Youth Substance  Use: State Estimates From the 1999 National Household Survey on Drug Abuse

4. MARIJUANA USE

In 1999, 7.2 percent of youths aged 12 to 17 reported using marijuana in the past month (SAMHSA, in press). Past month use of marijuana by youths peaked in the late 1970s at around 14 percent and reached a low in 1992 of approximately 3 percent (SAMHSA, 2000a). The measures discussed in this chapter include past month marijuana use, average annual incidence of marijuana use, perceived risk of marijuana use, average age at first use, dependence on marijuana, and difficulty of obtaining marijuana.

4.1 Model-Based Estimates

• In 1999, the estimated national average annual incidence rate for marijuana use among youths was 6.3 percent (see Section 1.3.1 for definitions of incidence rates) (Table B.7B). At the State level, Arizona had the highest average annual incidence rate (8.9 percent) over the previous 2 years (Table B.7B). Five of the States that were in the highest quintile for past month marijuana use among youths were also in the top quintile for new users of marijuana: Massachusetts, Nevada, Delaware, Colorado, and Alaska (Figure A.5). Of the 10 States with the highest estimated rates of incidence, 4 were in the West (Arizona, Nevada, Colorado, and Alaska), 2 were in the Northeast (Massachusetts and Vermont), 2 were in the Midwest (North Dakota and Wisconsin), and 2 were in the South (Delaware and Oklahoma).

• Four of the States in the highest quintile for youth incidence of marijuana use had youths who reported the lowest perceived great risk from smoking marijuana once a month (Figures A.5 and A.6, Table B.9B): Vermont (25.8 percent), Colorado (27.0 percent), Massachusetts (29.3 percent), and Nevada (29.8 percent). The other States reporting the lowest perceived risk included Montana (27.8 percent), Connecticut (28.3 percent), New Hampshire (29.9 percent), Oregon (30.6 percent), Washington (31.4 percent), and New Mexico (32.2 percent).

• The national average age for first use of marijuana by persons who initiated use in 1995 to 1997 at age 25 or younger was 16.2 years (Table C.5). The average age at first use of marijuana ranged from a low of 15.1 years in Montana and Nevada to 17.1 years in Maine, a range of 2.0 years. Four of the States that fell into the highest quintile for past month rates of use of marijuana among youths had lower than average ages at time of first use of marijuana: Montana (15.1 years), Nevada (15.1 years), Minnesota (15.6 years), and Washington (15.8 years). Three of the States in the lowest quintile of past month prevalence also had a higher than average age at first use: Iowa and Tennessee (16.9 years) and Idaho (16.7 years). Some of the confidence intervals for the State average age at time of first use of marijuana were quite large (anywhere from 0.6 to 3.7 years depending on the State); therefore, the estimates should be used with caution.

• The average dependence score for marijuana for the Nation was 0.30 (Table C.6), somewhat lower than those for alcohol (0.58) or cigarettes (0.56). The State with the lowest score was Nebraska (0.12), and the State with the highest dependence score was Delaware (0.57). The correlation of these State estimates with the estimated past month use of marijuana was less than those for alcohol and cigarettes. Six of the States in the highest quintile of marijuana dependence scores were also in the highest quintile for past month use of marijuana. Similarly, six of the States in the lowest quintile of marijuana dependence scores were also in the lowest quintile for past month use of marijuana.

• The average scale score for youths' difficulty in obtaining marijuana, if they wanted this drug, was 3.41 on a scale of 1 (probably impossible) to 5 (very easy) (Table C.7). The range between the lowest and highest State scores for the difficulty of obtaining marijuana was quite small. Youths in South Dakota reported the most difficulty in obtaining marijuana (score = 3.09), while youths in Delaware and Colorado reported the least difficulty (3.70). Both scores were significantly different from the national average (3.41). Youths in four of the States with the lowest rates of past month marijuana use among youths also reported higher than average difficulty in obtaining marijuana (Nebraska, Utah, Florida, and Texas). Similarly, youths in four of the States with the highest rates of past month marijuana among youths also reported less than average difficulty in obtaining marijuana (Delaware, Connecticut, Nevada, and Colorado).

This page was last updated on June 03, 2008.

SAMHSA, an agency in the Department of Health and Human Services, is the Federal Government's lead agency for improving the quality and availability of substance abuse prevention, addiction treatment, and mental health services in the United States.