A study led by the Hospital del Mar Medical Research Institute, the Barcelonaβeta Brain Research Center (BBRC) and the University of Gothenburg has compared for the first time the validity of nine biomarkers for the diagnosis of Alzheimer's disease in the daily routine of hospitals. This was done with a cohort of patients from the Hospital del Mar with various neurological pathologies.
Researchers have analysed the presence of nine variants of the Tau protein in blood samples from these individuals. Plasma biomarker determinations are less invasive than those performed after a lumbar puncture. For this reason, these markers may provide a tool to advance the diagnosis of Alzheimer's and determine which individuals need to undergo further testing to confirm the diagnosis.
One of the highlights of the study is that they have been studied at the same time and with the same samples, these Nine possible biomarkers, all variants of the Tau protein. The samples come from the BIODEGMAR cohort, of patients with cognitive impairment followed in the Neurology Department of Hospital del Mar. Specifically, the blood of 197 people with various pathologies, not just Alzheimer's, was analyzed, a fact that has given the work a specific value, as it is a representative group of the clinical reality that can be found in a hospital.
“The conclusion is that we do indeed have blood biomarkers that can be very useful in diagnosing Alzheimer's disease in daily clinical practice. However, they cannot yet be incorporated into everyday practice and cannot replace the standard tests, lumbar puncture and cerebrospinal fluid analysis,” explains one of the main authors of the work, the Dr. Marc Suárez-Calvet, neurologist and researcher at the IMIM-Hospital del Mar Research Group on Cognition Physiology and Alzheimer's Prevention and head of the Fluid Biomarkers and Translational Neurology Group at the Barcelonaβeta Brain Research Center (BBRC). These results will also allow “improve the diagnosis of patients with cognitive problems and to better select which people receive the reference test, which continues to be the lumbar puncture”, he adds.
Early diagnosis markers
The patient samples were sent to the University of Gothenburg, where they were divided for analysis in different laboratories that were unaware of the pathology of each patient. This allowed comparable results to be obtained. In people with Alzheimer's, the data obtained were compared with their cerebrospinal fluid samples obtained by lumbar puncture. This confirmed that some of the measurements of Tau protein in blood were capable of detecting Alzheimer's with an accuracy close to that of the reference test, that is, the lumbar puncture. Therefore, they can function as a diagnostic marker, even in the early stages of the disease.
“For the first time, we have been able to do a comparative analysis of all these biomarkers in blood at once”, explains the Dr. Marta Milà-Alomà, one of the main authors of the research and also a member of the Fluid Biomarkers and Translational Neurology Group of the BBRC. “Our results indicate that there are four that could potentially be useful in daily clinical practice in the future.”, he details.
Application in clinical practice
Dr. Dr. Albert Puig-Pijoan, co-author of the work, neurologist at Hospital del Mar and researcher at IMIM-Hospital del Mar, advances that this study will not replace the lumbar puncture as the standard test for diagnosing Alzheimer's. “In the short term, lumbar puncture will continue to be necessary, but it is clear that these results open the door to applying this less invasive blood test to better identify which patients need to undergo a lumbar puncture. On the other hand, it could be very useful for diagnosing Alzheimer's disease in patients for whom we cannot perform a lumbar puncture or other tests with biomarkers that are more difficult to access,” explains.
In the same sense, the Dr. Jaume Roquer, who also signs the work and is the head of the Neurology Service at Hospital del Mar and coordinator of the Neurovascular Research Group at IMIM-Hospital del Mar, points out that "We are relatively close to having, in people with cognitive impairment demonstrated by an adequate neuropsychological assessment, a positive blood biomarker that indicates a high possibility of Alzheimer's."
Researchers from the CIBER on Frailty and Healthy Ageing (CIBERFES) and the biomedical and imaging diagnostic network, dibi, also participated in the work.
Bibliographic reference
Ashton, Nicholas J.; Puig-Pijoan, Albert; Milà-Alomà, Marta et al. 'Plasma and CSF biomarkers in a memory clinic: Head-to-head comparison of phosphorylated tau immunoassays'. Alzheimer's & Dementia, 2022 Nov 12. DOI: https://doi.org/10.1002/alz.12841. Epub ahead of print. PMID: 36370462.
