When Dr. Dennis Charney, now dean of the Icahn School of Medicine at Mount Sinai, began researching the phenomenon of resilience, he could not have predicted the work would end up generating a breakthrough treatment for depression. Charney studied prisoners of war to better understand how the human mind copes with mental and physical trauma and found a common theme key to their survival: the prisoners described focusing on a mental task to distract themselves from their difficult reality. Some built a dream house in their head, while others mentally penned their future memoir. Still others practiced multiplying 12 numbers at a time.
It took nearly 20 years of further research for Charney and his mentee at the time, Brian Iacoviello, to turn that observation into the first digital treatment for major depressive disorder, called Rejoyn. Further developed by the pharmaceutical company Otsuka, the app was cleared by the U.S. Food and Drug Administration (FDA) in 2024. People with depression practice a series of exercises that rebalance the cognitive and emotional functions of the brain—which, in depression, tend to skew toward negative emotional states like rumination. Users do the memory- and emotion-based exercises three to six times a week for six weeks, practicing their recall of faces expressing various emotional states. Interpreting human emotions while flexing memory muscles helps redirect the brain away from the circuits typical of depression. Brain imaging studies of people who used Rejoyn confirmed that their brains had changed, to more closely resemble the brains of people without depression. “We showed, to my surprise, that their depression got better,” Charney says. Researchers are now studying whether the app can help those with other conditions such as PTSD.