Dementia is the biggest killer in Britain, yet we know so little about it – this book is the first to explain what is happening from the inside.

Wendy Mitchell managed rosters for hundreds of nurses in the NHS, raised her daughters single-handedly and spent her weekends running and climbing mountains. And then slowly, what she found at the top of those peaks was not clear, unencumbered views, but a mist that had settled deep inside the mind she once knew so well. She didn't know it then, but dementia was starting to take hold.

In 2014, at the age of fifty-eight, Wendy was diagnosed with early-onset Alzheimer's. What lay ahead was scary and unknowable: forced into early retirement, Wendy discovered a chronic lack of understanding about the diagnosis. But she was determined to outwit it for as long as she could. She continues to live independently, surrounded by yellow post-it notes to remind her of routines and a memory room where she displays photos and labels of her daughters and friends. And her sunny outlook persists.

Somebody I Used to Know is a beautiful and inspiring testament to one woman's indomitable spirit. A book about holding on to what is most important in life, it will provide hope for those living with dementia and insight for those supporting others with the diagnosis. The first of its kind, it chronicles the cruel ways that Alzheimer's dissembles a life as well as the surprising ways that it heightens the everyday – and even magnifies love.