Past 40 your body has a way of issuing subtle alarm signals to remind you that you are no spring chicken. There’s the odd ache here and twinge there, the increasing need for reading glasses, and the realisation that you can’t do two late nights in a row. If you’re not 50 yet, just wait. Invitations to NHS screening sessions become more frequent, your body begins to creak and it takes a while to progress beyond a shuffle when you get up. However, it’s the rising forgetfulness — losing your car keys and phone, missing birthdays and meetings — that causes the most creeping anxiety. It’s probably brain fog from feeling frazzled, but what if you really are starting to lose it?