“Okay,” Grayson barks as the group floods into a parking garage, “who is worried that their actions could cause harm to others?” Two women step forward. Normally if they were merely to touch a car, these women would get obsessed with the idea that the car is doomed to crash and kill its occupants. “In a mad, crazed rush,” Grayson says, “could you start kicking these car tires?” All of us, including the two women, descend upon a Toyota and proceed to give the radials a vigorous thwacking.

Onward. “Do we have any hoarders?” Grayson asks. “We’re going to do something special with you.” There’s a canal that runs beside the Marriott. The doctor leads the crowd to it, and at the edge he looks into their eyes and says, “Do you have a dollar with you? Is it worth a dollar to get better?” People open their wallets and pass bills to the front. “The trouble with hoarding,” Grayson says, “is that letting go of things is a loss.” With that, he rips up the money and throws the scraps into the canal. From the group come gasps.

You can’t tell right away. If you wander into the Woodlands Marriott by accident, a quick glance around might lead you to imagine that about 500 members of the Ecumenical Fellowship of Church Deacons are in town for their yearly prayer powwow. It’s not just that obsessive-compulsives look “normal.” It’s that a lot of them are abnormally tidy. Hair clipped. Shirts ironed and tucked in. Straight posture. Precise diction. Only by stepping back and scanning the room do you catch the signs that something is slightly off.

There’s the man striding across a hallway who stops at a table, freezes, and taps out a Morse code of arpeggios with his fingertips before he allows himself to move along. There’s the guy whose lunchtime ritual is as elaborate and mysterious as the Latin Mass: He keeps nudging his plate back and forth by a few millimeters, unwrapping a fresh set of plastic cutlery for the next round of bites, and studying the bottom of a cup of ice for minutes at a time. There’s the supersize bottle of hand sanitizer placed inside the entrance to each restroom. This might be the one convention in America where rampant handshaking is considered a faux pas.

They’re sort of like Rotarians from another planet, which makes sense, because the OCD beast is commonly said to have an appetite for successful strivers with higher-than-average IQs. “Anecdotally, yes, there’s something to it,” says Dr. Katherine Muller, an OCD expert at the Montefiore Medical Center in New York. “My theory is that OCD takes a certain level of smarts. Most folks can have random thoughts and dismiss them pretty easily, but the OCD person looks at their thoughts, they think about their thoughts. It’s meta-cognition: thinking about thinking.”

Although there appears to be a genetic basis for OCD, what triggers it is often a disorienting encounter with a transitional aspect of life: marriage, parenthood, a new job. It can flare up when a person is in his twenties or thirties, and when it does, that perfectionist pressure to get things right can, at least at first, bear the markings of a professional asset. “OCD runs on a spectrum, and if it’s just enough to give an edge in a career, it can actually be helpful,” Muller says. “But once it hits that tipping point, it can become a real detriment.” Here at the conference are several lawyers, along with editors and scholars and a willowy Manhattan model. Smith, a 25-year-old Ivy League-educated economist, looks as freshly scrubbed as an extra from Happy Days. (Like most of his comrades at the conference, he asked to have only his first name published.) He wears a red-striped Brooks Brothers oxford, pressed khakis, and Sperry Top-Siders, and it’s only after you’ve spoken for a few minutes that you realize he’s bound in a psychic tourniquet.