In the first study of its kind, researchers have found that peyote – for now, the only legal hallucinogenic drug in the United States – doesn't rob regular users of brain power over time.

While the findings don't directly indicate anything about the safety of psychedelic drugs like LSD and mushrooms, they do suggest that at least one hallucinogen is OK to use for months or even years.

"We really weren't able to find any (mental) deficits," said Dr. John Halpern, associate director of substance abuse research at McLean Hospital in Belmont, Massachusetts, and co-author of the study, released today in the Nov. 4 issue of the journal Biological Psychiatry. Hallucinogenic drugs have long fascinated researchers, who are now studying whether they hold the potential to treat mental illnesses like depression and obsessive-compulsive disorder.

But little is known about the long-term effects of hallucinogenic use. Part of the problem is that many users – such as LSD aficionados – take a variety of other drugs, so it's hard to tease out the specific effects of psychedelic drugs.

Enter peyote, currently the only hallucinogenic drug legally allowed for use outside research labs (although that may change). Compared with LSD and mushrooms, peyote is a bit obscure, with its use – at least legally – limited to the sacramental rites of the Native American Church, which has as many as 300,000 members. Many peyote users don't take other drugs, making them ideal subjects for hallucinogenic research.

Peyote comes from the crowns of a cactus that grows in northern Mexico and parts of Texas. Harvesters cut off the crown, dry it and sell it in "buttons," Halpern said. Generally, users eat the buttons whole or grind them up into a powder that can be mixed into food or brewed into a tea.

When enough peyote is eaten, users enter a hallucinogenic state thanks to its active ingredient, the chemical mescaline. Halpern and colleagues recruited three groups of Navajos – 61 members of the Native American Church who regularly ate peyote, 36 alcoholics who have been dry for at least two months and 79 people who reported little or no use of alcohol or drugs. The researchers then gave mental-health and cognitive tests to the subjects.

Only the alcoholics showed signs of brain problems. On the psychological front, Native American peyote users were actually in better shape emotionally than those who didn't use the drug.

Why? For one thing, the church provides plenty of emotional support to members, said Dennis J. McKenna, senior lecturer at the University of Minnesota's Center for Spirituality & Healing. For another, Native American users are careful about how they use peyote. "The context of the use is a really important thing," McKenna said. "Most people using mushrooms or LSD in a recreational way don't really have a context for this type of use," such as an emphasis on setting, à la psychedelic guru Timothy Leary.

By contrast, both alcohol and marijuana are considered bad for the brain if overused. Although there's still plenty of debate, some research suggests heavy pot use can harm memory for days after the last toke. And, of course, there's the anecdotal evidence of brain damage from everyone who's known a Jeff Spicoli-type stoner.

Marijuana damage seems to be temporary, while alcohol-related damage appears to be more permanent, said study co-author Dr. Harrison Pope Jr., director of the Biological Psychiatry Laboratory at McLean Hospital. The jury's still out, he said, on what damage LSD does to the brain, if any, and for how long.

Both researchers cautioned that the peyote findings shouldn't make anyone think LSD and mushrooms are safe.

The drugs are chemically different and appear to work differently too. Neither Pope nor Halpern, for example, has ever heard of a peyote user having a flashback. Even a person with memory impairment would likely remember that.