Blood biomarkers for Alzheimer’s disease
Recent developments in blood markers have made possible to track the different pathophysiological processes that occur in Alzheimer’s disease through plasma analysis. Our study “Use of plasma biomarkers for AT (N) classification of neurodegenerative dementias” evaluates three of these markers and has recently been published in the Journal of Neurology, Neurosurgery and Psychiatry.
What have we done in this study?
Using novel analysis techniques, we measured three markers in blood samples from 150 participants in the SPIN cohort of the Hospital de Sant Pau. Study participants were patients with mild cognitive impairment, Alzheimer’s disease dementia, frontotemporal dementia, Lewy body dementia, and cognitively healthy participants. We performed lumbar puncture on all participants, which allowed us to classify them into different categories according to the pathophysiological processes of Alzheimer’s disease: amyloidosis (A), neurofibrillary pathology (T) and neurodegeneration (N).
In plasma samples from these same participants, we measured the levels of beta-amyloid protein, pTau181, and neurofilament light chain (NfL). These determinations were made at the University of Montpellier, the University of Gothenburg and at the Hospital de Sant Pau. We used mass spectrometry-based techniques and the ultrasensitive SIMOA platform, which allows the quantification of proteins in very low concentrations. We evaluated the precision of these markers in blood to detect the pathophysiological processes of the disease by comparing them with those measured in cerebrospinal fluid.
Beta-amyloid, pTau181 and NfL in plasma obtained an accuracy of 75%, 78% and 88% to discriminate A, T and N categories, respectively. Among the three blood markers, pTau181 was the most accurate for detecting Alzheimer’s disease. The correlation between plasma and cerebrospinal fluid markers was moderate for beta-amyloid and pTau181, and high for NfL.
Relevance of the study
This study shows that recently developed blood markers can be useful in detecting the presence of Alzheimer’s disease. Although its use is still restricted to research, its implementation in clinical practice could facilitate the early diagnosis of the disease.