Perhaps years from now, after a scientific breakthrough has turned Alzheimer’s disease into a memory as distant as polio wards are to younger Americans today, someone will stumble upon Scott Kirschenbaum’s hard-to-watch documentary, “You’re Looking at Me Like I Live Here and I Don’t,” and be stunned. “I’ve read about Alzheimer’s,” this person will say, “but I had no idea what it was actually like.”


Alzheimer’s has been a trendy topic for writers of plays and television scripts in recent years. But those stories have often been primarily about the people surrounding the patient — family members, friends — and the effect of the disease on their lives.


Mr. Kirschenbaum, whose film will be broadcast nationally on PBS’s “Independent Lens” on Thursday (on Sunday on Channel 13 in New York), takes the simple but bold step of making Alzheimer’s the only thing in his tale. It’s not a plot point that propels a narrative; it’s an inescapable box.


The film zeros in on one woman, Lee Gorewitz, in a residential care center in Danville, Calif., and follows her through her daily routines. There are no talking heads describing current research into the disease, no family members waxing nostalgic about Ms. Gorewitz’s life before Alzheimer’s. Mr. Kirschenbaum sprinkles in some unobtrusive music and prods with an occasional question from behind the camera, but that’s it.


Ms. Gorewitz, who is in her 80s, is at a particularly heartbreaking stage of the disease: mobile and spry and cognizant enough to engage in conversation but not in control of the words that come out of her mouth or the thoughts behind them. Asked how old she was when she married, she produces a jumble that seems coherent only to her: “Oh, it was a year after this because I was, had been doing the other things you see, what you could see there. But that’s the way he did it himself.”


A question about where she was born elicits a long, indecipherable answer, at the end of which she says, “Brooklyn.” You can feel her clearing the mental debris out of the way to reach that nugget of information.


Ms. Gorewitz has a playful side, occasionally dancing or joking. But she has also lost enough of her social filter that a cruel streak comes out now and again. “That one looks like it’s dead,” she tells the camera as she points out a fellow resident who is slumped over. When another resident makes a harmless comment, she snaps: “Just keep your mouth shut. Shut up.”


“You’re Looking at Me” may seem like lazy filmmaking, but this kind of minimalism takes a certain amount of courage and a faith that the audience won’t switch over to something with a happy ending. Many viewers will certainly find it difficult to resist bailing out, especially when Mr. Kirschenbaum catches glimmers of self-awareness in Ms. Gorewitz, indications that she recognizes her diminished capacity and knows there’s nothing to be done about it.


INDEPENDENT LENS


You’re Looking at Me Like I Live Here and I Don’t


On PBS stations beginning Thursday (check local listings)


Produced by You’re Looking at Me LLC. Shane Boris and Scott Kirschenbaum, producers; Gracey Nagle, co-producer; Scott Kirschenbaum, director.