A recent study, conducted at the Washington University School of Medicine, has found that signs of brain damage can be detected by a simple blood test. It helps to detect damage among people who will develop Alzheimer’s, long before they show signs of memory loss or misperception.
These findings were published in journal Nature Medicine. It may one day be applied to inexpensively and quickly identify brain injury in people with not only Alzheimer’s disease but other neurodegenerative diseases like multiple sclerosis, traumatic brain injury or stroke.
Researchers found that it has been validated in people with Alzheimer’s disease. This is because their brains undergo lots of neurodegeneration. But this marker isn’t specific for Alzheimer’s. High levels could be a symptom of many different neural diseases and injuries.
This test detects the levels of neurofilament light chain (NfL). It is a structural nerve protein which leaks into the cerebrospinal fluid (CSF) and then the bloodstream, after the damaging of brain neurons.
High levels of NfL indicate brain cell damage
Increased NfL levels in the CSF have been indicated the damage to brain cells. But most of the patients are reluctant to experience the spinal tap which is needed for this fluid.
Researchers then investigated whether levels of NfL in blood could also act as a marker for neurological damage.
For this, the team evaluated about 400 participants. The participants included in the Dominantly Inherited Alzheimer’s Network (DIAN). They all had rare genetic variants in their families which cause Alzheimer’s to develop in the 30s, 40s, or 50s. All participants had formerly undergone a brain scan, blood test, and cognitive testing at a DIAN clinic.
The scientists found that protein levels of participants with the faulty gene variant were higher at baseline. And then rose over time. On the other hand, levels of protein were low and stable in people with healthy genes.
As reported in the journal Nature Medicine, this difference was noticeable 16 years before mental symptoms were estimated to arise.
Furthermore, after the brain scan analyses, researchers found that how quickly the protein levels rose followed with the speed with which the precuneus thinned and shrank. Precuneus is the part of the brain involved in memory.
According to the Stephanie Schultz, co-author of the study, sixteen years before signs arise is quite early in the disease process, but even then they saw differences. This could be a good preclinical biomarker for the identification of those who will go on to develop clinical symptoms.
Individuals with high NfL levels were most probable to show signs of brain atrophy
To check whether levels of NfL in blood could be predictive of cognitive weakening, the researchers performed brain scans and two cognitive tests. These tests were the Mini-Mental State Exam and the Logical Memory test.
These tests were conducted on 39 participants with an early-onset gene variant. These participants re-visited the DIAN clinic an average of two years after their last visit.
They found that the patients who had previously been identified as having fast increasing NfL levels were the most probable to show signs of brain atrophy and cognitive weakening.
But researchers found it to be significant to confirm these results in late-onset Alzheimer´s disease. And to define the period over which neurofilament variations have to be evaluated for optimum clinical predictability.
Gordon says that though he can see the experiment being used in the clinic in a few years’ time to identify brain damage signs, he does not feel it is possible to predict exactly when people will develop dementia.
But, “we are working towards that,” he concludes.