Contingency management for alcohol use disorder reduces cannabis use among American Indian and Alaska Native adults.

Objective: Determine whether a culturally tailored contingency management (CM) intervention targeting alcohol abstinence resulted in secondary effects on cannabis use among American Indian and Alaska Native (AI/AN) adults.

Methods: The research team conducted this secondary data analysis to examine cannabis abstinence using data from a randomized control trial of CM for alcohol use among three AI/AN-serving organizations. One hundred and fifty-eight adults met the randomization criteria (i.e., submission of 50% or more urine samples and one alcohol-positive urine test during a 4-week, pre-randomization, observation period). For 12 weeks after randomization, participants received incentives for submitting a urine test negative for ethyl glucuronide (EtG < 150 ng/mL, CM group) or incentives for submitting a urine sample regardless of abstinence (Non-contingent [NC] Control group). Generalized linear mixed effects models assessed group differences in cannabis abstinence during the intervention, verified by urine tetrahydrocannabinol negative tests (11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid <50 ng/mL).

Results: At baseline, 42.2% (n = 35) of participants in the NC group and 40.0% (n = 30) of those in the CM group had a cannabis positive urine test. An overall intervention by time interaction was detected for a cannabis negative urine test (χ = 13.40, p = 0.001). Compared to the NC group, the CM group had 3.92 (95% CI:1.23-12.46) times higher odds of having a cannabis negative urine test during the intervention period and 5.13 (95% CI:1.57-16.76) times higher odds of having a negative cannabis test at the end of intervention period.

Conclusion: CM addressing alcohol misuse may be an effective strategy for decreasing cannabis use among AI/AN adults.

Trial Registration: ClinicalTrials.gov number, Identifier: NCT02174315.