Substance abuse, pathological gambling, and impulsiveness

Dopaminergic and clinical correlates of pathological gambling in Parkinson's disease: a case report

Dopaminergic medication for motor symptoms in Parkinson's disease (PD) recently has been linked with impulse control disorders, including pathological gambling (PG), which affects up to 8% of patients. PG often is considered a behavioral addiction associated with disinhibition, risky decision-making, and altered striatal dopaminergic neurotransmission. Using [(11)C]raclopride with positron emission tomography, we assessed dopaminergic neurotransmission during Iowa Gambling Task performance. Here we present data from a single patient with PD and concomitant PG. We noted a marked decrease in [(11)C]raclopride binding in the left ventral striatum upon gambling, indicating a gambling-induced dopamine release. The results imply that PG in PD is associated with a high dose of dopaminergic medication, pronounced motor symptomatology, young age at disease onset, high propensity for sensation seeking, and risky decision-making. Overall, the findings are consistent with the hypothesis of medication-related PG in PD and underscore the importance of taking clinical variables, such as age and personality, into account when patients with PD are medicated, to reduce the risk of PG.

Decision-making deficits in pathological gambling: the role of executive functions, explicit knowledge and impulsivity in relation to decisions made under ambiguity and risk

BACKGROUND

A variety of cognitive and emotional processes influence the decision-making deficits observed in pathological gambling (PG). This study investigated the role of immediate/delayed sensitivity to reward and punishment, executive functions, impulsivity and explicit knowledge in relation to decision-making performance on the original Iowa Gambling Task (IGT-ABCD) and a variant (IGT-EFGH).

METHODS

We assessed 131 consecutive patients with a diagnosis of PG by using executive functioning and decision-making tasks, self-report measures of impulsivity and explicit knowledge.

RESULTS

The majority of pathological gamblers (PGs) showed deficits in decision-making, characterized mainly by myopia for the future. Decisions made under risk showed different predictors. Performance on the IGT-ABCD for decisions made under risk was predicted by medium and high levels of explicit knowledge of the task, as well as by scores on the Disorderliness subscale and the degree of Stroop interference. By contrast, IGT-EFGH results were only associated with self-report impulsivity measures.

CONCLUSIONS

Decision making in PG involves distinct patterns of deficits, and the predictors differ depending on the reinforcement schedule. Decisions made under risk on the IGT-ABCD are associated with explicit knowledge, executive functions and impulsivity traits related to conscious awareness and control processes. On the IGT-EFGH, however, only impulsivity traits predict decision making.

Pregabalin- and topiramate-mediated regulation of cognitive and motor impulsivity in DBA/2 mice

BACKGROUND AND PURPOSE

Impulsivity is a core symptom in many neuropsychiatric disorders. The main objective of this study was to evaluate the effects of topiramate and pregabalin on the modulation of different impulsivity dimensions in DBA/2 mice.

EXPERIMENTAL APPROACH

The effects of acute and chronic administration of pregabalin (10, 20 and 40 mg·kg(-1) ) and topiramate (12.5, 25 and 50 mg·kg(-1) ) were evaluated in the light-dark box (LDB), hole board test (HBT) and delayed reinforcement task (DRT). α(2A) -Adrenoceptor, D(2) -receptor and TH gene expression were evaluated by real-time PCR in the prefrontal cortex (PFC), accumbens (ACC) and ventral tegmental area (VTA), respectively.

KEY RESULTS

Acute pregabalin administration showed a clear anxiolytic-like effect (LDB) but did not modify novelty-seeking behaviour (HBT). In contrast, topiramate produced an anxiolytic effect only at the highest dose, whereas it reduced novelty seeking at all doses tested. In the DRT, acute pregabalin had no effect, whereas topiramate only reduced motor impulsivity. Chronically, pregabalin significantly increased motor impulsivity and topiramate diminished cognitive impulsivity. Pregabalin decreased α(2A) -adrenoceptor and D(2) -receptor gene expression in the PFC and ACC, respectively, and increased TH in the VTA. In contrast, chronic administration of topiramate increased α(2A) -adrenoceptor and D(2) -receptor gene expression in the PFC and ACC, respectively, and also increased TH in the VTA.

CONCLUSIONS AND IMPLICATIONS

These results suggest that the usefulness of pregabalin in impulsivity-related disorders is related to its anxiolytic properties, whereas topiramate modulates impulsivity. These differences could be linked to their opposite effects on α(2A) -adrenoceptor and D(2) -receptor gene expression in the PFC and ACC, respectively.

Dopamine D3 receptor antagonists: a patent review (2007 - 2012)

INTRODUCTION

The synthesis and characterization of new highly potent and selective dopamine (DA) D3 receptor antagonists has permitted to characterize the role of the DA D3 receptor in the control of drug-seeking behavior and in the pathophysiology of impulse control disorders and schizophrenia.

AREAS COVERED

In the present review, the authors will first describe most recent classes of DA D3 receptor antagonists by reviewing about 43 patent applications during the 2007 - 2012 period; they will then outline the biological rationale in support of the use of selective DA D3 receptor antagonists in the treatment of drug addiction, impulse control disorders and schizophrenia.

EXPERT OPINION

The strongest clinical application and potential for selective DA D3 receptor antagonists lies in the reduction of drug-induced incentive motivation, the attenuation of drug's rewarding efficacy and the reduction in reinstatement of drug-seeking behavior triggered either by re-exposure to the drug itself, re-exposure to environmental cues that had been previously associated with drug-taking behavior or stress. The selectivity of these antagonists together with reduced lipophilicity (minimizing unspecific binding), increased brain penetration and improved physico-chemical profile are all key factors for clinical efficacy and safety.

