You may have heard that psychedelics can help treat depression and PTSD. They’ve shown promise, but if neuroscientist Gul Dolen is correct, they can do a whole lot more than that. They might just be the master key that unlocks a whole array of other conditions, from stroke and autism to deafness and blindness.
Together with her colleagues at Johns Hopkins University, Dolen has shown in groundbreaking research published this year that all psychedelics have something special in common: the ability to reopen the “critical period” for social reward learning. A critical period is a window of time when the brain is extra malleable and sensitive to new experiences. As kids, we enjoy this higher plasticity, which means we have an easier time picking up languages or learning new behaviors. But as we get older, the window closes, and change becomes harder.
Psychedelics, it turns out, can hit the “reset” button on our brains, temporarily bringing them back to their childlike, open state. That may be why these drugs show promise in treating depression and PTSD: Under the right conditions, they help us get out of well-worn mental grooves so we can reappraise and chart a new course.
The Dolen lab discovered this by giving psychedelics to mice, who (like humans) have a critical period for social learning. Young mice will learn to prefer an environment if they associate it with hanging out with other mice — their impressionable brains link the environment to the joy of a hangout. Adult mice won’t form that link. But get them high on any type of psychedelics — MDMA, LSD, psilocybin, ketamine, ibogaine — and the adults will learn to prefer the social hangout spots too. Their critical period for social learning will reopen.
Our brains have other kinds of critical periods — for seeing, hearing, walking, you name it. Which raises the question: If psychedelics can reopen the critical period for social learning, can they do the same for others?
One tantalizing clue gives Dolen’s lab hope: In a 2020 study on vision, researchers found that ketamine can enable mice to recover from lazy eye. The visual cortex, like other parts of the brain, has a critical period early in life. If one eye doesn’t get proper inputs during that developmental period, the brain learns to neglect that eye. The result is a loss of vision. But because ketamine can reopen the critical period for vision, allowing the brain to learn afresh in a state of high neural plasticity, adult mice treated with the substance were able to recover vision in their lazy eye.
So in 2021, Dolen launched a new project called PHATHOM (Psychedelic Healing: Adjunct Therapy Harnessing Opened Malleability). The goal is to test whether psychedelics can unlock multiple critical periods across the brain and then harness them for healing. To start with, the researchers are looking at whether psychedelics can help restore movement in stroke patients — even if the stroke occurred years earlier. It’s a big bet, but if it pays off, it could change life for millions of people.