Marijuana Seen Linked to Mental Illnesses

By Jessica L. Tonn — May 10, 2005 1 min read

Smoking marijuana in adolescence increases an individual’s chance of developing mental illness, a new report by the U.S. Department of Health and Human Services suggests.

Read the report. “Age at First Use of Marijuana and Past Year Serious Mental Illness,” from the U.S. Department of Health and Human Services’ Office of Applied Studies.

Adults who reported having first used marijuana before age 12 were twice as likely to have had a serious mental illness in the past year than those who reported having first used the drug at age 18 or older. Two percent of reported lifetime marijuana users began using the drug before age 12, and nearly 53 percent started between 12 and 17.

The results are based on the 2002 and 2003 National Survey on Drug Use and Health conducted by the HHS Department’s Substance Abuse and Mental Health Services Administration.

The study also found that 13 percent of adults who reported lifetime marijuana use were diagnosed with a serious mental illness, compared with 9 percent of the general adult population.