The aging of people behind bars is "a national human-made epidemic decades in the making" associated with a swelling fiscal impact and a spreading moral stain, according to a report released Thursday by the Osborne Association.

The prison population aged 55 or older quadrupled from 1995 to 2010 and is expected to represent a third of the entire prison census by 2030, "amounting to a staggering 4,400 percent increase over a 50-year span," the report found. "Even as crime has drastically declined and the U.S. prison population has begun to shrink, the aging prison population continues to rise at a disproportionate rate."

Older people have more health problems—and incur higher health costs—in any setting, but the prison environment exacerbates those, and even makes people age faster. Even though prisoners uniquely have a right to healthcare, the delivery often falls short of that promise.

Parole and compassionate release are too rare to really address the problem, the report finds, echoing a 2013 investigation. In some cases, researchers found, "the effects of dementia become so pronounced that individuals have difficulty remembering why they are incarcerated to begin with even as they appear before the Parole Board."