"How do I look?" my mother asks.

"You look beautiful," say the nurses. "Quite the stunner, young lady." She looks every day her 84: crumpled paper for skin, red blue eyes in a pucker. Dementia is never about telling the truth. It makes a virtue of being a liar.

She nods off and wakes in different decades. Today is the day when she marries my father. Today is 46 years ago. She must practise the art of lipstick on her face, pink figure-eights as if kissing. Once her lick-nipple son, I'm his likeness now, near enough to the age he was when courting her.

She accuses the nurses of trying to steal her rings: greyed silver and diamonds, mini thistle-head crowns. I take them home, and bring them in when I travel up for visits. "Give me my rings and propose," she orders. She wants that nice blond nurse to be her bridesmaid, even though the nurse thieves her cask wine - which she doesn't: it's in the wardrobe.

Suddenly upset, she refuses my proposal. "Take those rings away. I'll go back to being single." Then she switches: "Please, please, put them on me again." I do. She says, "Say a marry-me, but more on-purpose."

She has been in this place two years. Before that she lived in her apartment, survived on tea and sweetener. I live 2000 miles away, and couldn't help to cook and feed her. She wouldn't let Meals on Wheels through the fortress door. The Alzheimer's people got similar treatment. Sometimes she didn't use the toilet and pissed on the floor. When they stepped in it, she said she'd spilt her cuppa. They'd try to coax her to the shower, but she accused them of wanting to see her nude.

Some days she couldn't work out how to unsnib the fortress' lock and chain. The woman downstairs heard her calling, "Mummy! Mummy!" Her husband rang me to complain that she'd be trapped if there was a fire. One time he tried to fix her tele. Nothing wrong with it: she'd forgotten to work the clicker. "Press the green button. The green. No, the green," he instructed her, and wrote it down as a prompt card. She called him a bossy bastard, and he lost his temper and swore back that he'd had a gutful. He rang me to say he was sorry. "You've got to put her away somewhere. It's time. I mean that nicely."

Five o'clock next morning she rode the lift - up, down, up, down - until it stopped going. They found her fallen over on the basement level, swearing blue murder about the faultiness of lifts.

At the hospital, she refused to undress or get into bed. She bared her teeth rather than let any doctors touch her. When I arrived, she demanded I take her home and count her rings to make sure none of these mongrels had robbed her. When I refused to take her home, she sat in a chair and hugged her handbag. She cursed me: "You never was worth a pinch of shit. You wouldn't treat me like this if your father was alive. Your father called you his biggest disappointment." She glazed over with a blank look, as if failing to recognise me for a second.

She yelled, "You're all talking about me behind my back! You and them out there. What are they saying about me?" I told her to stop embarrassing us both.

That's not the way to handle the matter, said the Alzheimer's nurse. "You are a parent to her now, and she's your child." I said: I feel like a thief of her life. I want some absolution from someone for what we're doing. To die young is a bitter business, but old like this is worse - slow, sadistic to us. "Pull yourself together," said the nurse. "You must learn to lie to her. We had a priest with a mother just like this. At first he wouldn't lie for religious reasons, but now he does it on his ear, with no Hail Marys."

The nurse said I'm not to call it a nursing home, this hotel where she's going. Tell her it's a holiday she's taking, a lovely room near the water where she'll be treated like a princess. When that failed and my mother hugged her handbag even tighter, I said the police would come if she didn't get in the cab.

Two years ago the rings hula-hooped her shrunken stick fingers like the property of someone else's bigger self. Her stay here in Island wing has fed her fingers back to normal. "Say you'll never leave me," she flirts and frets, her Magoo spectacles her see-through veil.

"Of course I won't," I lie, and she settles.

She says there's something wrong with the other patients; calls them oldies and maddies, lovelies and cows. She watches her watch until it ticks her asleep. She wakes in the '70s and asks, "How's the hotel going? Done the stocktaking, Bert?"

"Yes." Bert was my father.

"Good. Mum rang the other day." She's been dead for 30 years. "She's worried about me and wants me home at her place. You take me."

"Tomorrow."

"Good. I'm going to get her to mind my pennies. And I'll get her to make me a scarf."

Today a singing troupe uniformed in green is singing ‘Roll Out the Barrel' in the big lounge where the worst maddies and lovelies have been wheeled. When notes are missed there are no giggles or frowns - a saving grace because if laughter is numbed, so must be suffering.

"Do you want me to take your rings off?"

"No."

"I've got to go."                                   

"Where?"

"Home."

"I'll go with you."

"Not today."

"When?"

"When you get better."

"I'm better now."

"Maybe next time. Soon."

Soon is the other word for never.