A new study has found almost 15 percent of American teens believe they will die before age 35. This perspective is strongly linked to risky behavior.

The findings are based on a three-year tracking of attitudes and behaviors among more than 20,000 teens. The teens were interviewed periodically to gauge their views on personal mortality, and to tally the degree to which they engaged in such behaviors as attempting suicide, using illegal drugs and engaging in unprotected sex.

The interviews revealed that nearly 15 percent of the teens believed they had just a 50-50 chance of living to age 35. Teen who predicted a short lifespan was more likely to engage in subsequent risky behavior, and teens who engaged in risky behavior were likewise more prone to developing a pessimistic view of their future.