A ground-breaking blood test for the disease is finally in reach
Writer: Nishika Jain
Editor: Javier Bautista
Artist: Sam Vladimirsky
Imagine having a progressive, neurodegenerative disease that slowly embraces you and distances you from the world you once knew. Even worse, imagine seeing a loved one getting entangled in a state of complete confusion and paranoia, as they painstakingly try to navigate life. This is what living with Alzheimer’s disease is like, and in the past few decades the research on this condition has only seen failures ‒ until now. The long sought-after blood test for Alzheimer’s may have been finally found, allowing doctors to diagnose the disease a lot more accurately than existing methods.
Scientifically speaking, Alzheimer’s disease is a progressive disorder that causes the brain cells to degenerate and die. It results in a continuous decline in thinking and behavioural and social skills that disrupts a person’s ability to function independently. A startling 30 million people worldwide are a culprit of this disease, with the risk of one developing Alzheimer’s dementia greatly increasing with age. Around one in ten people aged 65 years and older have Alzheimer’s and now only have a fragmented idea of how the world looks.
While scientists do not yet fully understand what causes Alzheimer’s disease, it is often assumed to be due to a combination of age-related changes in the brain, along with genetic, environmental and lifestyle factors. This progressive disease occurs due to the abnormal build-up of proteins in and around brain cells. Two such notorious proteins are amyloid, whose deposits form plaques around the brain, and tau, which forms tangles inside brain cells. As the brain slowly becomes colonised, there is also a massive decrease in neurotransmitters, especially acetylcholine. Over time, different areas of the brain shrink, the first typically being the hippocampus that is essential for memory formation, leaving patients with books full of photographs but no memories to accompany them.
A sad reality of this condition is that its diagnosis is extremely difficult. In fact, a true Alzheimer’s diagnosis is not possible until after death, when the brain tissue can be examined in an autopsy. Thus, doctors diagnose the disease through a series of cognitive tests, brain imaging scans, and bloodwork that help them to rule out other conditions and make an educated guess. It can take six to twelve months to confirm the diagnosis; some people have to wait years before getting one. This leaves the family in a state of utter dismay as they are unable to even identify the condition their loved one is suffering.
However, the silver lining of the countless hours of research that have seen failure after failure, and have consumed millions of pounds of investment, is that the long sought-after blood test for this disease may have finally been found ‒ a remarkable medical breakthrough that shines a glimmer of light and hope for those walking down this gloomy path. The test helps to determine whether people with dementia have Alzheimer’s instead of another dementia-causing condition with around 96% accuracy. It has also been able to identify signs of the degenerative, deadly disease 20 years before memory and thinking problems were expected to manifest in people with a genetic mutation that causes Alzheimer’s.
Methods such as PET scans and spinal taps do not afford reliable Alzheimer’s diagnoses because they detect elevated levels of amyloid protein, which is an unreliable biomarker. Many people with high levels of amyloid do not develop the disease. The new blood test, on the other hand, has been able to accurately measure a form of the tau protein found in tangles that spread throughout the brain in Alzheimer’s. Another advantage of this test is that the detection of tau may be valuable for predicting how quickly a person’s cognitive abilities will decline, because, unlike amyloid, tau tangles tend to increase as dementia worsens. Researchers also compared findings of brain autopsies of donors from Arizona with test results on blood that they donated before they died. It found the blood test was 98% as accurate in diagnosing Alzheimer’s as autopsies of people found to have had a high likelihood of the disease because they had both amyloid plaques and extensive tau tangles in their brains.
While this revolutionary blood test is not yet available to the public, scientists believe that it should be accessible in a few years. This would accelerate the search for new therapies by making it faster and cheaper to screen participants for clinical trials, a process that often takes years and costs millions of pounds. This test is a great example of how close the medical world is to having quick tests that give us accurate predictions of our risk of developing brain disease. Hopefully this test will be the key that allows medicine to progress into a new world of certainty, a world where Alzheimer’s disease has a reliable diagnosis and no longer has the power to rob individuals of memories and families of beloved ones.