May 3, 2005

Age at First Use of Marijuana and Past Year Serious Mental Illness

In Brief

Among persons aged 18 or older, those who first used marijuana before age 12 were twice as likely to have serious mental illness in the past year as those who first used marijuana at age 18 or older

In 2002 and 2003, among persons aged 18 or older who reported lifetime marijuana use, 55 percent reported first using marijuana before the age of 18

Males aged 18 or older were more than twice as likely as females to report that they first used marijuana before age 12

Marijuana is the most widely used illicit drug, and it is usually the first drug used by persons who use illicit drugs.¹ Recent research points to an association between early marijuana use and a heightened risk of developing schizophrenia or other psychological disorders.^2,3,4 The National Survey on Drug Use and Health (NSDUH) asks persons aged 12 or older to report on their use of marijuana, including their age at first use. For persons aged 18 or older, NSDUH also asks questions to assess serious mental illness (SMI) during the 12 months prior to the survey. Individuals are classified as having SMI if at some time during the past 12 months they had a diagnosable mental, behavioral, or emotional disorder that met Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for a disorder⁵ and resulted in a functional impairment that substantially interfered with or limited one or more major life activities. NSDUH measures SMI using the K-6 distress questions.^6,7 This report focuses on the association between age at first use of marijuana and past year SMI. All of the findings presented in this report are annual averages based on the combined data from the 2002 and 2003 NSDUH.

Lifetime Marijuana Use

In 2002 and 2003, 42.9 percent of persons aged 18 or older (an estimated 90.8 million persons) had used marijuana at least once in their lifetime. Among adults aged 18 or older, lifetime marijuana use varied by gender: 48.4 percent of males reported lifetime use, while 37.9 percent of females reported lifetime use. Approximately 58.0 percent of adults aged 35 to 49 reported having used marijuana in their lifetime, while 22.5 percent of adults aged 50 or older reported having used marijuana in their lifetime. The percentage of lifetime marijuana use among persons aged 18 or older was higher for males than for females in each age group (Figure 1).

Figure 1. Percentages of Lifetime Marijuana Use among Adults Aged 18 or Older, by Gender and Age Group: 2002 and 2003	Figure 2. Percentages of Lifetime Marijuana Users Currently Aged 18 or Older by Age at First Marijuana Use: 2002 and 2003

Age at First Use of Marijuana

Among persons aged 18 or older who reported lifetime marijuana use, almost one half (45.2 percent) reported that they first used marijuana at age 18 or older. Almost 53 percent reported that they first used marijuana between ages 12 and 17, and about 2 percent reported that they first used marijuana before age 12 (Figure 2). Males aged 18 or older (2.9 percent) were more than twice as likely as females (1.1 percent) to report that they first used marijuana before age 12. Lifetime marijuana users currently aged 18 to 25 and 26 to 34 (3.2 percent for each group) were more likely to report that they first used marijuana before age 12 than lifetime marijuana users aged 35 to 49 (1.9 percent) and lifetime marijuana users aged 50 or older (0.3 percent).

Past Year Serious Mental Illness

In 2002 and 2003, 8.8 percent of adults aged 18 or older (an estimated 18.5 million persons) were classified as having SMI in the past year. Among adults aged 18 or older, past year SMI varied by gender: 11.0 percent of females had SMI compared with 6.4 percent of males. Adults aged 18 to 25 had the highest prevalence of past year SMI (13.6 percent), while adults aged 50 or older had the lowest prevalence of past year SMI (5.4 percent). In each age group, the prevalence of past year SMI was higher among females than among males (Figure 3).

Figure 3. Prevalence of Past Year SMI among Adults Aged 18 or Older, by Gender and Age Group: 2002 and 2003	Figure 4. Prevalence of Past Year SMI among Lifetime Marijuana Users Aged 18 or Older, by Age at First Marijuana Use: 2002 and 2003

Age at First Use of Marijuana and Past Year Serious Mental Illness

In 2002 and 2003, 12.5 percent of persons aged 18 or older who reported lifetime marijuana use were classified as having past year SMI. Adults who first used marijuana before age 12 (21.0 percent) were twice as likely as adults who first used marijuana at age 18 or older (10.5 percent) to be classified as having SMI in the past year (Figure 4).

