Ecstasy, the amphetamine-like drug made popular by ``raves'' and other mass dancing events, can severely deplete levels of a brain chemical linked with mood, researchers said on Monday.

This could explain why users report they feel depressed as they come down off a high, the Canadian team of researchers said. They said a 26-year-old man who had died of a drug overdose had very low levels of serotonin in his brain. Serotonin is an important neurotransmitter or message-carrying chemical linked with mood, appetite, sleep and emotions. The man had been using Ecstasy for nine years, and in the last months of his life had also started using cocaine and heroin, the researchers wrote in the journal Neurology. Ecstasy, known chemically as methylenedioxymethamphetamine, or MDMA, is related to the hallucinogen mescaline and the stimulant amphetamine. It causes brain cells known as neurons to release serotonin. Ecstasy users say the drug makes them feel intimacy with other people and more aware of their emotions.