Things did not work out that way, though. Ms. Sherman started having trouble with daily tasks, was found to have dementia and moved into an assisted-living facility and then a nursing home with specialized staff members for memory care patients. Along the way, the insurance company declared her not sufficiently ill to warrant paying out on the policy. Then the trust, which is common and legal, did not hold up to state scrutiny because of a problematic passage.

These twists and turns reveal two terrifying facts about aging and how we pay for it. While it’s hard to imagine a couple better suited to help an aging parent navigate her final years than a social worker-financial planner duo, the Pernas still ended up hiring five additional professionals to help them with complex, specialized tasks: a long-term care insurance salesman, a nurse consultant to help get the insurance company’s decision reversed, an elder care lawyer to set up the trust, another consultant to help with the Medicaid application, and a malpractice lawyer to sue the attorney who created the defective trust. (The family eventually received a settlement. And to the many readers who have asked about the ethics and economics of Medicaid planning and trusts, please watch this space in the coming weeks.)

So add aging to the maddeningly long list of enormously complex financial tasks that each of us faces. And pity those in their 70s or 80s who must navigate this morass without expert adult children or other advocates.

Second, for people like Rita Sherman who lead healthy lives for three-quarters of a century, it is often their brains that give out first, not their bodies. And when that happens, the decline can be both lengthy and expensive, given how much supervision dementia patients need.

Just over three years into Ms. Sherman’s nursing home stay, her money was gone and the long-term care insurance had been used up. She eventually did qualify for Medicaid, which paid for much of her final two years of care. By then, her daughter was calling the shots, since Ms. Sherman was no longer able to speak. “By the time my mother died, I had long since said goodbye to her,” Ms. Perna said.