In “Little Empty Boxes” and other films, the heartbreak of memory loss is intertwined with deeper cultural implications.When his creative, funny, independent mother, Kathy, began to exhibit signs of dementia, the writer Max Lugavere moved cross-country and picked up a camera to start documenting his journey to figure out how to help her. The result is “Little Empty Boxes,” a new documentary that’s strongest when it chronicles their relationship. Kathy’s memories of Max’s upbringing and his desire to be close to her bring them both a strange comfort. (She passed away in 2019.) The rest of the film — notably interviews with researchers studying links between nutrition, exercise and brain health — is uneven. Its visual language ranges from traditional, brightly lit talking heads to an observational approach, which can provoke whiplash for the viewer.But “Little Empty Boxes,” directed by Lugavere and Chris Newhard, made me think about other powerful documentaries that chronicle walking through memory loss with a loved one. The experience can be tremendously painful, with family and friends feeling helpless; watching a film about it can in turn be both gut-wrenching and cathartic.One of the best recent movies about memory loss — nominated for an Oscar last year — is “The Eternal Memory” about the Chilean journalist Augusto Góngora and his wife, the actress Paulina Urrutia. Directed by Maite Alberdi, the film (streaming on Paramount+) weaves Góngora’s slow decline into a broader meditation on cultural memory, and on what we lose as communities when we’re denied the ability to retain those memories — through book bans and state propaganda that whitewashes historical truth. But the broader metaphor doesn’t obscure Góngora and Urrutia’s love story, which is heartwrenchingly beautiful.Even more harrowing is “Tell Me Who I Am” (Netflix) directed by Ed Perkins. Like “Little Empty Boxes,” this 2019 film is more effective when exploring its subjects’ relationship than when it turns journalistic. Alex Lewis was in a motorcycle accident at 18, and when he woke up, he’d lost his memory. His twin brother, Marcus, helped him reconstruct his life, but as the film goes on, Alex — and the audience — realize that Marcus was holding back information about their past, and that revealing it is fraught. The brothers’ trust and love holds the film together.The most unmissable and life-affirming film of this sort, though, is “Dick Johnson Is Dead” (Netflix) from 2020. Dick Johnson is the father of the director Kirsten Johnson; years after losing his wife (Kirsten’s mother) to Alzheimer’s, he begins to exhibit signs of dementia. Facing an uncertain future, Dick and Kirsten work together to humorously and movingly stage different ways he might die, while exploring their relationship and the meaning of love, history and remembrance. It’s a vital, hilarious, gorgeous and truly innovative film, and I can’t think of a better exploration of the bond between a filmmaker and a parent in the face of impending loss. More