(Montreal) A biomarker could make it easier than ever to diagnose Parkinson’s disease, sometimes even before the first symptoms appear, it was announced on Wednesday.

The biomarker alpha-synuclein (or αSyn) was already known to researchers, but until now it was found in the brains of patients after their death. A study supported by the Michael J. Fox Foundation has now led to the development of a test (αSyn-SAA) capable of detecting it in the cerebrospinal fluid of patients.

Other scientists were also working on developing a similar test, but researchers funded by the Canadian-born actor’s foundation now appear to have demonstrated its effectiveness and reliability in a cohort important. The authors of the new study have also acknowledged that their results are based on work carried out for about five years in various leading laboratories.

This test could make it possible not only to confirm the presence of Parkinson’s disease, whose symptoms can resemble those of other neurological diseases, but also to characterize it – namely, to determine precisely what type of Parkinson’s disease the patient has, so as to offer him the most appropriate treatment.

Laboratory analyzes could henceforth make it possible to obtain all this information, instead of having to wait until after the death of the patient.

Parkinson’s disease begins to set in long before the first symptoms appear, said Dr. Rachel Dolhun, who acts as an advisor to the foundation.

“We’re starting to see that symptoms like REM sleep behavior disorder and loss of sense of smell are among the potential early signs of Parkinson’s,” she said on a conference call as part of the disclosure of the study.

“And in this study, we saw that the (αSyn-SAA) test is positive in most of these people, so it shows us that there is potential to change the way we detect and diagnose Parkinson’s disease. . We could identify the biological process involved and diagnose the disease much earlier. »

Early intervention could potentially prevent the onset of symptoms, added one of the study’s authors, Dr. Kenneth Marek. “It’s really exciting,” he said.

This will “test new therapies in the right populations, deliver the right therapy to the right patient at the right time, and initiate the study of agents with the potential to prevent Parkinson’s disease outright,” they said. they added.

The new test could, for example, contribute to the quality of clinical trials by making it possible to form very similar cohorts of patients.

“It will allow us to allocate patients to the clinical trials that are most suitable for them,” said Dr. Andrew Siderowf, also an author of the study, during the conference call. Patients who are unlikely to respond to a new treatment could be removed from these trials, increasing the chance of detecting an effect if there really is one. It is enormous. »

Researchers may one day identify new genes or new environmental risk factors that currently go unnoticed because patients are in the wrong group, he added.

The test has a sensitivity of 88% and a specificity of 96% (meaning it generates few false positive or false negative results). It accurately detected the presence of the disease in 99% of patients who had a loss of smell and Parkinson’s without a causative genetic mutation.

The test has also been validated in individuals aged 60 and over who have not been diagnosed with Parkinson’s, but who have an increased relative risk of disease due to genetic mutations, loss of sense of smell , or diagnosed with REM sleep behavior disorder.

“Parkinson’s disease could be prevented instead of just treated,” said Dr. Siderowf. It may seem utopian, but we already do it with other diseases, so it’s not inconceivable. »

This discovery was made as part of the PPMI initiative (for Parkinson’s Progression Markers Initiative), in which the Montreal Neurological Institute-Hospital participates.

The findings of this study were published by the medical journal The Lancet Neurology.