Illicit drug use and problem gambling

Problem gambling, substance use disorders, and their cooccurrence are serious public health concerns. We conducted a comprehensive review of the literature to understand the present state of the evidence on these coaddictions. Our main focus was illicit drug use rather than misuse of legal substances. The review covers issues related to gambling as a hidden problem in the illicit drug use community; prevalence, problem gambling, and substance use disorders as kindred afflictions; problem gambling as an addiction similar to illicit drug use; risk factors and problems associated with comorbidity, and gender issues. We end with some suggestions for future research.

Insula and orbitofrontal cortical morphology in substance dependence is modulated by sex

BACKGROUND AND PURPOSE

Frontolimbic circuits are involved in learning and decision-making processes thought to be affected in substance-dependent individuals. We investigated frontolimbic cortical morphometry in substance-dependent men and women and determined whether morphometric measurements correlated with decision-making performance.

MATERIALS AND METHODS

Twenty-eight abstinent SDI (17 men/11 women) were compared with 28 controls (13 men/15 women). Cortical thicknesses and volumes were computed by using FreeSurfer. After controlling for age and intracranial volume, group and sex effects were analyzed in 3 a priori regions of interest: the insula, orbitofrontal cortex, and anterior cingulate cortex by using analysis of covariance. A secondary whole-brain analysis was conducted to verify region-of-interest results and to explore potential differences in other brain regions.

RESULTS

Region-of-interest analyses revealed a main effect of group on the left insula cortex, which was thinner in SDI compared with controls (P = .02). There was a group by sex interaction on bilateral insula volume (left, P = .02; right, P = .001) and right insula cortical thickness (P = .007). Compared with same-sex controls, female SDI had smaller insulae, whereas male SDI had larger insulae. Neither ACC nor OFC significantly differed across group. Performance on a decision-making task was better in controls than SDI and correlated with OFC measurements in the controls.

CONCLUSIONS

SDI and controls differed in insula morphology, and those differences were modulated by sex. No group differences in OFC were observed, but OFC measurements correlated with negative-reinforcement learning in controls. These preliminary results are consistent with a hypothesis that frontolimbic pathways may be involved in behaviors related to substance dependence.

Striatal dopamine release codes uncertainty in pathological gambling

Two mechanisms of midbrain and striatal dopaminergic projections may be involved in pathological gambling: hypersensitivity to reward and sustained activation toward uncertainty. The midbrain-striatal dopamine system distinctly codes reward and uncertainty, where dopaminergic activation is a linear function of expected reward and an inverse U-shaped function of uncertainty. In this study, we investigated the dopaminergic coding of reward and uncertainty in 18 pathological gambling sufferers and 16 healthy controls. We used positron emission tomography (PET) with the tracer [(11)C]raclopride to measure dopamine release, and we used performance on the Iowa Gambling Task (IGT) to determine overall reward and uncertainty. We hypothesized that we would find a linear function between dopamine release and IGT performance, if dopamine release coded reward in pathological gambling. If, on the other hand, dopamine release coded uncertainty, we would find an inversely U-shaped function. The data supported an inverse U-shaped relation between striatal dopamine release and IGT performance if the pathological gambling group, but not in the healthy control group. These results are consistent with the hypothesis of dopaminergic sensitivity toward uncertainty, and suggest that dopaminergic sensitivity to uncertainty is pronounced in pathological gambling, but not among non-gambling healthy controls. The findings have implications for understanding dopamine dysfunctions in pathological gambling and addictive behaviors.

Gambling severity, impulsivity, and psychopathology: comparison of treatment- and community-recruited pathological gamblers

BACKGROUND AND OBJECTIVES

Because most studies of pathological gambling gather data from participants recruited from treatment, this study compared community and treatment-enrolled pathological gamblers (PGs) with respect to demographics, gambling severity, impulsivity, and psychopathology.

METHODS

One hundred six PGs were recruited as part of two larger studies in Farmington, Connecticut (n= 61) and Windsor, Ontario (n= 45) using radio advertising, word of mouth, and/or newspaper ads, as well as a gambling treatment program at each location.

RESULTS

Community (n= 49) and treatment-enrolled (n= 57) PGs did not differ on age, education, gender, race, employment, or marital status. Treatment-enrolled PGs were more likely to report past year illegal behaviors, preoccupation with gambling, and higher scores on the Barratt Impulsiveness Scale (BIS) Attention Impulsivity subscale. Assessment of psychopathology in the Ontario study indicated that treatment-enrolled PGs were more likely to present with Major Depressive and Dysthymic Disorders. Community-recruited PGs in the Connecticut study were overall more likely to present with any substance use disorder relative to their treatment-enrolled counterparts.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Our findings inform intervention and research within the field of pathological gambling. Specifically, the distressing aspects of pathological gambling, such as legal issues, preoccupation with gambling, and depression, may be present more in treatment-enrolled PGs than in those recruited from the community. Such emotional disturbances should be further explored to increase motivation and treatment adherence in PGs. In addition, due to relative absence of overall differences between the groups, research findings utilizing treatment-enrolled PGs may be a good representation of both groups.

Investigation of impulsivity in a sample of treatment-seeking pathological gamblers: a multidimensional perspective

Numerous studies have shown that problem gambling is characterised by lack of impulse control. However, they have often been conducted without considering the multifaceted nature of impulsivity and related psychological mechanisms. The current study aims to disentangle which impulsivity facets are altered in pathological gambling. Twenty treatment-seeking pathological gamblers (PGs) and 20 matched control participants completed a self-reported questionnaire measuring the various facets of impulsive behaviours (UPPS Impulsive Behaviour Scale), as well as two laboratory tasks assessing inhibitory control (the go-stop task) and tolerance for delayed rewards (single key impulsivity paradigm). Compared with matched controls, PGs exhibited higher urgency, lower premeditation, impairment in prepotent inhibition, and lower tolerance towards delayed rewards. Nevertheless, complementary profile analyses showed that impulsivity-related deficits found in PGs are highly heterogeneous, and that some PGs are neither impulsive in the impulsivity facets assessed nor impaired in the cognitive mechanisms measured. These findings underscore (1) the necessity to disentangle the construct of impulsivity into lower-order components and (2) that further studies should take into account, in addition to impulsivity-related mechanisms, other psychological factors potentially involved in pathological gambling.

