Gaspar Noé’s new film chronicles the decline of an elderly couple in remorseless, mesmerizing detail.According to Philip Roth, “Old age isn’t a battle; old age is a massacre.” Affirming that grim insight, Gaspar Noé’s “Vortex” is a relentless chronicle of carnage. From opening scenes that include a vintage video of the eternally young Françoise Hardy singing “Mon amie la rose” — a minor-key meditation on the passage of time and the decay of youth — it’s obvious that there is only one way that this story of an elderly Parisian couple will end.Maybe that’s true of all stories. Plenty of movies set their characters on a path to the grave. But very few chart the course with such exquisite, excruciating attention to the minor indignities and existential terrors along the way. “Vortex” is not without intimations of grace and episodes of tenderness, but it also refuses any gesture of consolation. “Grandma and Grandpa have a new home,” a young boy remarks as his grandparents’ ashes are sealed into a wall of tombs. “It’s not a home,” his father corrects him. “Homes are for the living.”The home that the deceased shared, an apartment near the Stalingrad metro station in Paris, is a vivid presence throughout the film, most of which takes place within its book-stuffed rooms and narrow corridors. The husband and wife, whose names are never uttered — she is played by Françoise Lebrun, he by Dario Argento — have clearly been here for a long time. The art on the walls and the volumes stacked on every surface, even in the bathroom, testify to lives of political radicalism and intellectual engagement.She is a psychiatrist. He is a writer, working (in longhand and on a manual typewriter) on a book about cinema and dreams. Infirmity has taken a toll on both of them. He has heart trouble and survived a stroke a few years earlier. She seems to have Alzheimer’s, though the diagnosis remains unspoken. “It’s a very well-known disease,” her husband says. “Everyone knows how it goes.”In the abstract, maybe — and also in movies like “The Father,” “Still Alice” and “Amour,” a Paris-set tragedy that “Vortex” very much resembles — but Noé is less interested in clinical details than in sensations and states of consciousness. A prominent avatar of what’s sometimes called the New French Extremity, he has specialized in immersive spectacles of shock, cruelty and disorientation. His films (“Irreversible,” “Enter the Void” and “Climax,” among others) don’t merely traffic in explicit images of sex, violence, sexual violence and drug-induced frenzy. They push at the boundaries of audience experience and defy conventions of cinematic space and time, trying not to represent reality but rather to supplant it.“Every movie is a dream,” the husband in “Vortex” muses, and his elaborations on the idea might serve as a running commentary on the movie he’s in. (He also likes to quote Edgar Allan Poe, who asked, “Is all that we see or seem/But a dream within a dream?”) Argento, a venerable Italian horror auteur, speaks with some authority on the matter, since, like Noé, he is an uncompromising creator of cinematic nightmares. This one is all the more unsettling for being grounded in the mundane.After a brief prologue that consists of a scene of the couple sipping wine on their terrace and that luminous Françoise Hardy clip, the screen splits into two squares with rounded corners and a narrow gutter in the middle. Sometimes, when the husband and wife are together, the images overlap, presenting slightly different angles on the same action. More often, each spouse occupies a separate frame, and they move in counterpoint through familiar routines and periods of panic and confusion, a technique that emphasizes their isolation from each other even in their most intimate moments.When their son, Stéphane (Alex Lutz), comes to visit, alone or with their young grandson (Kylian Dheret), the rhythms become both calmer and more chaotic. Stéphane tries to be a reassuring, reasonable presence in his parents’ lives, but his own history of mental illness and drug addiction makes this difficult. Mom’s unpredictability and Dad’s stubbornness don’t help.Argento and Lebrun, who improvised most of their dialogue, are terrifyingly real — so much so that Lebrun has said that some viewers assumed she actually had Alzheimer’s. Argento speaks in fluent but heavily accented French, sometimes pausing and fumbling to find the right word. Lebrun uncannily conveys the sense of having lost her grip on language itself, pushing breath through her lips to summon words that never arrive. At other times, though, she is possessed of an almost maniacal clarity and sense of purpose. At one point, she energetically tidies up her husband’s desk, tearing up his newly written manuscript pages and trying to flush them down the toilet.Lebrun and Argento in the film. Her character seems to have Alzheimer’s, and infirmity has taken a toll on the couple.Utopia“You’re killing me,” he says when that happens. Now and then, she expresses a wish to die, but what is striking and finally heartbreaking is how alive they both are right until the end. They fight to hold onto the life they have made, refusing to consider moving into a care facility and leaving behind the stuff that has accumulated around them.All those books, papers, videocassettes and pictures aren’t just set decoration. They are, in a profound sense, what the movie is about, and what — in contemplating the deaths of two fictional characters — it is specifically mourning. What the couple represents is a culture, a sensibility, a romantic, idealistic set of aspirations and commitments that flourished in the decades of their youth and young adulthood.Lebrun and Argento, as Noé takes care to document in the opening titles, were born in the first half of the 1940s and came of age amid the turmoil and promise of postwar Europe. Both participated in the cultural flowering of that era — Lebrun starred in “The Mother and the Whore,” Jean Eustache’s post-1968 masterpiece; highlights of Argento’s extensive filmography include “Deep Red” (1976) and “Suspiria” (1977) — and carry some of its aura with them. But among the comforts “Vortex” refuses is the bittersweet balm of nostalgia. It’s a blunt reckoning with the inevitability of loss, including the loss of memory. We dream for a while, and then we sleep.VortexNot rated. In French, with subtitles. Running time: 2 hours 20 minutes. In theaters. More