My wife knew there was something wrong when my mother started to be nice to her.

Instead of coming out with sarcastic and personal remarks, my mother seemed to be almost pleasant ... for the first time in 20 years.

We reckoned my mother's caustic temper had mellowed.

It was some time later that we realized there was something seriously wrong.

These thoughts were passing through my mind on Mother's Day. Unfortunately, I couldn't be with her this year as I'm in Beijing and she's in Scotland. But I can remember her.

I prefer to remember my mother as a feisty woman. Yes, a difficult woman, but a spirited one.

She had a vicious tongue and little sensitivity to other people's feelings.

As you can imagine, she had few friends. One by one she alienated people with her hurtful remarks.

On the other hand she was lively and vigorous, a good wife and mother and prided herself on her housekeeping. She was also an excellent baker. My mother's chocolate cake was legendary, her apple pies to die for and her swiss roll melted in the mouth.

Her advice to her sons was: "Choose a wife with cold hands. She'll be a better pastry cook."

But all that has changed as she forgets things, people's names and what she did yesterday.

My wife and I were having a party. Our youngest daughter, then 14, approached her grandmother, who asked her: "And who are you, my dear?"

My mother's driving, which had never been great, became even more erratic. Journeys became bare-knuckle rides. My wife and I decided we didn't want our daughters to be driven anywhere by their gran.

After my father suffered a mild heart attack, my mother drove to see him in hospital. She left the car on a yellow line, and got a 25 pound ($41) fine. My brother decided to give her a lift to the hospital so she didn't need to drive.

She lost her keys to the house and when they were found she couldn't distinguish her house keys from her car keys.

My wife arranged an appointment with the doctor.

My mother insisted the appointment was at 1:20 pm. My wife gently suggested it was at 2:20 pm. My mother insisted she was right. She wasn't.

"Tell the doctor why you are here, Margaret," my wife prompted her.

My mother began a rambling story about not getting out for walks since Rudi, her dog, had died.

"No, tell the doctor about your memory and how you keep forgetting things," said my wife.

The GP (general practitioner) tested my mother's memory: "What's the name of the prime minister? Who is the president of the United States?"

My mother's mind was fumbling in the dark: "Oh it's that man what's his name?"

The onset of dementia was rapid. My mother struggled to speak. Her sentences tailed off when words failed her. We tried to fill them in for her. She seemed happy and animated when our daughters visited and gave her their news.

But in the evenings she would tell my father: "Bill, it's time to go home."

And he would reply patiently: "But you are home, Margaret."

One day my mother got out of bed before my father awoke.

He looked in her room, in the lounge, in the conservatory, in the garden. She was gone. He put his coat on and went out to look for her.

He met her a few hundred meters down the road. She was with a neighbor who was bringing her back home.

My father says the evenings and nights are worst: Mother talks about going home and gets out of bed to search the house for a baby, which she thinks is missing.

Thankfully, I have two brothers and a sister who are attentive to our mother's needs. My father is her carer. Social services are to fit a hoist to enable her to bathe. A podiatrist will visit to trim her nails.

The family tries to spark her memories of days long gone by. Often there's a flicker of recognition and tears.

China Daily