PW: The subject of Exuberance: The Passion for Life is more upbeat than your previous analyses of depression and suicide. Do you view "exuberance" as its own topic or as an extension of your work on mood disorders?

Kay Redfield Jamison: Both, I think. I've always been interested in mania and in the positive sides of mild mania. I think it always got less attention clinically than it probably should.

You talk about the mania and hypomania associated with bipolar disorder. Is there a detectable line that separates those states of mind from healthy exuberance?

There certainly is with mania, because mania by definition is a very destructive state. But with milder forms of mania [i.e., hypomania], judgment is the primary difference. When you're mildly manic, even though you have some shreds of judgment, you have no pretense of judgment. When you're exuberant you by and large have pretty good judgment. I mean it may be a little bit... off, but for the most part you're certainly in the real world.

You mention in the book how positive emotion leads to mental health, which then leads back to more positive emotion. Can a person lacking an exuberant temperament start that type of cycle?

It's hard to know. I think to the extent that it's obviously got a very strong genetic component to it, you're probably not going to affect the genes once you're born with them. What's clear is that there's a real interaction between genes and the environment. Sometimes parents or teachers can inadvertently squash enthusiasm and exuberance. One of the things that I've been struck by, talking with colleagues who are exuberant scientists, is how many of them—despite the fact that they all, I would say, have pretty strong egos, to say the least—at one time or another feel very uncomfortable because people make them feel embarrassed about feeling so enthusiastic. You know, because their arms are out waving and they're talking a blue streak and they're just kind of over the top.

Right. But on the other hand, you say that exuberance is contagious. How does that work?

Well, I don't think anybody really knows how that works. I think that all moods are contagious. That's probably partly why they exist. We're herd animals, and if there's a situation out in the environment that we need to be anxious about, it's important that that gets transmitted quickly within the group. If you're treating someone who is depressed, you're going to feel it because of all the nonverbal cues. Their body language is going to be encasing. Whereas if you look at the Olympics, you see that wild throwing up of hands into the air. That look is highly contagious. It alerts the group that there's something to be enthusiastic about—so pay attention.

In your opinion, who is the most exuberant public figure alive today?

In politics, I would say Bill Clinton. In business, Ted Turner. In the performing arts, not everyone who acts exuberantly is exuberant. And writers are a funny batch altogether.

What about Robin Williams? Exuberant or manic?

I would say exuberant. He's a great example, actually. Somebody who you can't help but kind of be in his presence even if it's on the television screen or in a movie. It's hard not to respond. It's that high voltage, that extraordinary level of energy that's palpable. You can feel it.