Diagnosis of Alzheimer’s disease using Vibrational spectroscopy

Alzheimer’s disease is a well-known chronic neurodegenerative disease, which breaks down memory and other mental functions as it progresses. The increasing world population makes the occurrence of neurodegenerative diseases inevitable. Current diagnosis of Alzheimer’s disease involves careful medical evaluation including clinical history, memory testing, cerebrospinal fluid (CSF) tests and brain scans, however the disease can only be confirmed from post-mortem examination. 

The need for an accurate, but at the same time, inexpensive and minimally invasive, diagnostic test is crucial, not only to confirm the presence of the disease, but also to discriminate between different types of dementia. Fortunately, researchers have examined blood samples to create a novel and non-invasive method of diagnosing Alzheimer’s disease and distinguishing between different types of neurodegenerative disorders. The studies were carried out at Lancaster University, the University of Central Lancashire (UCLan), the University of Manchester and the Federal University of Rio Grande do Norte, Brazil. 

In this study, attenuated total reflection FTIR (ATR-FTIR) spectroscopy was used to cross-examine blood plasma samples from 549 individuals with various neurodegenerative diseases. From the 549 specimens. 347 had various neurodegenerative diseases while 202 were similarly-aged healthy individuals. By passing light through the diamond and observing its interactions with the blood plasma, specific chemical bonds were identified within the blood. This biochemical data was used to compare blood samples from cases of Alzheimer’s disease and other neurodegenerative diseases with those from healthy controls. Alzheimer’s disease was identified with 70% sensitivity and specificity, which after providing additional information, increased to 86%. 

                                            

            ATR-FTIR Spectrometer

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One of the researchers, professor Martin says: “For those suffering with Alzheimer’s disease, the damage is already well advanced once conventionally diagnosed, but this new method offers a potentially effective early screening tool when patients are only demonstrating signs of mild cognitive impairment. This is a potentially significant breakthrough for the prevention of different debilitating and chronic neurological diseases.”

This Alzheimer’s disease diagnostic method doesn’t have the disadvantages or inconveniences of current methods, such as brain scans being expensive and time-consuming. Cerebrospinal fluid collection by lumbar puncture, is invasive and unpleasant for many patients. Since small amounts of CSF are discharged into the bloodstream daily, blood tests are a better, non-invasive alternative for diagnosis. 

Vibrational spectroscopy is an ideal technique for analysis of biofluids, as it provides a “spectral fingerprint” of all of the molecules present within a biological sample, thus generating a complete picture of the sample’s status. 

The spectrochemical analysis technique was also researched for other neurodegenerative diseases such as Parkinson’s disease, vascular dementia and frontotemporal dementia. It also helped detect dementia with Lewy bodies, which is similar to Alzheimer’s disease and often leads to misdiagnosis. This method shows potential as a non-invasive, early diagnostic test for Alzheimer’s disease among other dementia. 

References: 

https://www.news-medical.net/news/20170906/Breakthrough-research-offers-novel-non-invasive-test-to-accurately-diagnose-Alzheimers-disease.aspx

Paraskevaidi, M., Morais, C. L., Lima, K. M., Snowden, J. S., Saxon, J. A., Richardson, A. M., Martin, F. L. (2017). Differential diagnosis of Alzheimer’s disease using spectrochemical analysis of blood. Proceedings of the National Academy of Sciences, 201701517.