A study in the Lancet looked at whether a blood test could indicate the most common form of dementia and diagnose people decades before symptoms are clear enough to be identified by medics
Alzheimer’s disease may be present in midlife and already causing subtle memory problems, research suggests.
A study in the Lancet looked at whether a blood test could indicate the most common form of dementia and diagnose people decades before symptoms are clear enough to be identified by medics.
Scans of Alzheimer’s patients show sticky proteins amyloid and tau build up in the brain. US researchers tested the blood of 1,350 people without dementia for biomarkers indicating whether this build-up had started. The average age of the participants was 61.
The study showed that 86 people recorded high levels of the biomarkers and, crucially, these participants also scored lower cognitive tests looking at verbal memory and thinking speed.
Author Prof Kristine Yaffe, of the University of California, said blood tests “could help target preventive strategies and clinical trials aimed at delaying or preventing the onset of dementia”. She said: “These findings support the concept that Alzheimer’s disease begins decades before clinical symptoms emerge and highlight the potential value of plasma biomarkers for early detection in the general population.”
It is not known yet whether the participants with amyloid and tau biomarkers will go on to develop and be diagnosed with Alzheimer’s.
Scientists are still trying to understand the role the “tangles” of two key proteins have in the development of the disease. They are present in the brains of those with Alzheimer’s but also in the brains of elderly people who experience no dementia symptoms.
The race is on to develop and licence an effective blood test to diagnose dementia before devastating degeneration of memory and thinking skills. The NHS is recruiting for a £10 million clinical trial called the ‘Blood Biomarker Challenge’ project, backed by the People’s Postcode Lottery.
Drugs are also in the clinical trial pipeline which could halt the progress of the disease but will have to be administered in the earlier stages of Alzheimer’s.
A separate study also published in the Lancet suggests a new way of performing brain scans could detect tau protein tangles before symptoms appear.
Researchers compared Flortaucipir, a radioactive tracer used in PET scans, to a newer agent called MK6240. The study of 682 patients in the US and Canada found MK6240 identified more than twice as many tau-positive cases as Flortaucipir in early tau regions. Flortaucipir, also known as Tauvid, is licensed in the UK but not routinely used on the NHS.
Dr Jacqui Hanley, head of research funding at Alzheimer’s Research UK, said: “These two studies add to a growing body of evidence showing progress in detecting the biological changes linked to Alzheimer’s disease much earlier in life, using a range of biomarkers from blood tests through to advanced brain imaging.
“Being able to identify these changes sooner than we can now could be incredibly valuable. If we can identify Alzheimer’s disease earlier on, it would open up opportunities for people to take part in studies of new treatments.
“We could also identify people who might benefit from disease-modifying treatments that are indicated for early-stage disease. In the UK, many people wait far too long for a dementia diagnosis, meaning they often miss out on these opportunities.”
About a million Brits have dementia and this is set to rise to 1.4 million by 2040. Alzheimer’s – the most common form of dementia – makes up between 60% and 80% of cases.
Professor Paresh Malhotra, head of neurology at Imperial College London, said: “This study has used the new blood tests-that have started to enter clinical practice-in a relatively large number of people below the age where cognitive symptoms become most frequent.
“This adds to our knowledge about how many people will have abnormal Alzheimer’s blood results at this age, and provides further information about how common these changes are. Because it is at a single time point, it does not tell us about how the proportions in this group will change over time.”
