A D2 antagonist enhances the rewarding and priming effects of a gambling episode in pathological gamblers

Dopamine and acetylcholine have distinct roles in delay- and effort-based decision-making in humans

In everyday life, we encounter situations that require tradeoffs between potential rewards and associated costs, such as time and (physical) effort. The literature indicates a prominent role for dopamine in discounting of both delay and effort, with mixed findings for delay discounting in humans. Moreover, the reciprocal antagonistic interaction between dopaminergic and cholinergic transmission in the striatum suggests a potential opponent role of acetylcholine in these processes. We found opposing effects of dopamine D2 (haloperidol) and acetylcholine M1 receptor (biperiden) antagonism on specific components of effort-based decision-making in healthy humans: haloperidol decreased, whereas biperiden increased the willingness to exert physical effort. In contrast, delay discounting was reduced under haloperidol, but not affected by biperiden. Together, our data suggest that dopamine, acting at D2 receptors, modulates both effort and delay discounting, while acetylcholine, acting at M1 receptors, appears to exert a more specific influence on effort discounting only.

A Systematic Review of Attentional Bias in Problem Gambling

A large body of previous research has provided support for the role of attentional bias as a maintaining factor in addiction. This systematic review aimed to investigate the extent and nature of attentional bias as a phenomenon which exists within problem gamblers. Studies were identified through searches of three databases (MedLine, PSYCHINFO, and Web of Science) and examination of the reference lists of the final studies meeting criteria for inclusion. The scope of the review included empirical studies making experimental comparisons of problem gamblers and non-problem gamblers across a range of attentional paradigms. A comparison of effect sizes was conducted across studies comparing problem to non-problem gamblers within and between attention paradigms. Twenty-two studies were reviewed systematically across ten experimental paradigms. Attentional bias was demonstrated in 16 of the 22 studies, with attentional bias effects varying across paradigms. Quality assessment revealed two main limitations across studies: lack of a priori power analysis, and failure to control for gambling frequency as a possible confounding variable. Findings support the role of attentional bias as a potential maintaining factor in problem gambling behaviour, in line with evidence for substance addiction. Recommendations for future studies are outlined alongside a discussion of clinical implications.

Pharmacological management of gambling disorder: an update of the literature

INTRODUCTION

Gambling disorder (GD) is a mental health condition characterized by persistent and problematic betting behavior. GD generates distress and impairment, and treatment options include psychological and pharmacological interventions.

AREAS COVERED

This narrative review explores existing pharmacological treatments for GD. The following classes of medications were considered: opioid-receptor antagonists (e.g. naltrexone and nalmefene), serotonin reuptake inhibitors (e.g. fluvoxamine, paroxetine, sertraline, escitalopram, and citalopram), glutamatergic agents (e.g. N-acetylcysteine (NAC), acamprosate, and memantine), mood stabilizers (e.g. topiramate, carbamazepine, lithium), and other medications (e.g. modafinil, nefazodone, olanzapine, haloperidol, tolcapone, and bupropion).

EXPERT OPINION

Due to the limitations of the studies reviewed, solid conclusions regarding the optimal choice of pharmacotherapy for individuals with GD are challenging to draw at this time. Despite some medications, such as naltrexone and nalmefene, showing promising results, efficacy has varied across studies. The review highlights current gaps/limitations, including small sample sizes, limited diversity in participant demographics, the need for exploring different gambling subtypes and treatment responses, high placebo response rates, lack of longer-term longitudinal information, limited investigation of neurobiological correlates and co-occurring disorders, and the importance of implementation research. Further research is needed to address these gaps and explore additional medications, as well as interventions like neuromodulation.

Priming effects of a slot machine game and amphetamine on probabilistic risk-taking in people with gambling disorder and healthy controls

INTRODUCTION

The Game of Dice Task (GDT) captures probabilistic risk-taking, which is an important feature of addictions and integral to gambling disorder (GD). No research appears to have assessed effects of gambling-specific priming manipulations or the pharmacological basis of such effects on the GDT.

AIMS

To investigate effects of slot machine gambling (Slots) and d-amphetamine (AMPH; 20 mg) on risk-taking in people with GD and healthy controls (HCs) (n = 30/group). The role of dopamine (DA) was assessed by pre-treating participants with the D2 receptor (D2R)-preferring antagonist, haloperidol (HAL; 3-mg) or mixed D1R-D2R antagonist, fluphenazine (FLU; 3-mg).

HYPOTHESES

Slots and AMPH will each increase risk-taking based on fewer (less probable) possible outcomes selected (POS) and poorer net monetary outcomes (NMO; gains minus losses) on the GDT, with stronger effects in Group GD. If DA mediates these effects, outcomes will vary with pre-treatment.

METHOD

Participants attended a pre-experimental baseline session and 4 test sessions. Antagonist Group (HAL, FLU) was manipulated between-participants. Pre-treatment (antagonist, placebo) was manipulated within-participants and counterbalanced over sessions for Slots and AMPH test phases. Moderator/mediator effects of trait and neuropsychological factors and GD severity (South Oaks Gambling Screen; SOGS) were explored via covariance.

RESULTS

AMPH led to an escalation in risky POS over trial blocks in both groups, regardless of pre-treatment. Cognitive inflexibility (high perseveration-proneness) moderated this effect in Group HC. In Group GD, SOGS selectively predicted riskier POS on AMPH sessions. Group GD achieved poorer NMO vs. Group HC on the pre-experimental baseline and Placebo-Slots sessions. Group HC selectively displayed poorer NMO on the Antagonist-Slots session.

CONCLUSIONS

The GDT can detect behavioral and pharmacological priming effects. Cognitive inflexibility and symptom severity moderate AMPH-induced risk-taking in HC and GD participants, respectively. Sensitization-related "wanting" of risk may contribute to the latter effect in people with GD.