Executive function in pathological gamblers and healthy controls

Executive function (EF) deficits may underlie some of the impulse control problems seen in pathological gambling. Pathological gamblers (PGs, n = 45) and controls (n = 45) were compared on several measures of EF (including measures of response inhibition, working memory, cognitive flexibility and perseveration, planning and decision-making), as well as memory and intelligence tests to examine whether PGs evidence EF dysfunction. Compared with controls, PGs exhibited specific deficits on measures of planning and decision-making. PGs also exhibited relative deficits on a measure of perseveration, but this deficit was no longer significant after controlling for group differences in intelligence. These results suggest that PGs may experience deficits on specific components of EF.

Impaired probability estimation and decision-making in pathological gambling poker players

Poker has gained tremendous popularity in recent years, increasing the risk for some individuals to develop pathological gambling. Here, we investigated cognitive biases in a computerized two-player poker task against a fictive opponent, among 12 pathological gambling poker players (PGP), 10 experienced poker players (ExP), and 11 inexperienced poker players (InP). Players were compared on probability estimation and decision-making with the hypothesis that ExP would have significantly lower cognitive biases than PGP and InP, and that the groups could be differentiated based on their cognitive bias styles. The results showed that ExP had a significantly lower average error margin in probability estimation than PGP and InP, and that PGP played hands with lower winning probability than ExP. Binomial logistic regression showed perfect differentiation (100%) between ExP and PGP, and 90.5% classification accuracy between ExP and InP. Multinomial logistic regression showed an overall classification accuracy of 23 out of 33 (69.7%) between the three groups. The classification accuracy of ExP was higher than that of PGP and InP due to the similarities in probability estimation and decision-making between PGP and InP. These impairments in probability estimation and decision-making of PGP may have implications for assessment and treatment of cognitive biases in pathological gambling poker players.

Impulsivity, risk taking, and timing

This study examined the relations among measures of impulsivity and timing. Impulsivity was assessed using delay and probability discounting, and self-report impulsivity (as measured by the Barratt Impulsiveness Scale; BIS-11). Timing was assessed using temporal perception as measured on a temporal bisection task and time perspective (as measured by the Zimbardo Time Perspective Inventory). One hundred and forty three college students completed these measures in a computer laboratory. The degree of delay discounting was positively correlated with the mean and range of the temporal bisection procedure. The degree of delay and probability discounting were also positively correlated. Self-reported motor impulsiveness on the BIS-11 was positively correlated with present hedonism and negatively correlated with future orientation on the ZTPI. Self-reported non-planning on the BIS-11 was positively correlated with fatalism on the ZTPI. These results show that people who overestimate the passage of time (perceive time as passing more quickly) hold less value in delayed rewards. They also confirm previous results regarding the relation between delay and probability discounting, as well as highlight similarities in self-report measures of impulsivity and time perspective.

Self-reported differences on measures of executive function in a patient sample of pathological gamblers

Patients seeking help for pathological gambling often exhibit features of impulsivity, cognitive rigidity, poor judgment, deficits in emotion regulation, and excessive preoccupation with gambling. Some of these characteristics are also common among patients presenting with neurological pathology associated with executive deficits. Evidence of executive deficits have been confirmed in pathological gamblers using objective neurocognitive tests, however, it remains to be seen if such findings will emerge in self-report measures of executive control. These observations led to the current investigation of differences between a group of pathological gamblers (n = 62) and a comparison group (n = 64) using the Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A). Significant differences between the groups emerged over all nine subscales of executive functioning with the most dramatic differences on BRIEF-A subscales Inhibit, Plan/Organize, Shift, Emotion Control, Self-Monitor, and Initiate among the pathological gamblers. These results provide evidence that support findings among pathological gamblers using objective neuropsychological measures and suggest that the BRIEF-A may be an appropriate instrument to assess possible problems with executive control in this population.

Associations between pathological gambling and psychiatric comorbidity among help-seeking populations in Hong Kong

Problem gambling is complex and often comorbid with other mental health problems. Unfortunately, gambling studies on comorbid psychiatric disorders among Chinese communities are extremely limited. The objectives of this study were to (a) determine the prevalence of comorbid psychiatric disorders among treatment-seeking pathological gamblers; (b) compare the demographic profiles and clinical features of pathological gamblers with and without comorbid psychiatric disorders; (c) explore the associations between pathological gambling and psychiatric disorders and their temporal relationship. Participants (N = 201) who sought gambling counseling were examined by making Axis-I diagnoses including mood disorders, schizophrenia spectrum disorders, substance use disorders, anxiety disorders, and adjustment disorder. Results showed that 63.7% of participants had lifetime comorbid psychiatric disorder. The most common comorbid psychiatric mental disorders were mood disorders, adjustment disorder, and substance use disorders. Pathological gamblers with psychiatric comorbidities were significantly more severe in psychopathology, psychosocial functioning impairment, and gambling problems than those without the disorders.

Imaging genetics and the neurobiological basis of individual differences in vulnerability to addiction

BACKGROUND

Addictive disorders are heritable, but the search for candidate functional polymorphisms playing an etiological role in addiction is hindered by complexity of the phenotype and the variety of factors interacting to impact behavior. Advances in human genome sequencing and neuroimaging technology provide an unprecedented opportunity to explore the impact of functional genetic variants on variability in behaviorally relevant neural circuitry. Here, we present a model for merging these technologies to trace the links between genes, brain, and addictive behavior.

