Disordered gambling: the evolving concept of behavioural addiction
Clark (2014)
Annals of the New York academy of sciences

Introduction

There are similarities between gambling disorder and substance use disorders in symptom profile, comorbidity, heritability, and brain changes.

Neurotoxicity

Episodes of gambling are linked to activation of the sympathetic nervous system and cortisol release, with associated (nongenomic) changes. Gambling disorder is reasonably comorbid with substance use disorders.

Gambling disorder may constitute a prototypical addiction and offer a means of studying the addictive processes in brains that are not disrupted by exogenous drug effects. Impulsivity is a key shared marker. It is therefore proposed to reflect the predisposition to develop a range of addictive disorders.

Changes in whit matter tracts and resting-state connectivity have been reported in gambling disorder.

Dopamine and the brain reward system

Pathophysiology within the mesolimbic dopamine system has emerged as central to gambling disorder. There are consistent abnormalities across the key nodes in this circuit in gambling disorder, the striatum, medial PFC, amygdala and insula.

Addictions may be associated with an imbalance between different reward types. The compatibility of the task reward in research with the abused commodity will determine changes in the brain reward system.

There are clear perturbations in dopamine transmission.

The relative potency of drugs of abuse

There are dissociations in the processing of natural rewards and drug rewards. Treatments for addiction need not necessarily induce reductions in naturally rewarded behaviours.

Active ingredients

Drug-induced stimulation of dopamine transmission is exogenous. Pavlovian processes are pervasive in drug addiction. Comparable Pavlovian processes seem to occur in gambling behaviour.

Many people with gambling disorder retrospectively describe receiving major payouts in the first few times that they ever gambled. These wins constitute profound positive prediction errors that will activate the neural machinery of reinforcement learning.

There is a asymmetry between appetitive and aversive outcomes. Financial gains promote straightforward learning acquisition. Financial losses do not trigger simple unlearning. They may promote specific instances of learning. The explaining away of losses in a manner that does not erode the player’s belief in his/her ability to win is state splitting.

Drugs of abuse are quantitatively more potent than natural rewards. Behaviour addictions may require an added ingredient. These ingredients are: 1) Decision uncertainty, learning from prediction errors only occurs in uncertain environments 2) The potential for bivalent outcomes (gains and losses).

Gambling-related cognitive distortions

Humans display a number of systematic errors in processing under conditions of chance, which come to the force in gambling games and are known as gambling-related cognitive distortions.

Two classes of distortion are: 1) The illusion of control, irrelevant features of a game that create a sense that one is developing some kind of skill over an outcome that is in fact determined by change alone. 2) The gambler’s fallacy, following a run of the same outcome, players typically predict that the other outcome will occur next.

Other specific phenomena within gambling games can be considered under the rubric of these two effects.

Most forms of gambling deliver near misses, outcomes that are perceived as having been close to a win, but that are in fact objective losses. They are perceived more aversive than complete misses, but increase the desire to continue the game. Given that near misses in skill-based games convey useful signals of skill acquisition, they may fuel the illusion of control. They may also feed into the processing of outcome sequences, by breaking up a perceived streak of losses. They increase the neural signal in brain reward circuitry, the insula.

There might be causal involvement of the insula in the two cognitive effects in gambling.

One dominant account of insula function is its role in interception. Gambling is intensely physiologically arousing. The insula might represent a gateway between the subcortical reward system and the prefrontal system responsible for decision making and inhibitory control.

Future behavioural addictions

If choice uncertainty or cognitive distortions play a key role in driving the neural circuitry that ordinarily underpins reinforcement learning and compensation for the lack of exogenous drug stimulation, then it is possible that only a finite number of behaviours will have the capability ot be addictive.

Obesity and binge eating

There are comparable phenomena for drug self-administration and food rewards in experimental animals. There is a similar profile in the brain with drug addiction and gambling disorder.

Obesity and binge eating can be conceptualized as persistent bias toward an option that offers immediate gratification with long-term negative consequences.

But these overeating phenotypes do not evidently involve the distortions in prediction-error signalling or deficits in the processing of chance that are described for gambling disorder.

Compulsive shopping

Trait-reward sensitivity predicts compulsive-buying tendencies. It is arguably facile to consider compulsive shopping as a persistent choice of an immediate reward with long-term negative consequences, but it is unclear whether further parallels exist in the processing of choice uncertainty.

Internet gaming disorder

This is associated with trait impulsivity, and cognitive impairments. It is also associated with substantial physiological arousal.

Actions within video game generate bivalent outcomes, and it is self-evident that humans will work to achieve symbolic gains and avoid symbolic losses, in much the same way as for monetary outcomes.