Sex-specific decision-making impairments and striatal dopaminergic changes after binge drinking history in rats

Binge drinking (BD) is a harmful behavior for health and is a predictive factor for the development of alcohol addiction. Weak decision-making (DM) capacities could play a role in the vulnerability to BD which in turn would lead to DM impairments, thus perpetuating BD. Longitudinal preclinical studies are however lacking and necessary to understand this complex relationship. Both DM and BD are influenced by sex and involve dopamine release in the core of the nucleus accumbens, a central mechanism regulated by dopamine D2/3 autoreceptors. In this context, we used an operant self-administration procedure of BD in male and female rats, and longitudinally assessed DM capacity, memory and anxiety-like behavior. To better understand the mechanisms potentially involved in the relationship between DM and BD, ex vivo dopamine transmission was assessed short term after the end of the binge exposure in the core of the nucleus accumbens (NAc) using the fast-scan cyclic voltammetry (FSCV) technique and the D2/3 agonist quinpirole. We found important basal sex differences in DM, with female rats showing better performances at baseline. Choice processes were impaired exclusively in males after BD history, associated with a decrease in impulse control in both sexes, while memory and anxiety-like behavior were not affected. Our neurobiological results demonstrate that BD did not affect basal dopamine signaling in the NAc core, regardless of the sex, but reveal changes in the sensitivity to the inhibitory effects of quinpirole in females. DM impairments were neither associated with changes in basal dopamine signaling nor pre-synaptic D2 activity. Overall, our findings show that BD affects both DM processes and dopamine transmission in the core of the NAc in a sex-related manner, further suggesting that these effects may play a role in the vicious cycle leading to BD perpetuation and the early onset of AUD. Our results may inform novel strategies for therapeutic and prevention interventions.

Drug-Induced Gambling Disorder: Epidemiology, Neurobiology, and Management

Problematic gambling has been suggested to be a possible consequence of dopaminergic medications used mainly in neurological conditions, i.e. pramipexole and ropinirole, and possibly by one antipsychotic compound, aripiprazole. Patients with Parkinson's disease, restless legs syndrome and other conditions potentially treated with dopamine agonists, as well as patients treated for psychotic disorders, are vulnerable patient groups with theoretically increased risk of developing gambling disorder (GD), for example due to higher rates of mental ill-health in these groups. The aim of the present paper is to review the epidemiological, clinical, and neurobiological evidence of the association between dopaminergic medications and GD, and to describe risk groups and treatment options. The neurobiology of GD involves the reward and reinforcement system, based mainly on mesocorticolimbic dopamine projections, with the nucleus accumbens being a crucial area for developing addictions to substances and behaviors. The addictive properties of gambling can perhaps be explained by the reward uncertainty that activates dopamine signaling in a pathological manner. Since reward-related learning is mediated by dopamine, it can be altered by dopaminergic medications, possibly leading to increased gambling behavior and a decreased impulse control. A causal relationship between the medications and GD seems likely, but the molecular mechanisms behind this association have not been fully described yet. More research is needed in order to fully outline the clinical picture of GD developing in patient groups with dopaminergic medications, and data are needed on the differentiation of risk in different compounds. In addition, very few interventional studies are available on the management of GD induced by dopaminergic medications. While GD overall can be treated, there is need for treatment studies testing the effectiveness of tapering of the medication or other gambling-specific treatment modalities in these patient groups.

Update on Gambling Disorder

Gambling disorder (GD) is estimated to be experienced by about 0.5% of the adult population in the United States. The etiology of GD is complex and includes genetic and environmental factors. Specific populations appear particularly vulnerable to GD. GD often goes unrecognized and untreated. GD often co-occurs with other conditions, particularly psychiatric disorders. Behavioral interventions are supported in the treatment of GD. No medications have a formal indication for the GD, although clinical trials suggest some may be helpful. Noninvasive neuromodulation is being explored as a possible treatment. Improved identification, prevention, and treatment of GD are warranted.

Towards a Unifying Account of Dopamine’s Role in Cost-Benefit Decision Making

Dopamine is thought to play a crucial role in cost-benefit decision making, but so far there is no consensus on the precise role of dopamine in decision making. Here, we review the literature on dopaminergic manipulations of cost-benefit decision making in humans and evaluate how well different theoretical accounts explain the existing body of evidence. Reduced D₂ stimulation tends to increase the willingness to bear delay and risk costs (i.e., wait for later rewards, take riskier options), while increased D₁ and D₂ receptor stimulation increases willingness to bear effort costs. We argue that the empirical findings can best be explained by combining the strengths of two theoretical accounts: in cost-benefit decision making, dopamine may play a dual role both in promoting the pursuit of psychologically close options (e.g., sooner and safer rewards) and in computing which costs are acceptable for a reward at stake. Moreover, we identify several limiting factors in the study designs of previous investigations that prevented a fuller understanding of dopamine's role in value-based choice. Together, the proposed theoretical framework and the methodological suggestions for future studies may bring us closer to a unifying account of dopamine in healthy and impaired cost-benefit decision making.

Subjective and Cardiovascular Responses to an Acute Laboratory Gambling Task in Men and Women

Men have previously been overrepresented in gambling for money but in recent years there has been an increase in recognition that women who gamble are "catching up" with their male counterparts. There have been few experimental studies investigating the subjective effects of gambling, and even less have explored the gender differences. As gender differences previously have been reported in the subjective effects of several drugs of abuse such as opioids, amphetamines and alcohol, we sought to investigate if the subjective effects of gambling also differed by gender. The present article analyzes if gender modulates the subjective and physiological effects of an acute laboratory gambling task in healthy men and women. Eighty-two men and women (n = 35 men, n = 47 women) were tested with an online slot machine gambling session and self-report questionnaires of mood and blood pressure were taken before and after gambling. Both men and women showed stimulatory effects of gambling i.e., feelings of high and euphoria and but no differences were found between genders. Findings suggest that both men and women equally experience a pattern of stimulatory effects of gambling from the gambling situation. Gambling therefore seems to have the same abuse potential in both men and women. Although the gap between men and women is narrowing, immediate subjective and physiologic responses do not explain gender differences in the epidemiology of pathological gambling. The contexts and factors that foster or hinder the evolution of gambling addiction in males and females should be further explored. This conclusion is interesting in light of that men are over three times more at risk to experience gambling related problems than women and this risk may depend on other factors involved in the development of addiction.

