Marijuana: Age at First Use Has Impact

A new report from SAMHSA's Office of Applied Studies (OAS), Age at First Use of Marijuana and Past Year Serious Mental Illness, found that among persons age 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.

"Kids today are using marijuana at younger ages, putting them at greater risk for future health and mental health problems," said Mr. Curie. "We have found that younger persons who start smoking marijuana are at greater risk of developing an addiction and serious mental illness later in life."

Marijuana is the most widely used illicit drug, and it is usually the first drug used by persons who use illicit drugs.

The report, from SAMHSA's National Survey on Drug Use and Health (NSDUH), cites recent research pointing to an association between early marijuana use and a heightened risk of developing schizophrenia or other psychological disorders.

Data from NSDUH show that among persons age 18 or older who reported lifetime marijuana use, 55 percent reported first using marijuana before age 18.

In addition, males age 18 or older were more than twice as likely as females to report that they first used marijuana before age 12.

In 2002 and 2003, 42.9 percent of persons age 18 or older (an estimated 90.8 million persons) had used marijuana at least once in their lifetime. Among adults age 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.

All of the findings presented in this report are annual averages based on the combined data from the 2002 and 2003 surveys.

NSDUH asked persons age 12 or older to report on their use of marijuana, including their age at first use. For persons age 18 or older, NSDUH also asked questions to assess serious mental illness during the 12 months prior to the survey.

For a copy of the OAS report, Age at First Use of Marijuana and Past Year Serious Mental Illness, contact SAMHSA's National Clearinghouse for Alcohol and Drug Information at P.O. Box 2345, Rockville, MD 20847-2345. Telephone: 1 (800) 729-6686 (English and Spanish) or 1 (800) 487-4889 (TDD). Online, the report is available on the SAMHSA Web site at www.oas.samhsa.gov/2k5/MJageSMI/MJageSMI.cfm. 

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