Pubdate: Sun, 22 Dec 2013
Source: Arizona Republic (Phoenix, AZ)
Copyright: 2013 The Arizona Republic
Website: http://www.azcentral.com/arizonarepublic/
Details: http://www.mapinc.org/media/24
Author: Dennis Thompson, HealthDay
Page: A25

'POTHEAD' IMAGE MAY HAVE EXPLANATION

Study: Memory Goes Up in Smoke for Heavy Weed Users

Shrunken structures inside the brains of heavy marijuana users might
explain the stereotype of the "pothead," brain researchers report.

Northwestern University scientists studying teens who were marijuana
smokers or former smokers found that parts of the brain related to
working memory appeared diminished in size - changes that coincided
with the teens' poor performance on memory tasks.

"We observed that the shapes of brain structures related to short-term
memory seemed to collapse inward or shrink in people who had a history
of daily marijuana use when compared to healthy participants," said
study author Matthew Smith. He is an assistant research professor in
psychiatry and behavioral sciences at the Northwestern University
Feinberg School of Medicine, in Chicago.

The shrinking of these structures appeared to be more advanced in
people who had started using marijuana at a younger age. This suggests
that youngsters might be more susceptible to drug-related memory loss,
according to the study, published in the Dec. 16 issue of the journal
Schizophrenia Bulletin.

"The brain abnormalities we're observing are directly related to poor
short-term memory performance," Smith said.

The participants had not been using marijuana for a couple years,
indicating that memory problems might persist even if the person quits
smoking the drug, said Dr. Frances Levin, chairman of the American
Psychiatric Association's Council on Addiction Psychiatry.

At the same time, Levin cautioned that the paper presents a
chicken-or-egg problem. It's not clear whether marijuana use caused
the memory problems or people with memory problems tended to use marijuana.

"The big $64,000 question is (whether) these memory problems predate
the marijuana use," Levin said.

Tests of working memory further found that marijuana users scored
lower compared with non-users.

Working memory is the ability to remember and process information in
the moment and, if needed, transfer it to long-term memory. Poor
working memory can lead to poor academic performance and problems with
everyday life.

Healthy people who never used marijuana scored 37 times better, on
average, than healthy users who had smoked in the past on memory
tests, while "clean" schizophrenics scored nearly four times better
than schizophrenic marijuana users.

The study confirms earlier findings that showed memory loss in young
marijuana users, said Dr. Scott Krakower, assistant unit chief of
psychiatry at Zucker Hillside Hospital in Glen Oaks, N.Y.

But Krakower said more work needs to be done before it's proven that
marijuana actually causes changes in the brain.

Dr. Mitch Earleywine, a professor of psychology and director of
clinical training at the State University of New York at Albany,
agreed that the results need to be replicated.

"Brain structural studies often look at every single spot and then
capitalize on the ones that are significant by chance," said
Earleywine, author of the book "Understanding Marijuana." "We've had
no structural deficits in folks who started using as adults, so
researchers went to adolescents."

Earleywine said marijuana users have been shown to perform more poorly
on memory tests due to the stress they endure taking such tests.
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