WEDNESDAY, Feb. 26, 2020 (HealthDay News) -- U.S. life expectancy hasn't kept up with other wealthy nations and experts have cited health care, drug addiction and mental health woes as possible causes.

But maybe the key to longevity can be found in the classroom, new research suggests.

In the new study, a team from Yale and the University of Alabama-Birmingham sought to tease out the impact of race and education on life expectancy, and found that education is the best predictor of who will live longest.

For the study, the researchers compared data from about 5,100 black and white Americans in four U.S. cities recruited for a study about 30 years ago. Of that group, 395 had died.

"These deaths are occurring in working-age people, often with children, before the age of 60," said study author Dr. Brita Roy. She's assistant professor of medicine and epidemiology at Yale School of Medicine.

The study revealed racial differences in rates and causes of death. About 9% of black study participants died at an early age compared with 6% of white participants. Black men were also more likely to die by homicide and white men from AIDS, the findings showed.

Heart disease and cancer were the most common causes of death overall, according to the report.

Rates of early death by education level also varied. About 13% of those with a high school education or less died early, compared with 5% of college graduates. When looking at race and education together, rates of early death among blacks and whites were nearly equal.

Overall, the study showed that each reduction in education level cut life expectancy by 1.4 years.

"These findings are powerful," Roy said in a Yale news release. "They suggest that improving equity in access to and quality of education is something tangible that can help reverse this troubling trend in reduction of life expectancy among middle-aged adults."

The findings were published online Feb. 20 in the American Journal of Public Health.

More information

The U.S. Centers for Disease Control and Prevention has more on life expectancy.