Amidst the nationwide marijuana myth vs. fact controversy, a recent scientific study provides evidence about the long-term effects of marijuana use.

The Research Report on Marijuana Use published by the National Institute on Drug Abuse (NIDA) identifies the short-term effects of marijuana use, including: impairment of memory, attention, judgment, and other cognitive functions as well as coordination and balance.

However, a long-term study confirms suspicions; marijuana use by teens is harmful to their developing brain.  The study, which was published in August of 2012 in the Proceedings of the National Academy of Sciences by Dr. Madeline Meier of Duke University, reveals permanent and detrimental effects.

Researchers in New Zealand administered IQ tests to over 1,000 individuals at age 13 and assessed their patterns of cannabis use at several points as they aged. Participants were again tested for IQ at age 38, and their two scores were compared as a function of their marijuana use.   The results were striking: participants who used cannabis heavily in their teens and continued through adulthood showed a significant drop in IQ between the ages of 13 and 38—an average of 8 points for those who met criteria for cannabis dependence.

The loss of 8 IQ points could drop a person of average intelligence into the lowest third of the intelligence range.

In Arizona, the 2014 Arizona Youth survey reveals that 7% of 8th graders, 17% of 10th graders and 23% of 12 graders have smoked marijuana within the last 30-days, indicating a more regular use.

The high percentage of youth who are regular users of the drug marijuana are putting themselves and their future at great risk.

Nora D. Volkow, M.D., NIDA Director, posted on the NIDA website on March 21, 2013:  “Regular marijuana use in adolescence is part of a cluster of behaviors that can produce enduring detrimental effects and alter the trajectory of a young person’s life—thwarting his or her potential. Beyond potentially lowering IQ, teen marijuana use is linked to school dropout, other drug use, mental health problems, etc. Given the current number of regular marijuana users and the possibility of this number increasing with marijuana legalization, we cannot afford to divert our focus from the central point: Regular marijuana use stands to jeopardize a young person’s chances of success—in school and in life.”