The writer, who has penned a memoir, Where Memories Go: Why Dementia Changes Everything, recording her mother's Mamie's illness, said that listening to familiar songs from her past could help push back the worst symptoms of the disease.
Mamie Magnusson was regarded as one of the finest journalists of her generation and her daughter said she was "exhilarating" company before dementia took hold.
The illness robbed her of her ability to recognise even close relatives, but she was able to recall songs after listening to them again.
Ms Magnusson has set up the charity Playlist For Life to encourage others with dementia sufferers in the family to prepare a selection of their favourite music and play it in times of stress.
She said: "It can bring them back into a sense of their own identity. Music seems to root them in something familiar and bring about a sense of belonging.
"People need to get their loved ones a playlist for life and offer it to them when they are distressed. It can have a wonderful effect."
Ms Magnusson's book is published today and contains harrowing descriptions of the effect the disease had on her mother. Speaking yesterday, she told how at one stage, her mother was unable to remember the death of her son Siggy, who died in an accident aged 12.
She said: "That was one of the greatest blows to me because any mother who has gone through that knows it becomes the very stuff of her whole being.
"My mother would never acknowledge she was a mother of four. She always said she was a mother of five, and that one child had gone.
"Then one day she asked me, quite pleasantly, 'Just remind me, who is Siggy?' and it just hit me in the stomach like the biggest blow. The idea that she would ever have forgotten Siggy would just have floored her."