METH'S HARM TO BRAIN WORSE THAN BELIEVED

Year After Quitting Stimulant, Users Lag In Learning, Memory

Heavy users of methamphetamine -- a highly addictive stimulant that
can be made at home in the kitchen sink -- are doing more damage to
their brains than scientists had thought, according to the first study
that looked inside addicts' brains almost a year after they stopped
using the drug.

At least a quarter of a class of molecules that help people feel
pleasure and reward were knocked out by methamphetamine, the study
found. Some of the addicts' brains resembled those of people with
early and mild Parkinson's disease. But the biggest surprise is that
another brain region responsible for spatial perception and sensation,
which has never before been linked to methamphetamine abuse, was
hyperactive and showed signs of scarring.

On tests of memory, attention and movement, the methamphetamine
addicts did worse compared with people who do not use drugs, the study
reported. The researchers said it was too soon to know if people who
stop taking the drug for more than a year will recover lost brain function.

The study was led by Dr. Nora Volkow, associate director for life
sciences at the Brookhaven Haven National Laboratory in Upton, N.Y.,
and appears in the March issue of the American Journal of Psychiatry.

Landmark Research

This is the first study to show directly that brain damage caused by
methamphetamine produces deficits in learning and memory, said Dr.
Alan Leshner, director of the National Institute on Drug Abuse, which
helped fund the new research. Use of the drug has reached epidemic
proportions in Hawaii, California and parts of the Midwest, he said.

Made in clandestine laboratories from cheap ingredients, the drug is
known as speed, meth, chalk, ice, crystal and glass. It can be smoked,
snorted, injected or taken by mouth. A $5 dose produces euphoria and
increases energy for hours.

Estimates are that 5 million Americans have experienced
methamphetamine and maybe 1 million to 2 million are regular users.
"It's a bigger problem that heroin," Volkow said.

In the study, Volkow used an imaging technique called positron
emission tomography to measure dopamine levels in the brains of 15
recovering addicts and 18 healthy volunteers. Dopamine is a brain
chemical that regulates movement, attention, pleasure and motivation.
When the dopamine system goes seriously awry, she said, people lose
their excitement for life and can no longer move their limbs. Their
brains were then imaged a second time to measure how different parts
of their brains metabolize energy.

Systems Taken Hostage

The addicts smoked or injected methamphetamine all day for several
years, Volkow said. They had started out as occasional users, but over
time the drug hijacked their natural dopamine systems. Two weeks after
the brain images were taken, the addicts and the volunteers were
brought back to the laboratory and asked to do tasks such as walking
as fast as possible in a straight line, rapidly inserting pegs into
small holes angled in different directions, matching numbers with
symbols, recalling lists of unrelated words and carrying out other
tests that measure brain acuity.

On average, dopamine was 24 percent lower in addicts than in normal
volunteers, Volkow said. They were clumsier at putting pegs in the
holes and had difficulty remembering words. Half the addicts said they
felt their brains were not working as well as they used to.

But the study's biggest surprise is that the addicts' parietal lobes,
the part of the brain used for feeling sensation and recognizing where
your own body is in space, were metabolically overactive, Volkow said.
Other studies show that metabolism increases when the brain suffers
traumatic injury or gets a high dose of radiation, she said. It's the
equivalent of an inflammation or scarring response.

Future Impact A Mystery

The loss of dopamine is also worrisome, Volkow said. Three drug
abusers had dopamine levels that fell within the range seen in
patients with low-severity Parkinson's disease. Because dopamine
levels fall naturally with age, it's unclear what will happen to these
people 30 years from now.

"We don't know if they will recover dopamine function or not," she said.