The neural basis of gambling cognitions: relevance for vulnerability and treatment of gambling addiction

The lure of gambling has fascinated scientists and observers of human behaviour for centuries. Roughly 70% of the population gamble, and 3-5% gamble to excess, with negative consequences in terms of debt, relationships, and sometimes illegal acts. Pathological Gambling, the most extreme form, is a psychiatric disorder that bears many similarities to drug addiction, including withdrawal symptoms and tolerance. However, there is no chemical entering the brain of the gambler, and the features of gambling games that enable the hijacking of the brain?s motivational systems are unclear. We argue that people gamble because of natural decision-making biases (?gambling distortions?) that cause an overestimation of their chances of winning. Some individuals are more susceptible to these distortions than others, and this is thought to be a risk factor for Pathological Gambling. In our recent work, we have developed a slot machine game to elicit one common distortion, the ?near-miss? effect (e.g. two cherries on the slot machine payline, with the third falling short). Near-misses do not pay out, and provide no information for future gambles. Nevertheless, brain areas that code wins also respond to near-misses, and this response is greater in gamblers with more gambling problems. The current application will extend this work by developing a second task to elicit another distortion: the biased processing of recent outcomes. In roulette, for example, if the last four spins have landed RED, gamblers are often convinced that BLACK is now due (aka ?the Gambler?s Fallacy?). We will use a coin-flipping task to measure brain responses as participants fall prey, or overcome, this bias. We will compare brain responses in Pathological Gamblers against healthy non-gamblers, as they perform the two tasks. We will explore the specificity of any changes to Pathological Gambling by testing a group with alcohol dependence, a form of drug addiction. We will determine their relevance to vulnerability, by testing the unaffected siblings of gamblers, who share some of the genetic and familial risk for the disorder. The final aim is to examine the brain chemistry that regulates these distortions. We will study the opioid system, because drugs that block this system are promising treatments for Pathological Gambling. We will compare brain responses after a dose of an opiate blocker and a placebo drug in a group of Pathological Gamblers. The findings will inform our understanding of the psychological factors involved in disordered gambling, and their relevance to vulnerability and treatment.

Pathological Gambling is a debilitating and poorly understood condition that is known to have several core similarities with drug addiction. The study team represents a collaboration between cognitive neuroscientists and addiction researchers at the University of Cambridge, Imperial College London and the University of Oxford, and the National Problem Gambling Clinic in the Central and North West London NHS Trust. The clinic is a unique NHS facility for patients with gambling problems, and the proposed work will build upon a current MRC grant to characterise Pathological Gamblers attending the clinic using cognitive and brain pharmacology probes. The proposed work is driven by a cognitive formulation of Pathological Gambling, which proposes that distorted styles of thinking about recent outcomes (e.g. the ?Gambler?s Fallacy?), and inappropriate appraisals of skill (the ?Illusion of Control?), cause gamblers to over-estimate their chances of winning. Two tasks will be used to elicit gambling distortions during functional Magnetic Resonance Imaging (fMRI), in order to visualise and quantify brain responses in reward-related circuitry during the gambling process. One task resembles a slot machine, and detects brain responses to unpredictable wins and ?near-misses?. The second task, to be developed in year 1 of the grant, will elicit biased processing of recent outcomes, in the form of the ?Gambler?s Fallacy? and the ?Hot Hand Belief?. Building on our recent research, we will determine the relevance of these tasks to Pathological Gambling, by comparing brain responses in Pathological Gamblers and healthy controls. By employing a substance misuse control group (individuals with alcohol dependence), we will examine whether these distortions are specific to Pathological Gambling or generalise across the addictions. We will establish the relevance of these distortions to the vulnerability to Pathological Gambling, by studying a fourth group of unaffected biological siblings of Pathological Gamblers. Finally, we will establish the relevance to treatment by assessing the modulation of brain responses in Pathological Gamblers by the opiate antagonist naltrexone, the best-validated pharmacotherapy for Pathological Gambling at the current time.