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NRGP

National Gambling Board

South African Responsible Gambling Foundation

IMPULSIVITY & PATHOLOGICAL GAMBLING: A Neurophysiological approach

  • Introduction
  • Neurocognitive Deficits in Problem Gamblers
  • Neuroimaging of Pathological Gamblers
  • Reward & Punishment Processing
  • Cue Reactivity
  • Impulsivity in Pathological Gambling
  • Decision Making in Pathological Gambling
  • Conclusions

Introduction

It is apparent to anyone who has ever observed a problem or pathological gambler, that impulsivity is a key component of this behaviour. Indeed under the DSM IV-TR pathological gambling is classed as an impulse-control disorder rather than an addiction. There is increasing evidence though that pathological gambling is a behavioural addiction as opposed to a substance addiction. As discussed elsewhere in the Handbook, the new DSM V will be classifying pathological gambling as an addiction.

Clearly a key difference between behavioural and substance addictions is that an activity such as gambling does not cause actual brain damage in the way that substance abuse and dependence can.

What follows is a detailed look at two recent interesting research articles on impulsivity and risk taking, and neurophysiology and addiction in general. In addition there is a summary of a third study which is of interest.

Study One: Neurocognitive Deficits in Problem Gamblers

We need to understand that pathological gambling shares characteristics with substance dependence. Some of these traits are craving; withdrawal and tolerance. This fact is combined with the fact that certain common genetic risk factors have been implicated in both, according to Andrew J Lawrence, Jason Luty, Nadine A Bogdan, Barbara J Sahakian, and Luke Clark in their article Problem gamblers share deficits in impulsive decision-making with alcohol-dependent individuals Journal compilation 2009 Society for the Study of Addiction

These researchers made the assumption that factors which predisposed individuals’ vulnerability to addiction would be present in both problem gamblers and in alcohol dependent individuals. A presumed difference would be that in the substance abusers there would be an indication that brain functioning had been affected by the use of the substance whilst in problem or pathological gamblers no such impairments would be found.

On the other hand they made the assumption that risky decision making and a high degree of impulsivity with respect to reflection would be present in both groups; substance abusers and problem gamblers. They make the point that recent research demonstrates that in pathological gamblers who seek treatment there are observable neurophysiological changes in impulsivity and decision making.

This study found there were neurocognitive deficits present in both alcohol dependence and problem gambling subjects, relative to healthy controls who were group-matched for age and education. While some deficits were common to the two target groups, others were unique to the alcohol-dependent group.

The common or shared deficits were in neuropsychological impairments in reflection impulsivity and in risky decision making. However the alcohol dependent subjects showed marked impairment in working memory and in the deliberation time taken for decision making, as compared to both the problem gambling subjects and the control group.

As mentioned elsewhere on this website, when we looked at the work of Don Ross et al,  there is a growing  inclination to view gambling as the "purest" form, or prototype of addiction as it is purely behavioural and is not contaminated or confused by any possible damaging effects of substance abuse may have on the brain.  A major implication of this is that research into the neuropsychology and neurobiology of problem gambling could lead us to discover insights into underlying predisposing vulnerabilities that underpin the entire range of addictions.

Let us look at the researchers closing comments:-

In summary, the present data indicate overlapping impairments in reflection impulsivity and risky decision-making in a community-recruited group of problem gamblers and a clinically referred group of alcohol-dependent patients. This profile is consistent with pathophysiology in the….(brain), and the presence of this profile in a putative behavioural addiction supports impulsive decision-making as a candidate vulnerability marker in the addictions. The alcohol-dependent participants showed additional neurocognitive deficits in working memory and deliberation, which are hypothesized to reflect long-term effects of alcohol consumption:
www.ncbi.nlm.nih.gov/pmc/articles/PMC2773538/