Psychiatric Drug Prescription and Temporal Associations with a First Diagnosis of Gambling Disorder—Results from a National Register Study

Psychiatric comorbidity is common in gambling disorder (GD), but there are few studies on larger nationwide samples of treatment-seeking patients. Also, temporal associations between GD and other psychiatric disorders are often difficult to study. To address the prevalence and the temporal associations of prescriptions for psychiatric disorders — both in specialized care and primary care — in patients with a GD diagnosis (ICD-10 F63.0). Data was derived from national health registers in Sweden. All patients who were diagnosed with GD in specialized health care in 2005–2016 were included and run against the nationwide database on prescription of pharmaceuticals aimed for psychiatric disorders (n = 2018). Prevalence of psychiatric drug prescription was used as a proxy for psychiatric comorbidity and studied for two 2-year periods (period 1 and 2) prior to GD and one 2-year period (period 3) after the diagnosis. Controlling for gender, age, and time periods, for eight drug categories (anti- epileptics, anti-psychotics, benzodiazepine derivatives, anxiolytics, hypnotics, anti- depressants and drugs used in addictive disorders), significant increases in drug prescription were seen. For central stimulants, a significant increase was seen upon receiving the GD diagnosis (from period 2 to 3), and for benzodiazepines, an increase was seen prior to the GD diagnosis (from period 1 to 2), but not upon diagnosis (from period 2 to 3). Psychiatric comorbidity in GD is common. Drug prescription for psychiatric problems increased markedly in the years temporarily associated with a first diagnosis of GD. The findings may call for early screening for problem gambling in patients with treatment contacts for increasingly poor mental health.

Increased risk for developing gambling disorder under the treatment with pramipexole, ropinirole, and aripiprazole: A nationwide register study in Sweden

Gambling Disorder (GD) has recently been reclassified from an impulse-control disorder to a behavioural addiction and, as in other addictive disorders, the dopaminergic reward system is involved. According to neuroimaging studies, alterations within the striatal dopaminergic signalling can occur in GD. However, the findings to date are controversial and there has been no agreement yet on how the reward system is affected on a molecular basis. Within the last 20 years, there has been growing evidence for a higher risk to develop GD in response to certain dopaminergic medication. Especially the dopamine agonists pramipexole and ropinirole, and the dopamine modulator aripiprazole seem to increase the likelihood for GD. The goal of this study was to examine the association between a prescription for either of the three pharmaceuticals and a GD diagnosis in a large cross-sectional study of the Swedish population. Compared to patients with any other dopaminergic drug prescription (38.7% with GD), the diagnosis was more common in patients with a dopamine agonist prescription (69.8% with GD), resulting in an odds ratio of 3.2. A similar association was found between aripiprazole prescriptions and GD diagnoses, which were analysed within the subgroup of all patients with schizophrenia or a schizotypal, delusional, or another non-mood psychotic disorder. An aripiprazole prescription increased the likelihood of GD (88.8%) in comparison to patients without an aripiprazole prescription (71.2%) with an odds ratio of 3.4. This study contributes to the increasingly reliable evidence for an association between several dopaminergic drugs and a higher risk for developing GD. Therefore, one future research goal should be a better understanding of the neurobiology in GD to be able to design more selective dopaminergic medication with less severe side effects. Additionally, this knowledge could enable the development of pharmacotherapy in GD and other addictive disorders.

Using pharmacological manipulations to study the role of dopamine in human reward functioning: A review of studies in healthy adults

Dopamine (DA) plays a key role in reward processing and is implicated in psychological disorders such as depression, substance use, and schizophrenia. The role of DA in reward processing is an area of highly active research. One approach to this question is drug challenge studies with drugs known to alter DA function. These studies provide good experimental control and can be performed in parallel in laboratory animals and humans. This review aimed to summarize results of studies using pharmacological manipulations of DA in healthy adults. 'Reward' is a complex process, so we separated 'phases' of reward, including anticipation, evaluation of cost and benefits of upcoming reward, execution of actions to obtain reward, pleasure in response to receiving a reward, and reward learning. Results indicated that i) DAergic drugs have different effects on different phases of reward; ii) the relationship between DA and reward functioning appears unlikely to be linear; iii) our ability to detect the effects of DAergic drugs varies depending on whether subjective, behavioral, imaging measures are used.

Pre-clinical models of reward deficiency syndrome: A behavioral octopus

Individuals with mood disorders or with addiction, impulsivity and some personality disorders can share in common a dysfunction in how the brain perceives reward, where processing of natural endorphins or the response to exogenous dopamine stimulants is impaired. Reward Deficiency Syndrome (RDS) is a polygenic trait with implications that suggest cross-talk between different neurological systems that include the known reward pathway, neuroendocrine systems, and motivational systems. In this review we evaluate well-characterized animal models for their construct validity and as potential models for RDS. Animal models used to study substance use disorder, major depressive disorder (MDD), early life stress, immune dysregulation, attention deficit hyperactivity disorder (ADHD), post traumatic stress disorder (PTSD), compulsive gambling and compulsive eating disorders are discussed. These disorders recruit underlying reward deficiency mechanisms in multiple brain centers. Because of the widespread and remarkable array of associated/overlapping behavioral manifestations with a common root of hypodopaminergia, the basic endophenotype recognized as RDS is indeed likened to a behavioral octopus. We conclude this review with a look ahead on how these models can be used to investigate potential therapeutics that target the underlying common deficiency.

