Identifying and Treating Specific Decision-Making Dysfunction in Methamphetamine Use Disorder

Decision-making is particularly relevant to methamphetamine use disorder (MUD) - as people repeatedly act towards methamphetamine at the expense of long-term well-being. This thesis aimed to clarify the cognitive and computational mechanisms driving such decision-making behaviour; and evaluated a new intervention that attempts to improve decision-making in MUD. Overall, participants with MUD differed from drug-naïve controls in that they had: 1) difficulties in learning which actions were advantageous; 2) a reduced sensitivity to reinforcement; and 3) a use of fewer previous decision-making outcomes to guide future choices. The new treatment, Goal Management Training+, improved impulsive decision-making and reduced methamphetamine dependence.