He says people suffering from OCD are afraid of uncertainty—like illnesses caused by germs—and retreat to actions or thoughts that they believe will protect them, such as constant cleaning or hand-washing. Their fear of uncertainty is so severe that normal activities become difficult. "You're making stories in your mind to defend why you're not acting," Dr. Oz says.
Dr. Oz says OCD, which affects an estimated one in 40 Americans, is both learned and biological. "Their brains are a little more sensitive to uncertainty, so it makes them more anxious than it makes other people. But the form it takes is learned," he says. "So I could [be] afraid of germs and worry about getting sick, or I could be worried about the thoughts in my head."