Polygenic Risk Scores for Psychiatric Disorders Reveal Novel Clues About the Genetics of Disordered Gambling

Disordered gambling (DG) is a rare but serious condition that results in considerable financial and interpersonal harms. Twin studies indicate that DG is heritable but are silent with respect to specific genes or pathways involved. Existing genomewide association studies (GWAS) of DG have been substantially underpowered. Larger GWAS of other psychiatric disorders now permit calculation of polygenic risk scores (PRSs) that reflect the aggregated effects of common genetic variants contributing risk for the target condition. The current study investigated whether gambling and DG are associated with PRSs for four psychiatric conditions found to be comorbid with DG in epidemiologic surveys: major depressive disorder (MDD), attention-deficit hyperactivity disorder (ADHD), bipolar disorder (BD) and schizophrenia (SCZ). Genotype data and survey responses were analyzed from the Wave IV assessment (conducted in 2008) of the National Longitudinal Study of Adolescent to Adult Health, a representative sample of adolescents recruited in 1994-1995 and followed into adulthood. Among participants classified as having European ancestry based on genetic analysis (N = 5215), 78.4% reported ever having gambled, and 1.3% reported lifetime DG. Polygenic risk for BD was associated with decreased odds of lifetime gambling, OR = 0.93 [0.87, 0.99], p = .045, pseudo-R2(%) = .12. The SCZ PRS was associated with increased odds of DG, OR = 1.54 [1.07, 2.21], p = .02, pseudo-R2(%) = .85. Polygenic risk scores for MDD and ADHD were not related to either gambling outcome. Investigating features common to both SCZ and DG might generate valuable clues about the genetically influenced liabilities to DG.

Impulsivity moderates the effects of dopamine D2 and mixed D1-D2 antagonists in individuals with gambling disorder

BACKGROUND

The functional role of dopamine D1 and D2 receptors in gambling disorder (GD) remains unclear.

AIMS

This study aimed to investigate the role of D1 activation and the moderating effects of impulsivity, a trait linked with weaker D2-mediated inhibition of dopamine release, in GD subjects.

METHODS

Thirty (nine female) non-comorbid GD subjects with low (LI), moderate (MI), or high impulsivity (HI) received the preferential D2 antagonist haloperidol (HAL; 3 mg) or the mixed D1-D2 antagonist fluphenazine (FLU; 3 mg), on separate sessions before a 15-minute slot machine game or amphetamine (AMPH; 20 mg), in a placebo-controlled, double-blind, counterbalanced design.

RESULTS

On their own, HAL and FLU led to linear increases and decreases, respectively, in desire to gamble across increasing levels of impulsivity. The slot machine and AMPH each evoked an inverted-U pattern of desire to gamble across increasing impulsivity. HAL reversed this effect of the game, whereas FLU did not alter post-game desire. HAL and FLU decreased and increased psychostimulant-like effects of the game, respectively, in LI and MI subjects, but consistently reduced these effects in HI subjects. HAL also altered the salience of negative affective words on a reading task, such that greater salience of negative words coincided with lower post-game desire to gamble.

CONCLUSIONS

D1 receptors appear to gauge the incentive value of gambling in GD subjects. D1 activation has negative reinforcing effects in HI gamblers and positive reinforcing effects in LI gamblers. Medications that activate D1 could curtail chasing in HI gamblers. D1 blockade could benefit HI gamblers whose main concern is craving.

Gambling disorder

Gambling disorder is characterized by a persistent, recurrent pattern of gambling that is associated with substantial distress or impairment. The prevalence of gambling disorder has been estimated at 0.5% of the adult population in the United States, with comparable or slightly higher estimates in other countries. The aetiology of gambling disorder is complex, with implicated genetic and environmental factors. Neurobiological studies have implicated cortico-striato-limbic structures and circuits in the pathophysiology of this disorder. Individuals with gambling disorder often go unrecognized and untreated, including within clinical settings. Gambling disorder frequently co-occurs with other conditions, particularly other psychiatric disorders. Behavioural interventions, particularly cognitive-behavioural therapy but also motivational interviewing and Gamblers Anonymous, are supported in the treatment of gambling disorder. No pharmacological therapy has a formal indication for the treatment of gambling disorder, although placebo-controlled trials suggest that some medications, such as opioid-receptor antagonists, may be helpful. Given the associations with poor quality of life and suicide, improved identification, prevention, policy and treatment efforts are needed to help people with gambling disorder.

Facilitated attention for gambling cues in adolescent problem gamblers: An experimental study

BACKGROUND

Studies investigating attentional biases in gambling have observed that problem gamblers' attention is biased toward gambling cues. Despite the increase of gambling among adolescents, to date, no study has ever examined the role of attentional bias in adolescent gambling, as well as the relationships between adolescent gambling severity, craving, and alcohol use.

METHODS

The present study comprised 87 adolescent participants. Based on South Oaks Gambling Screen Revised for Adolescents (SOGS-RA) scores, participants were assigned to non-problem or problem gamblers groups. Participants performed a modified Posner Task (with cue presentation times at 100 and 500 ms) to assess attentional biases. Following the experiment, participants completed the Gambling Craving Scale (GACS) and the Alcohol Use Disorders Identification Test (AUDIT).

RESULTS

Compared to non-problem gamblers, problem gamblers displayed facilitation bias for gambling cues at 500 ms and reported higher levels of craving and alcohol consumption. Results also indicated that alcohol use correlated with facilitation bias.

LIMITATIONS

The recruitment of a predominantly male sample and the use of an indirect measure of attentional bias may have affected the findings concerning attentional processes.

CONCLUSIONS

The present study provides the first empirical evidence of attentional processes in adolescent gambling, and confirms the role of attentional biases, craving, and alcohol use being associated factors in adolescent problem gambling. The results of the present study stress the importance of attentional biases in the initial stages of problem gambling and suggest the need for clinical interventions aimed at reducing attentional bias before they became automatic. Overall, the present study stressed the role of attentional bias as both facilitator and a consequence of gambling involvement.

