IN 20 MONTHS on the job, Rushern L. Baker III, Prince George’s County executive, has fashioned a reputation as a tough-minded, decent and aboveboard local leader, a sharp departure in a county whose government was synonymous with graft, dishonesty and sleaze. Few knew that even as Mr. Baker was devoting long hours to govern Prince George’s, population 880,000, and remake its administrative mechanics and image, he was also struggling to manage his wife Christa Beverly’s rapidly deteriorating condition following her diagnosis with early onset Alzheimer’s disease in 2010.

Alzheimer’s, for which there is no known cure and no effective treatment, is a particularly cruel disease, taking its toll not only on the victim but on his or her family, too. Like millions of other Americans whose families or friends have been afflicted, Mr. Baker, 53, has surely suffered sleepless nights and anguished days as Ms. Beverly’s mind and memory fade away.

He has done so with uncommon grace, judging from the courageous interview he gave to The Post’s Miranda S. Spivack. As Mr. Baker and his three young-adult children scramble to care for Ms. Beverly, who is 52, they were frank about the wrenching changes her disease has wrought in all their lives, and the strains, too.

“When I go home, I don’t know what I am getting into,” Mr. Baker said. Quinci Baker, the couple’s 17-year-old daughter, was equally upfront in speaking of her mom. “We switched roles,” she said, “and I became my mother’s mother.”

More than 5 million Americans suffer from Alzheimer’s, and that number is expected to more than double by 2050 or so. Already the fifth-leading cause of death for people age 65 or older, it has taken on the dimensions of an epidemic. Of the nation’s roughly 75 million baby boomers, one in every seven or eight is likely to die of the disease. In the absence of a cure or effective treatment, the purely monetary costs of caring for Alzheimer’s patients will be staggering; the emotional burden on families like the Bakers will be incalculable.

The Obama administration announced this year that it is boosting funding on research to fight the disease by more than 25 percent over the next two years. It is also funneling more money to supporting caregivers and for public awareness.

Despite the $150 million in new outlays, government spending on Alzheimer’s — the major source of research funds — remains severely inadequate when measured against the disease’s public-health impact. Experts say that with more resources, odds would improve for treatment, preventative measures and, possibly, a cure. Yet Congress has shied away from bold measures, such as the Alzheimer’s Breakthrough Act, a measure introduced with bipartisan sponsorship last year that would dramatically boost outlays for the National Institutes of Health to combat the disease.

Mr. Baker, who is managing both the affairs of a sprawling county and his family’s private tragedy, seems a model of equanimity under pressure. But it will take more than Mr. Baker’s commendable model to address Alzheimer’s ravages.