The purpose of this study is to evaluate the Computerized Exercise to Alter Stimulant Approach Responses (CEASAR), a novel stimulant use cessation intervention, for clients currently enrolled in a treatment centre for mental health and addiction. The investigators plan to conduct a randomized, single-blind controlled trial involving inpatients presenting with concurrent disorders to test the impact of this novel computerized intervention. This pilot study will be conducted at the Burnaby Centre for Mental Health and Addiction (BCMHA) in Burnaby, BC, Canada.

Purpose: To examine a novel computerized exercise intervention as an add-on to currently available evidence-based stimulant use cessation treatments. This study will evaluate whether or not this intervention can improve stimulant use disorder outcomes in a population with concurrent disorders that are difficult to treat.

Hypothesis: 1) The intervention will be easy to integrate in the existing program. 2) Participation in the experimental (stimulant-avoidance) condition will reduce craving (as assessed by the stimulant craving questionnaire brief version), show reduction in an automatic association of activities with stimulant use and stimulant relapses (as assessed by behaviour association questionnaires) and have reduced relapses as assessed by urine drug screens in 12 weeks following initiation of the intervention.

Justification: Stimulant use disorders are among the most challenging disorders, specifically in individuals suffering from concurrent disorders or also identified as dual diagnosis. While medication is available to support the treatment of other substance use disorders (alcohol, opioids, tobacco), currently there is none to treat stimulant use disorders, such as cocaine use disorder and methamphetamine use disorder. Recently, a group in Europe developed the "retraining of automatic approach" intervention, which is based on simple mechanistic retraining for avoidance of substances. This method was successfully applied to change drinking behaviour in a sample of alcoholic inpatients. Participants respond to substance cues by initiating a distancing activity (pushing a joystick away). In contrast, healthy activities are "approached" or pulled in using the joystick. This differential activity trains participants to alter initial responses and "cognitive biases" to simply and automatically avoid substances.

Objectives: Test the hypothesis and evaluate whether or not the Computerized Exercise to Alter Stimulant Approach Responses (CEASAR) can improve stimulant use disorder outcomes in a population with concurrent disorders that are difficult to treat.

Research design: This study is a randomized, single blind, controlled trial involving in-patients with a stimulant use disorder. The participants will be split up equally into 2 groups: the active CEASAR intervention (experimental condition) and the placebo intervention (control). Patients are able to stay at the BCMHA for 6 months with the average being 4-5 months and the study will take place over 12 weeks during their stay. Both groups will use a joystick to push away ("avoid") or pull in ("approach") randomized stimulant and healthy cues presented on a computer screen. In the experimental condition, pushed pictures will exclusively be stimulant use-related pictures, while pulled pictures will be exclusively healthy. In the control condition, stimulant use-related pictures will be equally divided into push and pull conditions. Some of the cues will be visual (e.g. pictures of cocaine powder, pipes, needles etc.) and some of them will be textual (e.g. words like eight ball, rock, etc.).

Inclusion Criteria:

• In-patient of the Burnaby Centre of Mental Health & Addiction
• 19 years of age or older
• Individuals with a current stimulant use disorder (cocaine, crack cocaine, amphetamine, methamphetamine, crystal meth), active before intake at BCMHA (as assessed by the MINI)
• Proficiency to read and write English and competent to provide consent

Exclusion Criteria:

• Individuals not stabilized enough to allow for regular participation in the intervention (determined by treating psychiatrist)