Cannabis-Use Disorder Self-Directed Brief Change With Motivational Interviewing

Short-term changes in problematic cannabis frequency of use among individuals who wish to recover with minimal professional support may be achieved with a self-directed workbook plus a single session of motivational interviewing (MI), according to study findings published in Frontiers in Psychiatry.

Researchers sought to evaluate the clinical utility of a brief self-directed intervention aimed at individuals who wished to recover from problematic cannabis use with minimal professional support.

They initiated a 3-arm randomized controlled trial (RCT) to determine if a brief self-directed workbook (WB), or the workbook combined with a single MI session (WMI) vs a delayed workbook treatment (workbook received at 3-month follow-up) control condition (DT) would be most efficacious to produce significant short-term change in cannabis use among individuals with cannabis use problems who wish to address those problems without professional intervention.

Researchers recruited 186 such adults across Canada who were randomly assigned into 3 arms stratified by gender and problem severity. Participants were followed-up at 3 and 6 months.

Eligibility criteria included fluency in English, cannabis use problem perception, cannabis use within the last month, not currently treated for cannabis use problems, a score of at least 13 on the Cannabis Use Disorders Identification Test-Revised, and at least 18 years of age with a valid Canadian address. Participants (demographics based on N=183 after 3 withdrew) were mostly women (53%), mostly White (83%), mostly single (61%), and mostly employed (79%). Almost 88% had at least 1 previous attempt to reduce cannabis use.

Most participants reported starting use around age 16 years with current regular mean use of about 10 years. Almost 20% reported their goal as abstinence, and roughly 80% were seeking to reduce use. They reported overall average use of 3 daily sessions, 24 days per month.

All participants received a mailed self-directed workbook. Participants in the WMI group received their workbook following a brief MI conducted via telephone, audio only. MIs were conducted by 6 graduate students trained and tested in protocol.

Researchers found the greatest reduction in cannabis frequency of use from baseline to 3 months in the WMI group vs WB (P =.005) and WMI vs DT (P =.02), according to generalized equation modeling. Participants in the WMI group showed greater rates of abstinence at the 3-month follow-up than participants in the WB or DT group (P =.046), according to Chi-square analysis, with significant loss-to-follow-up (WB, n=47; WMI, n=47; DT, n=55).

They noted no significant between-group changes in frequency of cannabis use between 3 months and 6 months (all P >.05). Quantity of cannabis use showed no significant between-group changes from baseline to 3 months or from 3 months to 6 months (all P >.06). Individuals not completing the 6-month follow-up reported less THC in edibles but significantly greater THC in their concentrated cannabis products.

Researchers noted 18% of participants reported seeking other professional treatment at 3 months, and 22% at 6 months with no between-group differences.

Study limitations include the delayed treatment period of 3 months in this study design, underpowered sample size, quantity of cannabis use measured by averaging z-score transformed measures of quantity thus limiting ability to detect between-group differences, assessing frequency of cannabis use becomes an imperfect outcome variable given varying goals of abstinence or reduction, inconsistent self-reporting of THC usage, and the self-reporting nature of cannabis use lacking objective measurement.

Researchers believe their results “support the utility of a brief self-directed workbook in combination with a single MI session at promoting changes in cannabis use.” They stated, “It would be beneficial to consider the efficacy of the intervention in a larger sample and over a longer follow-up period.”