Correlates of frequent gambling and gambling-related chasing behaviors in individuals with schizophrenia-spectrum disorders

Background and aims Published research on the relationship between disordered gambling and schizophrenia is limited. However, existing data suggest that individuals with schizophrenia/schizoaffective disorder may have a high prevalence of co-occurring disordered gambling. As such, effective strategies for screening and assessing gambling-related problems in individuals with psychosis are needed. The goal of this study was to explore the correlates of increased gambling frequency and chasing behavior, a hallmark feature of gambling disorder, in a sample of individuals with schizophrenia and schizoaffective disorders. Methods Data from 336 participants who met DSM-IV criteria for schizophrenia or schizoaffective disorder were used to examine differences between non-gamblers, infrequent gamblers, frequent gamblers who do not report chasing, and frequent gamblers who report chasing on a variety of associated features and symptoms of schizophrenia and disordered gambling. Results and discussion The results of the study support the conclusion that chasing behavior in individuals with schizophrenia/schizoaffective disorder lies on a continuum of severity, with more frequent gamblers endorsing greater chasing. Chasing was also associated with indicators of lower functioning across co-occurring disorders, such as greater problems with alcohol and drugs, greater gambling involvement, and a family history of gambling problems. The findings from the study suggest the utility of screening for chasing behavior as a brief and efficient strategy for assessing risk of gambling problems in individuals with psychotic-spectrum disorders.

The specificity of attentional biases by type of gambling: An eye-tracking study

A growing body of research indicates that gamblers develop an attentional bias for gambling-related stimuli. Compared to research on substance use, however, few studies have examined attentional biases in gamblers using eye-gaze tracking, which has many advantages over other measures of attention. In addition, previous studies of attentional biases in gamblers have not directly matched type of gambler with personally-relevant gambling cues. The present study investigated the specificity of attentional biases for individual types of gambling using an eye-gaze tracking paradigm. Three groups of participants (poker players, video lottery terminal/slot machine players, and non-gambling controls) took part in one test session in which they viewed 25 sets of four images (poker, VLTs/slot machines, bingo, and board games). Participants' eye fixations were recorded throughout each 8-second presentation of the four images. The results indicated that, as predicted, the two gambling groups preferentially attended to their primary form of gambling, whereas control participants attended to board games more than gambling images. The findings have clinical implications for the treatment of individuals with gambling disorder. Understanding the importance of personally-salient gambling cues will inform the development of effective attentional bias modification treatments for problem gamblers.

Dopamine and Stress System Modulation of Sex Differences in Decision Making

Maladaptive decision making is associated with several neuropsychiatric disorders, including problem gambling and suicidal behavior. The prevalence of these disorders is higher in men vs women, suggesting gender-dependent regulation of their pathophysiology underpinnings. We assessed sex differences in decision making using the rat version of the Iowa gambling task. Female rats identified the most optimal choice from session 1, whereas male rats from session 5. Male, but not female rats, progressively improved their advantageous option responding and surpassed females. Estrus cycle phase did not affect decision making. To test whether pharmacological manipulations targeting the dopaminergic and stress systems affect decision making in a sex-dependent manner, male and female rats received injections of a dopamine D₂ receptor (D₂R) antagonist (eticlopride), D₂R agonist (quinpirole), corticotropin-releasing factor 1 (CRF₁) antagonist (antalarmin), and α₂-adrenergic receptor antagonist (yohimbine; used as a pharmacological stressor). Alterations in mRNA levels of D₂R and CRF₁ were also assessed. Eticlopride decreased advantageous responding in male, but not female rats, whereas quinpirole decreased advantageous responding specifically in females. Yohimbine dose-dependently decreased advantageous responding in female rats, whereas decreased advantageous responding was only observed at higher doses in males. Antalarmin increased optimal choice responding only in female rats. Higher Drd2 and Crhr1 expression in the amygdala were observed in female vs male rats. Higher amygdalar Crhr1 expression was negatively correlated with advantageous responding specifically in females. This study demonstrates the relevance of dopaminergic- and stress-dependent sex differences to maladaptive decision making.

A little rein on addiction

Rewarding and aversive experiences influence emotions, motivate specific behaviors, and modify future action in animals. Multiple conserved vertebrate neural circuits have been discovered that act in a species-specific manner to reinforce behaviors that are rewarding, while attenuating those with an adverse outcome. A growing body of research now suggests that malfunction of the same circuits is an underlying cause for many human disorders and mental ailments. The habenula (Latin for "little rein") complex, an epithalamic structure that regulates midbrain monoaminergic activity has emerged in recent years as one such region in the vertebrate brain that modulates behavior. Its dysfunction, on the other hand, is implicated in a spectrum of psychiatric disorders in humans such as schizophrenia, depression and addiction. Here, I review the progress in identification of potential mechanisms involving the habenula in addiction.

Parallel role for the dopamine D1 receptor in gambling and amphetamine reinforcement in healthy volunteers

This study investigated the role of dopamine, and specifically the D1 receptor (D1R), in the reinforcing effects of a slot-machine game in healthy volunteers ( n=30). To compare gambling and drug effects, subjects received the prototypic psychostimulant drug d-amphetamine (AMPH; 20 mg) in a multi-session, placebo-controlled design. To isolate D1R, half the subjects were pretreated with the preferential D2 receptor antagonist haloperidol (HAL; 3 mg), and the other half with the mixed D1-D2 antagonist fluphenazine (FLU; 3 mg) before the game (Phase I) and AMPH (Phase II). HAL decreased and FLU increased the post-game desire to gamble and post-AMPH desire to take AMPH again, as well as amphetamine scale ratings on the Addiction Research Center Inventory after gambling and AMPH. The effects of the antagonists on desire to gamble and to take AMPH again were significantly intercorrelated. HAL increased and FLU decreased the salience of negative affective words on a rapid reading task after both reinforcers. HAL also decreased the salience of gambling words after AMPH. Both reinforcers increased diastolic blood pressure equally under antagonists and placebo. Results indicate that D1R plays a parallel role in the psychostimulant-like, incentive-motivational, and salience-enhancing effects of gambling and AMPH. Moderate D1R activation appears to optimize these effects in healthy subjects.