Study Two: Neuroimaging of Pathological Gamblers

This study essentially reviews current research dealing with neuroimaging of pathological gamblers. It is written by Ruth J. van Holst, Wim van den Brink, Dick J. Veltman, and Anna E. Goudriaan and was published in Current Psychiatry Reports. 2010 October; 12(5): 418–425; and published online 2010 July 30. (FULL STUDY: Brain Imaging Studies in Pathological Gambling)

As the authors state in the Abstract, due to the often observed and reported similarities between substance dependence and pathological gambling (PG), research on PG has used similar models to those used in substance abuse research. Often this research has focused on reward and punishment sensitivity, cue reactivity, impulsivity, and decision making; as we saw in the previous study which looked at impulsivity in problem (as opposed to pathological) gamblers. This review shows that PG is consistently associated with blunted mesolimbic-prefrontal cortex brain activation to nonspecific rewards, whereas these areas show increased activation when exposed to gambling-related stimuli in cue exposure models. In other words pathological gamblers need very specific reward cues in order to demonstrate certain brain activity – not just general reward cues.

The authors believe that in reality not much is known about what underpins neural responses and reactions when it comes to impulsivity and decision making in pathological gamblers. For this reason they feel that more research needs to be done.. Their review ends with a section which discusses issues relating to the challenges and the new developments in the arena of neurobiologically based  gambling research and at the implications of these new developments for the treatment options for PG.

Pathological gambling is as we have already discussed, classified as a mental disorder in the DSM IV- TR. It is classified as an impulse control disorder but as discussed has many features of addiction but of a behavioural type as opposed to addiction to a substance. Essentially though, the diagnosis is made in a similar manner using similar criteria, which we have discussed at length in the section on Pathological Gambling in this Handbook.

The authors concur with the ones of the previous study when they state:-

Investigating PG as a model of addictive behavior is attractive because it may reveal how addictive behaviors can develop and affect brain function, without the confounding effects of (neurotoxic) substances. Moreover, better understanding of the neurobiological basis of PG could help improve treatment for this disorder.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425.
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7

At present theories about addiction identify four cognitive-emotional processes that are also apposite when looking at pathological gambling. These are:-

  • Reward and punishment processing and its relation to behavioural conditioning;
  • Increased relevance of gambling cues that often result in strong urges or craving for gambling;
  • Impulsivity, which is relevant as it has been implicated as both as a vulnerability characteristic for developing  PG and as a consequence of gambling problems;
  • Finally there is deficient or impaired decision making which is apparent as we know that pathological gamblers continue gambling even in the light of severe negative consequences.

 

Reward and Punishment Processing

Responsiveness to reward and punishment, when measured neurologically, shows a blunted effect. This is similar to those people with substance use disorders (SUDs). SUDs are found to have low levels of dopamine levels which plays a role in the seeking out of rewards or pleasurable situations – this relative inability to experience pleasure in an average or "normal" way is known as anhedonism,. It can be hypothesised that PGs also suffer from anhedonism which causes them to seek further rewards when gambling in a compulsive manner. Interestingly though PGs also showed blunted neurological processes when experiencing losses (punishment).  In the words of the authors:-

In line with these theories, it has been hypothesized that pathological gamblers are more likely to seek rewarding events to compensate for a pre-existing anhedonic state comparable with that of substance-dependent individuals. However, from the existing literature on PG, it is not yet clear whether diminished reward and punishment sensitivity is a consequence or a precursor of problem gambling.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425.
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7

Cue Reactivity

Cue reactivity studies based on neuroimaging have so far shown inconclusive results. The authors believe that future studies should place more emphasis on the exact type of stimuli that elicit the strongest cue reactivity (for example movies or pictures of gambling scenarios – both of which have been used). One thing that could be preventing researchers’ power to detect differences in cue-reactivity in PG studies, unlike those involving SUDs where cue reactivity is more apparent; is that gambling may involve a range of different gambling activities, such as horse racing, slot machines, blackjack, poker and so on. However cue reactivity to a substance is specific for the targeted substance, for example cocaine; marijuana and so on and will therefore garner responses in brain processes in the majority of SUDs.

