Marijuana Use, by Age Group (Tables 3.1 to 3.4)

Prevalence of lifetime, past year, and current marijuana use varied significantly across all age groups. Lifetime use ranged from 48% of middle adults in the 26 to 34 age group to 19% of the youths in the 12 to 17 age group. Past year and current marijuana use were highest among young adults in the 18 to 25 group (22% and 13%, respectively), and lowest among older adults in the 35 or older group (4% and 3%, respectively).

Table 3.4 gives a more refined picture of marijuana use by age. Lifetime prevalence of marijuana use increased with each age group from 12 to 13 years of age to 35 to 39 years of age, and then decreased gradually. The largest age gradients in the prevalence of marijuana use occurred among youths in their teenage years. In particular, only about 4% of youths aged 12 or 13 had used marijuana in the past year. For ages 14 and 15, the prevalence quadrupled (16%), and by ages 16 and 17, more than one-fourth (27%) had used marijuana in the past year. Similarly, the rate of past month use tripled from ages 12 to 13 (3%) to ages 14 to 15 (9%), and then nearly doubled by ages 16 and 17(16%). This phenomenon reflects an age-of-onset effect: First-time use of marijuana occurs most often at these ages. The 1997 Monitoring the Future study reported a similar phenomenon, with large proportional differences between 8th and 10th grade students for past year use (18% vs. 35%) and current use (10% vs. 21%) (Johnston et al., 1998a, 1998b; NCADI, 1998).

This page was last updated on December 30, 2008.

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