MARIJUANA AGAIN TIED TO MEMORY PROBLEMS

Athens - People who regularly smoke marijuana may find their
memories growing hazy over time, a study published 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.

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 program; 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.