Detecting Alzheimer disease is complicated. There are no simple tests. Doctors can perform cognitive function evaluations and order brain imaging, but to date definitive diagnosis relies on autopsy examination. Now, however, a new blood test for Alzheimer disease may allow for early diagnosis.
What Is the Blood Test for Alzheimer Disease?
Researchers report that a blood test may be able to detect signs of neuron degeneration many years before symptoms appear (Preische et al, Nature Medicine, Jan. 21, 2019). The investigators published their findings in Nature Medicine. For this ground-breaking research, they utilized an unusual group of volunteers, including 247 people who had a genetic risk for early-onset Alzheimer disease. Importantly, those who had this particular rare genetic marker were predestined to show symptoms of dementia at approximately the same age as their nearest relatives with the disease. The scientists matched these individuals to family members without the genetic marker. All the subjects gave blood, performed cognitive tests and underwent imaging scans.
A Special Protein Appears in the Blood Test for Alzheimer Disease:
The researchers analyzed the participants’ blood for a protein called neurofilament light chain that is released when brain cells disintegrate. The people with a gene for early Alzheimer disease had higher protein levels when first tested. Moreover, their levels of neurofilament rose steadily over time. The other participants had steady low levels of the protein.
Differences in the protein were detectable sixteen years before the expected onset of symptoms. Rapid increases in neurofilament light chain levels were also linked to brain shrinkage visible on scans. This preliminary test is not yet ready for clinical use, but the authors hope that it will someday allow doctor to diagnose Alzheimer disease when intervention might still make a difference.
This new blood test for Alzheimer disease will be welcome if it actually assists with early diagnosis. Some specialists are already using a variety of tests to determine if someone may be vulnerable to this devastating condition and, most importantly, to treat the factors that contribute to cognitive dysfunction. To learn more, you may wish to listen to our interview with Dr. Dale Bredesen. It is Show 1092: How Can You Overcome Alzheimer Disease?
You may also wish to read about other new tests being developed to detect Alzheimer disease early, including a type of MRI called diffusion tensor imaging. Special retinal imaging called optical coherence tomography angiography also shows promise for early diagnosis of Alzheimer disease.