This study aims to assess the feasibility, acceptability and preliminary effectiveness of Acceptance Commitment Therapy, in conjunction with motivation enhancement, and the use of the ChillTime App, in reducing methamphetamine use in women with MUD with or without co-occurring psychiatric disorders. This intervention is designed to be delivered remotely (e.g., participants can complete the entire study from home), with the option for in person attendance if it is not feasible or safe for participants to attend from home.

Women and gender non-conforming (GNC) individuals with methamphetamine use disorder (MUD) are a particularly vulnerable population in need of complex interventions that can address the range of severe clinical issues with which they often present. However, there are currently no existing psychosocial interventions that are considered preferred for MUD generally, much less in women and GNC individuals with complex psychological profiles and social positioning.

Complex interventions refer to a multifaceted approach to the treatment of psychiatric conditions and may consist of several therapeutic modalities (e.g., behavioural, pharmacological, technological, family engagement; May et al., 2007). These interventions are designed with the intent that they are easy to incorporate into everyday clinical practice (May et al., 2007) and will be effective in treating members of the general population, who present with complex conditions.

As such, the investigators aim to assess the feasibility, acceptability, and effectiveness of a) Acceptance Commitment Therapy delivered in a group format twice weekly, b) an intrinsic motivation building session and contingency management (i.e., progressive monetary incentivizing) targeting session attendance, and c) the ChillTime App to promote the use of emotional coping strategies between sessions.

The program will be 15 sessions/8 weeks long with outcome data collected at a 1-month follow up to assess longevity of effects on MUD harm reduction, abstinence, and mental health.

The investigators will recruit 60 participants through existing service providers in the Greater Toronto Area. As a broader aim of our study is to promote generalizability to the community and ensure the intervention will be accessible to all women and GNC individuals with MUDs, the following are implemented: a) group sessions will be delivered remotely, with an option for in person attendance if remote access is not feasible; b) broad inclusion criteria (e.g., not excluding on the basis of other mental health/substance use comorbidities); and c) qualitative interviews during which patient perspectives will be gathered and the intervention will be adapted accordingly, where warranted. Results will be used to inform a large-scale, randomized, controlled clinical trial.

Study Design: Each participant will undergo a screening/baseline assessment where they will complete clinical assessments to determine eligibility. Following the screening period and signing of the consent form, the study clinician will schedule a 1:1 motivation building session with participants. Participants will be given the 8-week ACT group schedule and research staff will assist them with downloading the ChillTime App. Over the course of the 8-week treatment, participants will learn coping and emotional regulation strategies, and will be able to access additional strategies through the use of the app. After the last group session, participants will once again complete clinical and quality of life assessments. The research staff administering the adverse events and outcome measures will not be the study clinician. The same questionnaires will be used at the 1 month follow-up, along with a qualitative interview asking about their satisfaction with and experience in the program as well as any changes in drug use reflective of harm reduction (e.g., stopped sharing pipes). Participants who missed a session will be offered the chance to make it up 1-1 with the study therapist; participants who dropped out of the group will also be contacted for an Early Termination Visit and will be asked to identify their reasons for dropping out.

Inclusion Criteria:

• Meet SCID DSM-5 criteria for Methamphetamine Use Disorder
• Over the age of 18
• Female, woman, or non-binary and comfortable participating in women's group
• Capacity to provide informed consent
• Adequate English language abilities

Exclusion Criteria:

• Experiencing acute or unmedicated psychosis that would reasonably prevent them from engaging in and/or benefiting from the intervention
• Experiencing acute and severe suicidal ideation such that institutionalization and supervised care is warranted
• Experiencing severe cognitive deficits that would reasonably prevent them from consenting, engaging in, and/or benefiting from the intervention

Identifies as female, woman, or non-binary and is comfortable participating in a women's group