The psychedelic drug MDMA can reopen a window to a ‘critical period’ in the brain’s development when it was first learning social behaviours, researchers at Johns Hopkins University have found. Harnessing this effect may make it helpful for treating people with post-traumatic stress disorder (PTSD) and other psychiatric disorders, they


Critical periods are stages of an organism’s lifespan during which the nervous system is particularly sensitive to picking up new skills or behaviours. For example, there is a critical period for the acquisition of language that typically lasts for the first several years of a person’s life. After this period is over it is much more difficult to learn how to speak a language fluently. Similar critical periods exist for the development of vision, touch and movement.

“We wanted to know if there was a critical period for learning social reward behaviours, and if so could we reopen it using MDMA, since this drug is well-known to have prosocial effects,” said research leader Ass Prof Gül Dölen.

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To find out, the team placed a group of mice all together in a enclosure filled with a specific type of bedding for 24 hours. They then separated the mice and placed them in individual enclosures filled with a different type of bedding for 24 hours. This taught the mice to associate the two types of bedding with isolation or companionship.

Then, they let the mice wander between enclosures with the two types of bedding and tracked how long they spent in each - the more time the mice spent in the bedding linked to their companions the more they were working to deepen their social bonds. By studying the mice as they matured they found that mice exhibit far less of this social bonding behaviour after hitting puberty.

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However, when they gave adult mice a dose of MDMA they found that most of them began to act like juveniles again by forming a positive association between social interactions and the bedding. This suggests that the MDMA was able to revert the mice’s brains to a critical period when they were learning how to establish social bonds.

“As we develop new therapies or determine when to give these therapies, it's critical to know the biological mechanism on which they act,” says Dölen. “This suggests that we've reopened a critical period in mice, giving them the ability to learn social reward behaviours at a time when they are less inclined to engage in these behaviours.”

Reopening the critical period for social reward behaviour may also have implications for treating psychiatric conditions as a strong bond between a psychotherapist and patient is known to be important for successful treatment, Dölen says.


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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.