At some point in the life of the average adult, the conversation shifts from “How are the kids?” to “What’s happening with your parents?”

If you’re lucky, you can talk about two silver-haired retirees, enjoying their relative good health, their Road Scholar vacations, and their time with the grandkids.

But no matter how lucky you or they are, the conversations will one day become less pleasant and more fraught. Mom or dad will inevitably decline, and you’ll start to talk about “options”: perhaps an aide to help around the house, or maybe a move to an assisted living center. If, God forbid, one or the other dies, you might ask the survivor if he or she wants to live with you or would prefer to find a “place.”

One week you are helping to fill out permission slips and college applications; the next, you are cosigning advance medical directives and power-of-attorney applications.

This is the territory Roz Chast stakes out in her variously hilarious and heartbreaking graphic memoir, Can’t We Talk About Something More Pleasant? The book is “graphic” in every sense. Chast, an iconic New Yorker cartoonist, chronicles her parents’ decline and fall in words and drawings, using the same spidery lines and nervous energy that has made her the poet laureate of middle-class neurosis. And the book is unsparing in its details about her parents’ personalities, their medical issues, their final days, and the searing mood swings — from guilt to amusement to sorrow to exasperation — that have afflicted anyone tasked with caring for an elderly relative.

Chast gave the Jack and Lewis Rudin Lecture at the Jewish Theological Seminary in New York last week, although what she delivered was less a lecture than a spellbinding performance based on her book. Although charming and as funny as her wonderfully weird cartoons, Chast seemed militantly un-philosophical. When David Kraemer, the JTS librarian and himself a scholar of Jewish death and dying, sought to draw her out on the Jewish and spiritual ideas in her work, Chast wouldn’t bite. (She didn’t disagree when Kraemer suggested that the book is a chronicle of the biblical commandment to honor one’s mother and father, but suggested Torah was Kraemer’s bailiwick, not hers.) When an audience member asked what she “learned” from watching her parents’ decline, Chast advised hiring an “elder lawyer” to help with the bureaucracy and buying a notebook to write down your parents’ social security numbers, medications, doctors’ numbers, etc.

It’s clear that everything Chast has to say on caring for one’s aging parents is found on the 228 pages of Can’t We Talk…. She describes her parents as “soul mates” who were born 10 days apart and who, “Aside from WWII, work, illness, and going to the bathroom…did everything together.” Mom, a former assistant principal, is domineering and oddly patrician; her dad, a former schoolteacher, is submissive, easily distracted, and anxious. When the two seem no longer capable of living safely in their Brooklyn apartment (“I worried about them constantly,” writes Chast), she must convince them to consider assisted living — the kinds of places, she writes, with euphemistic names like “End-of-the-Trail Acres” and “Final Bridge Rest Home.”

Chast describes the options available for those in life’s “late stages” (that’s the clinical term, not hers) as a series of painful, unsettling, and obscenely expensive choices. Society, she suggested in her remarks, hasn’t adapted to the reality of people living so long in poor or declining health. “We don’t have the signposts we once had,” she said. “We don’t talk about it as a culture.” She suggests, only half-joking, that the frail elderly be allowed to live out their final years blissfully high on opium or heroin, eating as much ice cream as they want. “Extreme palliative care,” she calls it, “for when you’ve had it with everything else: the X-rays, the MRIs, the boring food, and the pills that don’t do anything at all. Would that be so bad?”

Kraemer, meanwhile, recalled a line from Philip Roth’s Everyman: “Old age isn’t a battle; old age is a massacre.”

Despite the medical emergencies and the endless trips down the “Depressing Aisle” for adult diapers and nutrition shakes, Chast also finds moments of love and grace during her parents’ final years. But she knows that as much as we cherish our parents and want what’s best for them, caregiving is a clash of generous and selfish impulses. The “gallant” daughter-caretaker “treasures the time spent with her parents, because she knows that soon, they’ll be gone.” Meanwhile, the “goofus” daughter-caretaker “[m]ostly, when with her aged parents, wishes she were somewhere else.”

The evening at JTS ended on a sweet and unexpected note. During the question-and-answer period, three members of the audience surprised Chast by explaining that they had met her parents. One, a student of her father, thanked him for turning his life around. Another met them in a hospital where they boasted about their daughter, the cartoonist. And another, an art teacher, said she taught the two how to make paper cuts.

Funny and sad, Chast’s book is about how two people die. These strangers reminded us all how they lived.