What Are The Commercially Available Biomarker Assay For Cerebrospinal Fluid (CSF)?
Today cerebrospinal fluid (CSF) biomarker assay is a foundational component in diagnosing several cognitive disorders. Biomarkers provide underlying information of clinical presentations, which mostly begins several years before the onset of the disease symptoms. Currently, for cognitive and neurodegenerative disorders, biomarkers are employed in three distinct applications:
● diagnosing neuropsychiatric disorders before onset of symptoms,
● demonstrating the effectiveness of therapeutics, and
● differentiating disease subtypes.
But why biomarkers?
Let us take the example of Alzheimer’s disease (AD) as it is one of the most commonly observed dementia. We can also observe the other types of dementia including vascular cognitive impairment, frontotemporal dementia, dementia with Lewy bodies, etc. The earlier researchers diagnosed AD based on clinical presentations. Such diagnosis had higher accuracy. Yet, in early and typical cases, the diagnosis rate would drop down to 62.5%. What is important to understand that is the same disease may have different phenotypes. A particular phenotype may result from distinct pathologies, further mixing the pathological presentation of the disorders. Biomarkers let us know proteins or antibodies associated with AD, and thus they are the ideal solutions for objectively diagnosing the disease early in life.
Commercially available biomarkers
Amyloid plaques and neurofibrillary tangles are the two hallmarks of AD. Amyloid plaques are associated with aggregation of Aβ and aggregation of the microtubule-associated protein tau. A 42 amino acid Aβ peptide (Aβ42), total tau protein (τT), and hyperphosphorylated tau (τP-181) are the most common biomarkers that researchers quantify in the CSF. Traditionally in AD pathophysiology, τT increases indicating neuronal/axonal injury, τP-181 increases indicating tangle formation, and Aβ42 reduces that suggests amyloid burden.
As this data is crucial in the successive diagnosis of AD, biomarker labs need to strengthen the study data by developing effective biomarker testing services protocols. All these hallmark biomarkers help in distinguishing AD from other dementias and standard physiological changes. Combining all the biomarker testing in distinct formulas such as the Hulstaert formula or ratios further increases its relevance in diagnosing neurodegenerative disorders.
Elisa validation for Aβ42, τT, τP-181; INNOTEST AlzBio3 and Meso Scale Discovery assays are the most commonly employed commercial assays for CSF. However, these assays demonstrate substantial inter-assay and intra-assay variability. Therefore, next-gen automated assays are developed to overcome these challenges. Elecsyscobas e 601 analyzer is one such assay platform available for biomarker services. This next-gen assay platform has a high degree of accuracy, precision, reproducibility, and reliability rendering robust study results.
CSF biomarkers can detect normal and abnormal cognitive biochemistry and offer an alternative to detect neurodegenerative disorders, especially atypical cases or cases early in life. Many cases can accurately be diagnosed, however, inconclusive results may need repetition of the study or additional diagnostic options. CSF biomarker assay are likely to benefit from automated systems. These automated systems will help differentiate a specific form of psychiatric disorder from all other forms of brain-related disorders, which are intricately connected. Although biomarkers are a great diagnostic tool, scientists should always combine them with other neuropsychological, clinical, and imaging data. Moreover, biomarkers demonstrate variable measurements, and each biomarker lab should have its cut-off values.