Some young people's expectations that they will not live long, healthy lives may actually foreshadow such outcomes.

New research published August 1 in the open access journal PLOS ONE reports that, for American teens, the expectation of death before the age of 35 predicted increased risk behaviors including substance abuse and suicide attempts later in life and a doubling to tripling of mortality rates in young adulthood.

The researchers, led by Quynh Nguyen of Northeastern University in Boston, found that one in seven participants in grades 7 to 12 reported perceiving a 50-50 chance or less of surviving to age 35. Upon follow-up interviews over a decade later, the researchers found that low expectations of longevity at young ages predicted increased suicide attempts and suicidal thoughts as well as heavy drinking, smoking, and use of illicit substances later in life relative to their peers who were almost certain they would live to age 35.

"The association between early survival expectations and detrimental outcomes suggests that monitoring survival expectations may be useful for identifying at-risk youth," the authors state.

The study compared data collected from 19,000 adolescents in 1994-1995 to follow-up data collected from the same respondents 13-14 years later. The cohort was part of the National Longitudinal Study of Adolescent Health (Add Health), conducted by the Carolina Population Center and funded by the National Institutes of Health and 23 other federal agencies and foundations.