsive sexual activity, pathological gambling, Internet addiction and physical exercise addiction. Potential risk factors and underlying brain mechanisms are also examined, with particular emphasis given to the role of sex hormones in modulating addictive behaviours. Investigations on factors allowing the pursuit of non-drug rewards to become pathological in men and women are crucial for designing gender-appropriate treatments of both substance and non-substance addictions.

Treatment of Gambling Disorders

Preclinical and clinical research implicate several neurotransmitter systems in the pathophysiology of gambling disorder (GD). In particular, neurobiological research suggests alterations in serotonergic, dopaminergic, glutamatergic and opioidergic functioning. The relative efficacy of medications targeting these systems remains a topic of ongoing research, and there is currently no Food and Drug Administration (FDA) approved medication with an indication for GD. Considering co-occurring disorders may be particularly important when devising a treatment plan for GD: extant data suggest that the opioid antagonist naltrexone may by the most effective form of current pharmacotherapy for GD, particularly for individuals with a co-occurring substance-use disorder (SUD) or with a family history of alcoholism. In contrast, lithium or other mood stabilizers may be most effective for GD for patients presenting with a co-occurring bipolar-spectrum disorder (BSD). Further, serotonin reuptake inhibitors (SRIs) may be efficacious in reducing GD symptoms for individuals also presenting with a (non-BSD) mood or anxiety disorder. Finally, elevated rates of GD (and other Impulse Control Disorders; ICDs) have been noted among individuals with Parkinson's Disease (PD), and clinicians should assess for vulnerability to GD when considering treatment options for PD. Reducing levodopa or dopamine agonist (DA) dosages may partially reduce GD symptoms among patients with co-occurring PD. For GD patients not willing to consider drug treatment, n-acetyl cysteine or behavioral therapies may be effective. Ongoing research into the effectiveness of combined behavioral and pharmacotherapies is being conducted; thus combined treatments should also be considered.

Neurobiology of gambling behaviors

For many, gambling is a recreational activity that is performed periodically without ill effects, but for some, gambling may interfere with life functioning. A diagnostic entity, pathological gambling (PG), is currently used to define a condition marked by excessive and problematic gambling. In this review, the current status of understanding of the neurobiologies of gambling and PG is described. Multiple neurotransmitter systems (norepinephrine, serotonin, dopamine, opioid and glutamate) and brain regions (ventral striatum, ventromedial prefrontal cortex, insula, among others) have been implicated in gambling and PG. Considerations for future directions in gambling research, with a view towards translating neurobiological advances into more effective prevention and treatment strategies, are discussed.

A targeted review of the neurobiology and genetics of behavioural addictions: an emerging area of research

This review summarizes neurobiological and genetic findings in behavioural addictions, draws parallels with findings pertaining to substance use disorders, and offers suggestions for future research. Articles concerning brain function, neurotransmitter activity, and family history and (or) genetic findings for behavioural addictions involving gambling, Internet use, video game playing, shopping, kleptomania, and sexual activity were reviewed. Behavioural addictions involve dysfunction in several brain regions, particularly the frontal cortex and striatum. Findings from imaging studies incorporating cognitive tasks have arguably been more consistent than cue-induction studies. Early results suggest white and grey matter differences. Neurochemical findings suggest roles for dopaminergic and serotonergic systems, but results from clinical trials seem more equivocal. While limited, family history and genetic data support heritability for pathological gambling and that people with behavioural addictions are more likely to have a close family member with some form of psychopathology. Parallels exist between neurobiological and genetic and family history findings in substance and nonsubstance addictions, suggesting that compulsive engagement in these behaviours may constitute addictions. To date, findings are limited, particularly for shopping, kleptomania, and sexual behaviour. Genetic understandings are at an early stage. Future research directions are offered.

Compulsive features in behavioural addictions: the case of pathological gambling

AIMS

To describe, in the context of DSM-V, how a focus on addiction and compulsion is emerging in the consideration of pathological gambling (PG).

METHODS

A systematic literature review of evidence for the proposed re-classification of PG as an addiction.

