These memories have tormented Cowley his whole adult life. For 30 years he suffered from flashbacks and insomnia. He had trouble working but was too ashamed to talk to his wife. He blocked out the worst of it by drinking. In 2004 one doctor referred him to a trainee therapist, but it didn't help, and he dropped out after a couple of sessions. But two years ago he spotted a poster advertising therapy over the internet, and he decided to give it another go.

Some experts believe AI can make treatment more accessible and affordable. There has long been a severe shortage of mental-health professionals, and since the Covid pandemic, the need for support is greater than ever. For instance, users can have conversations with AI-powered chatbots, allowing then to get help anytime, anywhere, often for less money than traditional therapy. The algorithms underpinning these endeavors learn by combing through large amounts of data generated from social-media posts, smartphone data, electronic health records, therapy-session transcripts, brain scans and other sources to identify patterns that are difficult for humans to discern. Despite the promise, there are some big concerns.

Some experts believe AI can make treatment more accessible and affordable. There has long been a severe shortage of mental-health professionals, and since the Covid pandemic, the need for support is greater than ever. For instance, users can have conversations with AI-powered chatbots, allowing then to get help anytime, anywhere, often for less money than traditional therapy. The algorithms underpinning these endeavors learn by combing through large amounts of data generated from social-media posts, smartphone data, electronic health records, therapy-session transcripts, brain scans and other sources to identify patterns that are difficult for humans to discern. Despite the promise, there are some big concerns.

BOSTON – A few years ago, toward the end of his life, my father battled severe depression. As a physician and professor, he did not lack access to mental-health care. But he had grown up in a society that stigmatized mental illness, and he was unwilling to seek professional help. As a son, it was devastating to watch my father suffer. As a public-health researcher, I gained a new awareness of the myriad systemic failures in the provision of care.