Can a Blood Test Predict Alzheimer’s Disease?

Alzheimer’s disease is an irreversible, progressive neurodegenerative illness that affects the brain. Over a period of time, Alzheimer’s disease destroys a person’s memory and thinking skills and disrupts their ability to function independently. In most people, the first symptoms of the disease start appearing in their mid-60s. There is no cure for Alzheimer’s disease yet, and neither is there any way of predicting the risk of developing Alzheimer’s. However, researchers now say that a new blood test can predict the chances of developing Alzheimer’s disease with a 94 percent accuracy. Let us take a closer look at can a blood test predict Alzheimer’s disease or not.

Alzheimer’s disease is the most common form of dementia that causes problems with thinking, memory, and behavior.^(1,2,3) This is a progressive disease in which the symptoms tend to develop slowly and worsen over time. Eventually, the symptoms become severe enough to start interfering with your daily life. Alzheimer’s disease finishes off the ability of a person to function independently. According to estimates of the Alzheimer’s Association, nearly 60 to 80 percent of all dementia cases are due to Alzheimer’s, with most people getting a diagnosis after the age of 65.^(4,5)

There is no cure for Alzheimer’s disease, and neither is there any way to gauge the risk of developing this condition accurately. However, this is now set to change as researchers claim to have found a new blood test that, when combined with other risk factor evaluation, can help predict the risk of developing Alzheimer’s disease with an accuracy of 94 percent.

Scientists have been experimenting and searching for many years to come up with a reliable blood test that can detect the presence of amyloid-beta. Amyloid beta is the protein that is commonly associated with Alzheimer’s disease.^(6,7) Researchers from the Washington University in St. Louis have now announced that they have discovered a new blood test that can help with the diagnosis of Alzheimer’s.⁽⁸⁾

Amyloid is the protein that is commonly associated with brain cell physiology. When there is a loss of balance between the production of this protein and the elimination of it from the brain, it leads to an abnormal accumulation of amyloid-beta in the brain, causing neuronal cell death.⁽⁹⁾ It is possible for amyloid-beta protein to build up in the brain at an abnormal rate and to develop into plaques that are commonly associated with neuron cell death in the brain as well as memory loss.

Alzheimer’s disease is commonly diagnosed by determining memory loss that is not because of normal aging, or any other neurological disease or medical condition. However, the accuracy of this diagnosis being carried out without the availability of specialized scans and only with a thorough work by a doctor is only around 70 percent.^(10,11)

As of now, diagnosis of Alzheimer’s disease is typically made by full clinical examination, brain imaging to rule out any other physical abnormalities, memory testing that is known as neuropsychological testing to determine if there is memory loss that is linked with the person’s age, and blood tests to rule out other medical conditions such as kidney or liver disease, or an infection that can affect memory and brain function.

The new study from Washington University in St. Louis hails the blood test as predicting the risk of Alzheimer’s disease with 94 percent accuracy, after combining the results with age and family history of the condition. The results of this study demonstrated that the blood test is able to detect the start of amyloid accumulation in the brain. The blood test is being hailed as becoming the foundation for developing a rapid and cheap blood screening test that can identify people who are at a higher risk of developing Alzheimer’s.

However, the development has to be taken with a pinch of caution as well because the accumulation of amyloid-beta and the formation of the amyloid plaques are only one of the hallmarks of Alzheimer’s, but this is not specific to the disease and has also been known to be found in other types of dementia. In fact, the amyloid plaques are sometimes also found in cognitively healthy people. As of now, there are still many unknown facts about the role of amyloid in the brain due to which detecting amyloid plaques alone cannot guarantee for sure that it is a sign of Alzheimer’s disease.^(12,13) In the past, studies carried out by the Massachusetts General Hospital and Harvard Medical School have shown that the amyloid protein may also help with immunity.⁽¹⁴⁾ However, more research is still needed to understand the many roles of amyloid in the body.

During this novel study, the researching team made use of a technique known as mass spectrometry to measure the amount of two types of amyloid-beta proteins in the bloodstream. These two forms of amyloid beta are known as amyloid-beta 40 and 42.^(15,16)

The team found that the ratio of these two types of amyloid-beta in the blood went down as the amount of the protein accumulated and increased in the brain.

The 158 participants of the study were adults older than 50 years, and most of them were cognitively healthy. The research team reported that while they saw some false positives during the early tests, the test results still predicted a buildup of amyloid in the brain. The results suggested that the new blood test can be a possible warning system for detecting amyloid deposits forming several years before they can be identified by positron emission tomography (PET) scans, which is what doctors use for diagnosing Alzheimer’s disease. An early detection of this buildup of amyloid can allow people to take the necessary actions for slowing down the progression of Alzheimer’s.

Alzheimer’s disease can be slowed by a drug called memantine and three acetylcholinesterase inhibitors.^(17,18) These substances have shown modest benefits in slowing down the progression of the disease. Combined with a healthy lifestyle, a well-balanced diet, and regular exercise, it is possible to slow down the progression of Alzheimer’s to a great extent.

This new blood test can open up a whole new range of benefits by detecting the risk of Alzheimer’s disease at an early stage. The test will also be much less expensive than the commonly prescribed PET scan and also cause less discomfort than a spinal tap, both of which are techniques used today for diagnosing Alzheimer’s. This blood test will also help people who have early memory concerns to find out if they are at a risk of Alzheimer’s and if their memory problems are due to an abnormal buildup of amyloid in the brain. At the same time, the test will lessen the financial burden on people to undergo the expensive PET scan and spinal tap, both of which are usually not covered by insurance packages. The risk of radiation exposure from having to undertake repeated scans will also be significantly reduced.

While more research is needed to conclusively make this blood test a reality soon, but there is no doubt that such an advancement in the diagnosis of a disease like Alzheimer’s will benefit one and all.

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• How Can Stress Increase the Risk of Alzheimer Disease?
• Risk of Alzheimer Disease In African-American Population
• Dementia vs Alzheimer’s
• Role of Genes in Alzheimer’s Disease & Its Causes, Symptoms, Treatment