RESULTS

Findings include: (i) phenomenological models of addiction highlighting a motivational shift from impulsivity to compulsivity associated with a protracted withdrawal syndrome and blurring of the ego-syntonic/ego-dystonic dichotomy; (ii) common neurotransmitter (dopamine, serotonin) contributions to PG and substance use disorders (SUDs); (iii) neuroimaging support for shared neurocircuitries between 'behavioural' and substance addictions and differences between obsessive-compulsive disorder (OCD), impulse control disorders (ICDs) and SUDs; (iv) genetic findings more closely related to endophenotypic constructs such as compulsivity and impulsivity than to psychiatric disorders; (v) psychological measures such as harm avoidance identifying a closer association between SUDs and PG than with OCD; (vi) community and pharmacotherapeutic trials data supporting a closer association between SUDs and PG than with OCD. Adapted behavioural therapies, such as exposure therapy, appear applicable to OCD, PG or SUDs, suggesting some commonalities across disorders.

CONCLUSIONS

PG shares more similarities with SUDs than with OCD. Similar to the investigation of impulsivity, studies of compulsivity hold promising insights concerning the course, differential diagnosis and treatment of PG, SUDs, and OCD.

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

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

The Neuropsychopharmacology of Pathological Gambling

Pathological gambling (PG) is an impulse control disorder with prevalence estimates in the range of 0.2-2% in the general population. PG can significantly impact one's ability to function as it may negatively influence social, financial, and occupational aspects of life. Historically, PG has received relatively little attention from researchers and clinicians, and few treatments, particularly pharmacological, have been both validated and widely employed. Given the clinical relevance of PG, it is important that researchers examine pharmacological and behavioral treatments for their safety and efficacy and that clinicians use empirically validated therapies. Multiple neurochemicals, including serotonin, dopamine, norepinephrine, and opioids, and related neurocircuitry, particularly ventral cortico-striatal pathways, have been implicated in PG. The neurobiological rationale for therapies, particularly pharmacological ones, is reviewed with a perspective on the generation of improved prevention and treatment strategies for PG.

Similarities and differences between pathological gambling and substance use disorders: a focus on impulsivity and compulsivity

RATIONALE

Pathological gambling (PG) has recently been considered as a "behavioral" or nonsubstance addiction. A comparison of the characteristics of PG and substance use disorders (SUDs) has clinical ramifications and could help advance future research on these conditions. Specific relationships with impulsivity and compulsivity may be central to understanding PG and SUDs.

OBJECTIVES

This review was conducted to compare and contrast research findings in PG and SUDs pertaining to neurocognitive tasks, brain function, and neurochemistry, with a focus on impulsivity and compulsivity.

RESULTS

Multiple similarities were found between PG and SUDs, including poor performance on neurocognitive tasks, specifically with respect to impulsive choice and response tendencies and compulsive features (e.g., response perseveration and action with diminished relationship to goals or reward). Findings suggest dysfunction involving similar brain regions, including the ventromedial prefrontal cortex and striatum and similar neurotransmitter systems, including dopaminergic and serotonergic. Unique features exist which may in part reflect influences of acute or chronic exposures to specific substances.

CONCLUSIONS

Both similarities and differences exist between PG and SUDs. Understanding these similarities more precisely may facilitate treatment development across addictions, whereas understanding differences may provide insight into treatment development for specific disorders. Individual differences in features of impulsivity and compulsivity may represent important endophenotypic targets for prevention and treatment strategies.

Relations among delay discounting, addictions, and money mismanagement: implications and future directions

BACKGROUND

Delay discounting is a reduction in the subjective value of a delayed outcome. Elevated delay discounting is a type of impulsivity that is associated with harmful behaviors, including substance abuse and financial mismanagement.

METHODS

Elevated delay discounting as related to addiction and financial mismanagement was reviewed from psychological, neurobiological, and behavioral economic perspectives.

RESULTS

Addiction and financial mismanagement frequently co-occur, and elevated delay discounting may be a common mechanism contributing to both of these problematic behaviors.

CONCLUSIONS

Future research on the relationships between delay discounting, substance abuse, and financial mismanagement can provide important insights for developing improved prevention and treatment strategies.