METHODS

We describe imaging genetics and discuss the utility of its application to addiction. We then review data pertaining to impulsivity and reward circuitry as an example of how genetic variation may lead to variation in behavioral phenotype. Finally, we present preliminary data relating the neural basis of reward processing to individual differences in nicotine dependence.

RESULTS

Complex human behaviors such as addiction can be traced to their basic genetic building blocks by identifying intermediate behavioral phenotypes, associated neural circuitry, and underlying molecular signaling pathways. Impulsivity has been linked with variation in reward-related activation in the ventral striatum (VS), altered dopamine signaling, and functional polymorphisms of DRD2 and DAT1 genes. In smokers, changes in reward-related VS activation induced by smoking abstinence may be associated with severity of nicotine dependence.

CONCLUSIONS

Variation in genes related to dopamine signaling may contribute to heterogeneity in VS sensitivity to reward and, ultimately, to addiction. These findings illustrate the utility of the imaging genetics approach for investigating the neurobiological basis for vulnerability to addiction.

Obesity and risk taking. A male phenomenon

There is a growing tendency to regard overeating as an addiction, with obesity as its primary symptom. We propose that similar to other addictions, obesity is associated with excessive risk-taking in men, though not in women. To examine this suggestion we conducted two studies, one involving a sample of overweight and normal-weight students, and the other involving obese adults drawn from a dataset of health care clients, and a control sample of normal-weight adults. In both of these studies, we found that overweight and obese men took more risk in a laboratory task than normal-weight men, while overweight and obese women did not differ from normal-weight women in this respect. At the same time, obese women (but not overweight women) displayed higher impulsivity levels than normal-weight women. These findings shed light on the cognitive characteristics of obesity in men, and accent the importance of taking gender into account when developing research paradigms and treatment methods for obesity.

Pathological gambling: a systematic review of biochemical, neuroimaging, and neuropsychological findings

Pathological gambling is an emerging psychiatric disorder that has recently gained much attention because of its increasing prevalence and devastating personal, familial, and social consequences. Although its pathophysiology is largely unknown, the shared similarities with both addiction and obsessive-compulsive spectrum disorders have suggested the possibility of common psychobiological substrates. As with many other psychiatric disorders, it is believed that pathological gambling may result from the interplay between individual vulnerability and environmental factors. The aim of this article is to offer a comprehensive review of the main neurobiological aspects of pathological gambling, with particular attention to neuropsychological and related findings. A deeper understanding of the biological correlates of pathological gambling is required in order to develop effective treatment strategies.

An eight component decision-making model for problem gambling: a systems approach to stimulate integrative research

Problem Gambling (PG) represents a serious problem for affected individuals, their families and society in general. Previous approaches to understanding PG have been confined to only a subset of the psychobiological factors influencing PG. We present a model that attempts to integrate potential causal factors across levels of organization, providing empirical evidence from the vast literature on PG and complimentary literatures in decision-making and addiction. The model posits that components are arranged systematically to bias decisions in favor of either immediately approaching or avoiding targets affording the opportunity for immediate reward. Dopamine, Testosterone and Endogenous Opioids favor immediate approach, while Serotonin and Cortisol favor inhibition. Glutamate is involved in associative learning between stimuli and promotes the approach response through its link to the DA reward system. GABA functions to monitor performance and curb impulsive decision-making. Finally, while very high levels of Norepinephrine can induce arousal to an extent that is detrimental to sound decision-making, the reactivity of the Norepinephrine system and its effects of Cortisol levels can shift the focus towards long-term consequences, thereby inhibiting impulsive decisions. Empirical evidence is provided showing the effects of each component on PG and decision-making across behavioural, neuropsychological, functional neuroimaging and genetic levels. Last, an effect size analysis of the growing pharmacotherapy literature is presented. It is hoped that this model will stimulate multi-level research to solidify our comprehension of biased decision-making in PG and suggest pharmacological and psychological approaches to treatment.

The utility of rat models of impulsivity in developing pharmacotherapies for impulse control disorders

High levels of impulsive behaviours are a clinically significant symptom in a range of psychiatric disorders, such as attention deficit hyperactivity disorder, bipolar disorder, personality disorders, pathological gambling and substance abuse. Although often measured using questionnaire assessments, levels of different types of impulsivity can also be determined using behavioural tests. Rodent analogues of these paradigms have been developed, and similar neural circuitry has been implicated in their performance in both humans and rats. In the current review, the methodology underlying the measurement of different aspects of impulsive action and choice are considered from the viewpoint of drug development, with a focus on the continuous performance task (CPT), stop-signal task (SST), go/no-go and delay-discounting paradigms. Current issues impeding translation between animal and human studies are identified, and comparisons drawn between the acute effects of dopaminergic, noradrenergic and serotonergic compounds across species. Although the field could benefit from a more systematic determination of different pharmacological agents across paradigms, there are signs of strong concordance between the animal and human data. However, the type of impulsivity measured appears to play a significant role, with the SST and delay discounting providing more consistent effects for dopaminergic drugs, while the CPT and SST show better predictive validity so far for serotonergic and noradrenergic compounds. Based on the available data, it would appear that these impulsivity models could be used more widely to identify potential pharmacotherapies for impulse control disorders. Novel targets within the glutamatergic and serotonergic system are also suggested.

Taking More, Now: The Optimality of Impulsive Choice Hinges on Environment Structure

Impulsivity is a stable personality trait associated with myopic choice behavior that favors immediate rewards over larger, delayed rewards and is often characterized as maladaptive inside and outside of the laboratory. An alternative view suggests that the consequences of trait impulsivity depend on the nature of the task environment. On this view, the optimal level of impulsivity varies across task payoff structures. This hypothesis is tested in two dynamic decision-making tasks that differ in the relative payoffs of delayed and immediate rewards. In a task that favors delayed rewards to immediate rewards, high-impulsive participants perform worse than low-impulsive participants. In contrast, in a task that favors immediate rewards over delayed rewards, high-impulsive participants outperform low-impulsive participants. These results suggest a more nuanced conceptualization of trait impulsivity as it applies to rewards-related decision-making that may help explain the variability observed in this trait across individuals.

