MDMA, also known as ecstasy, is known to make users more empathetic and willing to connect with other people. According to a new study, this may partly be explained by the drug’s ability to boost cooperative behavior. These findings suggest that MDMA causes changes in activity in brain regions linked to social processing, making it relevant for treating psychiatric conditions such as post-traumatic stress disorder (PTSD).

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Researchers at King’s College London gave 20 healthy adult men either a typical recreational dose of MDMA or a placebo. The participants then had to complete several tasks while in an MRI machine that scanned their brain activity, including the Prisoner’s Dilemma.

The Prisoner’s Dilemma is one of the most famous and most discussed case studies in both economics and psychology introductory classes. In this scenario, two prisoners are each isolated from one another and have to make one of two choices: either they turn the other in (sabotage) or remain silent (cooperate). If both players cooperate, they each receive some points (both win) but if one player chooses to compete, they receive all the points while the other player gets nothing (one wins, the other loses).

In this experiment, the participants thought they were playing the Prisoner’s Dilemma game with other real people. In fact, the other player was a pre-programmed computer response which would behave either in a trustworthy or untrustworthy manner throughout the various rounds of the game.

While under the influence of MDMA, participants were more inclined to cooperate than those who just received a placebo — but only when interacting with trustworthy players.

“We asked people what they thought of their opponent and, surprisingly, MDMA did not alter how trustworthy they thought the other players were. Untrustworthy players were rated as low on the scale, whether on MDMA or placebo, and trustworthy players were given equally high ratings,” senior author Professor Mitul Mehta said in a statement.

“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 scans showed that while high on MDMA, participants had increased activity in the superior temporal cortex and mid-cingulate cortex, which are areas known to be important in understanding the thoughts, beliefs, and intentions of other people. More importantly, MDMA increased activity in the right anterior insular when the participants played the game with trustworthy players, and decreased activity in the brain region when processing the behavior of untrustworthy players. This shows that MDMA impacts the way we process other people’s behavior, rather than altering the decision-making process itself, the authors noted in The Journal of Neuroscience.

Some psychiatric conditions are underlied by improper brain activity connected to social behavior. Understanding how MDMA affects social interactions is important in the context of psychotherapy, where the drug could become a valuable tool in treating patients.

Right now, MDMA is currently undergoing phase 3 clinical trials for treating PTSD and has been given Breakthrough Therapy designation by the FDA.