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Source: United Press International (Wire)
Author: Steve Mitchell
Published: October 13, 2005
Copyright 2005 United Press International
Website: http://www.upi.com/
Contact: sciencemail@upi.com
Washington, D.C. -- Scientists said Thursday that marijuana appears to
promote the development of new brain cells in rats and have anti-anxiety
and
anti-depressant effects, a finding that could have an impact on the
national
debate over medical uses of the drug.
Other illegal and legal drugs, including opiates, alcohol, nicotine and
cocaine, have been shown to suppress the formation of new brain cells when
used chronically, but marijuana's effect on that process was uncertain.
Now, a team led by Xia Zhang of the department of psychiatry at the
University of Saskatchewan in Saskatoon may have found evidence the drug
spurs new brain cells to form in a region of the brain called the
hippocampus, and this in turn reduces anxiety and depression.
Marijuana appears "to be the only illicit drug whose capacity to produce
increased ... neurons is positively correlated with its (anti-anxiety) and
anti-depressant-like effects," Zhang and colleagues wrote in the November
issue of the Journal of Clinical Investigation. The paper was posted
online
Thursday.
In the study, rats were given injections of HU210 -- a synthesized version
of a cannabinoid chemical found in marijuana -- twice per day for 10 days.
Zhang told United Press International this would be "a high dose" of
smoked
marijuana, but he added he is not certain how many equivalent joints it
would take or whether patients now using the drug typically would be
getting
this much HU210.
Although HU210 was injected, Zhang said there would be no difference if it
was obtained by smoking marijuana.
The rats showed evidence of new neurons in the hippocampus dentate gyrus,
a
region of the brain that plays a role in developing memories.
Zhang's team suspected the new brain cells also might be associated with a
reduction in anxiety and depression, because previous studies had
indicated
medications used to treat anxiety and depression achieve their effect this
way.
To find out, they treated rats with HU210 for 10 days and then tested them
one month later. When placed in a new environment, the rats were quicker
to
eat their food than rats that did not receive the compound, which
suggested
there was a reduction in anxiety behaviors.
Another group of rats treated with HU210 showed a reduction in the
duration
of immobility in a forced swimming test, which is an indication the
compound
had an anti-depressant effect.
Asked how he thought the findings might impact the debate over using
marijuana to treat medical conditions, Zhang said, "Our results indicate
cannabinoids could be used for the treatment of anxiety and depression."
He added that his view is "marijuana should be used as alcohol or
nicotine,"
noting "it has been used for treating various diseases for years in other
countries."
Last June the U.S. Supreme Court voted 6-3 that the federal ban on
marijuana
supersedes the laws of certain states that allow the substance to be used
for medicinal purposes, such as the treatment of pain, nausea in cancer
patients and glaucoma. Eleven states have passed laws legalizing marijuana
use by patients with a doctor's approval, including California, Alaska,
Colorado, Hawaii, Maine, Montana, Nevada, Oregon, Vermont and Washington.
The Bush administration, through the Department of Justice's Drug
Enforcement Agency, began conducting raids in California in 2001 on
patients
using marijuana. Two of those arrested by the DEA -- Angel Raich, who
suffers from brain cancer, and Diane Monson, who used the drug to help
alleviate chronic back pain -- sued Attorney General John Ashcroft,
requesting a court order to be allowed to grow and smoke marijuana, which
led to the Supreme Court decision.
Paul Armentano, senior policy analyst with the National Organization for
the
Reform of Marijuana Laws, told UPI he thought the findings "would have a
positive impact on moving forward this debate, because it is giving ... a
scientific explanation that further supports long-observed anecdotal
evidence, and further lends itself to the notion that marijuana, unlike so
many other prescription drugs and controlled substances, appears to have
incredibly low toxicity and as a result lacks potential harm to the brain
that many of these drugs have."
The DEA Web site, however, contends that "marijuana is a dangerous,
addictive drug that poses significant health threats to users," including
cancer and impaired mental functioning.
Armentano said this is a distortion of what scientific studies actually
show. Studies in animals indicate marijuana actually may protect against
many forms of cancer, rather than cause the disease, he said. In addition,
studies in marijuana smokers have found little evidence of cognitive
deficits, and even when they do, the defects disappear if the person stops
smoking for 30 days.
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