Treatment modalities for patients with gambling disorder

BACKGROUND

Gambling disorder (GD) is defined as persistent and recurrent problematic gambling behavior leading to clinically significant impairment or distress. The prevalence of GD has been shown to be 1.2-7.1% in the general population. GD can severely impact on personal and vocational wellbeing as well as lead to financial problems, and has been known to be difficult to treat. This review describes the available pharmacotherapy/psychosocial treatments for GD patients, and summarizes data on the effectiveness of these GD treatments.

METHODS

This review refers to newly as well as previously published studies and guidelines.

RESULTS

The description of pharmacotherapy mainly focuses on opioid receptor antagonists, selective serotonin reuptake inhibitors, and mood stabilizers. Psychosocial treatments/strategies mainly include cognitive behavioral therapy, motivational interviewing, and Gamblers Anonymous. We also introduce relatively novel treatment modalities.

CONCLUSIONS

This review can help clinicians to decide treatment plans for their GD patients. In addition, it can be used as a reference for designing future research.

Amplified Striatal Responses to Near-Miss Outcomes in Pathological Gamblers

Near-misses in gambling games are losing events that come close to a win. Near-misses were previously shown to recruit reward-related brain regions including the ventral striatum, and to invigorate gambling behavior, supposedly by fostering an illusion of control. Given that pathological gamblers are particularly vulnerable to such cognitive illusions, their persistent gambling behavior might result from an amplified striatal sensitivity to near-misses. In addition, animal studies have shown that behavioral responses to near-miss-like events are sensitive to dopamine, but this dopaminergic influence has not been tested in humans. To investigate these hypotheses, we recruited 22 pathological gamblers and 22 healthy controls who played a slot machine task delivering wins, near-misses and full-misses, inside an fMRI scanner. Each participant played the task twice, once under placebo and once under a dopamine D2 receptor antagonist (sulpiride 400 mg), in a double-blind, counter-balanced design. Participants were asked about their motivation to continue gambling throughout the task. Across all participants, near-misses elicited higher motivation to continue gambling and increased striatal responses compared with full-misses. Crucially, pathological gamblers showed amplified striatal responses to near-misses compared with controls. These group differences were not observed following win outcomes. In contrast to our hypothesis, sulpiride did not induce any reliable modulation of brain responses to near-misses. Together, our results demonstrate that pathological gamblers have amplified brain responses to near-misses, which likely contribute to their persistent gambling behavior. However, there is no evidence that these responses are influenced by dopamine. These results have implications for treatment and gambling regulation.

Attentional biases in problem and non-problem gamblers

BACKGROUND

From a cognitive perspective, attentional biases are deemed as factors responsible in the onset and development of gambling disorder. However, knowledge relating to attentional processes in gambling is scarce and studies to date have reported contrasting results. Moreover, no study has ever examined which component and what type of bias are involved in attentional bias in gambling.

METHODS

In the present study, 108 Italian participants, equally divided into problem and non-problem gamblers, were administered a modified Posner Task, an attentional paradigm in which - through the manipulation of stimuli presentation time - it is possible to measure both initial orienting and maintenance of attention. In addition to the experimental task, participants completed self-report measures involving (i) craving (Gambling Craving Scale), (ii) depression, anxiety and stress (Depression Anxiety Stress Scale) and (iii) emotional dysregulation (Difficulties in Emotion Regulation Scale).

RESULTS

Analyses revealed facilitation in detecting gambling-related stimuli at the encoding level in problem gamblers but not in non-problem gamblers. Compared to non-problem gamblers, problem gamblers also reported higher levels of craving, emotional dysregulation, and negative mood states. Furthermore, all measures correlated with the gambling severity.

LIMITATIONS

The use of indirect measure of attentional bias could be less accurate compared to direct measures.

CONCLUSIONS

The facilitation in detecting gambling-related stimuli in problem gamblers and the correlation between subjective craving and facilitation bias suggests that attentional bias could not be due to a conditioning process but that motivational factors such as craving could induce addicted-related seeking-behaviors.

Effects of High Frequency Repeated Transcranial Magnetic Stimulation and Continuous Theta Burst Stimulation on Gambling Reinforcement, Delay Discounting, and Stroop Interference in Men with Pathological Gambling

BACKGROUND

Repeated transcranial magnetic stimulation (rTMS) can reduce cravings and improve cognitive function in substance dependent individuals. Whether these benefits extend to individuals with pathological gambling (PG) is unclear. High-frequency rTMS of the medial prefrontal cortex (PFC) and continuous theta burst stimulation (cTBS) of the right dorsolateral PFC can reduce impulsive choice in healthy volunteers.

OBJECTIVE

This study aimed to assess the effects of these two protocols on gambling reinforcement and related responses in otherwise healthy men with PG.

METHODS

Participants (n = 9) underwent active or sham treatments at weekly intervals in a repeated-measures, Latin square design. Subjective and physiological responses were assessed before and after a 15-min slot machine game on each session. Delay discounting and Stroop tasks measured post-game impulsive choice and attentional control.

RESULTS

Multivariate analysis of covariance, controlling for winnings on the slot machine under each treatment, found that rTMS reduced the post-game increase in Desire to Gamble; cTBS reduced amphetamine-like effects, and decreased diastolic blood pressure. Treatment had no significant univariate effects on bet size or speed of play in the game; however, a multivariate effect for the two indices suggested that treatment decreased behavioral activation. Neither treatment reduced impulsive choice, while both treatments increased Stroop interference.

CONCLUSIONS

rTMS and cTBS can reduce gambling reinforcement in non-comorbid men with PG. Separate processes appear to mediate gambling reinforcement and betting behavior as against delay discounting and Stroop interference. Interventions that modify risky as opposed to temporal aspects of decision making may better predict therapeutic response in PG.

A review of gambling disorder and substance use disorders

In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), gambling disorder was recategorized from the "Impulse Control Disorder" section to the newly expanded "Substance-related and Addictive Disorders" section. With this move, gambling disorder has become the first recognized nonsubstance behavioral addiction, implying many shared features between gambling disorder and substance use disorders. This review examines these similarities, as well as differences, between gambling and substance-related disorders. Diagnostic criteria, comorbidity, genetic and physiological underpinnings, and treatment approaches are discussed.

