Taking Ecstasy did not decrease mental ability compared with with those who did not use the drug which researchers say runs contrary to earlier studies.

In one of the largest studies on the cognitive effects of the illegal party drug, U.S. researchers started with a pool of 1,500 potential participants.

While researchers found no concerning risks to cognitive performance from taking Ecstasy, it is not 'risk-free.' (Vancouver Police Department)

Of these, 52 Ecstasy users were compared with 59 non-users of the same age and sex.

Participants were tested several times to check they were telling the truth about their drug and alcohol use.

Ecstasy users showed no signs of cognitive impairment attributed to drug use, Dr. John Halpern of McLean Hospital in in Belmont, Mass., and his co-authors concluded in Tuesday's issue of the journal Addiction.

The findings don't mean ecstasy is risk-free, Halpern cautioned.

"Ecstasy consumption is dangerous: illegally-made pills can contain harmful contaminants, there are no warning labels, there is no medical supervision, and in rare cases people are physically harmed and even die from overdosing," Halpern said in a release.

"It is important for drug-abuse information to be accurate, and we hope our report will help upgrade public health messages. But while we found no ominous, concerning risks to cognitive performance, that is quite different from concluding that ecstasy use is 'risk-free'."

Unlike in previous studies, the non-users frequented raves, all-night dances where people are repeatedly deprived of sleep and fluids, the researchers said.

The experiment also corrected for the possibility of cognitive impairments in the ecstasy group that occurred before they started using the drug.