USA – Teen Brains Damaged by Heavy Marijuana Smoking
In spite of continued claims that marijuana is harmless, researchers keep finding ways that it harms the body. A new study from the Children's Hospital of Philadelphia using imagining technology has found visible damage in the developing brains of teenagers who are heavy marijuana smokers. The affected areas of the brain are involved in memory, attention, decision-making, language and executive functioning skills. During the study, 14 heavy marijuana users, who were patients at a drug treatment center, were given a magnetic resonance imaging scan. The scan measures water movement throught brain tissues."The abnormal patterns of water diffusion that we found among the young men with histories of marijuana use suggest damage or an arrest in development of the myelin sheath that surrounds brain cells," said the study leader, Manzar Ashtari. "Myelin provides a coating around brain cells similar to insulation covering an electrical wire. If myelin does not function properly, signaling within the brain may be slower." The authors of the study conclude that early-onset substance abuse may alter the development of white matter circuits, especially those connections among the frontal, parietal and temporal regions of the brain, that could slow information transfer in the brain and affect cognitive functions. This study reinforces the idea that the adolescent brain may be especially vulnerable to risky behaviors such as substance abuse, because of crucial neural development that occurs during those years.
http://alcoholism.about.com/b/2009/02/05/teen-brains-damaged-by-heavy-marijuana-smoking.htm


USA - Marijuana May Raise Testicular Cancer Risk
Marijuana use may increase the risk of developing testicular cancer, in particular a more aggressive form of the disease, according to a U.S. study published recently. The study found that current marijuana users were 70 percent more likely to develop it compared to nonusers. The risk appeared to be highest among men who had reported smoking marijuana for at least 10 years, used it more than once a week or started using it before age 18, the researchers wrote in the journal Cancer. Stephen Schwartz of the Fred Hutchinson Cancer Research Center in Seattle, one of the researchers, said the study was the first to explore marijuana's possible association with testicular cancer. The study found the increased risk appeared to be in the form called nonseminoma testicular cancer. It accounts for 40 percent of cases and can be more aggressive and more difficult to treat, Schwartz said. Experts are unsure about the causes of testicular cancer, which often strikes men in their 20s and 30s. The disease is seen more commonly in men who have had an undescended testicle or have a family history of testicular cancer. Chronic marijuana use also can have effects on the male reproductive system including decreased sperm quality, they said.
http://www.javno.com/en/lifestyle/clanak.php?id=232267