Pubdate: Mon, 05 Mar 2001
Source: New York Times (NY)
Copyright: 2001 The New York Times Company
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Author: Sandra Blakeslee
Bookmark: http://www.mapinc.org/meth.htm (methamphetamine)

DRUG'S EFFECT ON BRAIN IS EXTENSIVE, STUDY FINDS

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 nearly 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 stopped taking the 
drug for more than a year would 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.

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 
finance 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, it is known as speed, 
meth, chalk, ice, crystal and glass. The drug can be smoked, snorted, 
injected or taken by mouth. A $5 dose produces euphoria and increases 
energy for hours, whereas a cocaine high may last only half an hour.

It's not clear why some people choose cocaine over methamphetamine or vice 
versa, Dr. Volkow said. Estimates are that five million American have 
experienced methamphetamine and maybe one million to two million are 
regular users. "It's a bigger problem that heroin," she said.

Over the years, the addicts in the study had taken pounds of 
methamphetamine, an amount that is enough to kill laboratory animals, Dr. 
Volkow said. "Actually, I am stunned these people are not dead."

In the study, Dr. 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.

The addicts smoked or injected methamphetamine all day for several years, 
Dr. 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 like 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, Dr. 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 was that the addicts' parietal lobes, the 
parts of the brain used for feeling sensation and recognizing where the 
body is in space, were metabolically overactive, Dr. Volkow said. Other 
studies showed that metabolism increased when the brain suffered traumatic 
injury or got high doses of radiation, she said. It is the equivalent of an 
inflammation or scarring response.

The loss of dopamine is also worrisome, Dr. 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.

Five of the fifteen addicts have not relapsed and are being re-examined 
with brain imaging to see if their dopamine levels rebound. All smoke 
heavily, and it may be that nicotine protects their brains from being more 
severely damaged, she said. If that is the case, treatments for 
methamphetamine abuse might include nicotine patches and drugs to enhance 
dopamine function along with behavioral therapy.
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MAP posted-by: Larry Stevens