Pregnancy, Babies, Parenting News & Tips

Marijuana Use in Adolescence May Cause Permanent Brain Abnormalities, Says Study

By Staff Reporter / Oct 10, 2013 01:52 PM EDT
  • Marijuana Use in Adolescence May Cause Permanent Brain Abnormalities, Says Study
  • (Photo : Flickr) A file photo of a brain

Regular marijuana use in adolescence, but not adulthood, may permanently impair brain function and cognition, and may increase the risk of developing serious psychiatric disorders such as schizophrenia, according to a recent study from the University of Maryland School of Medicine. Researchers hope that the study, published in Neuropsychopharmacology - a publication of the journal Nature - will help to shed light on the potential long-term effects of marijuana use, particularly as lawmakers in Maryland and elsewhere contemplate legalizing the drug.

Like Us on Facebook

"Over the past 20 years, there has been a major controversy about the long-term effects of marijuana, with some evidence that use in adolescence could be damaging," says the study's senior author Asaf Keller, Ph.D., Professor of Anatomy and Neurobiology at the University of Maryland School of Medicine. "Previous research has shown that children who started using marijuana before the age of 16 are at greater risk of permanent cognitive deficits, and have a significantly higher incidence of psychiatric disorders such as schizophrenia. There likely is a genetic susceptibility, and then you add marijuana during adolescence and it becomes the trigger."

"Adolescence is the critical period during which marijuana use can be damaging," says the study's lead author, Sylvina Mullins Raver, a Ph.D. candidate in the Program in Neuroscience in the Department of Anatomy and Neurobiology at the University of Maryland School of Medicine. "We wanted to identify the biological underpinnings and determine whether there is a real, permanent health risk to marijuana use."

The scientists - including co-author Sarah Paige Haughwout, a research technician in Dr. Keller's laboratory - began by examining cortical oscillations in mice. Cortical oscillations are patterns of the activity of neurons in the brain and are believed to underlie the brain's various functions. These oscillations are very abnormal in schizophrenia and in other psychiatric disorders. The scientists exposed young mice to very low doses of the active ingredient in marijuana for 20 days, and then allowed them to return to their siblings and develop normally.

"In the adult mice exposed to marijuana ingredients in adolescence, we found that cortical oscillations were grossly altered, and they exhibited impaired cognitive abilities," says Ms. Raver. "We also found impaired cognitive behavioral performance in those mice. The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood."

The scientists repeated the experiment, this time administering marijuana ingredients to adult mice that had never been exposed to the drug before. Their cortical oscillations and ability to perform cognitive behavioral tasks remained normal, indicating that it was only drug exposure during the critical period of adolescence that impaired cognition through this mechanism. The researchers took the next step in their studies, trying to pinpoint the mechanisms underlying these changes and the time period in which they occur.

"We looked at the different regions of the brain," says Dr. Keller. "The back of the brain develops first, and the frontal parts of the brain develop during adolescence. We found that the frontal cortex is much more affected by the drugs during adolescence. This is the area of the brain controls executive functions such as planning and impulse control. It is also the area most affected in schizophrenia."

Dr. Keller's team believes that the results have indications for humans as well. They will continue to study the underlying mechanisms that cause these changes in cortical oscillations. "The purpose of studying these mechanisms is to see whether we can reverse these effects," says Dr. Keller. "We are hoping we will learn more about schizophrenia and other psychiatric disorders, which are complicated conditions. These cognitive symptoms are not affected by medication, but they might be affected by controlling these cortical oscillations."

"This study is an example of how the basic science research taking place in our state-of-the-art laboratories can impact human health and inform health policy," says E. Albert Reece, M.D., Ph.D., M.B.A., Vice President for Medical Affairs at the University of Maryland and John Z. and Akiko K. Bowers Distinguished Professor and Dean of the University of Maryland School of Medicine. "We are proud of this groundbreaking discovery and look forward to watching this research develop further."

Provided by University of Maryland Medical Center

Physicists solve mystery of why cats rule, dogs drool

A Greyhound dog drinks water after a race in Santiago city, in this file picture taken March 1, 2014.

Read More »

U.N. to miss Dec 1 Ebola target due to rising Sierra Leone cases

A health worker fixes another health worker's protective suit in the Aberdeen district of Freetown, Sierra Leone, October 14, 2014.

Read More »

U.S. introduces menu calorie labeling to fight obesity

A pizza is served in Chicago January 20, 2010.

Read More »

New York's Cuomo warns snow-hit Buffalo of risk to roofs

Wreckage lays at a collapsed house following a massive snow storm in Alden, New York November 24, 2014.

Read More »

Dutch to destroy 8,000 ducks to prevent bird flu outbreak

Dutch to destroy 8,000 ducks to prevent bird flu outbreak

Read More »

Saudi Arabia tackles MERS virus, still hunting source

Saudi Arabia tackles MERS virus, still hunting source

Read More »

Mali records new Ebola case, linked to dead nurse

Mali records new Ebola case, linked to dead nurse

Read More »

"Assassin's Creed Unity" game delay hurts GameStop's revenue

The GameStop store sign is seen at its shop in Westminster, Colorado January 14, 2014.

Read More »

New York, Missouri patients test negative for Ebola virus

1 of 2. A view of Bellevue Hospital in the Manhattan borough of New York November 20, 2014.

Read More »

U.S. entrepreneur considered suing Uber over tracking activities

An illustration picture shows the logo of car-sharing service app Uber on a smartphone next to the picture of an official German taxi sign in Frankfurt, September 15, 2014.

Read More »

U.S. states get more, spend more on Medicaid under Obamacare: report

Six-month-old Hazel Garcia chews a pamphlet at a health insurance enrollment event in Cudahy, California March 27, 2014.

Read More »

Rocket Internet to launch another 10 start-ups in 2015

The logo of of Rocket Internet, a German venture capital group is pictured in this September 24, 2014 illustration photo in Sarajevo.

Read More »

Real Time Analytics