Age-varying trends in alcohol and cannabis co-occurring use: Implications for prescription drug misuse.

Background: Individuals who engage in alcohol and cannabis co-occurring use are at heightened risk for negative outcomes than individuals who only use alcohol or only use cannabis, but far less is known about implications of alcohol and cannabis co-occurring use for prescription drug misuse (PDM).Objectives: This study aimed to (1) identify whether co-occurring use was linked with greater risk for PDM across ages 18-60 and to determine ages at which this association was strongest, (2) determine whether associations remain after controlling for pain severity, and (3) test for gender differences.Methods: Cross-sectional data were from Wave 1 of the Population Assessment of Tobacco and Health (PATH) study. The analytic sample included 20,120 (50.6%wt men) individuals aged 18-60 reporting past-year alcohol and/or cannabis use.Results: Time-varying effect models indicated that individuals reporting co-occurring use were at increased risk for PDM than individuals reporting single-substance use across all ages, with odds ratios peaking at >3 at age 34. After controlling for pain severity, associations were only slightly weakened. Associations were slightly stronger for men than women from ages 28 to 35.Conclusion: Co-occurring use was linked with heightened risk for PDM compared to individuals who used only one substance; co-occurring use may be important to target for PDM prevention. Identifying factors underlying study associations, beyond pain, and how these factors evolve with age are important avenues for prevention work.