An overview of commonalities in the mechanisms underlying gambling and substance use disorders

The Incentive-Sensitization Theory of Addiction 30 Years On

The incentive-sensitization theory (IST) of addiction was first published in 1993, proposing that (a) brain mesolimbic dopamine systems mediate incentive motivation ("wanting") for addictive drugs and other rewards, but not their hedonic impact (liking) when consumed; and (b) some individuals are vulnerable to drug-induced long-lasting sensitization of mesolimbic systems, which selectively amplifies their "wanting" for drugs without increasing their liking of the same drugs. Here we describe the origins of IST and evaluate its status 30 years on. We compare IST to other theories of addiction, including opponent-process theories, habit theories of addiction, and prefrontal cortical dysfunction theories of impaired impulse control. We also address critiques of IST that have been raised over the years, such as whether craving is important in addiction and whether addiction can ever be characterized as compulsive. Finally, we discuss several contemporary phenomena, including the potential role of incentive sensitization in behavioral addictions, the emergence of addiction-like dopamine dysregulation syndrome in medicated Parkinson's patients, the role of attentional capture and approach tendencies, and the role of uncertainty in incentive motivation.

Voluntary Self-Exclusion and Contingency Management for the Treatment of Problematic and Harmful Gambling in the UK: An Exploratory Study

Research into self-directed methods for reducing problematic and harmful gambling is still in its infancy. One strategy that individuals use to prevent gambling involves voluntary self-exclusion (VSE) programs. For example, VSE programs can make it challenging to access betting sites or enable banks to block gambling-related transactions. Although individual VSEs can be helpful when used alone, it is unclear whether their efficacy is enhanced when combined. Furthermore, it is unknown how VSE compliance can be improved. We propose that contingency management (CM), an evidence-based strategy to incentivise abstinence, could encourage continued VSE use, promoting long-lasting recovery from problematic or harmful gambling. Here, we conducted exploratory analyses on VSE use and CM for gambling in two populations (members of the UK general population recruited and students). Participants responded favourably regarding combined VSE use. They felt that providing vouchers exchangeable for goods/services could incentivise gambling abstinence during VSE. However, some were concerned about people potentially "gaming" the system. Participants believed supplementing VSE and CM with social support could encourage abstinence. These attitudes, and recent research on treatment providers' opinions on CM for gambling, suggest that experimental evidence should be sought to determine the efficacy of combined VSE use and CM for gambling.

Separating desire from prediction of outcome value

Individuals typically want what they expect to like, often based on memories of previous positive experiences. However, in some situations desire can decouple completely from memories and from learned predictions of outcome value. The potential for desire to separate from prediction arises from independent operating rules that control motivational incentive salience. Incentive salience, or 'wanting', is a type of mesolimbic desire that evolved for adaptive goals, but can also generate maladaptive addictions. Two proof-of-principle examples are presented here to show how motivational 'wanting' can soar above memory-based predictions of outcome value: (i) 'wanting what is remembered to be disgusting', and (ii) 'wanting what is predicted to hurt'. Consequently, even outcomes remembered and predicted to be negatively aversive can become positively 'wanted'. Similarly, in human addictions, people may experience powerful cue-triggered cravings for outcomes that are not predicted to be enjoyable.

Unpredictable, intermittent access to sucrose or water promotes increased reward pursuit in rats

Reward uncertainty can sensitize reward pathways, promoting increased reward-seeking and -taking behaviours. This is relevant to human conditions such as pathological gambling, eating disorders and drug addiction. In the context of addiction, preclinical self-administration procedures have been developed to model the intermittency of human drug use. These intermittent-access (IntA) procedures involve intermittent but predictable access to drug during self-administration sessions. However, human drug use typically involves intermittent and unpredictable drug access. We introduce a new procedure modeling unpredictable, intermittent access (UIntA) to a reinforcer, and we compare it to procedures that provide predictable reinforcer availability; continuous (ContA) or intermittent (IntA) access. Female rats self-administered water or liquid sucrose in daily hour-long sessions. IntA and ContA rats had access to a fixed volume of water or sucrose (0.1 ml), under a fixed ratio 3 schedule of reinforcement. IntA rats had predictable 5-min reinforcer ON and 25-min reinforcer OFF periods. ContA rats had 60 min of reinforcer access during each session. For UIntA rats, variation in the length of ON and OFF periods (1, 5 or 9 min/period), response requirement (variable ratio 3 schedule of reinforcement), reinforcer probability (50%) and quantity (0, 0.1 or 0.2 ml) introduced reward uncertainty. Following 14 daily self-administration sessions, UIntA rats showed the highest levels of responding for water or sucrose under progressive ratio conditions, responding under extinction conditions, and cue-induced reinstatement of sucrose seeking. Thus, unpredictable, intermittent reward access promotes increased reward pursuit. This has implications for modeling addiction and other disorders of increased reward seeking.

