Thursday, April 24, 2014

Marijuana Legalization and Young Brains: Time for Serious Study

APA President Jeffrey Lieberman, M.D., is using the Psychiatric News Alert as a forum to reach APA members and other readers. This column was written by Dr. Lieberman and Robert DuPont, M.D. Please send your comments to

While we debate and differ on the risks and benefits of legalization, decriminalization, and medical uses of marijuana, all will agree (or say they do) that marijuana should remain illegal for young people. However, we should not deceive ourselves; just like with alcohol and tobacco, young people will almost certainly have ready access to pot with the liberalization of our laws and the commercialization of marijuana. What we are missing in fully understanding the ramifications of this new legislation, which can have broad effects on our country and culture, is firsthand knowledge of how marijuana affects the brain, particularly the young brain. Without more scientific evidence, we are gambling with the health and safety of our young people based on speculation and wishful thinking. Moreover, our national wager will increase as more states move to legalize marijuana.

The irony is that we currently have the capacity to determine whether there are harmful effects of marijuana on the developing brain. The rapid growth of brain science in the last two decades has provided the capacity to measure the effects of drugs on behavior and mental functions and to identify brain changes in structure and function—something not previously possible. Substantial evidence from animal models and several human studies has shown that drug use produces a sensitization of brain circuits that leads to sustained drug use and to progression to additional damaging drug use and to perpetuation and relapse during abstinence. The tragic death of Philip Seymour Hoffman is a prime example of these enduring effects. After a period of extensive drug use in his youth, he was drug-free for 20 years, only to fall victim to a common prescription for a pain medicine that triggered a fatal relapse into addiction at age 46.

The National Institute on Drug Abuse (NIDA) has funded groundbreaking research to understand specifically how drugs change the brain in a way that impairs mental functions and leads to addiction. This research has revealed how otherwise dissimilar drugs act through common neural pathways of reward to cause addiction. These fundamental pathways are hijacked by drugs that stimulate them far more intensely than do natural rewards like food and sex, which affect the same brain-reward system. That is why food and sex pathologies have so much in common with addiction to tobacco, alcohol, and other drugs, including marijuana.

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