High-pressure oxygen treatment, once reserved for deep sea divers suffering from “the bends,” is increasingly being tested to remedy other conditions.

Lee Frost, whose autistic son is being treated with hyperbaric oxygen therapy, is one of the growing number of people who have pursued HBOT for uses that mainstream doctors, government regulators and patient advocates say are unproven.

In a 2013 consumer alert, the US Food and Drug Administration warned that hyperbaric oxygen therapy “has not been clinically proven to cure or be effective in the treatment of cancer, autism, or diabetes” despite treatment centers’ claims.