From 1999 to 2010, the suicide rate among Americans ages 35 to 64 rose by nearly 30 percent, to 17.6 deaths per 100,000 people, up from 13.7. Although suicide rates are growing among both middle-aged men and women, far more men take their own lives. The suicide rate for middle-aged men was 27.3 deaths per 100,000, while for women it was 8.1 deaths per 100,000.

The most pronounced increases were seen among men in their 50s, a group in which suicide rates jumped by nearly 50 percent, to about 30 per 100,000. For women, the largest increase was seen in those ages 60 to 64, among whom rates increased by nearly 60 percent, to 7.0 per 100,000.

Suicide rates can be difficult to interpret because of variations in the way local officials report causes of death. But C.D.C. and academic researchers said they were confident that the data documented an actual increase in deaths by suicide and not a statistical anomaly. While reporting of suicides is not always consistent around the country, the current numbers are, if anything, too low.