Responding in a test of decision-making under risk is under moderate genetic control in the rat

BACKGROUND

Risk-taking, measured with laboratory tasks such as the Balloon Analog Risk Task (BART), is associated with real-life manifestations of risky behaviors, which may be an important component of inherited liability to alcohol use disorders. To identify genomic factors that influence these traits, the current study (i) characterized performance of a rodent version of the BART in multiple inbred rat strains, (ii) tested the degree to which performance was under genetic control, (iii) explored sex differences in performance, and (iv) evaluated the risk-taking behavior of F1 progeny of high-risk- and low-risk-taking strains to examine modes of inheritance.

METHODS

Male and female rats (N = 100) from 5 inbred strains (Wistar-Furth, Fischer-344, Lewis, Spontaneously Hypertensive, Brown Norway) and Wistar-Furth × Fischer-344 hybrids were tested in the rat-BART, as well as in tests of locomotor activity, sucrose preference, and general motivation.

RESULTS

About 55% of the variance in risk-taking behavior was attributable to heritable factors. The Fischer-344 strain was the most risk-taking and the most variable in responding. The mating of low-risk-taking Wistar-Furth and Fischer-344 rats produced progeny that behaved most like the Fischer-344 strain. Consistent with prior research in this laboratory (Jentsch et al., 2010), all rats were sensitive to changes in both risk and reinforcement parameters in the rat-BART; rats decreased voluntary risk-taking in the face of increasing risk and increased lever pressing when reinforcement probabilities were reduced.

CONCLUSIONS

Our results endorse a moderately heritable pattern of risk-taking behavior in rats. The behavior of the hybrid progeny suggests a polygenic model with most gene effects transmitted by mode of dominant inheritance. The identification of high-risk and low-risk strains allows for isolation of quantitative trait loci associated with task performance and for probing the relationships between risk-taking and dimensions of alcohol use disorders.

Selective IGT decision-making impairment in a patient with juvenile Parkinson's disease and pathological gambling: a role for dopaminergic therapy?

The orbitofrontal cortex and the dopaminergic system are structures involved in managing impulsivity and sensibility to reinforcements, and both are typically impaired in Parkinson's disease (PD). Also, l-DOPA treatment can contribute to the development of the 'Dopamine Dysregulation Syndrome', a syndrome that can influence the patients' personality and lead to risk-taking behaviors. In this study, we describe the case of a 42-year-old woman (LT) affected by juvenile PD, treated with both l-DOPA and dopamine agonists, who showed a sudden onset of pathological gambling (PG), as the only neuropsychiatric symptom. We assessed LT with a full neuropsychological battery and the Iowa Gambling Task (IGT), in order to describe her specific failure in decision making. LT's performance on the IGT is compared with that of 15 non-demented PD patients under therapy with dopamine agonists and no behavioral dysregulations and with that of 16 age- and education-matched healthy subjects. Results showed fully preserved memory, executive functions, and reasoning abilities for LT, but a remarkable and stable impairment in the IGT. Performance of LT on the IGT is significantly lower than that of both control groups. This case shows, for the first time, that high cognitive functioning and preserved executive functions are no guarantee for advantageous decision making, and that the onset of PG is consistent with selective orbitofrontal disruption and side-effects of dopamine agonist therapy. It is also showed that the IGT is a useful neuropsychological device to detect specific risk-taking behaviors, which compromise functioning in real life.

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.

Impulsivity and cognitive distortions in pathological gamblers attending the UK National Problem Gambling Clinic: a preliminary report

BACKGROUND

Pathological gambling (PG) is a form of behavioural addiction that has been associated with elevated impulsivity and also cognitive distortions in the processing of chance, probability and skill. We sought to assess the relationship between the level of cognitive distortions and state and trait measures of impulsivity in treatment-seeking pathological gamblers.

METHOD

Thirty pathological gamblers attending the National Problem Gambling Clinic, the first National Health Service clinic for gambling problems in the UK, were compared with 30 healthy controls in a case-control design. Cognitive distortions were assessed using the Gambling-Related Cognitions Scale (GRCS). Trait impulsivity was assessed using the UPPS-P, which includes scales of urgency, the tendency to be impulsive in positive or negative mood states. Delay discounting rates were taken as a state measure of impulsive choice.

RESULTS

Pathological gamblers had elevated impulsivity on several UPPS-P subscales but effect sizes were largest (Cohen's d>1.4) for positive and negative urgency. The pathological gamblers also displayed higher levels of gambling distortions, and elevated preference for immediate rewards, compared to controls. Within the pathological gamblers, there was a strong relationship between the preference for immediate rewards and the level of cognitive distortions (R2=0.41).

CONCLUSIONS

Impulsive choice in the gamblers was correlated with the level of gambling distortions, and we hypothesize that an impulsive decision-making style may increase the acceptance of erroneous beliefs during gambling play.

High calorie, low nutrient food/beverage intake and video gaming in children as potential signals for addictive behavior

Little is known about the co-occurrence of health risk behaviors in childhood that may signal later addictive behavior. Using a survey, this study evaluated high calorie, low nutrient HCLN intake and video gaming behaviors in 964 fourth grade children over 18 months, with stress, sensation-seeking, inhibitory control, grades, perceived safety of environment, and demographic variables as predictors. SEM and growth curve analyses supported a co-occurrence model with some support for addiction specificity. Male gender, free/reduced lunch, low perceived safety and low inhibitory control independently predicted both gaming and HCLN intake. Ethnicity and low stress predicted HCLN. The findings raise questions about whether living in some impoverished neighborhoods may contribute to social isolation characterized by staying indoors, and HCLN intake and video gaming as compensatory behaviors. Future prevention programs could include skills training for inhibitory control, combined with changes in the built environment that increase safety, e.g., implementing Safe Routes to School Programs.

