Alzheimer’s Research UK estimates that one in two people will be affected by dementia at some point in their lives, either as a carer, patient, or both. This is a stark statistic, but hope is on the horizon as the first treatments proven to slow the progression of Alzheimer’s disease have recently been approved for use in the United States.
Here in the UK, two new trials have just been announced to investigate the possibility of using blood tests to diagnose Alzheimer’s disease and other types of dementia in thousands of volunteers from around the country.
The first is to be carried out by scientists at University College London's Dementia Research Centre and the second by a team from the research group Dementias Platform UK. Both will search for traces of the toxic proteins that build up in the brains of those with dementia in simple blood samples.
One of the main hurdles in developing effective treatments for dementia is the difficulty of diagnosing the disease early on. Changes in the brain caused by dementia start decades before symptoms appear. If successful, these blood tests could provide early, accurate diagnoses, and so open the door to earlier treatments.
A second serious problem facing dementia researchers is figuring out exactly which type of dementia the patient has. Alzheimer’s disease, dementia with Lewy bodies, frontotemporal dementia, vascular dementia, and other conditions can all cause similar symptoms. But until recently, the only way to know for sure which disease was responsible was to look at brain tissue after death.
One recent development has come in the form of brain scans called positron emission tomography (PET). This method uses radioactive tracers to label toxic proteins (called amyloid and tau) that clump in the brains of people with Alzheimer’s.
Changes in these toxic proteins can also be detected through a technique that involves taking a sample of spinal fluid using a lumbar puncture (also known as a spinal tap). However, these procedures are expensive and invasive.
To make testing available to more people, and so catch the disease earlier, we need cheaper, less invasive procedures. This is where the new tests come in.
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The new trials will examine blood samples searching for the proteins that change in the brain in dementias. The samples will be collected in the same manner as existing blood tests – an easy procedure that most of us have experienced.
They will then be taken to labs and tested using sensitive techniques that can detect tiny amounts of the toxic proteins that leak out of the brain into the bloodstream. These can help identify which form of dementia could be present.
Importantly, 3,000 participants from diverse backgrounds from all around the country will be donating blood for this study. This increases the chances that the tests developed will work for people from all backgrounds including those who have not been included in previous research such as the very elderly, those from ethnic minorities, or those with other medical conditions.
The team at UCL will focus on a promising blood test specific for Alzheimer’s disease that detects a protein called pTau217.
Several studies from around the world have already provided strong evidence that this test is just as accurate as a lumbar puncture. The UK study will push current findings further to see if measuring pTau217 can improve the diagnosis of people with early dementia symptoms or mild memory problems.
Until very recently, there were no effective treatments for dementias, but new drugs that remove toxic amyloid from the brain have now been found to slow the decline in Alzheimer’s.
These drugs are not a cure and come with a high price tag and potentially dangerous side effects. But despite these limitations, the success of amyloid-lowering treatments proves that we can change the course of dementia.
Research into better ways to treat and prevent dementia is ongoing, with several exciting treatments coming through the pipeline. I am very optimistic that these studies will lead to life-changing approaches for people living with dementia in the coming years. And blood tests are likely to play an important part in getting effective treatments to everyone who needs them.
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