The authors state that future research should focus on:-

Selecting specific gambling types for cue reactivity stimuli and limiting participant inclusion to a specific gambling pathology (which) may result in a better matching of cues and PG pathology and thus result in more robust brain activations in response to cues in PG.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425  
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7

Impulsivity in Pathological Gambling

Impulsivity is often seen as comparable to disinhibition. Disinhibition happens when top-down mechanisms of control that would usually suppress automatic or powerfully reward driven behaviour responses do not function adequately. There has been much research on disinhibition in SUDs recently as it has been recognized as a trait of individuals vulnerable to developing SUD or PG.

A further characteristic of impulsivity that is researched in neurocognitive studies is the choice of immediate smaller rewards instead of delayed larger rewards - this is known as delay discounting: As of 2010 when the authors published this article they state that neuroimaging studies investigating the neural correlates of impulsivity/disinhibition in PG are scarce:-

In summary, although several neuropsychological studies have indicated higher impulsivity in pathological gamblers to date, only a single neuroimaging study on inhibition has been published. Therefore, additional neuroimaging studies are warranted, preferably with larger populations and assessment of a variety of impulsivity measures in pathological gamblers.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425.
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7

Decision Making in Pathological Gambling

Both PGs and SUDs display a pattern of decision making that is marked by ignoring the long-term negative consequences of their actions in order to attain immediate gratification. There are many emotional and cognitive factors which can impact on flawed decision making. Impulsivity and risk taking definitely play a role in the complex process of decision making.

The authors describe one interesting study:-

In a recent event-related potential (ERP) study, neurophysiologic correlates of decision making during a blackjack game were measured. Twenty problem gamblers and 21 normal controls (NCs) played a computerized blackjack game and had to decide if they would "hit" or "sit" a card to arrive as close as possible to, but not greater than 21 points. At the critical score of 16 points, problem gamblers decided more often than NCs to continue playing. Thus, gamblers showed more risk-taking behavior coupled with a stronger neural response to (infrequent) successful outcomes of this behavior compared with NCs. Interestingly, no neurophysiologic differences were observed between groups during loss trials.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425.
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7

Conclusions

The reviewed studies indicate that pathological gamblers show decreased responses to nonspecific rewarding and punishing stimuli. Notably, such blunted responses were not observed in problem gamblers playing a more realistic gambling game during the winning and losing of money. Three of four neuroimaging studies on cue reactivity in pathological gamblers showed increased brain activation to gambling-related stimuli whereas results from the other study, which reported diminished brain activation during a craving paradigm, were difficult to interpret due to the complex stimulus paradigm used The neurobiological mechanisms underlying abnormal cue reactivity in pathological gamblers are therefore not yet clear, and the same is true for the observed increased impulsivity and disinhibition in pathological gamblers. In addition, whereas a large number of neurocognitive studies on impulsivity have indicated that pathological gamblers are impaired in several inhibitory processes (e.g. filtering irrelevant information, inhibiting ongoing responses, and delay discounting) more definitive research needs to be done.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425.
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7

In terms of the direction for future research there are some interesting studies the authors allude to. Games of chance or gambling seem to encourage certain characteristics that lead to individuals overestimating their chances of winning. This in turn leads to the stimulation of the desire to continue gambling.

In a study done using functional Magnetic Resonance Imaging (fMRI) of the brain, personal control over the game and the “near-win” event on gamblers or NCs was researched. Near-wins occur when unsuccessful outcomes are very similar to the jackpot, such as when two matching icons are displayed on the slot machine pay line, and the last matching icon (such as a banana) ends up one position below or above the pay line. It was found that near-win outcomes activated the same brain processes that responded to actual monetary wins. These results may well give us some interesting insights into the underlying processes which lead to PGs continuing to gamble despite the acknowledged fact that one will lose money over time. Future research should develop these findings to assist us to better understand the transition from non-problematic gambling to problem gambling to PG and the addictive potential of certain games of chance or gambling.

