There are now nearly a million people suffering from dementia in the UK, and I feel as if most of my contemporaries have had some involvement in the affliction either through parents or friends. With my father, it came on very gradually, beginning with odd lapses of memory, repetitions in speech, loss of bearings, groundless anxieties. It was exhausting for my mother, so one afternoon we suggested we take her out for a break and arranged for one of the grandchildren to stay with my father for the few hours she was away. When we told him of this plan, my father was furious: he did not need watching over; he could perfectly well look after himself. Anger is common in the early stages of dementia, and it is fuelled by fear: a mental unravelling has begun, and from now on it will only gain momentum.