Former prisoners are more likely to die prematurely than those who have not been imprisoned, according to a recent study.

Researchers from Georgia State University found that men who have been incarcerated and released are more than twice as likely to die early from infectious and respiratory diseases, drug overdoses and homicides.

This "mortality penalty" can be attributed to increased exposure to diseases like tuberculosis and HIV, the prolonged stress of the prison environment, the disruption of important social bonds and, upon release, the struggle to reintegrate into society and employment.

"We know that stress can weaken immune systems," William Alex Pridemore, researcher and criminologist, said in a statement. "And in a very unpleasant twist of events, at the precise moment when these men are most vulnerable to a compromised immune system due to stress - that is, when they are incarcerated - they are most exposed to a host of communicable diseases whose rates are much higher in the prison population."

More than 2.5 million people are incarcerated in the United States - 95 percent of whom will eventually be released. Incarceration rates in the United States and Russia, at 730 and 519 per 100,000 residents, are among the highest in the world.

For the study, Pridemore looked at the short- and long-term impacts of incarceration on the mortality of prisoners after their release.

"Earlier research looked at the collateral consequences of mass imprisonment that started in the 1970s, when the U.S. went on an incarceration binge. Most focused on incarceration's limits on job prospects and earnings, marriages and its impact on communities," he said. "Now research is turning to its impact on health.

Pridemore suggests that prisons work with inmates, prior to their release and provide health screenings and treatment and help them plan for their short-term and long-term health care needs.

"This investment will benefit not only the individual health of current and former prisoners, but also taxpayers and the broader community by way of improved population health," he said.