Alzheimer’s Blood Tests Are Now Available. Here’s What You Need to Know
The Importance of Early Detection
Alzheimer’s disease affects a staggering 55 million people worldwide and currently has no cure. However, recent advancements in the field have led to the development of promising drugs that can slow the progression of the disease. The catch is that these drugs are most effective when taken early after symptoms begin. Unfortunately, current diagnostic techniques may not be able to detect Alzheimer’s early enough for these drugs to have a significant impact.
Research suggests that signs of Alzheimer’s disease can be detected in the blood up to 20 years before symptoms manifest. Identifying the disease at this early stage could greatly improve treatment outcomes for patients. Luckily, a couple of US companies have developed Alzheimer’s blood tests that are now available for consumers to purchase, either directly from the supplier or at the request of their doctor.
The Diagnostic Process
Alzheimer’s disease is diagnosed using a combination of tests. Cognitive tests assess a person’s memory recall and thinking abilities, while biomarker tests look for signs of the disease in the body, such as brain imaging scans or samples of cerebrospinal fluid. These biomarkers
correlate with three major signs of Alzheimer’s disease: the presence of amyloid-beta plaques outside brain cells, tau protein tangles inside brain cells, and brain cell death.Not all of these signs need to be present for a diagnosis, although the presence of amyloid-beta plaques or tau tangles in the brain is essential. Additionally, some people may show biomarker changes but never develop symptoms. Detecting these biomarker changes in the blood years before other signs appear in the brain could provide a faster and less invasive way of diagnosing Alzheimer’s disease.
Understanding Alzheimer’s Blood Tests
Currently, most available blood tests measure the levels of two different types of amyloid-beta proteins: amyloid-beta 42 and amyloid-beta 40. The ratio between these proteins is calculated, and a lower ratio indicates a higher likelihood of having amyloid plaques and, consequently, Alzheimer’s disease.
One FDA-approved test, PrecivityAD, can be used by doctors to measure the amyloid-beta ratio in patients exhibiting symptoms of Alzheimer’s. The company also analyzes the levels of another protein, apolipoprotein E, to determine the patient’s genetic risk for the disease. An algorithm considers the biomarker levels and the patient’s age to provide a probability score, with a high score suggesting Alzheimer’s disease. Test results are typically available within a few days.
Although the PrecivityAD test has shown a high correlation with signs of Alzheimer’s disease in several studies, it is not 100% accurate and cannot predict the progression of the disease in an individual. Furthermore, these studies often excluded certain participants and were primarily conducted on white individuals, so the accuracy of these tests for people from diverse backgrounds or with other health conditions remains uncertain.
Another test, produced by Quest, also measures the amyloid-beta ratio but can be purchased directly by consumers without a doctor’s referral. This test, however, has not yet been approved by the FDA or undergone extensive testing like PrecivityAD. Additionally, interpreting the results may be complicated without the guidance of a doctor.
Interpreting the Results
When interpreting the results of these tests, it is crucial to exercise caution. Currently, these tests only look for one of the biomarkers of Alzheimer’s disease, which means they cannot detect signs of other forms of dementia. They only provide information about one aspect of Alzheimer’s disease itself. Therefore, if a person’s test comes back negative for Alzheimer’s but they are experiencing concerning symptoms like memory loss, it is important for them to visit a GP as they may have another form of dementia or an unrelated condition.
Conversely, if the test is used by someone without symptoms but abnormal biomarkers are detected, it could cause unnecessary distress by making them believe they have or will develop Alzheimer’s. While these tests are valuable for investigating the possibility of having Alzheimer’s, they are not as accurate as the tests currently used by qualified doctors. However, this field is undergoing rapid developments, and these tests may become equally reliable in the future.
Researchers are currently exploring the accuracy of blood tests that measure concentrations of tau protein, which may be more effective than amyloid-beta at detecting both plaques and tangles in the brain. There are also tests in development that examine both tau and amyloid-beta, including an updated version of PrecivityAD called PrecivityAD2. Furthermore, promising finger-prick tests are being developed that show good correlation with brain scans and cerebrospinal fluid results so far.
In summary, advancements in Alzheimer’s disease diagnostics are making it possible to detect the disease earlier and with greater accuracy. As these tests continue to improve, they offer new hope to patients who can benefit from early-stage diagnosis and treatment.
Keywords: Alzheimer’s blood tests, early detection, cognitive tests, biomarker tests, amyloid-beta plaques, tau protein tangles, Alzheimer’s disease diagnosi