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
Featured Video : Never Leave Your Child Alone in the Car: Parents Urged to Take Heat Stroke Seriously Before it's too late

Johnson & Johnson pulls controversial hysterectomy tool from market

Johnson & Johnson is withdrawing from the global market a device used during hysterectomies and other uterine procedures after reports that it may spread and accelerate the growth of undetected cancer inside women.

Read More »

Fear of Losing Money, Not Spending Habits, Affects Investor Risk Tolerance

As the U.S. economy slowly recovers, many investors remain wary about investing in the stock market. Investors' "risk tolerance," or their willingness to take risks, is an important factor for investors deciding whether, and how much, to invest in the stock market. Now, Michael Guillemette, an assistant professor of personal financial planning in the University of Missouri College of Human Environmental Sciences, along with David Nanigian, an associate professor at the American College, analyzed the causes of risk tolerance and found that loss aversion, or the fear of losing money, is the primary factor that explains investors' risk tolerance.

Read More »

Research Reveals Pervasive Implicit Hierarchies for Race, Religion, and Age

As much as social equality is advocated in the United States, a new study suggests that besides evaluating their own race and religion most favorably, people share implicit hierarchies for racial, religious, and age groups that may be different from their conscious, explicit attitudes and values.

Read More »

Girls who start dieting at a young age are more likely to be obese by 30

New research found that girls who begin dieting at a young age may face health problems later in life.

Read More »

Many depressed preschoolers still suffer in later school years

Children diagnosed with depression as preschoolers are likely to suffer from depression as school-age children and young adolescents, new research shows.

Read More »

Birth weight and breastfeeding have implications for children’s health decades later, study finds

Young adults who were breastfed for three months or more as babies have a significantly lower risk of chronic inflammation associated with cardiovascular and metabolic diseases, according to research from the Brown School at Washington University in St. Louis.

Read More »

Infants smell threats by mother's odor: Study

The sense of smell seems to be behind a mother's ability to pass specific fears to her infant in the first days of life. Scientists believe fear can be passed between generations, with mother to child the primary route.

Read More »

Preterm children's brains can catch up years later

There's some good news for parents of preterm babies - latest research from the University of Adelaide shows that by the time they become teenagers, the brains of many preterm children can perform almost as well as those born at term.

Read More »

First Grade Reading Suffers in Segregated Schools

A groundbreaking study from the Frank Porter Graham Child Development Institute has found that African-American students in first grade experience smaller gains in reading when they attend segregated schools-but the students' backgrounds likely are not the cause of the differences.

Read More »

Lifestyle affects risks of developing metabolic syndrome in childhood cancer survivors: Study

Leading a healthy lifestyle may lower childhood cancer survivors' risk of developing the metabolic syndrome, says a study.

Read More »

​Children with Disabilities Benefit from Classroom Inclusion

Language skills improve when preschoolers with disabilities are included in classes with typical peers

Read More »

Preschoolers With Special Needs Benefit From Peers’ Strong Language Skills

The guiding philosophy for educating children with disabilities has been to integrate them as much as possible into a normal classroom environment, with the hope that peers' skills will help bring them up to speed. A new study provides empirical evidence that peers really can have an impact on a child's language abilities, for better or worse.

Read More »

Real Time Analytics