D.B. was one of the lucky ones — lucky to have made it through the years-long medical parole process alive. Lucky to have had someone to advocate on his behalf.

The “graying” of the nation’s prison system — and with it the challenges posed by an aging population — is now a well-recognized phenomenon.

“The number of state prisoners age 55 and older has increased by 400 percent from 1993 to 2013, and it is predicted that by 2030, this age group will account for one-third of the US prison population,” according to a 2022 report by the American Bar Association.

“As the US population ages and rates of dementia increase, the prevalence of dementia among those involved in the criminal legal system can also be expected to increase,” it noted.

The demographic time bomb — a function of long prison sentences and mandatory life sentences in the 1980s and 1990s — is about to go off. There is also a body of evidence that prison itself accelerates both the aging process — 55 is considered old in prison years — and the likelihood of developing dementia and Alzheimer’s. The latter may well be a function of lack of stimulation in prison, according to a study in the journal Health and Justice.

Of the 6,000 or so men and women currently incarcerated in Massachusetts state prisons, 933 are over the age of 60, according to Department of Correction data. Of the more than 1,000 inmates serving life without parole, nearly a third are over age 60.

S.G. was one of them. Sentenced to life behind bars as a teenager for a murder committed in 1975, S.G. was 63 and living in a prison infirmary unit when a petition for medical parole was first filed on his behalf based on his advanced Alzheimer’s disease. In fact, a 2017 parole hearing had to be halted because even then he was unable to answer simple questions. In the infirmary unit he had a fellow inmate designated as his caretaker to assist him with “tasks of daily living. He needed constant reminders about where he was going or what he was doing and was not oriented to time or location,” his lawyers report.

S.G. had no guardian appointed for him for all of those intervening years. It was just by chance that another inmate in the medical unit told a visiting lawyer about S.G.’s condition. DOC eventually approved him for medical parole in January 2020 although it took until May 2021 to find a placement, thus allowing his release.

Again, he was one of the lucky ones. In the latest report available from DOC, issued last December for the year ending June 30, 2022, of the 67 inmates who petitioned for medical parole, 15 were actually released, and the petitions of two others were granted, but they died prior to their release.

Since the state’s medical parole law went into effect as part of the landmark Criminal Justice Reform Act in 2018, only 69 inmates have been granted medical parole. The department includes in that tally those who never got to actually leave prison before their deaths.

A case decided last April by the Supreme Judicial Court clarified some parts of the medical parole law but didn’t expand the regulatory definition of what constitutes a “debilitating” condition, clearly at the heart of most cases involving inmates with dementia or Alzheimer’s.

“The commissioner seems to focus on physical incapacity,” said Ada Lin, an attorney at Prisoners’ Legal Services of Massachusetts, who worked on that case. “Meanwhile we have several clients with significant cognitive impairment. Sometimes we only find out about such people from their [inmate] caretakers.”

One man incarcerated at Old Colony, she added, just keeps roaming around getting lost, frequently ending up in the chaplain’s office.

“People linger in DOC without an advocate, when they have every right to be out on medical parole,” Lin said.

But without family or lawyers to advocate on their behalf, most will continue to linger and to roam.

DOC acknowledged to the Globe it doesn’t even have data on those incarcerated with dementia or Alzheimer’s.

Legislation filed by state Senator Pat Jehlen and state Representative Mindy Domb would clarify the 2018 law, especially with respect to prisoners with cognitive impairment. It would require DOC to routinely screen prisoners 55 and older for cognitive decline and, when found, would require the department to identify someone — a family member, guardian, lawyer — to petition on their behalf for medical parole. Failing that it would put the burden on the department to initiate a petition itself.

The Massachusetts Bar Association Clemency Task Force has also urged Governor Maura Healey to adopt clemency guidelines that would recognize “advanced age and diminished health” as relevant factors in granting sentence commutations that could make those serving life sentences eligible for parole.

The aging of the state’s prison population is an issue that isn’t going away. It will get worse. Assuring a way to diagnose those with cognitive issues in that population and setting up a humane and workable path for their end-of-life care is the least that any civilized society should do.

Editorials represent the views of the Boston Globe Editorial Board. Follow us @GlobeOpinion.