A newly developed blood test can identify or completely rule out what is known as brain amyloidosis, which is the most important and earliest pathology of Alzheimer’s, with very high accuracy. This prevents misdiagnoses, which means that those affected are spared unnecessary treatments and the healthcare system is spared high costs.
A new study involving experts from Lund University in Sweden has tested a blood test that uses a two-step workflow to reliably detect Alzheimer’s disease and reduce the need for confirmatory testing in people with mild cognitive impairment. The study results are published in the journal “Nature Aging”.
Biomarkers to identify Alzheimer’s
In recent years, great efforts have been made to identify biomarkers that can indicate Alzheimer’s. The focus was also on the tau protein (particularly its phosphorylated variant called p-tau) as one of the main proteins involved in Alzheimer’s pathology, the researchers report.
New blood-based p-tau biomarkers, particularly the p-tau217 variant, are clinically useful tools for studying people with memory problems or other early cognitive symptoms that indicate signs of Alzheimer’s, according to the team.
However, there is concern among experts that such tests could deliver a fairly high percentage of false-positive and false-negative results. Such incorrect diagnoses would not only result in high costs, but also expose those affected to unnecessary medical risks if, for example, a false positive result is obtained.
Reliably diagnose Alzheimer’s in two steps
Therefore, the team has now developed a two-step workflow, in which the first step is to assess the risk of amyloid PET positivity in people with mild cognitive impairment.
In step two, the people who had an uncertain result are subjected to confirmatory tests to get definitive clarity as to whether they have a disease or not.
The new study involved 348 people with mild cognitive impairment. The researchers used the p-tau217-based two-stage model to estimate the participants’ risk of developing the disease.
The participants were divided into different risk groups, in which the people had either a high, low or medium risk of brain amyloidosis and the early pathology of Alzheimer’s, the team explains in a press release.
Alzheimer’s identified with high accuracy
The blood test used in the first step had already shown a very high level of accuracy in identifying participants with a high risk of Alzheimer’s, and Alzheimer’s could be ruled out with a high degree of certainty in the group with a low risk, the researchers continue.
The intermediate risk group also comprised only about a third of the participants, which significantly reduces the need for confirmatory CSF or PET tests in specialist clinics and is therefore associated with lower costs for society. (as)