PICTURE OF YOUR BRAIN ON DRUGS

Brookhaven scientists are painting a picture of your brain on
drugs, and it's a frightening sight.

People who abuse methamphetamine-the drug commonly known as
"speed"-lose about a quarter of the brain cell receptors that regulate
a critical chemical called dopamine. A loss of dopamine receptors is
the hallmark of Parkinson's disease.

The study's participants also were found to have reduced cognitive and
motor functions.

"A drug abuser should know the damaging effects, the consequences, of
what they are using," said Dr. Nora Volkow, associate laboratory
director for life sciences at Brookhaven National Laboratory. "This is
a significant amount of damage." The changes, as documented by brain
scans, are greater than those that have been seen with heroin, alcohol
or cocaine, she said. The findings are published in the March issue of
the American Journal of Psychiatry.

The Brookhaven scientists recruited 15 methamphetamine users, all of
whom had smoked or injected the drug, practices that lead to high
concentrations in the brain. On average, the volunteers had five years
of chronic use, about five times a week. The study did not establish a
distinction between methamphetamine use and abuse.

At the time of the scan, the volunteers had not used the drug for two
weeks. Still, Volkow and her colleagues found a 25 percent reduction
of dopamine receptors. The scientists are now testing volunteers who
stopped methamphetamine use to see whether dopamine receptor levels
bounce back.

Dopamine is a neurotransmitter that regulates mood, movement and
behavior. People lose dopamine receptors as they age, about 6 percent
per decade. The brains of the participants "looked about 40 years
older than they should have," Volkow said.

People with Parkinson's disease have lost between 40 percent and 90
percent of their dopamine receptors before symptoms such as tremors
develop. Volkow said participants who had the most significant drop in
dopamine receptors also scored low on tests of motor performance and
memory.

Researchers also found evidence of a brain inflammatory response. An
area of the brain called the parietal lobes, which regulates sensation
and the ability to process visual and spatial information, appears to
be hyperactive on the brain scans.