Binge Drinking: In Search of its Molecular Target via the GABA(A) Receptor

Binge drinking, frequently referred to clinically as problem or hazardous drinking, is a pattern of excessive alcohol intake characterized by blood alcohol levels ≥0.08 g% within a 2-h period. Here, we show that overexpression of α1 subunits of the GABA_A receptor contributes to binge drinking, and further document that this involvement is related to the neuroanatomical localization of α1 receptor subunits. Using a herpes simplex virus amplicon vector to deliver small interference RNA (siRNA), we showed that siRNA specific for the α1 subunit (pHSVsiLA1) caused profound, long-term, and selective reduction of gene expression, receptor density, and binge drinking in high-alcohol drinking rats when delivered into the ventral pallidum (VP). Scrambled siRNA (pHSVsiNC) delivered similarly into the VP failed to alter gene expression, receptor density, or binge drinking. Silencing of the α1 gene in the VP, however, failed to alter binge sucrose or water intake. These results, along with our prior research, provide compelling evidence that the α1-containing GABA_A receptor subunits are critical in the regulation of binge-like patterns of excessive drinking. Collectively, these data may be useful in the development of gene-based and novel pharmacological approaches for the treatment of excessive drinking.

The influence of sex-linked genetic mechanisms on attention and impulsivity

It is now generally agreed that there are inherent sex differences in healthy individuals across a number of neurobiological domains (including brain structure, neurochemistry, and cognition). Moreover, there is a burgeoning body of evidence highlighting sex differences within neuropsychiatric populations (in terms of the rates of incidence, clinical features/progression, neurobiology and pathology). Here, we consider the extent to which attention and impulsivity are sexually dimorphic in healthy populations and the extent to which sex might modulate the expression of disorders characterised by abnormalities in attention and/or impulsivity such as attention deficit hyperactivity disorder (ADHD), autism and addiction. We then discuss general genetic mechanisms that might underlie sex differences in attention and impulsivity before focussing on specific positional and functional candidate sex-linked genes that are likely to influence these cognitive processes. Identifying novel sex-modulated molecular targets should ultimately enable us to develop more effective therapies in disorders associated with attentional/impulsive dysfunction.

The problem with self-forgiveness: forgiving the self deters readiness to change among gamblers

Self-forgiveness is generally understood to be a mechanism that restores and improves the self. In the current study, we examine the possible deleterious consequences of forgiving the self among gamblers-specifically in regard to gamblers' readiness to change their problematic behavior. At a large Canadian university, 110 young adult gamblers' level of gambling pathology was assessed, along with their readiness to change and self-forgiveness for their gambling. Participants were 33 females and 75 males (2 unspecified) with a mean age of 20.33. Results revealed that level of pathology (at risk vs. problem gamblers) significantly predicted increased readiness to change. Self-forgiveness mediated this relationship, such that level of gambling pathology increased readiness to change to the extent that participants were relatively unforgiving of their gambling. Implications for seeking professional assistance as well as treatment and recovery are discussed.

Selective decision-making deficits in at-risk gamblers

Despite reasonable knowledge of pathological gambling (PG), little is known of its cognitive antecedents. We evaluated decision-making and impulsivity characteristics in people at risk of developing PG using neuropsychological tests. Non-treatment seeking volunteers (18-29 years) who gamble ≥ 5 times/year were recruited from the general community, and split into two groups: those "at risk" of developing PG (n=74) and those social, non-problem gamblers (n=112). Participants undertook the Cambridge Gamble and Stop-signal tasks and were assessed with the Mini-International Neuropsychiatric Interview and the Yale Brown Obsessive Compulsive Scale Modified for Pathological Gambling. On the Cambridge Gamble task, the at-risk subjects gambled more points overall, were more likely to go bankrupt, and made more irrational decisions under situations of relative risk ambiguity. On the Stop-signal task, at-risk gamblers did not differ from the social, non-problem gamblers in terms of motor impulse control (stop-signal reaction times). Findings suggest that selective cognitive dysfunction may already be present in terms of decision-making in at-risk gamblers, even before psychopathology arises. These findings implicate selective decision-making deficits and dysfunction of orbitofronto-limbic circuitry in the chain of pathogenesis between social, non-problematic and pathological gambling.

Glücksspiel im Gehirn: Neurobiologische Grundlagen pathologischen Glücksspielens

Hintergrund: Pathologisches Glücksspielen (PG) wird in den internationalen Klassifikationssystemen bislang als Impulskontrollstörung klassifiziert. Erst in jüngster Zeit wird aufgrund der Ähnlichkeiten in Phänomenologie, Ätiologie, Verlauf sowie genetischen und neurobiologischen Faktoren mit der Substanzabhängigkeit eine Einordnung des PGs als Verhaltenssucht diskutiert. Insbesondere neurobiologische und neuropsychologische Befunde haben zu dieser veränderten Sichtweise beigetragen. Methode: Im vorliegenden Beitrag werden Befunde zu neurobiologischen Grundlagen PGs vorgestellt. Der Schwerpunkt liegt auf neurokognitiven Prozessen wie Belohnungs- und Bestrafungsverarbeitung, Cue-Reaktivität, Impulsivität und Entscheidungsfindung. Die Befunde werden im Hinblick auf Ähnlichkeiten und Unterschiede PGs zur Substanzabhängigkeit diskutiert. Ergebnisse: Ähnlich wie bei der Substanzabhängigkeit zeigt sich auch bei pathologischen Spielern Veränderungen mesolimbischer-präfrontaler Netzwerke, die sich in einer verminderten Belohnungs- und Bestrafungssensitivität, Impulshemmung und einer erhöhten Cue-Reaktivität auf glücksspielassoziierte Reize äußern können. Jedoch sind die Befunde teilweise nicht eindeutig und eine Vielzahl der Studien unterliegt methodischen Einschränkungen. Schlussfolgerungen: Bisherige Befunde stützen die Einordnung pathologischen Spielverhaltens als Verhaltenssucht.

