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.