End Notes

Gfroerer, J. C., Wu, L.-T., & Penne, M. A. (2002). Initiation of marijuana use: Trends, patterns, and implications (DHHS Publication No. SMA 02–3711, Analytic Series A–17). Rockville, MD: Substance Abuse and Mental Health Services Administration, Office of Applied Studies. Available at http://www.oas.samhsa.gov/analytic.htm
Green, B.E., & Ritter, C. (2000). Marijuana use and depression. Journal of Health and Social Behavior, 41, 40–49.
Rey, J. M., Martin, A., & Krabman, P. (2004). Is the party over? Cannabis and juvenile psychiatric disorder: The past 10 years. Journal of the American Academy of Child and Adolescent Psychiatry, 43, 1194–1205.
Smit, F., Bolier, L., & Cuijpers, P. (2004). Cannabis use and the risk of later schizophrenia: A review. Addiction, 99, 425–430.
American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.
Kessler, R. C., Barker, P. R., Colpe, L. J., Epstein, J. F., Gfroerer, J. C., Hiripi, E., Howes, M. J., Normand, S. L., Manderscheid, R. W., Walters, E. E., & Zaslavsky, A. M. (2003). Screening for serious mental illness in the general population. Archives of General Psychiatry, 60, 184–189.
For a discussion of the methodology used to generate SMI estimates see Appendix B, Section B.6 of the following document: Office of Applied Studies. (2003). Results from the 2002 National Survey on Drug Use and Health: National findings (DHHS Publication No. SMA 03–3836, NSDUH Series H–22). Rockville, MD: Substance Abuse and Mental Health Services Administration. Available at http://www.oas.samhsa.gov/NHSDA/2k3NSDUH/appb.htm

Figure Note

Source: SAMHSA, 2002 and 2003 NSDUH.

The National Survey on Drug Use and Health (NSDUH) is an annual survey sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA). Prior to 2002, this survey was called the National Household Survey on Drug Abuse (NHSDA). The 2002 and 2003 data used in this report are based on information obtained from 89,600 persons aged 18 or older. The survey collects data by administering questionnaires to a representative sample of the population through face-to-face interviews at their place of residence.

The NSDUH Report is prepared by the Office of Applied Studies (OAS), SAMHSA, and by RTI International in Research Triangle Park, North Carolina. (RTI International is a trade name of Research Triangle Institute.)

Information and data for this issue are based on the following publications and statistics:

Office of Applied Studies. (2004). Results from the 2003 National Survey on Drug Use and Health: National findings (DHHS Publication No. SMA 04–3964, NSDUH Series H–25). Rockville, MD: Substance Abuse and Mental Health Services Administration.

Office of Applied Studies. (2003). Results from the 2002 National Survey on Drug Use and Health: National findings (DHHS Publication No. SMA 03–3836, NSDUH Series H–22). Rockville, MD: Substance Abuse and Mental Health Services Administration.

Also available online: http://www.oas.samhsa.gov.

Because of improvements and modifications to the 2002 NSDUH, estimates from the 2002 and 2003 surveys should not be compared with estimates from the 2001 or earlier versions of the survey to examine changes over time.

The NSDUH Report (formerly The NHSDA Report) is published periodically by the Office of Applied Studies, Substance Abuse and Mental Health Services Administration (SAMHSA). All material appearing in this report is in the public domain and may be reproduced or copied without permission from SAMHSA. Additional copies of this report or other reports from the Office of Applied Studies are available on-line: http://www.oas.samhsa.gov. Citation of the source is appreciated. For questions about this report please e-mail: shortreports@samhsa.hhs.gov.

This page was last updated on May 16, 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.

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