MAPS: DPFCA: NORML re: JAMA on MJ & Cognition

[Peter Webster <vignes@xxxxxxxxx>]

NORML Foundation
1001 Connecticut Ave., NW
Ste. 710
Washington, DC 20036
202-483-8751 (p)
202-483-0057 (f)
www.norml.org
foundation@xxxxxxxxx

Today's topics:

* Science Challenges JAMA Report Linking Pot To Cognitive Decline
Cognition Unaffected by Long-Term Marijuana Use, Previous Studies Show

March 5, 2002

Science Challenges JAMA Report Linking Pot To Cognitive Decline
Cognition Unaffected by Long-Term Marijuana Use, Previous Studies Show
      Washington, DC: Numerous studies published between 1999 and 2001
challenge a report published today in JAMA (The Journal of the American
Medical Association) that marijuana smoking negatively impacts cognitive
function.
      "The only significant long-term impact marijuana has upon cognitive
function is upon those who continue to irrationally demonize and criminalize
this plant," said Allen St. Pierre, Executive Director of The NORML
Foundation.
      The JAMA study measured the cognitive skills of long-term marijuana users
seeking treatment for perceived cannabis dependence, many of whom voiced
previous concerns about perceived cognitive impairments. Controls (short-term
and non-users of marijuana) were selected from the general population.
Researchers found that long-term users who had abstained from marijuana for
an average of 17-hours performed significantly worse than controls on tests
of memory and attention.
      However, previous studies of long-term marijuana smokers not in treatment
have reached the opposite conclusion.
      In October, researchers at Harvard University reported that regular
marijuana smokers who abstain from pot for one week or more performed no
differently on cognitive tests than non-smokers.  According to findings
published in The Archives of General Psychiatry, chronic daily smokers
"showed virtually no significant differences from control subjects (those who
had smoked marijuana less than 50 times in their lives) on a battery of 10
neuropsychological tests."  The researchers concluded that their findings "do
not support the hypothesis that long-term heavy cannabis use causes
irreversible cognitive deficits."
      A recent meta-analysis of neuropsychological studies of long-term
marijuana smokers presented this summer at the NIDA (National Institute on
Drug Abuse) Workshop on the Clinical Consequences of Marijuana also found no
deficits in 7 of 8 neuropsychological ability areas.  "The studies ...
yielded no basis for concluding that long-term cannabis use is associated
with generalized neurocognitive decline," the researchers concluded.
      Additionally, a 1999 study of 1,300 volunteers published in The American
Journal of Epidemiology found that marijuana smoking, even long-term, failed
to significantly impact cognition.  Researchers administered subjects
Mini-Mental State Examinations (MMSE) in 1981 and 1982, and then measured
their performance on follow up tests some 12 to 15 years later.  In all,
researchers found "no significant differences in cognitive decline between
heavy users, light users, and nonusers of cannabis."
      Large government-sponsored studies conducted during the 1970s in Jamaica,
Greece and Costa Rica on marijuana smoking and cognition also reported no
significant differences between long-term smokers and non-smokers.
      NORML Foundation Chair and City University of New York (CUNY) medical
professor John P. Morgan M.D. said, "Based on this evidence, it does not
appear that long-term marijuana use causes any significant permanent harm to
intellectual ability."
      For more information, please contact either Allen St. Pierre or Paul
Armentano of The NORML Foundation at (202) 483-8751.



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