Chris Stephens, 28, who has been battling depression all of his life, plays with his dogs at home in Concord, Calif., on Friday. After a dose of ketamine, Stephens says, "I actually wanted to do things. I wanted to live life."
Lianne Milton for NPR
Nonnative pythons, like this one, are invading the Florida Everglades. As a top predator, the snakes have crippled the populations of rabbits, raccoons and other animals.
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Ketamine has been used as an anesthetic for decades. It's also a widely popular but illegal club drug known as "Special K." When administered in low doses, patients report a rapid reduction in depression symptoms.