Gambling Environment Exposure Increases Temporal Discounting but Improves Model-Based Control in Regular Slot-Machine Gamblers

Gambling disorder is a behavioral addiction that negatively impacts personal finances, work, relationships and mental health. In this pre-registered study (https://osf.io/5ptz9/) we investigated the impact of real-life gambling environments on two computational markers of addiction, temporal discounting and model-based reinforcement learning. Gambling disorder is associated with increased temporal discounting and reduced model-based learning. Regular gamblers (n = 30, DSM-5 score range 3-9) performed both tasks in a neutral (café) and a gambling-related environment (slot-machine venue) in counterbalanced order. Data were modeled using drift diffusion models for temporal discounting and reinforcement learning via hierarchical Bayesian estimation. Replicating previous findings, gamblers discounted rewards more steeply in the gambling-related context. This effect was positively correlated with gambling related cognitive distortions (pre-registered analysis). In contrast to our pre-registered hypothesis, model-based reinforcement learning was improved in the gambling context. Here we show that temporal discounting and model-based reinforcement learning are modulated in opposite ways by real-life gambling cue exposure. Results challenge aspects of habit theories of addiction, and reveal that laboratory-based computational markers of psychopathology are under substantial contextual control.

Gambling disorder in the UK: key research priorities and the urgent need for independent research funding

Gambling in the modern era is pervasive owing to the variety of gambling opportunities available, including those that use technology (eg, online applications on smartphones). Although many people gamble recreationally without undue negative effects, a sizeable subset of individuals develop disordered gambling, which is associated with marked functional impairment including other mental health problems, relationship problems, bankruptcy, suicidality, and criminality. The National UK Research Network for Behavioural Addictions (NUK-BA) was established to promote understanding of, research into, and treatments for behavioural addictions including gambling disorder, which is the only formally recognised behavioural addiction. In this Health Policy paper, we outline the status of research and treatment for disordered gambling in the UK (including funding issues) and key research that should be conducted to establish the magnitude of the problem, vulnerability and resilience factors, the underlying neurobiology, long-term consequences, and treatment opportunities. In particular, we emphasise the need to: (1) conduct independent longitudinal research into the prevalence of disordered gambling (including gambling disorder and at-risk gambling), and gambling harms, including in vulnerable and minoritised groups; (2) select and refine the most suitable pragmatic measurement tools; (3) identify predictors (eg, vulnerability and resilience markers) of disordered gambling in people who gamble recreationally, including in vulnerable and minoritised groups; (4) conduct randomised controlled trials on psychological interventions and pharmacotherapy for gambling disorder; (5) improve understanding of the neurobiological basis of gambling disorder, including impulsivity and compulsivity, genetics, and biomarkers; and (6) develop clinical guidelines based on the best contemporary research evidence to guide effective clinical interventions. We also highlight the need to consider what can be learnt from approaches towards mitigating gambling-related harm in other countries.

The transition time to gambling disorder: The roles that age, gambling preference and personality traits play

BACKGROUND AND AIMS

Gambling Disorder (GD) is considered a heterogeneous, multidimensional pathology with high personal and social consequences. The transition time (TT) between problematic gaming and pathological gambling, which varies significantly across patients, may predict the disorder's severity. As only limited studies have investigated the factors implicated in the TT, the current study set out to identify its predictors and their relationships with GD severity.

METHODS

Correlation were performed in 725 male GD patients to identify factors associated to TT and GD severity, including: age of onset of gambling behaviors, alcohol/drug use, personality traits and gambling preferences (i.e., strategic, non-strategic, and mixed). Then a regression analysis was performed to identify predictors of TT to GD.

RESULTS

Longer TT correlated with higher GD severity, early age of onset of problematic gambling, substance use and a non-strategic gambling preference. Personality traits including low self-directedness, high novelty seeking, and low cooperativeness were also related with longer TT. The strongest associations with GD severity were substance use, and some of the personality traits (i.e., low self-directedness and cooperativeness, high harm avoidance and self-transcendence). Factors significantly predicting longer transition to GD were older ages, low self-directedness, and non-strategic gambling.

CONCLUSIONS

A clinical profile characterized by a longer TT and more severe GD symptoms pertains to older patients with low self-directedness, and preference for non-strategic gambling. Other relevant factors associated with this profile of patients included early age of onset problematic gambling, substance consumption, high novelty seeking and low cooperativeness.