Commonly referred to as ecstasy or molly, MDMA is anecdotally known to make people more open to empathetically interacting with those around them. However, a new study from King's College London has revealed that while the drug may increase cooperative behavior, it does not make a person more gullible or naive to the influence of untrustworthy people.

The fascinating study took 20 healthy adult men and administered them either a placebo or a dose of MDMA. While lying in an MRI scanner, the participants played several rounds of a Prisoner's Dilemma game.

The Prisoner's Dilemma is a game often used by psychologists to evaluate cooperative behavior and involves players choosing whether they want to cooperate or compete with another player. Points are evenly shared if both players choose to cooperate, however if one player doesn't cooperate then that individual receives all the points.

In the latest MDMA study, participants were also asked to rate their competitor's trustworthiness after each round of the game. The overall results showed that MDMA tended to enhance cooperative behavior, but not when they were consistently betrayed.

"When trustworthy players betrayed the participants the breach in trust had an equally negative impact whether participants were under the influence of MDMA or not," explains first author on the study, Anthony Gabay. "However, MDMA led to a quicker recovery of cooperative behavior and this tendency to rebuild a relationship led to higher overall levels of cooperation with trustworthy partners."

Despite the large current wave of research into MDMA, particularly as a treatment for PTSD, there has been little work examining how the drug affects complex social behavior. This new study offers a compelling insight into how the drug can increase a person's tendency towards cooperative behavior but interestingly reveals MDMA does not cause people to naively risk betrayal by untrustworthy partners.

"We asked people what they thought of their opponent and, surprisingly, MDMA did not alter how trustworthy they thought the other players were," says Mitul Mehta, senior author on the study. "Untrustworthy players were rated as low on the scale, whether on MDMA or placebo, and trustworthy players were given equally high ratings. Importantly, MDMA did not cause participants to cooperate with untrustworthy players any more than normal. In other words, MDMA did not make participants naively trusting of others."

The MRI data revealed interesting differences in brain activity between the MDMA subjects and the placebo subjects. Generally, the biggest differences in brain activity for the MDMA group occurred not when an individual was making a decision, but when an individual found out what choice the other player had made.

MDMA also seemed to increase activity in an area of the brain called the right anterior insula, known for evaluating appraisals, risk and uncertainty. Activity in this area was primarily increased when an individual was processing the behavior of trustworthy individuals, suggesting MDMA alters brain activity in highly specific ways that can depend on the type of person one is interacting with.

"Understanding the brain activity underlying social behavior could help identify what goes wrong in psychiatric conditions," says Mehta, explaining the broader, pragmatic outcomes to the research. "Given the social nature of psychotherapy, understanding how MDMA affects social interaction sheds light on why the drug could become a valuable tool in treating patients."

The study was published in the journal JNeurosci.