Last year’s annual conference of the National Council of Behavioral Health brought thousands of therapists to Las Vegas, where showgirls opened the program showily and those who treat addictions got an after-hours view of all they’re up against.

This year, though, the conference is underway at the Gaylord National Resort at National Harbor outside Washington, and the showgirls have been replaced with a couple flashing far less flesh, dressed as George and Martha Washington. The biggest draw was keynote speaker Hillary Rodham Clinton, but the hottest topic here this week is psychosis prevention — or at least the kind of early intervention that can keep young people experiencing a “first break” with reality from ever having another psychotic episode.

Can we really do that? We can and we are, argues William R. McFarlane, a professor at the Tufts University School of Medicine who runs an early-intervention and prevention program in Portland, Maine. In his remarks at the conference, which runs through Wednesday and drew some 4,500 practitioners, he questioned why so little attention and funding goes to preventive mental-health care.

That’s shortsighted, he said, when preventing full-blown psychosis is as possible as preventing a heart attack. In fact, in the six American cities using a program designed at Yale, early intervention reduced the risk of a psychotic break by two-thirds in two years.

Ninety percent of those who’d already had a psychotic break had not had another one — numbers that would have been flipped without intervention, McFarlane said, with only 10 percent making it through the following two years without another frightening episode.

Prevention typically starts with community education — training high school counselors, pediatricians, resident assistants in college dorms and others who work with young people — on what warning signs to look for, since the age of onset for schizophrenia is 15 to 25 for men and 20 to 30 for women. Early intervention also requires a rapid response — a full assessment within 24 hours, usually — and intensive work with families and the young people themselves.

As McFarlane began to speak, a woman in the front row shouted that those running the sound system at the conference needed to stop the loud music out in the hall, because Stevie Wonder’s “Superstition’’ was making McFarlane’s explanation of evidence-based treatment hard to hear. “This is too important’’ to miss, she called.

According to those who run similar programs in Oregon, a major problem in much of the country is that while Medicaid pays for the case management and life skills training that are essential to prevention, private insurance usually does not cover those services, and didn’t before the implementation of the Affordable Care Act, either.

In Oregon, the early interventions that began with a pilot program more than a decade ago have worked so well that every county has a program now, and though it sounds funny to say, “we’ll treat you even if you do have insurance,” says my friend Mary Monnat, the chief executive of LifeWorks Northwest in Portland, Ore.

So just what it is that works so well? Amy Penkin, service director of LifeWorks Northwest, says that “the goal is to get them linked to the right kind of support” that helps young people stay in school or live on their own. They train parents how to keep a problem from escalating and help patients who may feel like staying in their rooms all day get out for a walk in a way that feels safe.

When I asked how a program like that might have helped prevent the tragic death of someone like Austin Deeds, the son of Virginia state Sen. R. Creigh Deeds, who committed suicide during a psychotic episode last November, she said that parents need help with young adults who often don’t want to take medication. “There is an art to engagement,” she said. There are clearly also times when a psych bed is the only way to keep a young person and those around him safe, “and if the young person has a homicidal plan, we won’t stand back.”

But there is a “gray zone,” too, in which even with all the “art of engagement” in the world, such plans are not so clear, Penkin said as we walked back to the main ballroom to hear Clinton speak. And in some states, the legal bar defining imminent danger is almost impossibly high.

The former secretary of state was at her best on Tuesday, touting her commitment to mental-health treatment and jokingly answering an audience question about her “guilty pleasures” by saying, “I’m trying to think of a G-rated one.” She even answered a question about what, all these years later, she thinks she might have done to prevent her friend Vince Foster’s suicide.

“Obviously, I’ve thought a lot about that,’’ she began. She didn’t say a lot beyond that “the ones I’ve known personally” who’ve taken their own lives “were all men, and particularly in the case you’re talking about there was a reluctance to seek help.” But she did readily reply, and the crowd was spared the look that any reporter asking that question would have received.

Clinton’s lines about everything from equal pay for women to helping those in “hollowed-out communities” drew big applause, but not everyone was enthusiastic. “It was okay, for a pre-campaign speech,” said a woman from Texas, “and I don’t appreciate them moving more people into programs when we’re stretched to the limits already.’’

Prevention, though, is surely a better way to keep caseloads manageable than limiting who gets access to care. And as the early interveners here told their colleagues, we can’t afford not to expand programs that can save so many among the 2.5 to 3 percent of the population that will develop a psychotic disorder.