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Marijuana Research


Daily Marijuana Use Could Cause Permanent Brain Damage (01/07/2010)

Animal studies show that daily marijuana use could permanently alter serotonin and norepinephrine levels in the brain, raising the risk of depression and anxiety, according to researcher Gabriella Gobbi of McGill University.

The Canadian Press reported Dec. 17 that Gobbi studied the brain chemistry of 18 adolescent lab rats exposed daily to marijuana and found that they had decreased levels of mood-controlling serotonin and higher levels of the stress hormone norepinephrine. Gobbi said that the effects were magnified because the adolescent brain is still developing. "These permanent changes in the brain are also linked to certain mental illnesses, like schizophrenia," she said. "And we showed that even if we stopped the cannabis use at the end of adolescence, the changes were still detectable in adulthood."

A future study will concentrate on adolescent marijuana use among humans. The study was published in the journal Neurobiology of Disease. Research summary reprinted with permission from Join Together.

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Marijuana Leads to Respiratory Illness (2003)

Doctors are finding an increase in respiratory illnesses, including the debilitating vanishing-lung syndrome, in people aged 25-40 who are regular marijuana smokers, the Independent reported February 27.

Vanishing-lung syndrome is a form of emphysema that reduces the surface of the lungs and replaces it with huge cysts. The cysts restrict the transfer of oxygen into the blood.

"Every couple of months I'm finding a new patient showing signs of this condition but nobody knows for sure just how many people are affected," said Dr. Mark Johnson, a specialist registrar in respiratory medicine at the Glasgow Royal Infirmary in the United Kingdom.

Johnson and his colleagues conducted a study that found that people who smoke two to three marijuana cigarettes a day suffer similar lung damage as those who smoke more than 20 conventional cigarettes a day. However, Johnson said that pot smokers are more at risk for vanishing-lung syndrome than cigarette smokers because they inhale more deeply and hold smoke longer in their lungs. "When this smoking practice is combined with the lack of filter tips on marijuana cigarettes, it leads to a fourfold greater delivery of tar and a five times greater increase in carboxyhemoglobin per cigarette smoked," the researchers said. This summary is reprinted with permission from Join Together Online.

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