From saliva a possible test To help diagnosis of Parkinson’s Disease

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saliva_testA major problem in Parkinson’s disease a is the difficulty in obtaining an accurate early diagnosis. Currently, identification of the disease is based mainly on clinical observation, a method that can be not sufficiently accurate, especially regarding differential diagnosis with atypical parkinsonism. Now a study conducted by the research group coordinated by Professor Alfredo Berardelli in I.R.C.C.S. Neuromed Institute in Pozzilli (Italy), in collaboration with Sapienza University of Rome, opens up the possibility of having a simple and non-invasive molecular test. All based on saliva.

The study, published in the journal PLOS One, focused on the characteristic protein of Parkinson’s disease: alpha-synuclein. Normally present in neurons in a non-aggregate form (monomer), in Parkinson’s disease this protein behaves in an unusual way: individual units tend to aggregate, forming the so-called “oligomers” that turn out to be highly toxic to cells.

At the basis of the research is the presence of those two forms of alpha-synuclein in saliva. The study showed that, in patients suffering from Parkinson’s disease, two effects can be detected: on one hand a decrease of the non-aggregated form of the protein (monomeric), on the other hand a marked increase in aggregate form (oligomeric). “Under normal conditions – says Dr. Giorgio Vivacqua, first author of the study – monomers to oligomers ratio is in equilibrium, and this tells us that the cleansing cellular processes are working properly, efficiently eliminating aggregated proteins before they can become harmful. In Parkinson’s disease, however, this relationship changes: the aggregate forms increase. A sign that those mechanisms are no longer doing their job”.

“Our research – explains Dr. Antonio Suppa, co-author of the study – highlights also a correlation between a change in the monomers-to-oligomers ratio and the progression of disease’s motor symptoms. This finding could help to develop in the future an objective method for assessing disease’s stage”.

“Alpha-synuclein – is the comment of Professor Giovanni Fabbrini, co-author of the study – has so far been sought in the cerebrospinal fluid, obtained by performing a lumbar puncture. An invasive, painful and difficult to repeat method. On the contrary, a non-invasive, painless and easily repeatable test, as the one that could be conducted on saliva, is a significant step toward an early diagnosis of the disease. We must be cautious, however, and more research is needed in order to standardize the procedure.

Vivacqua, G., Latorre, A., Suppa, A., Nardi, M., Pietracupa, S., Mancinelli, R., … & Berardelli, A. (2016). Abnormal Salivary Total and Oligomeric Alpha-Synuclein in Parkinson’s Disease. PloS one11(3), e0151156.