Old ideas up in smoke, pot might help the brain

October 13, 2005


While most addictive drugs, legal or illegal, have been proven to slow down or inhibit the growth of brain cells, a new study shows that marijuana might do just the opposite.

It might still be too early to claim pot smoking makes people smarter, but a new study from the University of Saskatchewan shows that some of the ingredients that make up marijuana can actually stimulate brain cell growth.

The study, headed up by Xia Zhang, an associate professor with the Neuropsychiatry Research Unit at the University of Saskatchewan, will be published in the Journal of Clinical Investigation in November.

The findings suggest controlled marijuana treatments can increase brain cell growth in the hippocampus area of the brain. The region is associated with learning and memory, as well as anxiety and depression.

The U of S study was performed on rats. They were injected with HU-210, a synthetic "cannabinoid" similar to a group of components found in marijuana, known as THC, but about 100 times the strength. THC is the compound of marijuana that produces the 'high,' sensation in users.

Zhang found that rats treated regularly with HU-210 experienced neurogenesis—they grew new brain cells in the hippocampus area.

Zhang's team believes depression and anxiety may be caused by a lack of brain cell growth in the hippocampal region. If that is true, marijuana, or at least HU-210, could offer a treatment for both depression and anxiety disorders by stimulating the growth of new brain cells.

The reaction is unique among drugs, both legal and illegal, such as alcohol, cocaine or heroine, which actually suppress the growth of new brain cells.

"Most 'drugs of abuse' suppress neurogenesis," said Zhang. "Only marijuana promotes neurogenesis."

But Zhang is quick to caution the findings don't mean marijuana is a miracle drug. His research has shown that using the drug comes with lots of side affects that aren't positive, such as memory impairment, addiction and withdrawal symptoms. And the version used in the tests was potent and pure. Nothing on the street would compare to it, he said.

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