(CNN) -- The number of aging men and women in U.S. prisons is growing rapidly, Human Rights Watch said Friday, and it expressed concern for their care behind bars.
Because of their age, older prisoners incur medical costs that are three to nine times as high as those for younger prisoners, the campaign group said in its 106-page report, titled "Old Behind Bars: The Aging Prison Population in the United States."
Prison officials are hard-pressed to provide the appropriate housing and medical care for older prisoners, the report says.
"Prisons were never designed to be geriatric facilities," said Jamie Fellner, a senior adviser to the U.S. program at Human Rights Watch and author of the report. "Yet U.S. corrections officials now operate old age homes behind bars."
Human Rights Watch pointed out that life sentences mean those prisoners reach old age in prison. Almost 10% of state prisoners are serving a life sentence, it said, and another 11.2% have sentences longer than 20 years.
Prisons face a number of challenges in caring for these prisoners, the group said. They include tight budgets, prison architecture not designed for age-related disabilities, limited medical facilities and staff, lack of support from elected officials, and the pressures of day-to-day operations.
It is equally as difficult for the older prisoners themselves who may be frail or impaired. Prison rules and customs weren't designed with them in mind, Human Rights Watch said.
"Walking a long distance to the dining hall, climbing up to a top bunk, or standing for count can be virtually impossible for some older prisoners," the group said. "Incontinence and dementia impose their own burdens."
Human Rights Watch called for changes to harsh sentencing rules regarding long mandatory minimum sentences and reduced opportunities for parole.
It also called for changes to prison facilities and medical care, as well as prison rules that are tough on older prisoners.
"How are justice and public safety served by the continued incarceration of men and woman whose bodies and minds have been whittled away by age?" Fellner asked.