Would you want to know how your days will end?

This week, an ‘ exciting’ breakthrough was announced — and, with it, a quick and cheap blood test to identify those at risk of developing Alzheimer’s has come one step closer.

Researchers have found that the presence of a toxic protein in the blood, called beta amyloid, can predict if someone will go on to develop the condition decades before they have symptoms.

i’m not at all sure that this prospect is ‘exciting’. Who, in all honesty, would take this test?

There is no cure for Alzheimer’s, so if the test showed you were going to develop the condition, you would have it hanging over you for years, along with a sense of impending doom.

i’ve seen patients faced with similar agonising decisions when i worked in dementia services, and it was torture for them.

Dementia is an umbrella term for problems with understanding and memory — and as well as Alzheimer’s, there are other types, including the genetic condition huntington’s disease. This is caused by an inherited faulty gene and develops in middle age. Quite rapidly, people develop problems with movement, thinking and memory, and within ten years they’re dead.

A blood test that can check for the faulty gene is offered to anyone with a family history of the condition once they reach 18. But choosing to have the test is not easy and under 20 per cent do.

i completely understand. Why know something that will overshadow your life but which you can do nothing about?

Even the dementia tests we have now, which look at symptoms rather than predicting the future, worry me. in the dementia clinic, i’d often see patients who had been referred with memory problems and, after a series of tests and scans, had been diagnosed with various types of dementia.

While many took this grave news bravely and stoically, others were chillingly calm. ‘Yes, i thought that is what you would say, doctor,’ they would reply without emotion when i broke the bad news.

something about their resigned response preyed on my mind, and sometimes they would even leave without making another appointment, which struck me as odd.

i mentioned it to the professor i worked under. ‘They are the ones who will probably kill themselves,’ he replied. i was horrified. ‘it is inevitable that some people, on hearing this news, decide to take control — and they will have concluded the only way to do this is to end their lives,’ he told me.

SincEthen, i’ve often thought how this kind of knowledge is the price we pay for everincreasing understanding about the body. it is a modern phenomenon for so many of us to face our own mortality in this way; to be able to see the end of the mortal coil — and, worse, know just how those last days will be played out before we shuffle off it.

Fifty or so years ago, doctors might have suspected a patient would die soon. But now, thanks to modern scanning and better understanding, the picture of what is happening is so much clearer. A friend recently died of cancer, yet knew for months before that it was terminal. Waiting to die, he grappled with big, unanswerable questions about the meaning of life, and we often spoke about whether knowing the end was nigh is always such a good thing.

certainly, it gives people the opportunity to say goodbye, but i’m still not convinced that this is medicine at its finest.

The psychological toll is considerable and there are no trite answers that can pacify the existential crisis that knowing your demise is imminent brings.

From my experience, people do come to terms with the fact that they’re going to die — but it is not an easy path. it reminds me of the line in the poem by Thomas Gray ‘where ignorance is bliss, ’tis folly to be wise’.

When it comes to our own death, sometimes it’s better not to know.