Functional Genetic Variation in Dopamine Signaling Moderates Prefrontal Cortical Activity During Risky Decision Making

Brain imaging has revealed links between prefrontal activity during risky decision-making and striatal dopamine receptors. Specifically, striatal dopamine D2-like receptor availability is correlated with risk-taking behavior and sensitivity of prefrontal activation to risk in the Balloon Analogue Risk Task (BART). The extent to which these associations, involving a single neurochemical measure, reflect more general effects of dopaminergic functioning on risky decision making, however, is unknown. Here, 65 healthy participants provided genotypes and performed the BART during functional magnetic resonance imaging. For each participant, dopamine function was assessed using a gene composite score combining known functional variation across five genes involved in dopaminergic signaling: DRD2, DRD3, DRD4, DAT1, and COMT. The gene composite score was negatively related to dorsolateral prefrontal cortical function during risky decision making, and nonlinearly related to earnings on the task. Iterative permutations of all possible allelic variations (7777 allelic combinations) was tested on brain function in an independently defined region of the prefrontal cortex and confirmed empirical validity of the composite score, which yielded stronger association than 95% of all other possible combinations. The gene composite score also accounted for a greater proportion of variability in neural and behavioral measures than the independent effects of each gene variant, indicating that the combined effects of functional dopamine pathway genes can provide a robust assessment, presumably reflecting the cumulative and potentially interactive effects on brain function. Our findings support the view that the links between dopaminergic signaling, prefrontal function, and decision making vary as a function of dopamine signaling capacity.

The Impact of Selective Dopamine D2, D3 and D4 Ligands on the Rat Gambling Task

Gambling is an addictive disorder with serious societal and personal costs. To-date, there are no approved pharmacological treatments for gambling disorder. Evidence suggests a role for dopamine in gambling disorder and thus may provide a therapeutic target. The present study therefore aimed to investigate the effects of selective antagonists and agonists of D2, D3 and D4 receptors in a rodent analogue of the Iowa gambling task used clinically. In this rat gambling task (rGT), animals are trained to associate different response holes with different magnitudes and probabilities of food pellet rewards and punishing time-out periods. As in the Iowa gambling task, the optimal strategy is to avoid the tempting high-risk high-reward options, and instead favor those linked to smaller per-trial rewards but also lower punishments, thereby maximizing the amount of reward earned over time. Administration of those selective ligands did not affect decision making under the rGT. Only the D4 drug had modest effects on latency measures suggesting that D4 may contribute in some ways to decision making under this task.

[Gambling addiction: insights from neuroscience and neuroimaging]

Although most people consider gambling as a recreational activity, some individuals lose control over their behavior and enter a spiral of compulsive gambling leading to dramatic consequences. In its most severe form, pathological gambling is considered a behavioral addiction sharing many similarities with substance addiction. A number of neurobiological hypotheses have been investigated in the past ten years, relying mostly on neuroimaging techniques. Similarly to substance addiction, a number of observations indicate a central role for dopamine in pathological gambling. However, the underlying mechanism seems partly different and is still poorly understood. Neuropsychological studies have shown decision-making and behavioral inhibition deficits in pathological gamblers, likely reflecting frontal lobe dysfunction. Finally, functional MRI studies have revealed abnormal reactivity within the brain reward system, including the striatum and ventro-medial prefrontal cortex. These regions are over-activated by gambling cues, and under-activated by monetary gains. However, the scarcity and heterogeneity of brain imaging studies currently hinder the development of a coherent neurobiological model of pathological gambling. Further replications of results and diversification of approaches will be needed in the coming years in order to strengthen our current model.

Pathological gambling induced by dopamine antagonists: a case report

Pathological gambling is defined as inappropriate, persistent, and maladaptive gambling behaviour. It is a non-pharmacological addiction classified as an impulse control disorder. However, pathological gambling has been associated with dopamine agonist use. Here we report of a 28-year-old man with a first major depressive episode and a post-traumatic stress disorder who has been treated with a combination of the serotonine/noradrenaline reuptake inhibitor duloxetine and the tricyclic antidepressant maprotiline. The administration of antipsychotic flupentixole (up to 7 mg) turned this slight online poker gambler into an excessive gambler. Only after the discontinuation of the antidopaminergic agents and the switch to bupropion did this gambling behaviour stop which suggests a causal relationship between dopamine antagonists and pathological gambling.

Bipolar disorder and gambling disorder comorbidity: current evidence and implications for pharmacological treatment

BACKGROUND

The co-occurrence of bipolar disorder (BD) and gambling disorder (GD), though of clinical and public health importance, is still scarcely investigated. Comorbid BD-GD subjects experience a more severe course of illness and poorer treatment outcome, due to a range of clinical and psychosocial factors that collectively impede remission and recovery. The aim of our paper is to review the role of pharmacotherapy in the treatment of comorbid BD-GD, in order to support clinical decisions according to the best available evidence.

METHODS

A qualitative systematic review of studies on pharmacological treatment in comorbid BD-GD was performed. A comprehensive literature search of online databases, bibliographies of published articles and gray literature was conducted. Data on efficacy, safety and tolerability were extracted and levels of evidence were assessed. We also provide a brief overview of current epidemiological, neurobiological and clinical findings, with the intention of proposing a dimensional approach to the choice of available drugs.

RESULTS

The only drug with a high level of evidence is lithium. Considering the inclusion of GD in DSM-5 'Substance-related and Addictive Disorders' category, we discuss the use of other drugs with a high level of evidence currently used in BD subjects with co-occurring substance use disorders.

LIMITATIONS

Only few clinical trials are available and the population is limited; therefore no conclusive evidence can be inferred.

CONCLUSIONS

Further randomized controlled trials are required to evaluate the efficacy of pharmacological treatment strategies in large samples of patients with comorbid BD-GD. Also, attempts should be made to identify other shared clinical and psychopathological domains that are amenable to treatment.

