Age of onset of heaviest use of cannabis or alcohol in persons with severe opioid or cocaine use disorders

•Exposure to cannabis and alcohol occurs at earlier ages than to heroin or cocaine.•Heavy adolescent exposure to cannabis or alcohol is associated with vulnerability to opioid or cocaine use disorders.•Persons with cocaine dependence diagnoses had early and heavy cannabis exposure.•Earlier age of adolescent cannabis exposure was associated with cocaine dependence diagnosis. Persons with severe opioid or cocaine use disorders are particularly vulnerable to morbidity and mortality. Heaviest use of mu-opioid receptor agonists and cocaine typically commences in early adulthood and is preceded by substantial adolescent exposure to cannabis and/or alcohol. Little information exists on the age trajectories of exposure to cannabis or alcohol in persons diagnosed with severe opioid or cocaine use disorders, compared to persons diagnosed with other substance use disorders (unrelated to opioids or cocaine). This observational study had n = 854 volunteers (male = 581, female = 273; ≥18 years of age at the time of interview) and examined the ages of onset of heaviest use of cannabis and alcohol in persons diagnosed by DSM-IV criteria with opioid dependence (OD), both opioid and cocaine dependence (OD + CD) and cocaine dependence (CD). These age trajectory measures were compared to persons with other substance use disorders (primarily cannabis and alcohol use disorders, termed “Any Other Diagnoses”). Unadjusted survival analyses showed persons diagnosed with either OD + CD or CD had earlier onset of heaviest use of cannabis (mean ages of 16.2 and 17.8, respectively) compared to the “Any Other Diagnoses” reference group (mean age = 19.5). A multivariate logistic regression showed that later onset of heaviest use of cannabis was associated with lower odds of being in the OD + CD or CD groups, when compared to the reference group. Persons diagnosed with severe cocaine use disorders or dual opioid and cocaine use disorders exhibit a pattern of heavy and especially early adolescent exposure to cannabis, compared to persons with other substance use disorders.