Mobile Application-Based Interventions for Cannabis Use in Young Adults With First Episode Psychosis (Mobile Health)

Experimental: CHAMPS - intervention group

Participants who receive the CHAMPS intervention

Sonstiges: CHAMPS

CHAMPS is a psychosocial e-intervention grounded in motivational interviewing (MI) and harm reduction principles, developed using the Behavioral Change Wheel (BCW) theoretical framework.

CHAMPS is delivered through a mobile health platform and comprises 6 sequential psychotherapeutic modules (5-15 minutes each) plus a booster session:

Module 1: Automatic personalized feedback on current cannabis PBS based on baseline assessment, with improvement suggestions and identification of strengths that facilitate change.

Module 2: Exploration of personal values and the potential benefits of safer cannabis use practices Module 3: Evidence-based cannabis PBS using interactive psychoeducational techniques Module 4: Goal-setting using the SMART technique; participants define their own realistic cannabis-focused goals Module 5: Review of goal progress; support to revise current goal or adopt new consumption habits Module 6: Reassessment of consumption habits (PBS)

Kein Eingriff: CHAMPS - no intervention group

Participants who are not receiving the CHAMPS intervention and are compared to the one who do

Experimental: I Can Change - Intervention group

Participants who receive the I Can Change intervention

Sonstiges: I Can Change

iCanChange (iCC) is a mobile app-based psychological intervention that incorporates principles of CBT, MI, and psychoeducation. It is available on Android and iPhone, in both English and French. Section 1 (10 modules): Modules 1 to 9 address topics such as cannabis dependence, myths, and its effects on psychosis, while helping users identify personal triggers, strengths, and benefits of reducing use. Section 1 concludes with Module 10, in which participants self-identify a flexible, person-oriented cannabis use goal such as reducing or stopping use. Two weeks after Module 10, an additional module is offered (up to two times) to consolidate and review goals.

Section 2 (8 modules): Modules aim at increasing coping skills, equipping users with practical tools to maintain progress, planning cannabis-free activities, building social support, managing stress, and adopting a healthy lifestyle. Booster modules (3 sessions, one per month during the 12-week follow-up)

Kein Eingriff: I Can Change - No intervention group

Participants who are not receiving the I Can Change intervention and are compared to the one who do

CHAMPS Primary Outcome Measure

To determine whether adding CHAMPS (an intervention aimed at developing safer consumption behaviors) to standard EIS is superior to standard EIS alone in reducing cannabis-related problems in young adults with FEP who are not seeking to cease or reduce their use. Total score of the Marijuana Problems Scale (MPS, 19 items, 0-38) at Week 8 post-randomization (also assessed at Week 12 post-randomization). Minimum clinically important difference (MCID): 2 points. For each MPS item, the participant rates a cannabis-related problem over the past month on a three-point scale: 0 = not a problem, 1 = a minor problem, 2 = a serious problem. Total scores range from 0 to 38; higher scores indicate more serious problems.

I Can Change Primary Outcome Measure

To determine whether adding iCC to standard services offered in EIS clinics is superior to standard EIS alone in reducing the frequency of cannabis use in individuals with FEP and CUD (moderate to severe) who are seeking to reduce or cease their use. Number of days of cannabis use in the past 14 days (Timeline Follow Back, TLFB) at Week 12 (also assessed at Weeks 6 and 24 post-randomization).

CHAMPS secondary Outcome Measure

Number of days of cannabis use in the past 14 days - Timeline Follow Back (TFLB) The TLFB will assess self-reported days of cannabis use over the past 14 days , as well as type of cannabis products, provenance, form, and quantity . The main endpoint for this outcome is the number of days per week of cannabis use. Days per week is the preferred manner of reporting cannabis use frequency in the field, and use of cannabis once per week or more is an established threshold for increased risk of adverse psychosis-related outcomes.

CHAMPS secondary Outcome Measure

Protective behavioral strategies: PBSM total score (17 items, 15-73) The PBSM is a 17-item, self-report measure including various evidence-based strategies that cannabis users can adopt to reduce harms or use more safely. For each item, participants rate the degree to which they engage in a specific protective behavior on a scale of 1 = Never to 6 = Always. Individual item responses are summed for a total score, which is then converted to an item-response theory scaled score (possible range: 15-73). Higher scaled scores indicate greater use of PBS.

CHAMPS secondary Outcome Measure

The proportion of participants in each State of Change Designation (i.e., precontemplation, contemplation, and action) Readiness to change Questionnaire (RCQ) Motivation to change cannabis use practices will be assessed using the adapted 12-item Readiness-to-Change Questionnaire (RCQ), modified for cannabis use. The RCQ is based on Prochaska and DiClemente's stages-of-change model and assesses three stages: pre-contemplation, contemplation, and action. For each scale, 4 items are summed (range: -8 to +8); the scale with the highest score represents the participant's Stage of Change Designation. The internal consistency of the three subscales is acceptable. The tool is designed for cannabis users not seeking treatment who may be unaware of a problem.

CHAMPS secondary Outcome Measure

Quality of life: WHOQOL-BREF (26 items, 4 domains, 0-100) Quality of life will be measured using the WHOQOL-BREF, which assesses four domains: physical health, psychological health, social relationships, and environment, plus two overall items. The WHOQOL-BREF consists of 26 items; each item is rated on a 5-point Likert scale ranging from very poor to very good. Domain scores are calculated according to WHOQOL-BREF guidelines and converted to a 0-100 scale; an overall total score will also be calculated .

I Can Change Secondary Outcome Measure

Cannabis dependence severity will be assessed using the Severity of Dependence Scale (SDS), a 5-item self-report questionnaire validated in people with early psychosis. Items are scored 0-3; total scores range from 0-15 (higher = greater dependence severity).

I Can Change Secondary Outcome Measure

Motivation to reduce cannabis use will be assessed using the Precaution Adoption Process Model (PAPM), a theoretical stage-based model that classifies individuals into 6 nominal stages: (1) unaware, (2) unengaged, (3) undecided, (4) decided not to act, (5) decided to act, (6) acting. Stages will be dichotomized for inter-group comparison (e.g., pre-action vs. action stages).

I Can Change Secondary Outcome Measure

In addition to frequency (primary endpoint), the timeline follow back (TLFB) will capture continuous abstinence (proportion of participants with 0 days of cannabis use in past 14 days) and estimated quantity of cannabis used per session.

I Can Change Secondary Outcome Measure

Quality of life will be measured using the WHOQOL-BREF, which has been validated in individuals with psychotic disorders and consists of 26 items across 4 domains: physical health, psychological health, social relationships, and environment. Each item is rated on a 5-point Likert scale ranging from very poor to very good. For each domain, scores are calculated according to WHOQOL-BREF guidelines and converted to a 0-100 scale.