Age of First Use as a Predictor of Current Alcohol and Marijuana Use Among College-Bound Emerging Adults

Abstract

Background: Alcohol and marijuana are the most commonly used psychoactive substances; however, the sequencing and relationship between age of first use and continued current problematic use among college-bound emerging adults is not well understood.

Methods: This is a cross-sectional study of current and historical alcohol and marijuana use among college-bound recent high school graduates (N = 1,365; age ∼18 years).

Results: Drinking was prevalent (78%, N = 1,055) and marijuana use was prevalent (46%, N = 622). Stepwise logistical regression revealed the lower the age of first use, the higher the prevalence of current problematic substance use. Those who initiate alcohol ≤ 12 are twice as likely to currently use marijuana frequently. A significant relationship was found between age of first use and non-social substance use (drinking, p = 0.0001; marijuana, p = 0.0025). The temporal ordering of substance use indicates that alcohol precedes marijuana use, and age of first alcohol use is relevant to rates of initiation and current marijuana use.

KEYWORDS:

• adolescent
• age first use
• alcohol
• emerging adult
• marijuana

Notes

*p < .05.

Notes. Reference groups for predictor variables: male, first drink after age 16, and first MJ use after age 16; NA = nonapplicable. First MJ use before age 12 category had an unreliable regression coefficient due to multicollinearity and was removed from the model.

Notes. Reference groups for predictor variables: male, first drink after age 16, and first MJ use after age 16; NA = nonapplicable.

Notes. Reference groups for predictor variables: male, first drink after age 16, and first MJ use after age 16; NA = nonapplicable. First MJ use before age 12 category had an unreliable regression coefficient due to multicollinearity and was removed from the model.

Notes. Reference groups for predictor variables: male, first drink after age 16, and first MJ use after age 16; NA = nonapplicable; n.s. = not specified.

Notes. Reference groups for predictor variables: male, first drink after age 16, and first MJ use after age 16; NA = nonapplicable.