This week scientists at King’s College London announced something that researchers had thought impossible — they said they had potentially found a blood test for Alzheimer’s disease.
There are 80,000 sufferers in the UK, a number expected to double within 20 years, and the disease is currently diagnosed by asking patients a set of questions to test their memory.
However, this process can take up to a year and is not definitive. At the moment, the only certain way to diagnose Alzheimer’s is by dissecting the brain tissue after death (see picture). The new test, which measures levels of two proteins in the blood, could offer 100 per cent certainty. In five years, after further trials, the test could be available in GP surgeries, enabling doctors to discover whether patients have the disease and how severe it is.
A blood test had been considered impossible because there is a mechanism, the blood-brain barrier, which prevents harmful proteins from entering the brain tissue from the bloodstream and vice versa. “The brain is protected by a covering that usually means that things don’t get out into the blood,” says Simon Lovestone, a professor of psychiatry at King’s College London, the author of the research.
This barrier led scientists to believe that the proteins that indicate Alzheimer’s couldn’t enter the rest of the body and be detected in the blood. But the new study, published in the journal Brain, found that by looking at a vast number of the proteins in the blood of people with Alzheimer’s, and comparing them with people without the disease, scientists can detect the presence of two proteins that can confirm the condition, although at this stage they don’t know what these proteins do.
Researchers believe this test will put an end to the slow and distressing way in which the disease is diagnosed. The test is currently based on the wait-and-see principle.
Your GP asks a number of simple questions such as what day it is, and who’s Prime Minister. The test is repeated either six months or a year later and the results compared. If you’ve got worse, it is assumed that you have got it. If not, you’re in the clear.
But, as well as speeding up diagnosis, there is another benefit of this new blood test that hasn’t been highlighted in the news this week. It will allow doctors to measure the progress of the disease and the efficacy of treatments. This will make testing new drugs much easier. At the moment there are hundreds of drugs being developed for Alzheimer’s, but no certain way of testing whether they are making a patient better or not.
There is no cure for Alzheimer’s and the drugs available treat only the symptoms, not the disease. So what is the point of knowing you’ve got this affliction if there is absolutely nothing you can do about it? The answer is that if you know, say, in your forties or fifties, that you have the disease, you may be able to stop it from progessing.
Someone can have Alzheimer’s for many years before they have any symptoms, says Professor Lovestone. “The evidence is that the changes that are associated with Alzheimer’s start to take place in the brain many years — some says decades — before they become obvious to people through symptoms such as forgetfulness.”
Rebecca Wood, the chief executive of the Alzheimer’s Research Trust, who funded Professor Lovestone’s work, says diet and exercise can stave off dementia. “It’s been shown that if you encourage people to have a better diet and more exercise you can influence whether or not they go on to develop dementia.”
A number of studies have linked omega-3 intake to improved memory in later life and a study last week, published in the journal Neurology, linked eating green vegetables to slower cognitive decline in the over-65s.
And Wood says that a test that measures the stage of the disease would also make determining who gets drugs for Alzheimer’s much more clear-cut. Present treatments have been the subject of bitter debate between the National Institute for Health and Clinical Excellence (NICE) and patient groups, with drugs for early-stage Alzheimer’s not deemed a cost-effective option by NICE, and therefore not available on the NHS.
“From November, patients will not be able to get any drugs for early-stage Alzheimer’s, unless they’ve been prescribed it before this date. It will go back to patients paying for their drugs, which will cost about £80 a month,” says Wood.
Whether or not a patient gets a drug is determined by how they score on the short test (see box). If someone gets a score of 10 to 20, out of a maximum of 30 (a perfectly fine brain), they are classed as moderate, and can get the drugs. Score higher than that and the disease is not serious enough to warrant the drugs.
However, this is a bit ad hoc, says Wood, with more intelligent people compensating and scoring higher, even though the disease may be quite severe. The new test will clarify who is entitled to the drugs.
However, with cost being a big issue in disease treatment, will this new blood test be affordable? Extremely affordable, says Professor Lovestone, in fact, it may be free. “The pharmaceutical industry wants a gold-standard test that is cheap or as close to free as possible.”
There are more than 500 drugs in the pipeline for treating Alzheimer’s but, so far, no cheap, reliable way of testing whether they are working.“I’ve every reason to be cautiously optimistic,” says Professor Lovestone, “and say that in five to ten years there should be a drug that will slow progression of Alzheimer’s and treat the very early stages.”
One of the big problems with Alzheimer’s is lack of cash. “There’s only about £11 spent on UK research into Alzheimer’s for every person with the disease, compared with £289 for cancer patients, yet the same number of people are affected,” says Wood.
“The cost of care of Alzheimer’s patients is £11 million a year — higher than heart disease, cancer and stroke put together. We are not saying give less to cancer but, if we put the effort and money that we do into cancer into Alzheimer’s, it will make a huge difference to the future of dementia,” she says. “Otherwise, with an ageing population, we’re sitting on a timebomb.”
For more information about the disease, contact the Alzheimer’s Research Trust (www.alzheimers-research.org.uk)
The Alzheimer's disease exam
To assess whether someone has Alzheimer’s, they are usually asked to do a test called the mini mental- state examination. A score of 26 (out of 30) or above is fine, 21 to 26 means mild Alzheimer’s, 10 to 20 is moderate; less than 10 is severe.
Easy ones first
The test starts with questions about the here and now, such as what’s the date and who’s the Prime Minister?
Memory test
Listen to a list of three objects and recall them after a short pause. This may be repeated shortly afterwards.
Saying things backwards
Count and spell words backwards.
Language test
Look at pictures of objects and name them; repeat a tongue-twister.
Drawing pictures
Draw a shape, such as a circle or a square, and fold a piece of paper neatly in half.
For more information about the test, contact The Alzheimer’s Society, on 0845 3000336; or visit www.alzheimers.org.uk. The full test can be bought from www.parinc.com.
