Nov. 27 (Bloomberg) -- Getting high just a few times using the drug known as ecstasy is enough to damage cells and reduce blood flow to the brain, possibly permanently, a study says.

Low doses of the drug were linked to subtle changes in the architecture of brain cells 18 months after first use, according to research presented today at a meeting of the Radiological Society of North America in Chicago. First-time users also showed a decrease in verbal memory.

Ecstasy, a stimulant that can cause hallucinations, is an illegal drug often found at nightclubs or all-night dance parties, called raves. While extensive use has already been shown to harm neurons in the brain, causing depression, anxiety and memory loss, this is the first study to identify the risk of brain damage among those who have taken only a few doses.

``We don't know if it's reversible or permanent,'' said Maartje de Win, a radiology resident at the University of Amsterdam, in a telephone interview today. ``People should know there might be some consequences for them even after incidental use.''

More than 11 million Americans say they have tried ecstasy at least once, according to the 2004 National Survey on Drug Use and Health. A 2005 survey found that 2.8 percent of eighth graders and 5.4 percent of 12th graders in the U.S. have tried the drug, the National Institute on Drug Abuse said.

De Win and her colleagues first took brain scans of 188 young adults with an average age of 22 who weren't ecstasy users, yet met certain criteria for being at risk for trying the drug in the near future. After 18 months, the researchers reexamined 59 people who had each taken an average of six tablets of ecstasy and 56 people who hadn't tried the drug.

Adverse Effects

When ecstasy, known chemically as MDMA or 3,4- methylenedioxymethamphetamine, first became popular in the late 1980s and early 1990s, part of the draw for young people was that many were under the impression that the drug wasn't addictive and could be used at parties or on the weekends without any adverse effects, de Win said.

De Win said she was surprised that 64 of the 188 young people selected for the study chose to try ecstasy on their own, even after researchers warned them about the potential risks in their initial examinations. Five of the youth declined to participate in the follow-up tests.

To contact the reporter on this story: Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: November 27, 2006 12:33 EST