Distorted thinking in gambling addiction: What are the cognitive and neural mechanisms?

Dr Luke Clark, a senior lecturer at the University of Cambridge (UK), told the meeting that neurocognitive tests of impulsivity and compulsivity, and also positron emission tomography (PET) imaging of the brain have started to show how gambling becomes addictive in pathological gamblers -- people whose gambling habit has spiralled out of control and become a problem.

"Around 70% of the British population will gamble occasionally, but for some of these people, it will become a problem," he said. "Our work has been seeking to understand the changes in decision-making that happen in people with gambling problems. It represents the first large scale study of individuals seeking treatment for gambling problems in the UK, at a time when this disorder is being re-classified alongside drug addiction as the first 'behavioural addiction'. Given the unique legislation around gambling from country to country, it is vital that we understand gambling at a national level. For example, 40% of the problem gamblers at the National Problem Gambling Clinic report that the game they have a problem with is roulette on Fixed Odds Betting Terminals; this kind of gambling machine is peculiar to the British gambling landscape."

In collaboration between the University of Cambridge and Dr Henrietta Bowden-Jones, director of the UK's only specialist gambling clinic in the Central and North West London NHS Trust, Dr Clark and his colleagues compared the brains and behaviours of 86 male, pathological gamblers with those of 45 healthy men without a gambling problem.

"We approach gambling within the framework of addiction, where we think that problematic gambling arises from a combination of individual risk factors, such as genetics, and features of the games themselves. To study individual factors, we have been testing gamblers at the National Problem Gambling Clinic on neurocognitive tests of impulsivity and compulsivity, and we have also measured their dopamine levels using PET imaging," said Dr Clark.

The tests showed that problem gamblers had increased impulsivity, similar to people with alcohol and drug addictions, but there was less evidence of compulsivity. Levels of dopamine -- a neurotransmitter involved in signalling between nerve cells and which is implicated in drug addiction -- showed differences in the more impulsive gamblers.

"Previous PET research has shown that people with drug addiction have reduced dopamine receptors. We predicted the same effect in pathological gamblers, but we did not see any group differences between the pathological gamblers and healthy men. Nevertheless, the problem gamblers do show some individual differences in their dopamine function, related to their levels of impulsivity: more impulsive gamblers showed fewer dopamine receptors," said Dr Clark. "These studies highlight the overlap between pathological gambling and drug addiction.

"To study the properties of the games themselves and how they relate to problem gambling, we have focussed on two psychological distortions that occur across many forms of gambling: 'near-miss' outcomes (where a loss looks similar or 'close' to a jackpot win) and the 'gambler's fallacy' (for example, believing that a run of heads means that a tail is 'due', in a game of chance). In one important discovery, we were the first lab to show that gambling 'near-misses' recruit brain regions that overlap with those recruited in gambling 'wins'. These responses may cause 'near-misses' to maintain gambling play despite their objective status as losses."

Dr Clark said that these findings had implications for both prevention and treatment. "Gambling distortions like the 'near-miss' effect may be amenable to both psychological therapies for problem gambling, and also by drug treatments that may act on the underlying brain systems. By understanding the styles of thinking that characterise the problem gambler, we may also be able to improve education about gambling in teenagers and young adults, to reduce the number of people developing a gambling problem."

The researchers also found a striking demonstration of the underlying brain regions that are involved in gambling when they studied the gambling behaviour of patients who had experienced brain injury due to a tumour or stroke.

"We have seen that two gambling distortions -- the 'gambler's fallacy' and the 'near-miss' effect -- that are evident in the general population, and which appear to be increased in problem gamblers, are actually abolished in patients with damage to the insula region of the brain," he said. "This suggests that in the healthy brain, the insula may be a critical area in generating these distorted expectancies during gambling play, and that interventions to reduce insula activity may have treatment potential.

"The insula is quite a mysterious part of the brain, tucked deep inside the lateral fissure. It is important in processing pain and, more broadly, in representing the state of the body in the brain, and it is striking that gambling is a very visceral, exciting activity. Our ongoing neuroimaging work will look at the relationship between responses in the insula and the body during our gambling tests."

Future work will investigate the styles of thinking that are in evidence when the problem gamblers at the National Problem Gambling Clinic play the simplified games the researchers have developed. "This is the first study to directly look at whether these biases are more pronounced in problem gamblers. We are also starting to recruit the siblings of problem gamblers (those who do not have a gambling problem themselves) in order to look at underlying vulnerability factors," concluded Dr Clark.

This research is funded by grants from the UK's Medical Research Council, and involves further collaboration with researchers at Imperial College London and the University of Oxford.