Disordered gambling: etiology, trajectory, and clinical considerations

Gambling-related research has advanced rapidly during the past 20 years. As a result of expanding interest in pathological gambling (PG), stakeholders (e.g., clinicians, regulators, and policy makers) have a better understanding of excessive gambling, including its etiology (e.g., neurobiological/neurogenetic, psychological, and sociological factors) and trajectory (e.g., initiation, course, and adaptation to gambling exposure). In this article, we examine these advances in PG-related research and then consider some of the clinical implications of these advances. We consider criteria changes for PG recently proposed by the DSM-V Impulse Control Work Group for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V). We also review how clinicians can more accurately and efficiently diagnose clients seeking help for gambling-related problems by utilizing brief screens. Finally, we consider the importance of future research that can identify behavioral markers for PG. We suggest that identifying these markers will allow clinicians to make earlier diagnoses, recommend targeted treatments, and advance secondary prevention efforts.

Risk-taking decisions in pathological gamblers is not a result of their impaired inhibition ability

This work investigates whether inhibition impairments influence the decision making process in pathological gamblers (PGs). The PG (N=51) subjects performed the Iowa Gambling Task (IGT as the measure of the decision making process) and two tests of inhibition: the Stroop (interference inhibition), and the Go/NoGo (response inhibition), and were compared with demographically matched healthy subjects (N=57). Performance in the IGT block 1 and block 2 did not differ between the groups, but the differences between the PGs and healthy controls began to be significant in block 3, block 4 and block 5. PGs learned the IGT task more slowly than the healthy controls and had non-optimal outcomes (more disadvantageous choices). Impaired IGT performance in PGs was not related to an inhibition ability measured by the Stroop (interference response time) and the Go/NoGo (number of commission errors) parameters. Further controlled studies with neuroimaging techniques may help to clarify the particular brain mechanisms underlying the impaired decision making process in PGs.

Measurement of constructs using self-report and behavioral lab tasks: is there overlap in nomothetic span and construct representation for impulsivity?

There has been little empirical evidence examining the overlap in nomothetic span for self-report measures and construct representation for behavioral lab tasks in most psychological constructs. Using the personality trait of impulsivity as an example, the authors completed a meta-analysis of 27 published research studies examining the relationship between these methods. In general, although there is a statistically significant relationship between multidimensional self-report and lab task impulsivity (r = 0.097), practically, the relationship is small. Examining relationships among unidimensional impulsivity self-report and lab task conceptualizations indicated very little overlap in self-report and behavioral lab task constructs. Significant relationships were found between lack of perseverance and prepotent response inhibition (r = 0.099); between lack of planning and prepotent response inhibition (r = 0.106), delay response (r = 0.134), and distortions in elapsed time (r = 0.104); between negative urgency and prepotent response inhibition (r = 0.106); and between sensation seeking and delay response (r = 0.131). Researchers should take care to specify which particular unidimensional constructs are operationalized with not only impulsivity, but with all traits. If self-report and lab task conceptualizations measure disparate aspects of impulsivity, we, as a field, should not expect large conceptual overlap between these methods.

Inverse association between dopaminergic neurotransmission and Iowa Gambling Task performance in pathological gamblers and healthy controls

The dopamine system is believed to affect gambling behavior in pathological gambling. Particularly, dopamine release in the ventral striatum appears to affect decision-making in the disorder. This study investigated dopamine release in the ventral striatum in relation to gambling performance on the Iowa Gambling Task (IGT) in 16 Pathological Gamblers (PG) and 14 Healthy Controls (HC). We used Positron Emission Tomography (PET) to measure the binding potential of [(11)C] raclopride to dopamine D2/3 receptors during a baseline and gambling condition. We hypothesized that decreased raclopride binding potentials in the ventral striatum during gambling (indicating dopamine release) would be associated with higher IGT performance in Healthy Controls, but lower IGT performance in Pathological Gamblers. The results showed that Pathological Gamblers with dopamine release in the ventral striatum had significantly lower IGT performance than Healthy Controls. Furthermore, dopamine release was associated with significantly higher IGT performance in Healthy Controls and significantly lower IGT performance in Pathological Gamblers. The results suggest that dopamine release is involved both in adaptive and maladaptive decision-making. These findings may contribute to a better understanding of dopaminergic dysfunctions in pathological gambling and substance related addictions.

Subtyping pathological gamblers based on impulsivity, depression, and anxiety

This study examined putative subtypes of pathological gamblers (PGs) based on the Pathways model, and it also evaluated whether the subtypes would benefit differentially from treatment. Treatment-seeking PGs (N = 229) were categorized into Pathways subtypes based on scores from questionnaires assessing anxiety, depression, and impulsivity. The Addiction Severity Index-Gambling assessed severity of gambling problems at baseline, posttreatment, and 12-month follow-up. Compared with behaviorally conditioned (BC) gamblers, emotionally vulnerable (EV) gamblers had higher psychiatric and gambling severity, and were more likely to have a parent with a psychiatric history. Antisocial impulsive (AI) gamblers also had elevated gambling and psychiatric severity relative to BC gamblers. They were more likely to have antisocial personality disorder and had the highest legal and family/social severity scores. They were also most likely to have a history of substance abuse treatment, history of inpatient psychiatric treatment, and a parent with a substance use or gambling problem. AI and EV gamblers experienced greater gambling severity throughout treatment than BC gamblers, but all three subtypes demonstrated similar patterns of treatment response. Thus, the three Pathways subtypes differ on some baseline characteristics, but subtyping did not predict treatment outcomes beyond a simple association with problem gambling severity.

