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Initiation of Marijuana Use: Trends, Patterns, and Implications |
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Highlights
Estimates of first-time drug use, referred to as incidence or initiation, provide an important measure of the Nation's drug use problem. They suggest emerging patterns of use and identify periods of heightened risk for an immediate focus on the prevention of substance use, particularly among children and youths. Incidence data also suggest the future burden on substance abuse treatment systems. This report contains an analysis of the initiation of marijuana use. Marijuana is the most widely used illicit drug in the United States and is, in most cases, the first illicit drug used by persons who have used an illicit drug. The analysis is based on data from the 1999 and 2000 National Household Surveys on Drug Abuse (NHSDAs). Selected findings are given below:
- An
estimated 2.0 million Americans aged 12 or older used marijuana for the first
time in 1999. This was fewer than the estimated number of new users in 1998
(approximately 2.5 million Americans), but still above the 1989 and 1990 levels
(1.4 million each year).
- The
rate of marijuana initiation increased during the late 1960s and early 1970s,
with a peak in 1976 and 1977 (21.0 per 1,000 potential new users). After that
period, the rate of new marijuana use decreased to 8.5 in 1990, followed by
an increase to 16.8 in 1996, then a decrease to 13.6 in 1999.
- The
trend in marijuana incidence since 1965 followed the same general pattern
for males and females, although rates for females were consistently below
rates for males. In 1999, the rates of new use per 1,000 potential new users
were 15.5 for males and 12.1 for females.
- The
rates of first marijuana use among American Indians/Alaska Natives were higher
than for other racial/ethnic groups during the 1990s. Unlike the overall trend
in rates, which showed a peak in 1996, the trend for American Indians/Alaska
Natives indicated a continuing increase, reaching 46.5 per 1,000 potential
new users in 1999.
- The
mean age at first marijuana use was 19 years in the early 1970s and decreased
to 17 years in the 1990s. The trends for males and females were parallel,
with males initiating at an earlier age than females, on average. The average
age of new marijuana users in 1999 was 16.4 years for males and 17.6 years
for females.
- These
average annual incidence rates varied slightly across different States and
age groups. Colorado, Delaware, Massachusetts, New Hampshire, and Vermont
were ranked in the top 10 for the overall age group (ages 12 or older), the
youth age group (ages 12 to 17), and the young adult age group (ages 18 to
25). New Mexico had the highest rate for the overall and youth age groups.
Minnesota had the highest rate for the overall and young adult age groups.
By comparison, Louisiana had the lowest rate of recent new users for the overall,
youth, and young adult age groups. Texas and Utah had the lowest rates of
recent initiation among youths and young adults.
- Among
recent initiates of marijuana (first use in 1998 or 1999), nearly three quarters
had first used between the ages of 13 and 18. More than a quarter initiated
use at age 14 or younger.
- Approximately
60 percent of recent initiates had used both alcohol and cigarettes prior
to their first use of marijuana. About 9 percent had never used alcohol or
cigarettes at the time of first marijuana use, and the remaining recent initiates
had used either alcohol only (16.6 percent) or cigarettes only (14.8 percent).
- The
average number of marijuana initiates per day during 1998 and 1999 was highest
in June and July. For females, the months with the highest rates of initiation
were January and July. On average during 1998 and 1999, there were 3,197 male
initiates and 2,989 female initiates per day. Among males, the number of daily
initiates increased to approximately 4,300 in June and July. Among females,
the estimated initiates per day rose to 3,625 in July and 3,519 in January.
- Prior
use of alcohol or cigarettes was highly correlated with becoming a new marijuana
user. Among persons aged 12 to 25 who had never used marijuana, those who
had smoked cigarettes were an estimated 6 times more likely than nonsmokers
to initiate marijuana use within 1 year. Alcohol users were an estimated 7
to 9 times more likely than nonusers to start using marijuana within a year.
Daily cigarette smoking was associated with a twofold increase in risk for
marijuana initiation.
- Initiation of
marijuana use before age 15 was associated with a greater risk of other drug
use behaviors at age 26 or older. These behaviors include heroin use, cocaine
use, nonmedical psychotherapeutic use, daily or almost daily marijuana use,
and weekly use of illicit drugs other than marijuana.
- Initiation of marijuana use before age 15 was associated with a greater risk of illicit drug dependence or abuse at age 26 or older. Relative to adults who had initiated marijuana use at age 21 or older, adults who had first used before age 15 were 6 times as likely to be dependent on an illicit drug.
This page was last updated on June 16, 2008. |
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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.
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