Guest guest Posted January 26, 2006 Report Share Posted January 26, 2006 This article is seriously on the front page of the Boston Globe today. While off-topic, I thought it might interest some because of the genetic risk factor mentioned. Jeannie Studies link psychosis, teenage marijuana use Some adolescents carry genetic risk By Carey Goldberg, Globe Staff | January 26, 2006 Researchers are offering new ammunition to worried parents trying to dissuade their teens from smoking marijuana: Evidence is mounting that for some adolescents whose genes put them at added risk, heavy marijuana use could increase the chances of developing severe mental illness -- psychosis or schizophrenia. This week, the marijuana-psychosis link gained ground when two major medical journals reviewed the research to date and concluded that it was persuasive. In PLOS Medicine, an Australian public health policy specialist wrote that genetically vulnerable teens who smoke marijuana more than once a week ''appear at greater risk of psychosis, " while the British medical journal BMJ cited estimates that marijuana use could contribute to about 10 percent of cases of psychosis. The new research has little hint of ''Reefer Madness " alarmism. Rather, a half-dozen long, careful studies published in the last several years have tried to determine whether marijuana-smoking is a cause rather than an effect of mental illness. And groundbreaking research has begun to try to pinpoint which genes and brain chemicals could do the damage. The conclusions remain controversial, in part because it would be unethical to randomly assign teens to smoke or not smoke marijuana -- which would be necessary to perform a gold-standard study to definitively show that adolescent marijuana use causes mental illness. It could be the other way around, or some other factor could put teens at risk of both. But the recent research has attempted to get around these hurdles by controlling for factors such as the presence of psychosis before the use of marijuana, family income, education, other drug use, and childhood traumas. ''No single study is perfect, " Wayne Hall, author of the PLOS Medicine essay and a professor at the University of Queensland, said in an e-mail interview. ''But the fact that so many individually imperfect studies so consistently find this relationship adds confidence to the conclusion that the relationship is causal. " The recent research points to adolescence as a particularly risky time to smoke marijuana heavily for those genetically predisposed to mental illness. Brain scientists theorize that marijuana may induce temporary changes in brain chemistry that, when reinforced over time, become permanent. Among the research cited by both papers appearing this week was an intriguing study published last year that followed a group of more than 800 New Zealanders from birth until age 26. The study looked at people with a gene variant that apparently predisposes them to developing psychosis, and people without it. The variant was carried by 25 percent of the study's participants. The study found that among those with this variant, smoking marijuana as teens increased their risk of psychosis in young adulthood nearly tenfold compared with those who did not smoke as teens. Those who smoked marijuana but did not have the gene variant incurred little or no added risk Studies link psychosis, teenage marijuana use Some adolescents carry genetic risk By Carey Goldberg, Globe Staff | January 26, 2006 Researchers are offering new ammunition to worried parents trying to dissuade their teens from smoking marijuana: Evidence is mounting that for some adolescents whose genes put them at added risk, heavy marijuana use could increase the chances of developing severe mental illness -- psychosis or schizophrenia. Article Tools Printer friendly Single page E-mail to a friend Health & Fitness RSS feed Available RSS feeds Most e-mailed Reprints/permissions More: Globe Health / Science stories | Health & Fitness section | Science section | Globe front page | Boston.com Sign up for: Globe Headlines e-mail | Breaking News Alerts This week, the marijuana-psychosis link gained ground when two major medical journals reviewed the research to date and concluded that it was persuasive. In PLOS Medicine, an Australian public health policy specialist wrote that genetically vulnerable teens who smoke marijuana more than once a week ''appear at greater risk of psychosis, " while the British medical journal BMJ cited estimates that marijuana use could contribute to about 10 percent of cases of psychosis. The new research has little hint of ''Reefer Madness " alarmism. Rather, a half-dozen long, careful studies published in the last several years have tried to determine whether marijuana-smoking is a cause rather than an effect of mental illness. And groundbreaking research has begun to try to pinpoint which genes and brain chemicals could do the damage. The conclusions remain controversial, in part because it would be unethical to randomly assign teens to smoke or not smoke marijuana -- which would be necessary to perform a gold-standard study to definitively show that adolescent marijuana use causes mental illness. It could be the other way around, or some other factor could put teens at risk of both. But the recent research has attempted to get around these hurdles by controlling for factors such as the presence of psychosis before the use of marijuana, family income, education, other drug use, and childhood traumas. FOR MORE INFORMATION: National Institute on Drug Abuse National Institute of Mental Health NIMH: Teens with Deletion Syndrome Confirm Gene's Role NIMH: Brain Scans Reveal How Gene May Boost Risk ''No single study is perfect, " Wayne Hall, author of the PLOS Medicine essay and a professor at the University of Queensland, said in an e-mail interview. ''But the fact that so many individually imperfect studies so consistently find this relationship adds confidence to the conclusion that the relationship is causal. " The recent research points to adolescence as a particularly risky time to smoke marijuana heavily for those genetically predisposed to mental illness. Brain scientists theorize that marijuana may induce temporary changes in brain chemistry that, when reinforced over time, become permanent. Among the research cited by both papers appearing this week was an intriguing study published last year that followed a group of more than 800 New Zealanders from birth until age 26. The study looked at people with a gene variant that apparently predisposes them to developing psychosis, and people without it. The variant was carried by 25 percent of the study's participants. The study found that among those with this variant, smoking marijuana as teens increased their risk of psychosis in young adulthood nearly tenfold compared with those who did not smoke as teens. Those who smoked marijuana but did not have the gene variant incurred little or no added risk http://www.boston.com/yourlife/health/mental/articles/2006/01/26/stud ies_link_psychosis_teenage_marijuana_use/?p1=MEWell_Pos1 Quote Link to comment Share on other sites More sharing options...
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