Study subjects were small mice which were administered active ingredients in marijuana for 20 days. It was found that brain activity was heavily damaged and this condition event continued into adulthood.
In the past 20 years experts were divided on the long-term effects of marijuana and there have been many controversies about this subject.
According to earlier studies children who consume marijuana before they turn 16 are at a higher risk of permanent brain damage. They present a significantly higher incidence of psychiatric disorders too.
It should be noted that researchers exposed young mice to the active ingredient in marijuana after which they allowed the mice to return to their habitat. It was noted that although the young mice were exposed for only a short period of time and that they were given very low doses of marijuana, their brain abnormalities persisted even into adulthood.
Researchers then made a vice versa experiment, respectively they gave marijuana to adult mice that were not exposed to the drug in childhood.
Because the mice ability to perform basic tasks and because their cortical oscillations seemed normal it was concluded that only drug exposure during the critical teenage years can lead to impaired brain activity.