January 8, 2009

Marijuana Use and Perceived Risk of Use among Adolescents: 2002 to 2007

Monitoring data on adolescents' marijuana use and their perceptions of risk in using it is vital for making decisions about implementing and targeting prevention programs. The National Survey on Drug Use and Health (NSDUH) includes questions on marijuana use and perceptions of risk from smoking marijuana.¹ This report examines trends in past month marijuana use and perceptions of its risk among adolescents aged 12 to 17 between 2002 and 2007. Additionally, this report uses 2007 data to explore demographic differences in marijuana use and perceptions of its risk, along with the correlation between use and risk perception.

The prevalence of past month marijuana use among adolescents decreased between 2002 (8.2 percent) and 2005 (6.8 percent), and then remained steady between 2005 and 2007 (Figure 1).

Figure 1. Percentages of Adolescents Who Used Marijuana in the Past Month: 2002 to 2007

The percentage of adolescents who perceived great risk from smoking marijuana once a month increased between 2002 (32.4 percent) and 2003 (34.9 percent), and then remained relatively stable from 2003 to 2007 (Figure 2).

Figure 2. Percentages of Adolescents Who Perceived Great Risk from Smoking Marijuana Once a Month***: 2002 to 2007

In 2007, 6.7 percent of adolescents (an estimated 1.7 million persons) used marijuana in the past month (Table 1). Males were more likely to have used marijuana than females (7.5 vs. 5.8 percent). In addition, use increased with age, from 0.9 percent of those aged 12 or 13 to 5.7 percent of those aged 14 or 15 and 13.1 percent of those aged 16 or 17.

In 2007, 34.5 percent of adolescents perceived great risk from smoking marijuana once a month (Table 1). Females were more likely to perceive great risk than were males (36.7 vs. 32.4 percent). The percentage who perceived great risk decreased with age, from 42.1 percent of those aged 12 or 13 to 35.1 percent of those aged 14 or 15 and 26.9 percent of those aged 16 or 17.

Adolescents who perceived great risk from smoking marijuana once a month were much less likely to have used marijuana in the past month than those who perceived moderate to no risk (1.4 vs. 9.5 percent) (Table 2). This finding held for both genders and all three age groups.

Trends among adolescents in past month marijuana use and perceptions of great risk from smoking marijuana once a month were generally on opposite trajectories between 2002 and 2007. Marijuana use decreased between 2002 and 2005, and then leveled out; the perception of risk increased between 2002 and 2003, and then leveled out. Comparisons between marijuana use and perceptions of its risk in 2007 by demographic characteristics also showed generally opposing patterns. Marijuana use increased with age and was higher for males than females, while the perception of great risk decreased with age and was higher for females than males. Additionally, adolescents who perceived great risk from smoking marijuana were much less likely to have used marijuana themselves than those who perceived only moderate to no risk from such use.

Shifts in perceived risk of use of a substance are generally thought to signal future changes in the prevalence of use, but in the opposite direction. Tracking these measures may be useful to policymakers, educators, and prevention program staff in making decisions about when to deploy prevention messages and what segments of the youth audience they should target.