A couple of years ago I went to the doctor because I was afraid I had Alzheimer’s. Suddenly names, facts and bits of poetry I thought I knew were not there anymore. I reached for them automatically and found – nothing. It was alarming.My doctor, a young Indian woman, looked at me sceptically and fired off some questions. I was as nervous as an Oxbridge entrant but I managed to answer correctly, until we got to the mental arithmetic and counting backwards. Then I was hopeless. She did not however condemn me to a diagnosis of Alzheimer’s but put it all down to stress, a polite way of saying I was wasting her time.