Is there a DNA test for dementia?

You might have heard about DNA tests for dementia, or maybe you know someone who's had one. But DNA testing can be complex - so here's the essential facts.

In a nutshell

There are several different DNA tests available, either privately or through your GP, which can reveal your likelihood of inheriting one of the main types of dementia, such as Alzheimer's or frontotemporal dementia (sometimes called Pick's disease). However you need to think carefully before having a DNA test for dementia because the results are rarely 100 per cent accurate - and may even raise more questions than they answer.

Fact

If you have a family history of frontotemporal dementia or young-onset Alzheimer's disease, it might be possible to discover through a DNA test whether you also carry the specific defective genes (sometimes called mutations) which are responsible for these diseases. This sort of DNA test is called a ‘predictive’ test.

BUT If you do find that you have these faulty genes they can't, sadly, be repaired – yet. So simply knowing about them might only cause you to worry. It's really important therefore to take advice. Start by going to your GP, he should then refer you for genetic counselling at your nearest regional genetic centre, usually based in a hospital.

What is genetic counselling?

Genetic counselling is not the same as psychological counselling. Your counsellor will be a health care professional who is an expert in genetics. He will explain more about what the test involves, give you an idea of the kind of result it might show and what that result could mean to you or your family. But he will not make a decision or try to influence you one way or another.

You are entitled to genetic counselling before having genetic test.

Did you know? Results from genetic testing for dementia cannot currently be used against you by insurance companies and shouldn't therefore affect your ability to plan ahead financially. A temporary agreement to stop insurance companies using the results of genetic tests was put in place in 2001 in order to protect people from discrimination. The agreement will last until November 2017 - but what happens then, is unclear.

Fact

Personal DNA testing kits which claim to reveal anyone's chance of developing Alzheimer's disease or dementia are now widely available to buy over-the-counter or online. Their proponents say that it's better to know your risk of dementia - and then make some positive lifestyle changes that could actually reduce it, such as giving up smoking, taking more exercise or eating healthy.

BUT Experts remain sceptical about the accuracy and worth of these tests, and say that anyone who is worried about inheriting dementia can take simple steps to reduce their risk anyway – without needing to buy a DNA test.

We've done the research for you

Genetic testing is available on the NHS if:

  1. You've already been diagnosed with young-onset Alzheimer's or frontotemporal dementia (both of which can be linked to faulty genes) and want to find out if you do, in fact, have one or more of the faulty genes involved.
  2. You have a family history of young-onset Alzheimer's or frontotemporal dementia and would like to know if you also carry one of more of the faulty genes.

Genetic testing is NOT available if you have:

  1. Vascular dementia - this isn't considered a hereditary form of dementia
  2. Dementia with Lewy bodies - although research is now being carried out to discover if this form of dementia is linked to genetics.
  3. Late-onset Alzheimer's - the most common form of dementia. However, if you want to find out if you have one of the genes associated with late-onset Alzheimers (the most well known is called APOE but there are many more) you could buy an over-the-counter DNA testing kit.