03-07-2002, 03:32 AM
This was an article too good not to post here, made front page on Yahoo...
<font size="3">Long-Time Pot Users Show Mental Deficits</font>
Tue Mar 5, 5:37 PM ET
By Amy Norton
NEW YORK (Reuters Health) - Long-time, heavy marijuana users may eventually see their memory and attention span go up in smoke, new research suggests.
Investigators found that, among pot smokers seeking treatment for marijuana dependence, long-time users performed more poorly on tests of memory and attention than shorter-term users and non-users.
The findings show that over time, marijuana smoking can cause intellectual impairments that "endure beyond the period of intoxication" and worsen the longer a person uses the drug, the study authors report in the March 6th issue of The Journal of the American Medical Association.
But another researcher not involved in the study pointed to shortcomings in the work that he says make it tough to draw that conclusion.
In an accompanying editorial, Dr. Harrison G. Pope, Jr. notes that marijuana users who seek drug treatment do not necessarily reflect users in general, since these individuals may have other health issues such as anxiety or depression.
In the study, researchers led by Dr. Nadia Solowij of the University of New South Wales in Sydney, Australia studied 102 pot-smoking Americans and 33 non-users. Marijuana users typically smoked every day, with long-time users doing so for an average of 24 years. Shorter-term users had smoked for about 10 years, on average. The vast majority said that they currently were not using other drugs, or did so only occasionally.
Results of the mental functioning tests--taken after at least 12 hours of abstinence--showed that long-time users performed less well than shorter-term users and non-users.
"We found that long-term users had problems with learning, storage of learned information and retrieval of information from memory," Solowij told Reuters Health.
This does not mean the drug caused brain damage in these cases, she said, explaining that the impairments seen in long-time users were "relatively subtle."
Still, Solowij noted, the deficits could affect daily functioning--hindering, for example, a person's ability to study or remember an item he or she just read.
But although such deficits, if prolonged or irreversible, would be of "grave concern," other studies have found no such impairments in long-time marijuana users, according to Pope, a researcher at Harvard Medical School and McLean Hospital in Belmont, Massachusetts.
Pope and his colleagues recently found "virtually no significant differences" between heavy marijuana users and non-users on a battery of neuropsychological tests.
Part of the difficulty in sizing up the impact of marijuana is weeding the drug's effects out from the "background noise" of other factors, like psychiatric problems and abuse of other drugs, according to Pope. In this study, nearly half of the long-time marijuana users had in the past regularly used or abused alcohol or other drugs.
But there are also plausible biological reasons for why sustained marijuana use could affect things like memory. Solowij noted that the brain receptors the drug acts on exist in large numbers in regions involved in memory. Over the years, she said, marijuana exposure might change the way these receptors and other brain chemicals operate.
According to Pope, it seems almost certain that marijuana produces short-lasting mental deficits, but whether they endure or worsen over time is still unclear.
Also unknown is whether any impairments are reversed after a person stops smoking pot, Solowij pointed out.
"We do not yet know whether the impairments recover after stopping or reducing (marijuana) use," she said. "We are currently investigating this question."
SOURCE: The Journal of the American Medical Association 2002;287:1123-
<font size="3">Long-Time Pot Users Show Mental Deficits</font>
Tue Mar 5, 5:37 PM ET
By Amy Norton
NEW YORK (Reuters Health) - Long-time, heavy marijuana users may eventually see their memory and attention span go up in smoke, new research suggests.
Investigators found that, among pot smokers seeking treatment for marijuana dependence, long-time users performed more poorly on tests of memory and attention than shorter-term users and non-users.
The findings show that over time, marijuana smoking can cause intellectual impairments that "endure beyond the period of intoxication" and worsen the longer a person uses the drug, the study authors report in the March 6th issue of The Journal of the American Medical Association.
But another researcher not involved in the study pointed to shortcomings in the work that he says make it tough to draw that conclusion.
In an accompanying editorial, Dr. Harrison G. Pope, Jr. notes that marijuana users who seek drug treatment do not necessarily reflect users in general, since these individuals may have other health issues such as anxiety or depression.
In the study, researchers led by Dr. Nadia Solowij of the University of New South Wales in Sydney, Australia studied 102 pot-smoking Americans and 33 non-users. Marijuana users typically smoked every day, with long-time users doing so for an average of 24 years. Shorter-term users had smoked for about 10 years, on average. The vast majority said that they currently were not using other drugs, or did so only occasionally.
Results of the mental functioning tests--taken after at least 12 hours of abstinence--showed that long-time users performed less well than shorter-term users and non-users.
"We found that long-term users had problems with learning, storage of learned information and retrieval of information from memory," Solowij told Reuters Health.
This does not mean the drug caused brain damage in these cases, she said, explaining that the impairments seen in long-time users were "relatively subtle."
Still, Solowij noted, the deficits could affect daily functioning--hindering, for example, a person's ability to study or remember an item he or she just read.
But although such deficits, if prolonged or irreversible, would be of "grave concern," other studies have found no such impairments in long-time marijuana users, according to Pope, a researcher at Harvard Medical School and McLean Hospital in Belmont, Massachusetts.
Pope and his colleagues recently found "virtually no significant differences" between heavy marijuana users and non-users on a battery of neuropsychological tests.
Part of the difficulty in sizing up the impact of marijuana is weeding the drug's effects out from the "background noise" of other factors, like psychiatric problems and abuse of other drugs, according to Pope. In this study, nearly half of the long-time marijuana users had in the past regularly used or abused alcohol or other drugs.
But there are also plausible biological reasons for why sustained marijuana use could affect things like memory. Solowij noted that the brain receptors the drug acts on exist in large numbers in regions involved in memory. Over the years, she said, marijuana exposure might change the way these receptors and other brain chemicals operate.
According to Pope, it seems almost certain that marijuana produces short-lasting mental deficits, but whether they endure or worsen over time is still unclear.
Also unknown is whether any impairments are reversed after a person stops smoking pot, Solowij pointed out.
"We do not yet know whether the impairments recover after stopping or reducing (marijuana) use," she said. "We are currently investigating this question."
SOURCE: The Journal of the American Medical Association 2002;287:1123-
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