Text-Message Cannabis Treatment Worked Indirectly by Boosting Motivation and Harm Reduction Skills | Research

The takeaway

While the text-message CUD treatment did not directly reduce cannabis use compared to controls, it worked indirectly by increasing readiness to change and protective behavioral strategies, which led to reduced use at 6 months.

Addiction treatment researchers and clinicians designing cannabis use disorder interventions.

Treatment worked through motivation and harm reduction, not direct behavior change

What the researchers found

No significant direct treatment effects on cannabis use were found between PNC-txt and control. However, PNC-txt significantly increased readiness to change and protective behavioral strategies at 1 month, which mediated decreases in cannabis use days from baseline to 6 months. The treatment works through its hypothesized clinical mechanisms rather than through direct behavioral change.

Why it matters

Understanding how treatments work is as important as knowing whether they work. This companion paper to the mediation analysis reveals that the text-message approach succeeds by activating motivation and teaching harm reduction, not by directly changing behavior. This has implications for refining and improving the intervention.

The numbers in context

N = 1,078 (Colorado and Tennessee). No direct treatment effect on use. Significant indirect effects: PNC-txt increased readiness to change and protective behavioral strategies at 1 month, leading to fewer cannabis use days at 6 months.

How the study worked

RCT with 1,078 US young adults from Colorado and Tennessee randomized to 4-week PNC-txt or wait-list control, followed 6 months. Latent change score mediation modeling tested indirect effects through readiness to change and protective behavioral strategies.

What this study cannot tell us

Wait-list control design. Mediation analysis is observational even within an RCT. The indirect-only effect pattern means the treatment may not help people who are not responsive to motivational approaches. Colorado and Tennessee represent different cannabis policy contexts.

How to read the evidence

Large RCT with sophisticated mediation modeling. The indirect-only effect pattern is a limitation but consistent with motivational interviewing theory.

When this study was published

Published in 2025.

The bigger picture

Many addiction treatments show indirect rather than direct effects, meaning they change the psychological precursors to behavior change rather than behavior itself. This is consistent with motivational interviewing theory and validates the text-message delivery format for activating these mechanisms.

Questions still open

Would combining PNC-txt with a more direct behavioral intervention improve outcomes? Are there baseline characteristics that predict who will respond to the motivational mechanisms?

Common questions

Why did the treatment not show a direct effect?

Motivational interventions typically work by changing how people think about their behavior rather than directly stopping the behavior. The 4-week text treatment activated motivation and taught strategies that led to use reduction over the following months.

What are protective behavioral strategies?

Specific actions people take to reduce harm from substance use, such as setting limits, avoiding high-risk situations, or choosing lower-potency products. The treatment taught these strategies through text messages.

Read the original research

Text message-delivered cannabis use disorder treatment with young adults: A large randomized clinical trial.

Journal of substance use and addiction treatment, 170, 209611

View on PubMed ↗Publisher’s paper ↗

Citation

Mason, Michael J; Coatsworth, J Douglas; Riggs, Nathaniel R; Russell, Michael; Mennis, Jeremy; Zaharakis, Nikola; Brown, Aaron. (2025). Text message-delivered cannabis use disorder treatment with young adults: A large randomized clinical trial.. Journal of substance use and addiction treatment, 170, 209611. https://doi.org/10.1016/j.josat.2024.209611