Pubdate: Tue, 07 Jan 2014 Source: Chronicle Herald (CN NS) Copyright: 2014 The Halifax Herald Limited Contact: http://thechronicleherald.ca/ Details: http://www.mapinc.org/media/180 Author: Lois Legge STUDY PROBES EFFECT OF CANNABIS ON BRAIN Researchers Seek Reasons Drug Can Prompt Psychosis in Youth Dr. Philip Tibbo clicks on an image of the brain and colour-coded white matter fills his office computer screen. But these days he is also delving into other mysteries of the mind as grey as the smoke from a controversial weed. Specifically, cannabis, a drug researchers believe can trigger psychosis in the still-developing brain, especially in people under 25. And especially those who may be predisposed to schizophrenia or other psychotic illnesses. That is something study after study has found, although no one knows exactly how it happens. "Now, we're looking at the biology behind it," says the Halifax psychiatrist, professor and researcher. Tibbo and a small team of researchers are looking inside young brains to see how cannabis disrupts the circuitry, hampers the vital connections needed to think, reason and remember clearly. The study is unique, he says, because it is using three MRI-based neuroimaging techniques he hopes will provide a clear map of what cannabis does to the white matter, neurochemicals and micro structure of the still-forming brain. It includes about 180 participants, divided into two main groups: a healthy control group and a patient group. Each will include people who have used cannabis before age 17, started using it later or never used it. Tibbo heads the Nova Scotia Early Psychosis Program, and his own studies and clinical experience already point to a clear link between cannabis use in young people and diagnoses of schizophrenia or other psychotic disorders. Research also shows it can worsen symptoms, usually delusions and hallucinations. Psychosis typically develops from ages 18 to 25, often the primary period - or even earlier - people smoke pot, Tibbo says. It's also a time when the brain's frontal lobe is still developing. "So what the research has shown is within that period if there's cannabis use, it can disrupt that process." That is especially true in those already predisposed to psychosis, perhaps even triggering its onset, says the Dr. Paul Janssen Chair in Psychotic Disorders at Dalhousie University. "You will increase your risk for psychosis by about four times. You look at a lot of the larger epidemiological studies and they can back that up." His centre helped develop a national study by Schizophrenia Society of Canada - Cannabis and Psychosis: Exploring the Link (www.cannabisandpsychosis.ca) that found more evidence of a strong connection. It trained 28 young people with psychosis to become research assistants in three Canadian centres: Halifax, London and Vancouver. They helped recruit other young people for one-on-one interviews or focus groups exploring their experiences with the drug. "We were trying to figure out why (they were) smoking and how did they feel that cannabis related to their illness," Tibbo says. "And most of them did say that, yes, they felt that (cannabis), if not precipitated their illness, made their symptoms worse and affected their recovery. Definitely they see that link." He says he stays away from the politics of the drug, which has been approved for some medical purposes. But Tibbo wants young people to know about its risks. "Even in the studies with cannabis in a regular population, we can show that it affects how you think and your cognition in the long term. So add psychosis on top of that (and) it's another hit on the brain. "As a doctor, we're trying to make sure everybody's as healthy as we possibly can and we know that cannabis itself can just derail everything." - --- MAP posted-by: Jay Bergstrom