Can a Blood Test Diagnose Alzheimer's Disease and Other Dementias?
Last updated: March 2023
Alzheimer's disease (AD) diagnosis is a challenge for patients, physicians, and researchers. There is no single accurate test to diagnose AD.1 People cannot be diagnosed until they begin to exhibit signs and symptoms of the disease.
Generally, a diagnosis is made by the process of elimination; a neurological evaluation doesn't occur until after people exhibit the signs and symptoms of the disease. Physicians rely on a series of tests, including blood and urine tests and imaging technology - including PET scans, CTs, or MRIs. Memory tests, symptom discussions with friends and family, and clinical observation are all considered in diagnosing AD. They are the same tools used to rule out other causes of memory loss and cognitive impairment.1
These tests are expensive, and can be time-consuming and invasive, like taking a sample of cerebrospinal fluid. Several new technologies under investigation have the same objective: to make an earlier and more accurate diagnosis of Alzheimer's disease.4,6
New blood test to help diagnose Alzheimer's
A new, easy-to-administer blood test, which is analyzed using mass spectrometry (an analytical technique used in chemistry), has been able to effectively detect changes in the amyloid protein levels of the blood before memory loss or mental decline. The results of these blood tests have been more precise in predicting the likely onset of Alzheimer's than PET scans.4-6
Current medications used in treating AD are only prescribed once symptoms are already present when the neurons in the brain have already been, and at this point, seem to be beyond repair.6
If an easy-to-use, inexpensive blood test could identify markers in the blood, it is possible that treatment could begin before symptoms develop.
Researchers at Washington University in St. Louis and the Alzheimer's Association consider this a breakthrough in the future combat of the disease.5
Initial studies show the blood test, when combined with analysis of other risk factors and PET scans, to be up to 94 percent accurate in identifying people who have brain changes consistent with early Alzheimer's.4-6
Amyloid build-up is common in people as they age, and the presence of amyloid plaques does not necessarily mean a person will develop AD. Establishing baseline criteria will be an important part of the ongoing research. But evaluating those at high risk and having a low-cost and reliable way to track changes in amyloid levels could benefit the AD community and the targeted development of effective treatments.
Benefits to diagnosing Alzheimer's early
Early diagnosis of AD is important for many reasons. Beginning treatment earlier may help to preserve a person's cognitive function for a longer period of time. An earlier diagnosis may create the opportunity to set up an advanced directive, choose a legal and medical power of attorney, make end-of-life decisions, and have discussions with their families about living arrangements and how those arrangements may change as their disease progresses.1
Setting up good support networks, participating in care decisions, and potentially taking advantage of advances in AD research, which may hold potential benefit to the patient and their family as well as future AD patients.1
Researchers have realized the value of diagnosing AD early, both for patients and for other researchers. Other Chicago-based researchers have found another company that is creating a blood test or skin biopsy to look at cellular biomarkers that can help identify AD and other cognitively impaired people accurately at an earlier stage in their disease.2
These biomarker tests can also monitor AD as the disease progresses. While part of the intention of this test is to work toward a personalized treatment, the other benefit is that people with AD can share their information with researchers to facilitate better medications and treatments for AD.2
Technology to help diagnose Alzheimer's
Advances in technology can look at patient DNA in real-time to understand cell functions and to classify biomarkers (chemical signals within cells) specific to AD and other neuro-cognitive impairments. These tests use DNA filaments to analyze cellular chemistry to understand cell functions better, both the normal processes and the cause and impact when they malfunction.2
These new technologies are still in development and require more extensive clinical trials. They have important implications for ongoing and future AD research. Currently, the only definitive way to diagnose someone with AD is by examining the brain in a post-mortem autopsy.1,2
There is a demand for new and better treatments for AD and other neurodegenerative diseases. Still, it has been over 20 years since there has been FDA approval for a new AD medication. More widespread clinical trials and access to AD patients and their information can help improve advances in diagnosis and effective treatment for this deadly disease.2
Science and technology are making strides to bring more accurate, less invasive, and lower-cost diagnostic tools to the public. While these tests are still being perfected, it is important to recognize the importance of collaboration. Finding a better way to diagnose and treat AD and other neurocognitive impairments will hopefully result in a better quality of life, lower healthcare costs, and possibly a cure.
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