The heavily trafficked subgenre of the neurodegenerative disease drama can be so punishingly bleak it often feels like a thankless dive into misery. But every now and then a film comes along that illuminates such irreversible conditions with fresh perspectives. Mia Hansen-Løve did that last year in narrative form with One Fine Morning, bringing emotional complexity and empathy to a young widow’s struggle to navigate the challenges of her life, among them the slide into dementia of her intellectual father. Chilean documentary maker Maite Alberdi brings similar qualities to the achingly tender nonfiction slice-of-life study, The Eternal Memory.

An Oscar nominee in 2021 for The Mole Agent, Alberdi makes her directorial hand virtually invisible, observing her subjects from a discreet distance that allows them to be narrators of their own story while never speaking directly to the camera.

That makes the film — from Pablo and Juan de Dios Larraín’s Fabula production company — a profoundly personal experience. It also acquires additional layers of meaning through the sad irony that Augusto Góngora, the veteran Chilean TV journalist and political commentator who was diagnosed with Alzheimer’s disease in 2014, made it his mission to keep the country’s painful memories of the Pinochet military dictatorship alive. It’s significant that one of his best-known publications is Chile: The Forbidden Memory. The quotidian battle he wages — some days more cooperatively than others — to conserve his own retreating memory is heartbreaking stuff.

The engine powering that battle is Góngora’s partner of 25 years, the actress turned arts and culture minister Paulina Urrutia, whom he married in 2016, two years after his diagnosis. Her determination, devotion and almost unfailing optimism while lovingly guiding her husband through the increasing fog of his past and their lives together gives the film a hopeful outlook, even as it becomes clear that hope will carry them only so far against an unforgiving disease.

That core of deep, richly resonant feeling ensures that The Eternal Memory never wanders into melodrama, even with such potentially sentimental enhancements as the gentle love songs that punctuate the soundtrack. The same grace and compassion evident here were distinguishing factors of The Mole Agent’s treatment of aging and elder care.

Alberdi swiftly presents the daily ordeal that Urrutia, fondly known as Pauli to her husband, faces as she wakes Augusto in the morning and patiently walks him through basic details he has lost since the night before — his name, hers, their relationship, the home that they built together. She coaxes him to fill in the same blank canvas over and over. Some days he has more recall than others. And some days he tumbles into despair, weeping over the inaccessibility of the books that were so precious to him, even as they line the shelves that surround him.

This may be purely subjective, but those moments of despondency are made somehow more moving by the presence of the couple’s cat, which hovers around them in that way that felines have of seeming simultaneously aloof yet attuned to human suffering.

The film observes Pauli reading to Augusto, walking with him in the park, doing physical therapy, watching protectively as he makes a wobbly attempt to ride a bicycle, including him in her rehearsals for a theater piece. Because both the subjects have been public figures in Chile for decades, there’s a wealth of footage documenting their lives and work. Seeing Augusto as a handsome, confident TV reporter (with a glorious mustache) in his younger years hammers home the distance from the prematurely aged man frequently overcome by abject confusion.

Archival video of his news reports — notably those from an underground network when the regime had taken control of public television to block coverage of their systemic oppression and brutality — deftly underlines The Eternal Memory’s central paradox: that a man so instrumental in preventing the erasure of his country’s consciousness should now be helpless to save his own. Footage of him on the protest frontlines amplifies this aspect, as do recollections of his association with iconoclastic Chilean director Raúl Ruiz, seen in an interview with Góngora in which they discuss the filmmaker’s fascination with resurrecting the dead.

These ample recollections of Augusto’s professional life and his passionate commitment to resistance and remembrance are woven delicately by editor Carolina Siraqyan into the tapestry of his quarter-century with Pauli to create a portrait that’s powerfully emotional and warmly romantic. The strain often shows on both their faces and the pain of forgetting cuts deep. But the strength of their relationship and the glimpses of the vibrant, intelligent man still there beneath the haze make this film as unexpectedly stirring as it is sorrowful.