Drako Oho Zarhazar has anterograde amnesia, a rare brain disorder that has left him unable to form new memories. The distant past—episodes from before the traumas that disabled his mind: a motorcycle accident; his car crushed beneath the wheels of a monster truck—remains to some degree with him, but he can hold almost no memory of anything that came after. He lives in a more or less permanent present, moving in a single interval of time, ghosted by his own slowly withdrawing past.

A former dancer, bohemian, drug dealer, fetishist, and one time muse to Salvador Dali, Drako is in his seventies and, it’s fair to say, he is slightly more than unusual. He strides into his documentary, caped like a magi, walking with his staff down the pebbled foreshore of Brighton beach. He is bald, pierced, crazily (almost childishly) made up, his upper lip horned with a black waxed Dali-esque moustache. Naked on the beach, his nipples are pierced, and a rather lovely tattoo of an ithyphallic ram wraps around his back and leaps down his flank.

Drako lives in a small council flat in Brighton. From the outside, nothing could be more ordinary, English, and banal. But inside, the pinched, slightly crepuscular spaces are dense with what can only be called the foliage of his mind. Like a strange avant-garde kelp forest, thousands of scraps of paper—notes to himself, photographs, drawings, stencilled quotes, and exhortations—hang on strings from the ceiling. The walls are likewise thick with scraps and cutouts. A crazed three dimensional memory map, every surface—every chair, ledge, and table—in his flat is silted with memorabilia.

The film maker Toby Amies—Drako calls him, rather sweetly, Toby Jug—spent four or so years befriending and recording his extraordinary subject. Early on the film looks set to be a low key, handheld biopic; an intimate, sketchy, and quite tender portrait of one of Brighton’s more flamboyant residents. There are repeat scenes of Amies’s feet heading up the path to Drako’s council block, ringing the bell, the camera nosing through the kelp towards Drako’s bed or chair.

But then the film, while tracking its subject, begins to shift. For Drako is declining, coming towards the end of things. And Amies’s relationship with him changes alongside. Filmmaker slowly morphs into concerned friend, nurse, and social worker. Amies begins to fret about Drako. He takes him to the doctor for an ulcerated leg. He warns him of the perils of burning candles—his paper memories are tinder. He schemes a little to keep him just out of reach of social services.

But there is also a niggling question, a little counter current of unease that tracks the film. The relationship between a documentary filmmaker and his subject is famously, notoriously complex. The slightly treacherous gap between what the subject says and what the audience hears has gulled a fair few demagogues and self satisfied celebrities over the years. And fair play. But what if its subject has a shattered mind? What if, as Drako suggests, every encounter with Amies might as well have been his first? What about consent?

The unease is strong enough to force itself into the open, and, towards the end of the film, Amies asks Drako if he thinks he is exploiting him. “Yes” comes the immediate response. “I like it.” But is that enough? There is no doubt that he is a fascinating subject, no doubt that Amies would get his film. But some of the footage is uneasy: Drako, the former fetishist, tugging at his pierced nipples, pleasuring himself. Is a film director always the best judge of the interests of his subject?

I watched the film a second time and stayed with this question, refracting it through what I know of ethics in this area. And slowly, the second time around, my unease began to give way. It matters that it is an extremely tender film—there is no whiff of exploitation here. It matters that those closest to Drako were heavily involved in the making of it: his sister, his nephew, his wonderful best friend.

But most of all it matters that the values that govern our living should be allowed to govern our decline. Be gently warned. This film is not for everyone. Drako was flamboyantly gay and among the kelp forest are numberless photographs of substantial male genitalia. But in his declining, just as in his living, Drako was an exhibitionist. Among his deepest desires seems to have been the desire to transgress, and to be watched in his transgressing. I do not know what kind of capacity you need to consent to being in a film. I’m not sure the law has commented on it. Much will depend no doubt on the nature of the film. But there is nothing here to make me doubt that the film was profoundly in step with its subject, and that in Toby Jug, Drako had found his filmmaker.

The Man Whose Mind Exploded will run for a week at the ICA, Brixton Ritzy; Duke’s at Komedia (Brighton); and Cambridge Picture House from Fri 13 June. It will be at Picturehouse cinemas across the UK from Tues 1 July.

Julian Sheather is ethics manager, BMA. The views he expresses in his blog posts are entirely his own.