Dopaminergic signaling of uncertainty and the aetiology of gambling addiction

Reward prediction-errors weighted by cue salience produces addictive behaviours in simulations, with asymmetrical learning and steeper delay discounting

Dysfunction in learning and motivational systems are thought to contribute to addictive behaviours. Previous models have suggested that dopaminergic roles in learning and motivation could produce addictive behaviours through pharmacological manipulations that provide excess dopaminergic signalling towards these learning and motivational systems. Redish (2004) suggested a role based on dopaminergic signals of value prediction error, while (Zhang et al., 2009) suggested a role based on dopaminergic signals of motivation. However, both models present significant limitations. They do not explain the reduced sensitivity to drug-related costs/negative consequences, the increased impulsivity generally found in people with a substance use disorder, craving behaviours, and non-pharmacological dependence, all of which are key hallmarks of addictive behaviours. Here, we propose a novel mathematical definition of salience, that combines aspects of dopamine's role in both learning and motivation within the reinforcement learning framework. Using a single parameter regime, we simulated addictive behaviours that the (Zhang et al., 2009; Redish, 2004) models also produce but we went further in simulating the downweighting of drug-related negative prediction-errors, steeper delay discounting of drug rewards, craving behaviours and aspects of behavioural/non-pharmacological addictions. The current salience model builds on our recently proposed conceptual theory that salience modulates internal representation updating and may contribute to addictive behaviours by producing misaligned internal representations (Kalhan et al., 2021). Critically, our current mathematical model of salience argues that the seemingly disparate learning and motivational aspects of dopaminergic functioning may interact through a salience mechanism that modulates internal representation updating.

Engineered highs: Reward variability and frequency as potential prerequisites of behavioural addiction

Influential learning-based accounts of substance addictions posit the attribution of incentive salience to drug-associated cues, and its escalation by the direct dopaminergic effects of drugs. In translating this account to disordered gambling, we have noted how the intermittent nature of monetary rewards in gambling (i.e. the variable ratio) may allow for analogous learning processes, via effects on dopaminergic signalling. The aim of the present article is to consider how multiple sources of reward variability operate within modern gambling products, and how similar sources of variability, as well as some novel sources of variability, also apply to other digital products implicated in behavioural addictions, including gaming, shopping, social media and online pornography. Online access to these activities facilitates not only unparalleled accessibility but also introduces novel forms of reward variability, as seen in the effects of infinite scrolls and personalized recommendations. We use the term uncertainty to refer to the subjective experience of reward variability. We further highlight two psychological factors that appear to moderate the effects of uncertainty: 1) the timecourse of uncertainty, especially with regard to its resolution, 2) the frequency of exposure, allowing temporal compression. Collectively, the evidence illustrates how qualitative and quantitative variability of reward can confer addictive potential to non-drug reinforcers by exploiting the psychological and neural processes that rely on predictability to guide reward seeking behaviour.

Smartphone addiction, gender and interpersonal attachment: A cross-sectional analytical survey in Taiwan

Overview

Smartphone use has dramatically increased worldwide, contributing to a profound change in interpersonal interactions. They have become the primary medium of human interaction, and smartphone addiction, consequently, has become a modern-day reality. Recent research on smartphone addiction has provided diverse explanations regarding the correlation between gender and addiction. Therefore, this study aims to analyse the correlation and variance among smartphone addiction, gender and interpersonal attachment.

Methods

The participants included Taiwanese citizens and the questionnaires were randomly distributed; 1190 valid questionnaires (534 males, 656 females) were collected. Descriptive statistics were computed to observe the average value and standard deviation between interpersonal attachment and gender. Next, Spearman's ρ was conducted to interpret the correlation among smartphone addiction, gender and interpersonal attachment. Finally, the participants were divided into three groups based on their pre-determined level of smartphone addiction: high, moderate and low addictions. The Analysis of variance (ANOVA) was performed based on interpersonal attachment as the independent variable to determine any statistically significant difference among the three levels.

Results

There are four patterns of interpersonal attachment: secure, avoidant, dismissing and anxious attachments. The correlation analysis revealed a significant positive correlation between interpersonal attachment and smartphone addiction (p > 0.000), while revealing no relationship between gender and smartphone addiction or gender and interpersonal attachment. Additionally, the ANOVA indicated the difference was statistically significant in the groups of high and moderate addictions; no statistical significance was identified in the group of low addiction (p < 0.204).

Conclusion

This study revealed that there was no correlation between gender and smartphone addiction, but rather, a positive correlation between smartphone addiction and interpersonal attachment. This positive correlation suggests both high and moderate addiction groups display insecurity in their interpersonal attachment. Therefore, to lower the prevalence of unhealthy smartphone addiction, maintaining healthy interpersonal relationships is suggested.

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.