According to the authors, a final area for future development is the arena of the ability to resist the development of addictive behaviours. A group of problem gamblers without co-morbidities and minimal pathology was studied.  Further research of various subgroups of PGs could lead to greater insight into the neuropsychological processes that are protect against the development of problem gambling into pathological behaviour. It could also lead to greater knowledge about how to protect against relapses.

We conclude this section with this statement by the authors:-

The neurobiological factors that are clearly involved in PG and that may influence the course of PG are executive functions, including decision making and impulsivity; cue reactivity; reward sensitivity; and erroneous perceptions. From the review of neuroimaging studies, it is clear that the neuronal background of these functions has not yet been identified in detail. However, these neurobiological vulnerabilities are likely to influence the course of PG in combination with psychological factors, such as subjective craving and coping skills; environmental factors (e.g., the vicinity of gambling opportunities); and genetic factors. How these factors interact is largely unknown. Understanding these phenomena and their interactions is of great importance because interventions focusing on these vulnerabilities could ultimately lead to targeted prevention measures.

Curr Psychiatry Rep. 2010 October; 12(5): 418–425.
Published online 2010 July 30. doi: 10.1007/s11920-010-0141-7.

We will conclude with a summary of a research study done by Eisenegger, Knoch, Ebstein, Gianotti, Sándor, Fehr published in European Psychiatry, Volume 26, Issue null, Page 1049 onwards. This is a fairly technical article but we have included their summary as those interested in the full study, which does raise some extremely interesting issues regarding neurobiology and pathological gambling.

A challenging question in the fields of neuroscience and addiction research is why some individuals are more vulnerable to addictive disorders than others. A possible solution for this question lies in pharmacogenetic studies that investigate how genetic variation leads to a differential drug response. Several lines of evidence link the dopaminergic system to impulse control and substance addiction as well as to nonsubstance addictions such as pathological gambling Existing evidence for the latter comes from clinical research describing the development of pathological gambling in Parkinson’s disease after initiation of dopaminergic drug treatment However, not all individuals with Parkinson’s disease are at risk of developing pathological gambling during dopaminergic treatment. The fact that only a subgroup of these patients develops pathological gambling suggests an underlying vulnerability possibly mediated by genetic factors. Support for this notion derives from research in healthy subjects suggesting that genetic vulnerability for pathological gambling may be linked to variation in the dopamine receptor D4 (DRD4) gene. The DRD4 gene contains a highly polymorphic region within its third exon, also referred to as the DRD4 exon III variable tandem number repeat polymorphism (DRD4 polymorphism). Presence of the 7-repeat (7R) allele has been associated with pathological gambling and other impulse control disorders such as attention-deficit/hyperactivity disorder (ADHD). Furthermore, the 7R allele has been associated with poor performance on laboratory measures of impulse control among individuals with ADHD as well. Finally, poor impulse control and ADHD are both associated with pathological gambling. These lines of evidence suggest that genetic variation in the DRD4 gene might determine an individual’s behavioral response to a dopaminergic drug challenge.

Up to now, no study has yet investigated how the interaction of genetic factors with the administration of a dopaminergic drug affects gambling behavior. This can be achieved by using a pharmacogenetic approach. Building on the above-mentioned evidence, we hypothesized that the administration of a dopaminergic drug has a differential effect on gambling behavior depending on variation in the DRD4 gene. To explore a gene-drug interaction on gambling behavior systematically, we used healthy subjects to avoid the confounding effects of Parkinson’s disease. We used L-dihydroxyphenylalanine (L-DOPA) versus placebo administration to investigate how the presence or absence of the 7R allele determines the impact of dopaminergic stimulation on gambling behavior measured in the laboratory. We hypothesized that subjects who carry a 7R allele would show increased gambling propensity in response to the administration of a dopaminergic drug.
http://linkinghub.elsevier.com/retrieve/pii/S0924933811727547

As we can see from all the above there is ample scope for much research into the neurophysiology of Pathological Gambling and the area of impulsivity amongst other contributing factors.