( 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 were n'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 .
Group says medical care and prison facilities are not equipped for older prisoners . The number of older prisoners in the state is growing , it says . It calls for changes to harsh sentencing practices and life behind bars .