Network Analysis of the Structure of the Core Symptoms and Clinical Correlates in Comorbid Schizophrenia and Gambling Disorder

Few studies have analyzed the clinical profile of treatment-seeking patients with the comorbid presence of schizophrenia (SCZ) and gambling disorder (GD), which warrants new research to assess the network structure of this complex mental condition. The aim of this study was to explore the organization of the symptoms and other clinical correlates of SCZ with GD. Network analysis was applied to a sample of N = 179 SCZ patients (age range: 19-70 years, mean=39.5, SD=9.9) who met clinical criteria for gambling disorder-related problems. Variables included in the network were the core GD symptoms according to the DSM-5, psychotic and paranoid ideation levels, global psychological distress, GD severity measures (debts and illegal behavior related with gambling), substances (tobacco, alcohol, and illegal drugs), and personality profile. The nodes with the highest authority in the network (variables of highest relevance) were personality traits and psychological distress. Four empirical modules/clusters were identified, and linkage analysis identified the nodes with the highest closeness (bridge nodes) to be novelty seeking and reward dependence (these traits facilitate the transition between the modules). Identification of the variables with the highest centrality/linkage can be particularly useful for developing precise management plans to prevent and treat SCZ with GD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11469-022-00983-y.

Latent Classes for the Treatment Outcomes in Women with Gambling Disorder and Buying/Shopping Disorder

BACKGROUND

The risk for behavioral addictions is rising among women within the general population and in clinical settings. However, few studies have assessed treatment effectiveness in females. The aim of this work was to explore latent empirical classes of women with gambling disorder (GD) and buying/shopping disorder (BSD) based on the treatment outcome, as well as to identify predictors of the different empirical groups considering the sociodemographic and clinical profiles at baseline.

METHOD

A clinical sample of n = 318 women seeking treatment for GD (n = 221) or BSD (n = 97) participated. Age was between 21 to 77 years.

RESULTS

The four latent-classes solution was the optimal classification in the study. Latent class 1 (LT1, good progression to recovery) grouped patients with the best CBT outcomes (lowest risk of dropout and relapses), and it was characterized by the healthiest psychological state at baseline, the lowest scores in harm avoidance and self-transcendence, and the highest scores in reward dependence, persistence, self-directedness and cooperativeness. Latent classes 3 (LT3, bad progression to drop-out) and 4 (LT4, bad progression to relapse) grouped women with the youngest mean age, earliest onset of the addictive behaviors, and worst psychological functioning.

CONCLUSIONS

GD and BSD are complex conditions with multiple interactive causes and impacts, which need wide and flexible treatment plans. Specific interventions should be designed according to the specific profiles of women for achieving early inclusion, retention and well-maintained long-term effects.

Gambling along the schizotypal spectrum: The associations between schizotypal personality, gambling-related cognitions, luck, and problem gambling

Objective

Schizotypal personality (schizotypy) is a cluster of traits in the general population, including alterations in belief formation that may underpin delusional thinking. The psychological processes described by schizotypy could also fuel cognitive distortions in the context of gambling. This study sought to characterize the relationships between schizotypy, gambling-related cognitive distortions, and levels of problem gambling.

Methods

Analyses were conducted on three groups, a student sample (n = 104) with minimal self-reported gambling involvement, a crowdsourced sample of regular gamblers (via MTurk; n = 277), and an additional crowdsourced sample with a range of gambling involvement (via MTurk; n = 144). Primary measures included the Schizotypal Personality Questionnaire - Brief (SPQ-B), the Peters et al. Delusions Inventory (PDI-21), the Gambling Related Cognitions Scale (GRCS), and the Problem Gambling Severity Index (PGSI). Luck was measured with either the Belief in Good Luck Scale (BIGLS) or the Beliefs Around Luck Scale (BALS).

Results

Small-to-moderate associations were detected between the components of schizotypy, including delusion proneness, and the gambling-related variables. Schizotypy was associated with the general belief in luck and bad luck, but not beliefs in good luck. A series of partial correlations demonstrated that when the GRCS was controlled for, the relationship between schizotypy and problem gambling was attenuated.

Conclusions

This study demonstrates that schizotypy is a small-to-moderate correlate of erroneous gambling beliefs and PG. These data help characterize clinical comorbidities between the schizotypal spectrum and problem gambling, and point to shared biases relating to belief formation and decision-making under chance.

Distinct motivations to seek out information in healthy individuals and problem gamblers

As massive amounts of information are becoming available to people, understanding the mechanisms underlying information-seeking is more pertinent today than ever. In this study, we investigate the underlying motivations to seek out information in healthy and addicted individuals. We developed a novel decision-making task and a novel computational model which allows dissociating the relative contribution of two motivating factors to seek out information: a desire for novelty and a general desire for knowledge. To investigate whether/how the motivations to seek out information vary between healthy and addicted individuals, in addition to healthy controls we included a sample of individuals with gambling disorder-a form of addiction without the confound of substance consumption and characterized by compulsive gambling. Our results indicate that healthy subjects and problem gamblers adopt distinct information-seeking "modes". Healthy information-seeking behavior was mostly motivated by a desire for novelty. Problem gamblers, on the contrary, displayed reduced novelty-seeking and an increased desire for accumulating knowledge compared to healthy controls. Our findings not only shed new light on the motivations driving healthy and addicted individuals to seek out information, but they also have important implications for the treatment and diagnosis of behavioral addiction.

