Research in Newcastle has shown that about a third of all children referred with psychiatric disorders also suffered from undiagnosed depression.

Low self-esteem, body image distortion and undiagnosed depression and anxiety can drive some to act self-destructively in the pursuit of some idealized image of beauty.

Mr. Paxton dedicates the album to his wife, for helping him bounce back from years of "undiagnosed depression."

For years, he had undiagnosed depression.

"If kids are unhappy at home and/or struggling with some form of undiagnosed adolescent depression, they are more prone to get involved with drugs and alcohol," he said.

Thoughts of suicide and requests to hasten death may be a marker of undiagnosed depression.

Berkow was correct in mentioning undiagnosed depression as a factor in unanticipated suicides.

What about the possibility that some of the pessimistic subjects were simply suffering from undiagnosed depression?

If pessimists should worry about anything, though, it's that they may have an undiagnosed - and treatable - depression.

Today, Ms. Cornwell acknowledges that her behavior turned erratic at times under the influence of her undiagnosed manic depression.