Teenagers who smoke cannabis damage their brains for LIFE

01 May 2012, Tilburg, Netherlands --- Heidi from Limburg, Belgium, smokes a joint in the Toermalijn coffee shop in Tilburg April 29, 2012. A controversial law that will make it harder for foreign tourists to buy cannabis at the Netherlands' famous coffee shops has been upheld by a Dutch court. The law, which goes into force in three southern provinces on May 1 before going nationwide next year, means coffee shops can only sell cannabis to registered members. Picture taken April 29, 2012. REUTERS/Michael Kooren (NETHERLANDS - Tags: SOCIETY BUSINESS DRUGS TRAVEL) --- Image by © MICHAEL KOOREN/Reuters/Corbis

Teenagers who regularly smoke cannabis suffer long lasting brain damage and are in much greater danger of developing schizophrenia.

American researchers say the drug is particularly dangerous for a group of people who have a genetic susceptibility to the mental health disorder – and it could be the trigger for it.

Asaf Keller, of the University of Maryland School of Medicine, said the results highlight the dangers of teenagers smoking cannabis during their formative years.

The study found that even short-term exposure to cannabis impaired brain activity, with the damage continuing into adulthood.

The study, published in the journal Neuropsychopharmacology, exposed young mice to the active ingredient in marijuana for 20 days.

It found that their brain activity was impaired, with the damage continuing into adulthood.

The past 20 years has seen major controversy about the long-term effects of marijuana, with experts divided over its long-term effects on teenagers.