Grant: Project Grant

Whether someone is dependent on a chemical substance like cocaine, or has developed a behavioural addiction such as gambling disorder, the maladaptive choice to pursue the addiction at the expense of other goals lies at the heart of the problem. Indeed, individuals with an addiction disorder, or who later develop problems with addiction, score poorly on laboratory-based decision-making tests such as the Iowa Gambling Task (IGT) that involve the weighing of costs and benefits. One hypothesis is that decision-making impairments may be compounded as the addiction develops because of the way in which addictive drugs, and also engagement in addictive behaviours, affect brain function, biasing the decision-making process in favour of the addiction. Choosing to abstain from the addictive substance or behaviour then becomes really hard. We have successfully developed an animal model of cost/benefit decision making based on the IGT: the rat Gambling Task (rGT). On both human and animal tests, subjects must choose between four different options, each of which is associated with different amounts of potential reward and loss. By avoiding high-risk, high-reward options, subjects can maximise gains. Most rats develop this optimal strategy, although some animals instead favour the risky options. These risk-preferring rats are uniquely and adversely affected by taking cocaine: their decision making gets worse and they show increased drug-seeking in withdrawal indicative of greater relapse risk. Adding sound and light cues when the rats win on this gambling task significantly increases the proportion of rats biased towards the risky options. We now want to use this model to understand why the addition of these "bells and whistles" potentiates risky choice and addiction vulnerability, and harness that knowledge to pilot potential therapies for addiction.