Dopamine Regulates Approach-Avoidance in Human Sensation-Seeking

BACKGROUND

Sensation-seeking is a trait that constitutes an important vulnerability factor for a variety of psychopathologies with high social cost. However, little is understood either about the mechanisms underlying motivation for intense sensory experiences or their neuropharmacological modulation in humans.

METHODS

Here, we first evaluate a novel paradigm to investigate sensation-seeking in humans. This test probes the extent to which participants choose either to avoid or self-administer an intense tactile stimulus (mild electric stimulation) orthogonal to performance on a simple economic decision-making task. Next we investigate in a different set of participants whether this behavior is sensitive to manipulation of dopamine D2 receptors using a within-subjects, placebo-controlled, double-blind design.

RESULTS

In both samples, individuals with higher self-reported sensation-seeking chose a greater proportion of mild electric stimulation-associated stimuli, even when this involved sacrifice of monetary gain. Computational modelling analysis determined that people who assigned an additional positive economic value to mild electric stimulation-associated stimuli exhibited speeding of responses when choosing these stimuli. In contrast, those who assigned a negative value exhibited slowed responses. These findings are consistent with involvement of low-level, approach-avoidance processes. Furthermore, the D2 antagonist haloperidol selectively decreased the additional economic value assigned to mild electric stimulation-associated stimuli in individuals who showed approach reactions to these stimuli under normal conditions (behavioral high-sensation seekers).

CONCLUSIONS

These findings provide the first direct evidence of sensation-seeking behavior being driven by an approach-avoidance-like mechanism, modulated by dopamine, in humans. They provide a framework for investigation of psychopathologies for which extreme sensation-seeking constitutes a vulnerability factor.

Abnormal modulation of reward versus punishment learning by a dopamine D2-receptor antagonist in pathological gamblers

RATIONALE

Pathological gambling has been associated with dopamine transmission abnormalities, in particular dopamine D2-receptor deficiency, and reversal learning deficits. Moreover, pervasive theoretical accounts suggest a key role for dopamine in reversal learning. However, there is no empirical evidence for a direct link between dopamine, reversal learning and pathological gambling.

OBJECTIVE

The aim of the present study is to triangulate dopamine, reversal learning, and pathological gambling.

METHODS

Here, we assess the hypothesis that pathological gambling is accompanied by dopamine-related problems with learning from reward and punishment by investigating effects of the dopamine D2-receptor antagonist sulpiride (400 mg) on reward- and punishment-based reversal learning in 18 pathological gamblers and 22 healthy controls, using a placebo-controlled, double-blind, counter-balanced design.

RESULTS

In line with previous studies, blockade of D2 receptors with sulpiride impaired reward versus punishment reversal learning in controls. By contrast, sulpiride did not have any outcome-specific effects in gamblers.

CONCLUSION

These data demonstrate that pathological gambling is associated with a dopamine-related anomaly in reversal learning from reward and punishment.

Gambling disorder and other behavioral addictions: recognition and treatment

Addiction professionals and the public are recognizing that certain nonsubstance behaviors--such as gambling, Internet use, video-game playing, sex, eating, and shopping--bear resemblance to alcohol and drug dependence. Growing evidence suggests that these behaviors warrant consideration as nonsubstance or "behavioral" addictions and has led to the newly introduced diagnostic category "Substance-Related and Addictive Disorders" in DSM-5. At present, only gambling disorder has been placed in this category, with insufficient data for other proposed behavioral addictions to justify their inclusion. This review summarizes recent advances in our understanding of behavioral addictions, describes treatment considerations, and addresses future directions. Current evidence points to overlaps between behavioral and substance-related addictions in phenomenology, epidemiology, comorbidity, neurobiological mechanisms, genetic contributions, responses to treatments, and prevention efforts. Differences also exist. Recognizing behavioral addictions and developing appropriate diagnostic criteria are important in order to increase awareness of these disorders and to further prevention and treatment strategies.

Impulsive actions and choices in laboratory animals and humans: effects of high vs. low dopamine states produced by systemic treatments given to neurologically intact subjects

Increases and decreases in dopamine (DA) transmission have both been suggested to influence reward-related impulse-control. The present literature review suggests that, in laboratory animals, the systemic administration of DA augmenters preferentially increases susceptibility to premature responding; with continued DA transmission, reward approach behaviors are sustained. Decreases in DA transmission, in comparison, diminish the appeal of distal and difficult to obtain rewards, thereby increasing susceptibility to temporal discounting and other forms of impulsive choice. The evidence available in humans is not incompatible with this model but is less extensive.

The neural bases of cognitive processes in gambling disorder

Functional imaging is offering powerful new tools to investigate the neurobiology of cognitive functioning in people with and without psychiatric conditions like gambling disorder. Based on similarities between gambling and substance-use disorders in neurocognitive and other domains, gambling disorder has recently been classified in the Diagnostic and Statistical Manual of Mental Disorders (5th edn) (DSM-5) as a behavioral addiction. Despite the advances in understanding, there exist multiple unanswered questions about the pathophysiology underlying gambling disorder and the promise for translating the neurobiological understanding into treatment advances remains largely unrealized. Here we review the neurocognitive underpinnings of gambling disorder with a view to improving prevention, treatment, and policy efforts.

Intersection of effort and risk: ethological and neurobiological perspectives

The physical effort required to seek out and extract a resource is an important consideration for a foraging animal. A second consideration is the variability or risk associated with resource delivery. An intriguing observation from ethological studies is that animals shift their preference from stable to variable food sources under conditions of increased physical effort or falling energetic reserves. Although theoretical models for this effect exist, no exploration into its biological basis has been pursued. Recent advances in understanding the neural basis of effort- and risk-guided decision making suggest that opportunities exist for determining how effort influences risk preference. In this review, we describe the intersection between the neural systems involved in effort- and risk-guided decision making and outline two mechanisms by which effort-induced changes in dopamine release may increase the preference for variable rewards.