Pubdate: Fri, 03 Nov 2006 Source: Peace Arch News (CN BC) Copyright: 2006 Peace Arch News Contact: http://www.peacearchnews.com/ Details: http://www.mapinc.org/media/1333 Author: Jeff Nagel POT LINKED TO PSYCHOSIS Survey Showing Wide Use Alarms Doc A new poll showing 53 per cent of B.C. residents have used marijuana at least once is disturbing, says a South Surrey psychiatrist. "People should be aware this isn't a benign substance," said Dr. Bill MacEwan, who addressed a Fraser Health Authority board meeting Wednesday. He said clinical evidence from here and around the world increasingly links pot smoking - especially heavy use at an early age - with psychosis. "It's a real concern to us that we're seeing these rates of substance abuse," he said, responding to the poll released last month by B.C.'s Centre for Addictions Research. Although crystal methamphetamine is more widely linked to psychosis, MacEwan said cocaine and marijuana can also stimulate dopamine receptors in the brain and lead to the mental disorder, often manifested by paranoia or hallucinations. "I'm not trying to imply that anyone who smokes marijuana can have psychosis," he said. "But it's a really interesting figure to see that more than half of our population is dabbling in drugs that are having an effect on a system we are looking at in terms of psychosis." The marijuana link to psychosis is being traced by Fraser Health's Early Psychosis Intervention program, where at least half of psychosis patients are substance users and many smoke pot. "With chronic long-term smokers who are smoking at least one time a week for longer than a couple of months, we're seeing people have an increased risk of psychosis," said MacEwan, who is EPI's clinical director as well as director of psychiatry at UBC. He estimates the rate of psychosis among those regular pot users is six to seven times the rate of non-users, who have a roughly one in 100 chance of suffering from psychosis. "We're finding that people within our program who actually smoke marijuana and have psychosis, their symptoms are far worse when they're smoking marijuana," MacEwan said, adding the drug can interfere with other prescriptions. One of the other risk factors for psychosis and schizophrenia is life in a highly urban environment, MacEwan said. That's why there are heavy clusters of patients in Fraser Health's EPI program in central Surrey, he said, mirroring a similar cluster in downtown Vancouver. Over the last three years, 221 cases were diagnosed in the South Fraser area, including 138 in Surrey, 39 in Langley, 34 in Delta and 10 in White Rock. Because the bulk of the risk is genetic, one family member with schizophrenia means other siblings or children are at a higher risk. But MacEwan said that danger has been over-estimated by people, leading too many to opt, for example, not to have children. The one per cent risk for the general population climbs to nearly 10 per cent if a sibling is schizophrenic. Fraser Health's six-year-old EPI program has been expanded in recent years to the rest of the health region. - --- MAP posted-by: Elaine