Would you want to know if you are at risk of developing Alzheimer’s Disease?
In the UK, there are currently around one million cases of people with dementia. Some 60-70% of all cases of dementia are a form of Alzheimer’s disease.
In Alzheimer’s disease, certain proteins build up in the brain. One protein called amyloid forms sticky clumps called ‘plaques’ outside the brain cells. Another protein known as ‘Tau’ collects inside the brain cells forming structures called ‘tangles’. Together, these deposits lead to inflammation of the brain, ultimately resulting in damage to the brain. This process can begin up to 20 years before any signs of Alzheimer’s disease appear (e.g., memory issues, difficulty in decision-making, etc).
There are several tests to help diagnose Alzheimer’s disease. These include checking a person’s memory, ability to make decisions and coping with day-to-day activities. They also look for the presence of amyloid and Tau proteins in the brain or the fluid around the brain and the spine, called cerebrospinal fluid.
One way to see the proteins in the brain is with a special type of scan called a PET scan (positron emission tomography). Before the scan, a small amount of a safe radioactive material (called a ‘Tracer’) is injected into a vein. This helps the scan show where the proteins are in the brain.
Another way is by collecting a small sample of the fluid around the brain and spine. This is done with a needle in the lower back and is called a lumbar puncture or ‘spinal tap’. Only specially trained doctors do this, and it happens during a hospital visit.
These tests (PET scan and lumbar puncture) along with other checks, help doctors confirm if someone has Alzheimer’s disease.
New technology is now emerging which can help to detect Alzheimer’s disease earlier by using a simple blood test. This test looks for special substances in the blood, called ‘biomarkers’. Biomarkers can show if someone might have a disease, how it is changing, or how well treatment is working. In Alzheimer’s disease, the important biomarkers are small pieces of the amyloid and Tau proteins. These can be found in the blood and indicate changes in the brain before any symptoms appear.
If the test is positive, it may mean there is a higher likelihood that the person has Alzheimer’s disease. Finding the disease earlier can help people start treatment sooner, which may slow it down and lead to better outcomes for patients. These biomarkers are now being tested in research studies to see how useful they are in spotting Alzheimer’s disease in people who might be at risk. They are usually used alongside memory tests. In the future, blood-based biomarker tests might be used instead of PET scans and lumbar punctures to help diagnose Alzheimer’s disease.
Research has improved our understanding of Alzheimer’s disease. This has led to the development of newer treatments that can slow down the disease process in the early stages of Alzheimer’s disease. These are known as disease-modifying drugs. Two examples are lecanemab and donanemab. These treatments work by helping to remove amyloid from the brain.
Disease modifying drugs are for patients who have early stages of Alzheimer’s disease or have mild cognitive impairment. To receive these anti-amyloid treatments, a person must first have a positive blood biomarker test to show signs of Alzheimer’s . At present these drugs are not approved for use in the NHS.
For seven years, I have been a participant in a programme with the acronym CHARIOT: PRO * which is a series of studies looking at risk factors associated with dementia. Recently I became a member of an Advisory Panel which inputs a lay element into discussions around blood-based biomarker tests. Would you want such a test and would you want to know the result?
* CHARIOT: PRO = Cognitive Health in Ageing Register: Investigational, Observational and Trial Studies in Dementia Research: Prospective Readiness Cohort Study