Prevalence, correlates, and comorbidities of adult ADHD symptoms in Korea: results of the Korean epidemiologic catchment area study

We examined the prevalence, correlates, and comorbidities of adult attention-deficit hypersensitivity disorder (ADHD) symptoms in a Korean community using data from the National Epidemiological Survey of Psychiatric Disorders in Korea conducted in 2006. A total of 6081 subjects aged 18 to 59 years participated in this study. Diagnostic assessments were based on the Adult ADHD Self-Report Scale Screener and Composite International Diagnostic Interview administered by lay interviewers. The frequencies of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) disorders, sleep disturbances, and suicidal tendency were compared in the ADHD and non-ADHD groups. Odds ratios and significance levels were calculated. The 6 month prevalence of adult ADHD symptoms was 1.1%. Associations between ADHD symptoms and alcohol abuse/dependence, nicotine dependence, mood disorders, major depressive disorder, bipolar disorder, anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorder, social phobia, specific phobia, somatoform disorder, sleep disturbances, and suicidality were overwhelmingly positive and significant (P<0.05), after controlling for gender and age. Adult ADHD symptoms are highly associated with substance abuse, mood and anxiety disorders, somatoform disorders, sleep disturbances and suicidality, suggesting that clinicians should carefully evaluate and treat such psychiatric disorders in adults with ADHD symptoms.

Dopamine release in ventral striatum during Iowa Gambling Task performance is associated with increased excitement levels in pathological gambling

AIMS

Gambling excitement is believed to be associated with biological measures of pathological gambling. Here, we tested the hypothesis that dopamine release would be associated with increased excitement levels in Pathological Gamblers compared with Healthy Controls.

DESIGN

Pathological Gamblers and Healthy Controls were experimentally compared in a non-gambling (baseline) and gambling condition.

MEASUREMENTS

We used Positron Emission Tomography (PET) with the tracer raclopride to measure dopamine D 2/3 receptor availability in the ventral striatum during a non-gambling and gambling condition of the Iowa Gambling Task (IGT). After each condition participants rated their excitement level.

SETTING

Laboratory experiment.

PARTICIPANTS

18 Pathological Gamblers and 16 Healthy Controls.

FINDINGS

Pathological Gamblers with dopamine release in the ventral striatum had significantly higher excitement levels than Healthy Controls despite lower IGT performance. No differences in excitement levels and IGT performance were found between Pathological Gamblers and Healthy Controls without dopamine release. Pathological Gamblers showed a significant correlation between dopamine release and excitement level, while no such interaction was found in Healthy Controls.

CONCLUSIONS

In pathological gamblers dopamine release in the ventral striatum appears to be associated with increased excitement levels despite lower IGT performance. The results might suggest a 'double deficit' function of dopamine in pathological gambling, where dopamine release reinforces maladaptive gambling through increasing excitement levels, reducing inhibition of risky decisions, or a combination of both. These findings may have implications for the understanding of dopamine in pathological gambling and other forms of addiction.

Dopamine release in ventral striatum of pathological gamblers losing money

OBJECTIVE

To investigate dopaminergic neurotransmission in relation to monetary reward and punishment in pathological gambling. Pathological gamblers (PG) often continue gambling despite losses, known as 'chasing one's losses'. We therefore hypothesized that losing money would be associated with increased dopamine release in the ventral striatum of PG compared with healthy controls (HC).

METHOD

We used Positron Emission Tomography (PET) with [(11)C]raclopride to measure dopamine release in the ventral striatum of 16 PG and 15 HC playing the Iowa Gambling Task (IGT).

RESULTS

PG who lost money had significantly increased dopamine release in the left ventral striatum compared with HC. PG and HC who won money did not differ in dopamine release.

CONCLUSION

Our findings suggest a dopaminergic basis of monetary losses in pathological gambling, which might explain loss-chasing behavior. The findings may have implications for the understanding of dopamine dysfunctions and impaired decision-making in pathological gambling and substance-related addictions.

Decision-making in people who relapsed to driving under the influence of alcohol

BACKGROUND

Alcohol use has been previously associated with neurocognitive impairments, especially in decision-making cognition. However, some studies have shown little to no decision-making deficits in relation to different characteristics of people with drinking problems. Relapsing to driving under the influence (DUI) of alcohol is an important issue with legal and psychosocial aspects. We evaluated decision-making performance in second-time DUI offenders by using the Iowa Gambling Task (IGT).

METHOD

Thirty-four male second-time DUI offenders who had been selected for an official psychoeducational rehabilitation program and 31 healthy controls that were matched for age, education, and alcohol use were included. Along with psychiatric assessment, we applied conventional neuropsychological testing comprising cognitive set-shifting, response inhibition, attention, and visuospatial abilities. Also, we used the Temperament and Character Inventory (TCI) to assess personality patterns. A computerized version of IGT was used.

RESULTS

No significant differences were found between the groups in regard to sociodemographics and conventional neuropsychological testing. DUI participants had significantly higher scores only in "self-transcendence" subdomain of TCI. On the fifth block of the IGT, DUI participants had significantly lower net scores than controls (U = 380.0, p < 0.05). Also, DUI participants chose significantly more risky decks compared to controls.

CONCLUSIONS

Our results suggest that there may be subtle decision-making deficits in DUI participants, which goes undetected on conventional neuropsychological testing and which is not correlated with TCI subdomains related with impulsivity patterns.