I worry about developing my mother's dementia. I don't want to unravel as she has, lose the essence of me, all my stories, my connection to my children. I don't want them to have to look after me when I'm her age.

Naturally then, stories like Chris Hemsworth's alarm me. The Australian actor and star of Marvel's Thor movies has recently been found to be at heightened risk of developing Alzheimer's disease due to his genetics.