A promising new blood test for Alzheimer’s disease is now on the horizon. The newly reported test proved to be just as reliable as more invasive and costly tests at detecting Alzheimer’s and may even be able to detect the disease as long as 20 years prior to symptoms. This is an exciting new development that could make detecting the disease much easier and speed up enrollment in clinical trials.
The blood test results were announced at the virtual Alzheimer’s Association International Convention in July 2020 and simultaneously published in the Journal of the American Medical Association. The test detects the protein P-tau217. This and other tau proteins are found in tangles in the brains of people with Alzheimer’s.
"While there is still more work to be done, this biomarker (P-tau217) has the potential to have a transformational impact on research, treatment, prevention, and therapy development, and in the clinical setting," said senior author Eric Reiman, MD, executive director of Banner Alzheimer's Institute in Phoenix, Arizona.
An international team of scientists examined blood samples from 1,402 participants in Sweden, Colombia and Arizona. Their results show this test is highly specific to Alzheimer’s disease. The test discriminated Alzheimer’s from other neurodegenerative diseases with better accuracy than MRI brain scans and produced results similar to PET scans and spinal fluid tests. People with Alzheimer’s were shown to have seven times more P-tau217 in their blood than those with other forms of dementia such as vascular dementia and Parkinson’s disease.
The test also appears to be able to predict Alzheimer’s decades before symptoms appear. In Colombia, where members of a large extended family carry a rare gene that predisposes them to Alzheimer’s at early ages, the test accurately differentiated between those who carry the gene versus those who do not beginning around age 25, about 20 years before symptoms would emerge.
Currently, Alzheimer’s diagnoses are made through clinical examinations and assessments of memory and thinking. This approach is not always accurate since Alzheimer’s symptoms can be similar to other types of dementia. In clinical trials, scientists often use PET scans and spinal fluid to identify participants who have the disease. These tests are costly and not readily available to the general public.
With these findings there is hope a simple blood test could be available within the next few years. It will be a significant tool to help physicians diagnose and treat people experiencing memory and thinking problems as well as help patients and families plan for the future.
“One of the things I’m really excited about is the idea that the blood test can cause physicians to start thinking about this problem, finding out if people have it, and then developing strategies where families can get assistance to navigate through some of these challenging issues to improve their quality of life – even while we’re working to find more effective treatments,” Reiman said. "I think it's going to have a profound benefit — and soon.”