The good news: Life expectancy in the United States is increasing to as high as 82.

The bad news: It only applies to people who have more than a high school education.

As unrelated as it may sound on the surface, it appears that your academic achievements--or lack thereof--can be a crystal ball that will tell you how long you can expect to live. Americans who have more than a high school diploma can expect to live to the ripe old age of 82, but those who have 12 years or less of education have a life expectancy of just 75, according to a study from Harvard Medical School in Cambridge, Mass.

Using the National Longitudinal Mortality Study, death certificates and estimates from the U.S. Census Bureau, the researchers collected data on two sets of individuals. One covered 1981 to 1988 and the other covered 1990 to 2000. In both sets of people, life expectancy rose--but only for those who had more than 12 years of schooling. For those who had 12 years or less of formal education, life expectancy remained flat. Among women, the less-educated had a decline in life expectancy.

"If you look in recent decades, you will find that life expectancy has been increasing, which is good, but when you split this out by better-educated groups, the life expectancy gained is really occurring much more so in the better-educated groups," lead researcher Ellen R. Meara told HealthDay News. "The puzzle is why we have been successful in extending life span for some groups. Why haven't we been successful in getting that for less advantaged groups?"

The simple answer: tobacco. Fully 20 percent of the difference in mortality rates between the well-educated and less-educated is due to smoking-related diseases, including lung cancer and emphysema.

But it doesn't end there. Those who never had the advantage of an education beyond high school are more likely to have less income and live in areas that have their own types of health risks, such as crime or poor housing. In addition, they are less likely to have access to health insurance coverage and health services. The less wealthy and less educated are also less healthy.

Meara told HealthDay News that the challenge is to figure out ways to extend life expectancy of all groups in our society. "We need to get a better understanding of how we can extend these great things we're learning about how to lead healthier lives into these groups," she told reporter Steven Reinberg.

The study was published in the journal Health Affairs.