Clinicians now believe that modern strains of super-strength cannabis are increasingly triggering psychoses, depression and anxiety disorders in teenagers. Many young people begin smoking cannabis before they have even hit their teens and experts are warning that the younger the smoker, the greater the risk of mental illness. Recent research shows that the human brain does not fully develop until a person reaches their twenties. Teenage brains, therefore, are more vulnerable than adults to cannabis. Modern technology multiplies the dangers. Hydroponically grown, genetically modified varieties of marijuana plants are believed to contain much greater concentrations of the chemical THC, or tetrahydrocannabinol. Cannabis is cheap, too, making it more easily available to today's teenagers than it was for their parents' generation. Young cannabis users in treatment for psychoses speak openly about their experiences to reporter Janine Cohen, while doctors and drug specialists explain what the new research means for young people's mental health.

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