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:-

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:-

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:-

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:-

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:-

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:-

Conclusions

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:-

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.

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.