• Michael Gill with his son A. A. Gill in 2003. “The illness gave us a long time to make our farewells. There was nothing left unsaid between us,” says the writer Peter Marlow/Magnum

The thing with this sentence, this arrest of dementia, is that its greatest victims aren’t those who have it. That’s not to say that the diagnosis isn’t dreadful for the recipient, but there is a peculiar and particular hammering sadness for those that love and care for an Alzheimer’s spouse or parent.

It is a wearying and lonely obligation, but with the added cruelty that the person you’re looking after vanishes, escapes before your eyes. In the end, you’re caring for the case that someone came in.

The job of keeping them alive and comfortable becomes a monumental act of memory, which is, among all the other sad ironies of age, a particularly poignant one. As the patient forgets, so the carer has to remember for both of them. There is nothing good or positive to be said about Alzheimer’s disease, no redeeming or consoling posy to be plucked from its miserable wreath.

I remember — how many sentences about Alzheimer’s begin “I remember”? — I remember when my father had the illness diagnosed. Our family’s sad shock, the retrospective detective-work and the realisation — or admission — that we’d sort of known for some time.

But there was his own sanguine and often funny acceptance of his lot. He was a man who’d lived almost entirely in his own head, in the cerebral, always surrounded by books, walled in by the tomes of his broadly intellectual life. When reading and writing became impossible, he stared at the page and said with a resigned wonder that the words ran like ants in the snow. Then he would sit and watch the autumn sunlight fall across the room.

Since his death, I’ve seen a number of Alzheimer’s patients in their homes and in care, and I’ve grown to recognise that look; the quiet regard. They aren’t seeing what we see. They watch some personal reverie, and in it, rise above their sickness, are perhaps untouched by its humiliations and losses. But there is no such place for those who feed, wash, turn and continue to chat with the one-sided monologue of cheery commonplaces. The lists of names and destinations, the harking back to perhaps ignite some last, glowing memory, to connect once more, however briefly, with a shared life.

When he was very close to the end, I took my daughter to see her grandfather in hospital. She was upset, not just by the passing of her granddad but by a closer fear: “I don’t want to see you like that, Dad.”

There was, and is, no guarantee. As we continue to survive other once-fatal conditions, to live longer, so dementia claims more of us. And while we may wish for the kindly, instant death of the calamitous stroke, the speeding aneurism, or the firm embrace of a cardiac arrest, to depart in our sleep or, like my grandfather, watching the nine o’clock news, increasing numbers of us will drift away, one ripped-up photograph at a time.

An Alzheimer’s carer must face a wave of ancient fear. More than the illness itself, we dread its imposition on our family, the guilt, the expense, the damnable pity, the waste of other, active lives that should have better, more productive things to achieve, the leeching of fun and laughter. And we fear above all its imposition on our memory, the further irony that this is, after all, how we will be remembered.

In particular, over the years of my dad’s illness, I had the constant worry that my abiding image of him would be with Alzheimer’s. The final, penurious cruelty is that it would wipe all the other memories of him away, that I would only think of him as an ancient, rheumy-eyed, gentleman.

But now, as the years pass I still think of him often, and it is in all the ways I knew him: picking me up from school, smoking his pipe, in his skinny safari jackets in the 60s, his shock of white hair in middle age, telling me stuff, showing me things, mostly just sitting in his armchair writing on a clipboard, surrounded by books.

And I also remember the Alzheimer’s, I haven’t been rid of that. But now it’s not with anger or resentment. The illness gave us a long time to make our farewells. There was nothing left unsaid between us, and that is a boon not allowed by the sudden coronary or the number nine bus.

There were no more rows or arguments that had punctuated the earlier part of our lives. The fights of fathers and sons were done. What we did have in the end, to share, was food.

It was ever the leitmotiv of our family. My brother was a chef, I wrote about it, and Daddy loved to eat. When finally he had no idea who I was, when, as Shakespeare has it, he was sans sight, sans teeth, sans everything, I would visit with a tub of chocolate ice cream, his lifetime joy, and we would sit together in silence, eating. That, now, is one of my dearest remembrances. Food is ever the great simile and metaphor, the binding of us, the evocation of the past, the fuel of the future.

As I write this, on my desk is a picture of my Dad and me. Of all the photographs I could have chosen, it is a very late one. He has that pensive, distant look of dementia. We’re sitting in the park, my arm through his. I’m looking off into the distance. He’s inverted into the past, me into the future. It’s a maudlin and precious image.

There is nothing good to say about Alzheimer’s, but there there will never cease to be marvellous things to say and remember of those who suffer it.

A.A. Gill is an ambassador for the Alzheimer’s Society, one of the charities chosen for The Times Christmas Appeal. The first £30,000 of donations will be matched by Tesco

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