As an activist for the mentally ill, I am relieved that the Oregon Cannabis Tax Act will likely not be on the November ballot [
]. Scientific evidence is increasing that marijuana use is a risk factor in triggering schizophrenia, which affects more than 1 percent of the population, burdening society with huge risks all too familiar to Portland readers. Researchers in 30 studies during the past 20 years have linked the use of marijuana in adolescents to the increased probability of developing psychosis and schizophrenia.
A partial list of the studies, conducted in the U.K., Sweden, Australia, and New Zealand, can be accessed at www.schizophrenia.com/prevention/streetdrugs.html. One study conducted in Sweden concluded that heavy young consumers of cannabis at age 18 were 600 percent more likely to be diagnosed with schizophrenia than those who did not take it. Research by psychiatrists in inner-city areas described cannabis as being a factor in over 80 percent of cases of schizophrenia. As explained by Sanjiv Kumra, M.D., at the Albert Einstein College of Medicine in New York, "In addition to interfering with normal brain development, heavy marijuana use in adolescents may also lead to an earlier onset of schizophrenia in individuals who are genetically disposed to the disorder." Even as few as five uses of cannabis increased the risk of developing psychosis significantly, according to a 2005 Dutch study.
Self-medication with pot is very common in sufferers from schizophrenia, who in doing so counteract the medications that may improve their condition. Legalizing pot may have tragic consequences to them.
Ann T. Donnelly, Ph.D.
Member of the Board of Directors
National Alliance for Mental Illness (NAMI)–Clark County