The second biggest fear, after cancer, in the United States, is Alzheimer’s. This degeneration of the brain can not only rob you of your memory and clarity of purpose but, seemingly, of your identity; the stuff that, when in conjunction and melded into a composite, makes you who you are. Thus it is that the former elements of decay become disturbingly obvious to the sufferer and the latter, in the later stages, become an ordeal for family and friends.

The notion that our identity is nested in groups of cells firing electrical charges to each other is bizarre, is it not? Somehow, the traditional view of personality is that it is a mysterious non-material part of us, much as believers think of the spirit or the soul. But, as the cells die and holes appear in our brains, we lose even our selves. Oliver Sachs said in one of his books – probably The Man Who Mistook His Wife For A Hat – a book which is surprisingly positive about degenerative conditions, that the last thing to go which is recognisably the person, is his or her signature. Like the Cheshire Cat our identities fade away, leaving only a just legible scrawl, which is our name.

In the interests of your health, wherever you are, I watched a brilliant documentary on this whole area, pulling together the latest scientific developments. There is no doubt that a cure is on the way – an injection which rids the brain of the plaque and tau-tangles that kill cells. But in the mean time, here’s what you must do if all this scares you.

1 Don’t eat processed fats and sugars or go mad on alcohol but take in lots of fruit and veg

2 Take lots of exercise – which makes brain cells work more efficiently

3 Keep a strong social network (isolates die a lot earlier)

4 Profens, normally used to kill pain, protect brain cells against the assault

5 Take up new activities which demand you learn – languages, music, crosswords

Then, even if your brain is showing advanced signs of degeneration, the brain may still function remarkably well.

Whether we have one or a number of identities – the jury is still out! – we’d like it or them to ride to the last sunset, carrying us along, lightly and with grace. So, we must do what we can and follow the rules until the drug arrives on the market that gives us protection.