A chemical that is responsible for the effects of "love" ecstasy promotes co-operation but not curiously, research suggests.
Scientists found that MDMA, the main drug active ingredient, brings people together – but only when they trusted each other.
For the study, 20 adult men had either a typical MDMA recreational port or a fake pill and were asked to complete a number of tasks.
One task, a game called the Prisoner Dilema, meant choosing either to co-operate or compete with another player.
Points were awarded for collaboration, but if one player chose to compete, his opponent did not get anything.
The experiment, under the influence of MDMA, showed that the participants become more cooperatively – but only when interacting with players that they could trust.
Lead researcher, Professor Mitul Mehta, from the Institute of Psychiatry at King's College, London said: "We asked people what they thought about their opponent and, surprisingly, MDMA did not change their reliability of the opinion that the other players.
"The unexpected players were rated so low on the scale, whether it was MDMA or placebo, and reliable players were getting equally high.
"Significantly, MDMA did not cause participants to cooperate with unexpected players more than normal. In other words, MDMA did not mean that participants trusted other naive."
Although the volunteers thought they were playing real people through a computer, they were actually asked to respond to a program designed to appear reliably or incredibly.
King Anthony Gabay, a member of the King's College team now said at Oxford University: "When reliable players betrayed the participants, the breach of trust had an equally negative impact Participants under the influence of MDMA or not.
"MDMA, however, led to a faster recovery of cooperative and this relationship reconstruction tends to higher levels of collaboration with reliable partners."
Magnetic resonance imaging (MRI) scans were performed as the game was played.
It showed that MDMA is increasing activity in the brain parts that is known to be part of understanding other people's thoughts, beliefs and intentions.
When processing the behavior of reliable players, MDMA activity increases in the island region in the right.
But activity in the same region decreased when the brain processed the behavior of unexpected players.
The right-hand insulin is important for integrating evaluations, risk and uncertainty, the researchers who wrote in the Journal of Neuroscience said.
Professor Mehta added: "Understanding the activity of the brain that is a basis for social behavior can help identify what is going from a place in psychiatric conditions.
"Given the social nature of psychotherapy, understanding how MDMA affects social interaction sheds illuminates why the drug could become a valuable tool in treating patients."
– Press Society