Sept. 17 (HealthDay News) -- A national survey has found that more than 8 million adults in the United States seriously considered suicide last year, with younger adults the most likely to contemplate taking their own lives.

In addition to nearly 8.3 million thinking about committing suicide, 2.3 million made a plan to do so, and 1.1 million actually attempted it, according to a federal government study released Thursday.

The findings are from data collected in a 2008 survey of 46,190 people aged 18 or older. It's the first national scientific survey of its size to examine this public health issue, according to the Substance Abuse and Mental Health Services Administration (SAMHSA).

The study found significant age-related differences in the risk of suicidal thoughts, planning and attempts. For example, adults aged 18 to 25 were far more likely (6.7 percent) to have seriously considered suicide than those aged 26 to 49 (3.9 percent) and those aged 50 and older (2.3 percent). Similar disparities were found in suicide planning and attempts.

Females had marginally higher levels of suicidal thoughts and behaviors than males. Only 62.3 percent of those who attempted suicide received medical attention for their suicide attempts, while only 46 percent of those who attempted suicide stayed in a hospital overnight or longer for treatment of their suicide attempts.

Substance abuse was associated with increased risk of seriously considering, planning or attempting suicide, the report showed. People with substance abuse disorders were more than three times as likely to have seriously considered suicide as those without substance abuse disorders -- 11 percent versus 3 percent. Those with substance abuse disorders were four times more likely to have planned a suicide (3.4 percent versus 0.8 percent) and nearly seven times more likely to have attempted suicide (2 percent versus 0.3 percent).

"This study offers a far greater understanding of just how pervasive the risk of suicide is in our nation, and how many of us are potentially affected by it," Eric Broderick, SAMHSA acting administrator, said in a news release from the agency.

"While there are places that people in crisis can turn to for help like the National Suicide Prevention Lifeline [1-800-273-TALK], the magnitude of the public health crisis revealed by this study should motivate us as a nation to do everything possible to reach out and help the millions who are at risk -- preferably well before they are in immediate danger," Broderick said.

SOURCE: U.S. Substance Abuse and Mental Health Services Administration, news release, Sept. 17, 2009