Mice, MDMA and the Brain: Why Drug Could Be Used to Treat PTSD

Researchers have found that the psychedelic drug MDMA reawakens a critical period in brain development in mice—a finding that casts new light on why the substance may be helpful in treating some people with post-traumatic stress disorder (PTSD). According to a study published in the journal Nature, just a single dose of MDMA helps to re-open this critical period—think of it as a kind of window—in adult mice. During the window, the brain is more sensitive to environmental stimuli and social interaction is more rewarding. Firstly, the researchers, led by Gül Dölen from Johns Hopkins University, identified that the critical period in mice begins at sexual maturity and ends when the rodents become mature adults. After the period finishes, the animals display a diminishing desire for social interaction—a process that is influenced by responses to the hormone oxytocin (sometimes referred to as the "love hormone"), which is produced in a brain region known as the hypothalamus and acts as signal between neurons that communicate information about social rewards. In an attempt to "reopen" this critical period in adult mice, the researchers gave them MDMA and observed them in their enclosures after waiting 48 hours for the drug to wear off. They found that this single dose caused most of the animals to respond to social interactions much like juveniles—and this effect lasted for about two weeks. "This suggests that we've reopened a critical period in mice, giving them the ability to learn social reward behaviors at a time when they are less inclined to engage in these behaviors," Dölen said in a statement. During the critical period, the team noticed that the mice that were given MDMA exhibited increased oxytocin signaling in certain areas of their brain—something that is not normally seen in adult mice. "We think that what MDMA does is cause oxytocin to be released," Dölen told Newsweek. "That extra oxytocin in turn causes the critical period for social reward learning to come back in adults." The researchers say that their new findings could potentially have implications for the development of treatments for certain mental health conditions in humans. In the case that MDMA reopens the critical period in people, just like it does for mice, then it could help to create a stronger bond between psychotherapist and patient—something that research shows significantly increases the chances that treatment will be successful. This could also explain why MDMA-assisted psychotherapy has shown promise for the treatment of post-traumatic stress disorder. "As we develop new therapies or determine when to give these therapies, it's critical to know the biological mechanism on which they act," Dölen said. MDMA-assisted psychotherapy is currently undergoing phase III clinical trials for the treatment of PTSD. If these demonstrate that it is effective with acceptable levels of safety, FDA approval could be expected by as early as 2021. This article was updated to include additional comments from Gül Dölen.