BETHESDA, MD (NIH) -- In a study supported by the National Institute on Drug Abuse (NIDA), researchers found that heavy stimulant abuse can result in changes in attention and motor skills that can persist for at least a year.

The investigators studied 50 pairs of twins; in each pair, one twin had a history of abusing cocaine and/or methamphetamine and the other had no history of drug abuse. Thirty-one monozygotic (identical) and 19 dizygotic (fraternal) adult male twin pairs were tested for attention and motor skills, executive functioning, intelligence, and memory at least one year after the drug-using twin's last-reported use of stimulants.

The researchers, led by Dr. Rosemary Toomey from Massachusetts General Hospital, found that the twin with a history of stimulant abuse performed significantly worse on several tests of attention and motor skills than did the sibling who had never used drugs.

However, abusers outperformed their non-drug-using twin on visual vigilance, a test measuring the ability to pay attention over time.

WHAT IT MEANS: This study provides evidence that stimulant abuse can result in long-term residual neuropsychological effects.

The study was published in the March 2003 issue of the journal Archives of General Psychiatry.