Blood test may be able to predict Parkinson's before first symptoms appear

Genetic analysis of a blood sample could become an effective tool for early diagnosis of Parkinson's disease, so much so that it could reveal the future development of the disease even before it shows its first symptoms.

This is the main result of a new study carried out by a team of researchers from the institute of neurosciences, a joint centre of the Spanish national research council (CSIC) and Universidad Miguel Hernández (UMH). Although it is not yet available for clinical use, the method has been tested on newly diagnosed patients and opens the door to simpler and earlier detection, as well as to better monitoring of the disease.

The discovery, published in the Neurotherapeutics journal, is the result of the collaboration of researchers led by UMH professor Jorge Manzanares.

Parkinson's disease affects around 12 million people worldwide and around 150,000 in Spain. It is the second most common neurodegenerative disease and one of the main causes of neurological disability. One of the great challenges is early diagnosis, which should ideally take place before the most severe motor symptoms appear.

Currently, diagnosis of the disease starts with a clinical examination when the most visible symptoms begin. "However, tremors appear when there is already advanced neurological damage and they can be confused with those of other neurological diseases," Manzanares says.

"Until a few years ago, the only way to definitively diagnose the disease was by analysing post mortem tissues," the expert states, adding that "it is crucial to have low-invasive and rapid methods that detect the disease earlier".

The method studied by the experts requires only a blood test. The analysis of the sample is performed with equipment available in many hospital laboratories and allows the identification of genetic alterations associated with the disease in its early stages.

"The key is to analyse gene expression in a type of immune system cell called peripheral blood mononuclear cells," says author Professor Francisco Navarrete.

Navarette explains that, as with all cells, they contain genetic information, but not all their genes are active all the time. Some genes are switched on or off depending on the needs of the organism, for example, in the face of an infection or a disease.

Using sequencing techniques and bioinformatics analysis, the team has identified 22 genes whose activity is altered in patients with Parkinson's disease who have not yet received drug treatment.

"These changes are not observed in healthy individuals," pre-doctoral researcher Marina Gillot says. "This indicates that they could be considered good markers for diagnosis and provide clues about the biological mechanisms underlying disease development and progression."

Some of these genes are involved in immune responses, which supports the hypothesis that inflammation and the immune system play a role in the development of Parkinson's disease. Other genes are associated with substance transport mechanisms in brain tissue and with iron homeostasis, whose dysfunction has previously been linked to neurotoxicity.

In addition to changes in gene expression, the researchers have detected alterations in cellular pathways linked to survival, inflammation, cell death and immune cell composition. "How Parkinson's disease develops and progresses is still not known in detail and current treatments have limited effects," Manzanares says, hoping that these analyses will contribute to the design of more effective and personalised therapies in the future.