Early onset of drug and polysubstance use as predictors of injection drug use among adult drug users

Early onset of alcohol, marijuana, and cigarette use is an indicator of later substance use problems in adulthood such as alcohol or other drug dependence. This paper seeks to address the association between early onset alcohol, marijuana, cigarette, and polysubstance use with injection drug use among recent illicit drug users. The current study used baseline data from the Baltimore site of the NEURO-HIV Epidemiologic Study, an investigation of neuropsychological and social-behavioral risk factors of HIV, hepatitis A, hepatitis B, and Hepatitis C among both injection and non-injection drug users in Baltimore, Maryland. The present study used a subset (N=651) of the larger parent study that identified as White or Black, and reported any drug use in the past 6 months. In the full sample slightly more than half (52.5%) of study participants were IDUs. IDUs differed from non-IDUs on age of initiation for cigarettes, marijuana, and alcohol, with IDUs initiating the use of all three substances significantly earlier than non-IDUs. IDUs also had significantly greater proportions of early onset of alcohol (χ(2)=19.71, p<.01), cigarette (χ(2)=11.05, p<.01), marijuana (χ(2)=10.83, p<.01), and polysubstance use (χ(2)=23.48, p<.01) than non-IDUs. After adjusting for age, gender, and race/ethnicity, only participants identified as early onset alcohol users (AOR=1.47, 95% CI: 1.00-2.18) and early onset polysubstance users (AOR=1.62, 95% CI: 1.10-2.38) were more likely to have IDU status than those who reported initiating substance use later. IDU status was then stratified by race/ethnicity. After controlling for age and gender, only early polysubstance use was a significant predictor of IDU status for Whites (AOR=2.06, 95% CI: 1.07-3.93). Consistent with literature on early substance initiation and later illicit substance use, early onset of alcohol and polysubstance use is an important risk factor for IDU in adulthood.     

Getting Higher: Co-Occurring Drug Use Among Marijuana-Using Emerging Adults

The most widely used illicit drug in the United States continues to be marijuana, and its use among emerging adults continues to increase. Marijuana use can result in a range of negative consequences and has been associated with other drug use in adolescents and emerging adults. This study examined the relationship between marijuana use frequency and the use of six other drug classes (opiates, cocaine, stimulants, hallucinogens, inhalants, and sleep medications) among emerging adults. A cross-sectional interview design was used with a community sample of 1,075 emerging adults in the northeastern United States. Using logistic regression analysis controlling for age, ethnicity, gender, and frequency of binge alcohol, daily marijuana use was found to be associated with a significant increase in the expected odds of opiate, cocaine, stimulant, hallucinogen, inhalant, and tobacco use. The findings identify a subgroup of emerging adult marijuana users—those who use daily—that may be vulnerable to additional negative consequences associated with polysubstance use.     

Mostly Smokers: Identifying Subtypes of Emerging Adult Substance Users

Background: The concurrent use of marijuana and other substances among emerging adults (ages 18–25) is a major public health problem. This study examined if there are distinct subtypes of emerging adult marijuana users and if these are associated with demographic and substance use variables. Methods: The design was a cross-sectional interview with a community sample of 1,503 emerging adults in the northeastern U.S. who reported last month marijuana use. We used latent class analysis (LCA) to identify distinct subtypes of emerging adults who used additional substances and examined predictors of the latent classes. Results: We identified three distinct classes of emerging adults who use substances: “mostly smokers” (those who primarily use marijuana and nicotine), “moderate users” (those who primarily use marijuana and/or heavy episodic alcohol), and “polysubstance users.” Polysubstance users had higher probabilities of use of all assessed substances (e.g. cocaine, opiates, sleep medications, stimulants, synthetic marijuana, and inhalants) than the other two groups. Not being currently enrolled in school and male gender were associated with mostly smokers and polysubstance users group status. Conclusions: We identified a distinct group of emerging adult marijuana users who primarily smoke marijuana and cigarettes, suggesting that there could be a shared vulnerability for risk of co-occurrence.     

High prevalence of substance use disorders among adolescents who use marijuana and inhalants

BACKGROUND: We examined the association between the use of inhalants, marijuana, and other drugs and recent DSM-IV substance use disorders among adolescents aged 12-17 years. METHODS: Data were drawn from 2000 to 2001 National Household Surveys on Drug Abuse. Adolescents aged 12-17 years who reported having ever used an illicit drug in their lifetime were categorized into four mutually exclusive groups: inhalant users (16%), marijuana users (53%), inhalant and marijuana users (16%), and other drug users (15%). Logistic regression models were used to estimate associations with recent substance use diagnoses among lifetime adolescent drug users (N=10,180). RESULTS: We found that 31% of lifetime drug users reported having never used marijuana. One half of these atypical drug users were predominantly nonmedical users of pain relievers. Adolescents who used inhalants or other drugs but not marijuana were least likely to report multidrug use. Adolescents who reported using both inhalants and marijuana were most likely to use three or more classes of drugs (73%) and to receive a diagnosis of past year alcohol (35%) and drug (39%) abuse or dependence. CONCLUSIONS: Our study findings suggest that among lifetime adolescent drug users, those who use both inhalants and marijuana are at very high risk for alcohol and drug use disorders.