According to a recent article by Patricia Cohen in The New York Times, researchers report that Americans in midlife are a remarkably contented lot, and that they also have the highest rate of suicide. What's up with that?

Arthur A. Stone, lead author of a study based on the Gallup poll, suggests that changes in brain chemistry are also at work. Neuroscientists have shown that in younger adults, the amygdala, the brain's emotional nut, is activated when exposed to negative and positive input, whereas adults in their middle and upper decades seem to have the ability to screen out or tamp down negative emotions; their amygdalas light up when they see positive images, and they tune out the negative.

Accentuate the positive, eliminate the negative? Lyricist Johnny Mercer would have loved getting some credit.

Myrna Weissman, an epidemiologist at the New York State Psychiatric Institute, according to the Times article, offers a more intriguing theory. She believes that the baby boom generation has a higher incidence of depression than previous ones.

"That's a cohort that came to maturity when there were great social changes, more instability, more divorce and separation, more moves, an increase in drug use, and war," Weissman said. And what about those happy midlifers? "They're different people; less vulnerable and subjected less to these adverse life effects." Something may be going on in the 45-to-54 age group.

Some say it could be that additional stresses may be hitting people in middle age, like the double burden of caring for children and for aging parents whose lifespans are increasing. It could also be something like having to go back to work because of the economy, loneliness, and feeling that the world is out of control.

What's up with your amygdalas these days? On a scale of 1 to 10, how happy are you now?