Parkinson’s Disease: How the First Affected Side Shapes the Course of Symptoms
Share this article
New research from the University of Geneva (UNIGE) and Geneva University Hospitals (HUG) reveals that the side of the body where Parkinson’s disease first manifests plays a critical role in the development of non-motor symptoms such as cognitive decline, anxiety, and depression.
Parkinson’s disease, which affects over 10 million people globally, typically begins asymmetrically—impacting either the right or left side of the body first. While much attention has focused on motor symptoms like tremors or muscle stiffness, non-motor symptoms have often been overlooked.
In a study published in npj Parkinson’s Disease, the Geneva team has shown that this initial asymmetry influences the type and severity of non-motor complications. When symptoms begin on the right side of the body, indicating dysfunction in the left hemisphere of the brain, patients are more prone to global cognitive decline and dementia. Conversely, when the left side is affected first, linked to the right brain hemisphere, patients are more likely to experience psychiatric symptoms such as depression, anxiety, and impaired emotional recognition.
“These results represent a crucial breakthrough in the study of the disease’s non-motor symptoms, which have long been underestimated,” explains Julie Péron, Associate Professor at UNIGE and Consulting Neuropsychologist at HUG, who led the research.
Based on an analysis of 80 studies spanning five decades, the findings point to the urgent need for personalized care in Parkinson’s disease. “Taking this factor into account would allow for early intervention and targeted therapies tailored to each patient’s Parkinsonian profile,” adds Philippe Voruz, lead author and postdoctoral researcher at EPFL and UNIGE.
Looking ahead, the research team aims to refine methods for reliably measuring asymmetry in clinical settings and to explore whether similar patterns are present in other Parkinson’s-related disorders.
➡️ Source: PR UNIGE | 📸 Canva Library