Researchers from Washington University School of Medicine and Lund University have identified a highly accurate blood test that can both diagnose and assess the severity of Alzheimer’s disease.
“This blood test clearly identifies Alzheimer’s tau tangles, which is our best biomarker measure of Alzheimer’s symptoms and dementia,” co-senior author Randall J. Bateman, MD, said in a news release.
“In clinical practice right now, we don’t have easy or accessible measures of Alzheimer’s tangles and dementia, and so a tangle blood test like this can provide a much better indication if the symptoms are due to Alzheimer’s and may also help doctors decide which treatments are best for their patients.”
Setting up the test
The researchers explained that there are two primary proteins that are closely associated with Alzheimer’s – amyloid and tau. A buildup of amyloid in the brain is typically the first indicator of Alzheimer’s, while the presence of tau on a scan typically happens later in the disease progression.
Additionally, patients often need either spinal taps or brain scans for accurate diagnoses – both of which can be difficult to obtain.
To simplify and streamline the process, the researchers tested a new blood test on nearly 200 patients enrolled in two study cohorts – the Charles F. and Joanne Knight Alzheimer Disease Research Center and Swedish BioFINDER-2 cohort.
The participants presented with a range of Alzheimer’s symptoms. Some were yet to show symptoms but had high levels of amyloid in their brains, others had mild symptoms, and others had more serious dementia symptoms.
The researchers had the participants undergo this new blood test and compared the results with brain scans for efficacy. They also compared all of the results to a group of cognitively healthy individuals, and a group of individuals with cognitive impairments unrelated to Alzheimer’s.
The results
The researchers were most interested in seeing the participants’ MTBR-tau234 levels. This protein is directly linked to the level of tau tangles found in the participants’ brains.
Ultimately, the blood test was 92% successful at detecting MTBR-tau234 levels that reflected the level of tau tangles found in the brain scans.
Additionally, the blood test showed that those in later stages of dementia had the highest levels of the protein, whereas those in the earlier stages still had elevated levels, but not as high as those further along in their disease progression. The researchers found that those who had progressed to the dementia stage had as much as 200 times more MTBR-tau234 than those who had mild cognitive impairments.
The findings also indicated that cognitively healthy people, those who were pre-symptomatic, and those who had cognitive issues unrelated to Alzheimer's all had healthy levels of MTBR-tau234.
The future of Alzheimer’s treatment
With these positive study results, the researchers are hopeful that the future of Alzheimer’s care will be directly geared towards patients’ needs.
“We’re about to enter the era of personalized medicine for Alzheimer’s disease,” researcher Kanta Horie, Ph.D., said in a news release. “For early stages with low tau tangles, anti-amyloid therapies could be more efficacious than in late stages. But after the onset of dementia with high tau tangles, anti-tau therapy or one of the many other experimental approaches may be more effective.
“Once we have a clinically available blood test for staging, plus treatments that work at different stages of the disease, doctors will be able to optimize their treatment plans for the specific needs of each patient.”