|
Pot smoking 'dulls memory'
14/03/2006 14:19 - (SA)
New York - People who regularly smoke
marijuana may find their memories growing hazy over time, a
study published on Monday suggests.
In a study of long-term and shorter-term marijuana users,
researchers in Greece found that both groups performed more
poorly on tests of memory, attention and other cognitive
abilities than a comparison group who'd only occasionally used
the drug.
Long-term users - who'd smoked four or more joints per week
for at least 10 years - showed the greatest deficits.
The findings, published in the journal Neurology, add to
the conflicting body of research on the effects of marijuana on
the brain. While many studies have suggested that long-time pot
smoking dulls memory, attention span and mental acuity, some
have found no large differences in these skills between
marijuana users and non-users.
One recent analysis of 15 studies found only minor effects
on memory among long-time pot users, and no clear effect on
attention, language, reasoning and a number of other cognitive
functions.
Stupid or stoned?
One problem is that it's difficult for studies such as the
current one to establish a definite cause-and-effect
relationship between marijuana and intellectual deficits, Dr
Lambros Messinis, the study's lead author, told Reuters Health.
Though the researchers accounted for a number of variables
- like education, use of other drugs and the presence of
clinical depression - it's tough to control for all the
factors that could make heavy marijuana users different from
other people, according to Messinis.
Still, he and his colleagues say, their findings are in
line with certain past studies linking heavy, long-term pot
smoking to "subtle" deficits in intellectual abilities.
The study included 40 marijuana users ages 17 to 49 who
were in a drug abuse treatment programme; all had used the drug
frequently for at least five years, but half - those
considered long-term users - had smoked for 10 years or more.
They were compared with 24 adults the same age who had used pot
no more than 20 times in their lives.
Overall, both long- and shorter-term marijuana users
performed more poorly on tests of memory, attention and
mental-processing speed. The proportion of study participants
deemed "impaired," according to the researchers, was highest in
the long-term group and lowest in the comparison group.
Long-time pot users showed the greatest problems on tests
where they were asked to learn and remember a series of words.
They were "significantly" below the published norms for these
tests, according to Messinis and his colleagues.
It's not yet clear whether the intellectual deficits linked
to marijuana are lasting, Messinis said, but research
"generally supports" the notion that these problems are
reversible after longer periods of abstinence. People in his
study were required to have been abstinent only for the 24
hours before taking the tests.
Another unknown, according to Messinis, is whether
marijuana use at a young age may affect the brain differently
than use during adulthood. Knowledge in this area, he said, is
still "poor."
- Reuters
|
News