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.

The prevalence and features of schizophrenia among individuals with gambling disorder

BACKGROUND-OBJECTIVES

Few studies have analyzed the comorbid presence of gambling disorder (GD) with schizophrenia, its sociodemographic correlates and clinical implications. This study estimated the prevalence of the dual diagnosis (GD with schizophrenia) and the differences in the profiles of patients with and without the dual condition.

METHOD

The sample included n = 3,754 patients consecutively accepted for treatment for GD. Sociodemographics, gambling-related variables, psychopathological state and personality traits were assessed and compared between the groups.

RESULTS

The prevalence of schizophrenia within patients who met clinical criteria for GD was 4.4% (95% confidence interval: 3.8%-5.1%). Variables related to the dual presence of GD with schizophrenia were single marital status, lower education level, inactive working status, socioeconomic disadvantage, younger age, earlier onset of gambling problems, worse global psychopathological state and more dysfunctional personality profile (higher level in harm avoidance and lower level in cooperativeness, reward dependence, persistence and self-directedness).

CONCLUSION

The presence of schizophrenia among patients with GD was around 4 times higher than the prevalence rate estimated in the reference general population. The differences in the profiles of GD patients with and without schizophrenia suggest that individuals with the dual diagnosis condition require unique assessment considerations and tailored treatment interventions specifically designed for the clinical and functioning higher risk.

Non-invasive brain stimulation targets and approaches to modulate gambling-related decisions: A systematic review

INTRODUCTION

Despite intense neuroscience research on the neurobiological underpinnings of Gambling Disorder (GD) and gambling-related decision-making, effective treatments targeting these dysfunctions are still lacking. Non Invasive Brain Stimulation (NIBS) techniques, such as transcranial Direct Current Stimulation (tDCS) and Transcranial Magnetic Stimulation (TMS), selectively modulate activity of brain circuits and have the potential to reverse alterations sustaining GD symptoms. Therefore, the aim of this systematic review was to determine the impact of different NIBS interventions on gambling-related decision processes.

METHODS

We conducted a comprehensive and translational search in three online databases (MEDLINE via PubMed, Scopus, Web of Science), in accordance with the PRISMA guidelines. We included studies applying neuromodulation (TMS, tDCS) techniques in GD patients or assessing gambling-related decision-making in healthy subjects. In addition, we explored the potential impact of NIBS in drug-induced GD (e.g., Parkinson's Disease).

RESULTS

Twenty-seven studies have been included. We summarized results to detect the impact of different targets and stimulation/inhibition protocols in terms of gambling-related decision-making. The majority of both tDCS and TMS studies targeted the dorsolateral prefrontal cortex. Although heterogeneous in protocols and parameters, results from tDCS and TMS studies converge in indicating that the stimulation (instead of inhibition) of prefrontal regions could be beneficial to contrast dysfunctional gambling-related decision processes.

CONCLUSION

NIBS interventions show promise to be further tested in controlled clinical settings for the treatment of behavioral addictions. Further studies are also necessary to investigate connectivity changes and laterality issues (unilateral versus bilateral; left versus right) of NIBS application in GD.

Maladaptive consequences of repeated intermittent exposure to uncertainty

Recently we reported that nucleus accumbens (NAcc) dopamine (DA) tracks uncertainty during operant responding for non-caloric saccharin. We also showed that repeated intermittent exposure to this uncertainty, like exposure to drugs of abuse, leads to sensitization of the locomotor and NAcc DA effects of amphetamine and promotes the subsequent self-administration of the drug. Here we review these findings together with others showing that NAcc glutamate signaling is similarly affected by uncertainty. Extracellular levels of glutamate in this site also track uncertainty in a task in which nose poking for saccharin on an escalating variable ratio schedule of reinforcement is associated with progressively increasing variance between performance of the operant and payout. Furthermore, sensitized behavioral responding to and for amphetamine following exposure to uncertainty is accompanied by increased levels of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC) phosphorylation as well as altered protein levels of the transcription factor ∆FosB (increased) and glutamate transporter 1 (GLT1; decreased) in NAcc tissues. Notably, phosphorylation by CaMKII and PKC regulates AMPA receptor trafficking and function in this site, is elevated following psychostimulant exposure, and is necessary for the expression of enhanced drug taking. Increased ∆FosB and decreased GLT1 levels are observed following psychostimulant exposure, are associated with increased drug taking and seeking, and are known to modulate AMPA receptors and extracellular glutamate levels respectively. These adaptations in glutamate transmission as well as those observed with DA following repeated intermittent exposure to uncertainty are similar to those produced by exposure to abused drugs. Together, they point to the recruitment of both DA and glutamate signaling pathways in the NAcc in both drug and behavioral addictions. As uncertainty is central to games of chance, these findings have particular relevance for gambling disorders known to exhibit comorbidity with drug abuse.