A new study involving the stimulant methamphetamine adds more credence to the notion that it's never too late to stop doing drugs.

Researchers at the University of California, Davis, have found that methamphetamine-related brain abnormalities are partially or completely reversed in users who steer clear of the substance for at least a year.

The findings are published in the April issue of the Archives of General Psychiatry.

People who abuse methamphetamine risk long-term attention and memory problems. Studies have suggested, however, that the changes may not be permanent and that the brain could actually repair itself with extended abstinence.

Meth Changes Brain Chemistry

Methamphetamine — sometimes known as "meth" — is an addictive, stimulant drug that strongly activates certain areas of the brain. The drug closely resembles amphetamine. However the stimulating effects of methamphetamine are much stronger.

According to the National Institute on Drug Abuse (NIDA), methamphetamine releases high levels of dopamine. Dopamine is a brain chemical that stimulates brain cells — enhancing mood and body movement. It also appears to have a toxic effect, damaging brain cells that contain dopamine and serotonin — another neurotransmitter. Over time, methamphetamine appears to cause reduced levels of dopamine, which can result in symptoms like those of Parkinson's disease, a severe movement disorder.

Thomas E. Nordahl, MD, PhD, and colleagues studied the brain imagesof eight methamphetamine users who had not used the drug in one to five years, 16 methamphetamine users who recently quit, and more than a dozen healthy people who were not substance abusers.

An imaging technique called MRS allows doctors to determine whether certain chemicals are present in the brain. For the study, Nordhal's team measured levels of N-acetylaspartate (NAA) and choline (Cho) in areas associated with attention.

Low NAA levels indicate nerve tissue loss in the brain and were used to monitor the amount of damage. Cho levels were used to measure how much the brain had recovered.

Brain Heals Itself

The researchers found abnormally low levels of NAA in all 24 former methamphetamine users, indicating that drug use does affect brain function. The longer a person had used the drug, the lower his NAA level.

However, Cho levels were elevated in those who had abstained from methamphetamine from one to six months. The levels were normal in former users who had quit the habit for several years.

"The relative Cho normalization across periods of abstinence suggests that when drug exposure is terminated, adaptive changes occur, which may contribute to some degree of normalization" in brain structure and function, the authors write in the journal report.

Researchers say understanding how the brain can repair itself in former drug users has important implications for neurobiologists studying addiction and for substance abuse treatment.

By Kelli Miller, reviewed by Brunilda Nazario, MD

SOURCES: Nordahl, T. Archives of General Psychiatry, April 2005; vol 62: pp 444-452. National Institute on Drug Abuse.