People with OCD dwell on certain thoughts (obsessions) and engage in rituals (compulsions) to alleviate the anxiety the obsessions provoke. At its worst, OCD can compel people to spend hours each day rehearsing an intricate mental dance they feel powerless to end. At an OCD conference in Chicago this July, I met one mother of a young girl who is so afraid of getting dirty, she opens doors with her feet. A 19-year-old college sophomore, profoundly insecure about his appearance, told me he spends an hour and 20 minutes each morning brushing his teeth and washing his face. (Pop-culture often portrays the OCD-afflicted as washing their hands frequently, but excessive cleanliness is just one of the disease’s many manifestations.)

Along with medication, exposure and response prevention, or ERP, therapy is the gold-standard treatment for people with OCD. It is radically different from more traditional talk therapy, which excavates patients’ childhoods or past relationships for clues to their present-day problems. In ERP, none of that matters. Instead, a person is forced to confront their obsessive thoughts relentlessly. The goal is to make the sufferer so accustomed to their obsessions that they no longer feel tempted to engage in soothing compulsions.

At the conference, Scott Granet, a clinical social-worker who struggles with body dysmorphic disorder, a type of OCD, showed how this can be done. Because of an acute fear of having his hair look rumpled, he avoids hats at all costs. Standing before a room of conference attendees, he took a deep breath and slowly drew a baseball cap over his head. “I don’t feel too bad, actually,” he said, his voice trembling.

Other interventions are more extreme: People obsessed with not offending God might hold a satanic ritual. Those assailed by persistent (and baseless) fears they will molest their siblings might read the incest tome Flowers in the Attic.

“When people have [intrusive] thoughts, they’re worried that it means something about them or expresses their potential for harm,” said Karen Cassiday, a psychologist who practices ERP at the Anxiety Treatment Center of Greater Chicago. ERP teaches people, “these thoughts are meaningless, you need to learn to ignore them.”

Many OCD sufferers and their families say finding the right kind of therapy is the most difficult part of overcoming the disease. Because of the dearth of psychologists with experience in ERP, as well as geographic and financial barriers, some studies estimate it takes OCD sufferers 17 years to find proper treatment from the onset of symptoms. Seeking certain forms of talk therapy can make them worse, not better. In the meantime, some experience symptoms so debilitating they are confined to their homes.

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The tough-love story of ERP begins in the 1950s. The psychologist Richard Solomon trained dogs to avoid an electric shock, which was heralded by a bright light, by leaping across a barrier in their cages. Eventually, the light would make the dogs jump the barrier, even if no shock followed. Solomon, in other words, gave the dogs OCD, making them irrationally obsessed with a harmless light.