DR MAX PEMBERTON: I’ll never take a blood test to reveal whether I will get dementia – sometimes, it’s better not to know

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Written By Rivera Claudia

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If you were offered a simple blood test that could reveal whether or not you would one day get dementia, would you take it?

It is a question that millions of us could soon be facing, after researchers at the University of Gothenburg in Sweden announced a revolutionary new way of detecting Alzheimer’s disease – the most common cause of dementia in the UK – up to 15 years before symptoms emerge.

Reading the research, I was reminded of working at a memory loss clinic in London some years ago. There I met a number of patients with suspected Huntington’s disease, which causes degeneration of nerve cells in the brain.

Huntington’s is genetic, and it has long been possible to test for whether someone has inherited the ‘faulty’ gene.

I remember one young man in his late 20s who had watched his father finally succumb to the disease just months before. Towards the end of his life, the father was no longer able to recognise any of his family.

Alzheimer’s disease, which is the most common cause of dementia in the UK, causes the brain to degenerate – as in the brown areas in the image above

This young man refused a blood test.

At first, I was confused. But then he asked me: ‘Would you want to face years of anxiety over whether forgetting someone’s name or misplacing your car keys was simply scattiness – or the start of terminal cognitive decline?’

And his was far from an isolated case, as I soon came to learn. In fact, only 20 per cent of those offered a Huntington’s test choose to take one. When it comes to this most cruel of diagnoses, it seems ignorance is bliss.

Dementia is an umbrella term for a range of diseases that cause cognitive decline. Of the roughly 950,000 dementia sufferers in the UK, the vast majority have Alzheimer’s.

Now there is no doubt that, for many people already exhibiting dementia symptoms, this new blood test will provide sobering clarity.

Currently, 98 per cent of people with suspected Alzheimer’s receive a diagnosis based solely on their symptoms. This is because the only means of definitive testing are invasive and expensive.

One option is a ‘PET’ scan – which uses a radioactive ‘tracer’ drug to monitor cell activity in the body. The other is a lumbar puncture, or spinal tap, where a needle is inserted into a space surrounding the spinal cord in the lower back to remove cerebrospinal fluid.

Previous attempts to develop a blood test for Alzheimer’s have either proven insufficiently sensitive (returning false negatives) or not specific enough (returning false positives).

From 1906 when clinical psychiatrist  Alois Alzheimer first reported a 'severe disease of the cerebral cortex' to the recent 'breakthrough' drug lecanemab,  scientists have spent over a century trying to grapple with the brutal disease

From 1906 when clinical psychiatrist  Alois Alzheimer first reported a ‘severe disease of the cerebral cortex’ to the recent ‘breakthrough’ drug lecanemab,  scientists have spent over a century trying to grapple with the brutal disease

However, this new blood test is 95 per cent accurate and therefore undoubtedly marks a scientific breakthrough.

However, I am deeply concerned by the suggestion from some members of the medical profession that the test could be used as a screening tool for anyone over the age of 50.

We currently have no cure for Alzheimer’s, nor do we have any clinically proven treatments. So why should we look to screen millions of people for a disease they could do little to hold at bay?

Those diagnosed would be condemned to years of stress and anxiety – even before they started showing symptoms of the illness.

By 2030, over a million people are expected to be living with dementia in the UK – a figure that will double by 2045. Until we have truly effective treatments, I fail to see any good in forewarning them of this horrendous fact.

With a condition like high cholesterol, for which we do have very effective treatments, it makes compelling sense to screen people so that action – such as taking statins and stopping smoking – can be taken.

Alzheimer’s is different. Yes, drugs known as ‘cholinesterase inhibitors’ such as donepezil and galantamine can temporarily slow the impact of memory loss and cognitive decline. But these don’t affect the trajectory of the disease and typically work for only 18 months.

There are new medications in the pipeline. But when and if they become available, they are likely to only be suitable for a small number of patients, due to side effects.

It may well be that in the future we develop comprehensive and effective treatments for Alzheimer’s – at which point I would encourage all those over 50 to take a blood test.

But until then, mass screening will do nothing but cast a terrible pall over millions of lives.

That’s why if I’m offered the test, I’ll be making the same decision as that young man all those years ago in the memory-loss clinic. Sometimes, it’s better not to know.

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