Parkinson's, a neurodegenerative disease that affects more than 160,000 people in Spain, has no specific test to diagnose it. Detection is complicated until the first characteristic symptoms appear, which makes it difficult to research treatments and apply medical strategies to slow its progression. However, a new laboratory test is able to detect the disease before symptoms appear. We are facing a possible paradigm shift in diagnosis, research and treatment trials, which was one of the star themes of the sixth edition of the World Congress of Parkinson's which concluded yesterday in Barcelona.
In May, The Lancet Neurology published the first large-scale trial of a technique to detect alpha-synuclein, a protein that accumulates abnormally in neurons of people with Parkinson's and may be linked to impaired functioning of the nervous system. Developed by 33 centers in twelve countries and with the participation of more than a thousand patients, the study concludes that the test identifies Parkinson's in 87.7% of cases. Accuracy increases to 98.6% of those with the typical olfactory deficit of the disease.
The test is done by extracting cerebrospinal fluid, an invasive technique that requires a lumbar puncture, similar, for example, to when epidural anesthesia is applied during childbirth. However, a Japanese research group has just described in Nature Medicine "the possibility of doing the test with blood, which would facilitate its application", explains Miquel Vila, director of the research group on neurodegenerative diseases of the Vall Hebron Research Institute.
At the moment, says Vila, the test is not yet systematically applied. "It is done on an experimental and research scale, but the idea is that it can be generalized." One of the centers where it is practised, and where care can be applied for, is the Clínic de Barcelona hospital, explains neurologist Eduard Tolosa, world authority on Parkinson's and one of the presidents of the congress held in Barcelona. In his opinion, the alphasynuclein test "is a before and after". It will avoid visits to different doctors due to the disparity of symptoms and, "perhaps more importantly, it will allow the disease to be detected before the classic symptoms of tremors, or slowness, or speech difficulties manifest themselves."
It is the first time that scientists have identified a target biomarker that can be found not only in people with symptoms (they mostly appear after the age of 60), but also in younger individuals (those diagnosed in their 40s account for 10%) that do not show symptoms, but have some risk factors.
Early detection is essential, according to Dr. Tolosa: "The clinical trials that have been carried out in the last fifteen years to slow down the disease have failed, and the reason, we think, is that they have been carried out in too late phases, when the motor disease has already been declared and irreversible brain damage has occurred”.
The Clínic hospital is involved in the Healthy Cerebral Aging project, with the aim of determining the percentage of the population with risk factors for Parkinson's (genetic in 10% of cases, loss of smell, sleep disorders with aggressive nightmares) , which will make it easier to diagnose it before neuronal deterioration occurs. "It is an online questionnaire that can be answered in no more than twenty minutes by anyone over the age of 50 who has not been diagnosed. It is a great help for us", explains Tolosa.
Nearly 3,000 people participated in the world congress in Barcelona, a forum that brought together doctors and researchers as well as Parkinson's patients and carers.
