Study Ties Marijuana Use in Adolescence to Permanent Brain Abnormalities

Most of America's youth get hooked on marijuana at a very early age.  The use of marijuana is definitely problematic but it rarely leads to addiction. A new study cautions those young kids who have been pot smokers for a long time and sheds light on the long-term effects of marijuana use.

The new study reveals that regular use of marijuana in adolescence may permanently damage the brain and doubles the risk of developing serious psychiatric disorders such as schizophrenia.

"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.

Prior to this, other studies have revealed that those children who start using marijuana before the age of 16 face an elevated risk of developing permanent cognitive deficits and the chances of psychiatric disorders like schizophrenia also doubles. Mostly it is a genetic susceptibility, and using marijuana during adolescence worsens the condition.

According to Sylvina Mullins, the lead author of the study, the use of marijuana especially during adolescence which is a critical period can be very damaging. Through this study researchers wanted to determine the real permanent health risks of regular marijuana use. 

The study was conducted on mice, in which the researchers examined the cortical oscillations - patterns of the activity of neurons in the brain and they underlie various brain functions. In people with psychiatric disorders and schizophrenia the oscillations are extremely abnormal.

In this study 20 young mice were exposed to extremely low doses of active ingredient in marijuana for nearly 20 days and later they were let free to join their siblings and grow normally.

They noticed that adult mice that were exposed to the marijuana ingredients in adolescence, the cortical oscillations altered to a great extent and they showed impaired cognitive behavioural performance. What they found, as predicted, is that even though the young mice were exposed to low dose of the drug and that too for a short duration their brain abnormalities continued till adulthood.

They again repeated the experiment on adult mice that have never been exposed to the drug, on administering the drug contents to adult mice they noticed that their ability to perform cognitive behavioural task remained normal. From this they concluded that adolescence remains a critical period.

Further, they noticed that the during adolescence the frontal cortex is affected the most on exposure to the drug and   this part of the brain controls executive functions like impulse control, planning etc. This area gets more affected in case of schizophrenia.

Dr. Keller concludes saying, "The purpose of studying these mechanisms is to see whether we can reverse these effects. 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."

The study was published in the journal Neuropsychopharmacology.