I wrote a long time ago that cannabis sativa may not be good for your health, and today I see that the University of South Wales, Sydney has published a research paper titled Heavy teenage cannabis use linked with anxiety disorders in late 20s. The article cites a noted relationship between teenage weed use and late-20s anxiety mental disorders:
Teenagers who smoke cannabis weekly or more are twice as likely as non-users to have an anxiety disorder in their late 20s, even if they stop using, a study of 2000 Victorian teenagers has found. [...] [T]he really striking finding say the authors is the persistent association between frequent teenage cannabis use and adult anxiety disorders up to a decade after cannabis use has ceased. The relationship between cannabis use and anxiety disorders was present even after the researchers took into account other possible explanations such as mental health problems in their teens or other drug use in their twenties.
The researchers note that causation has not yet been explained:
Professor Patton, lead investigator of the 2000 stories cohort, said that the findings could be explained by lasting changes to brain function caused by introducing cannabis at a time when the brain is developing rapidly. Equally it could be that the very factors which predispose people to use cannabis early also predispose them to common mental health problems.
The study itself notes a possible positive note:
There were no consistent associations between adolescent cannabis use and depression at age 29 years.
You can read the research paper (PDF) for yourself to get the dirty details.
