Free Water Molecules in Brain Region Could Help Track Parkinson’s Progression, Study Suggests

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by Alice Melão |

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Quantifying changes in fluid in a specific brain area, using a magnetic resonance imaging (MRI)-based method, could provide a way to track brain damage in patients with Parkinson’s disease, a new study suggests.

The study, “Progression marker of Parkinson’s disease: a 4-year multi-site imaging study,” appeared in the journal Brain.

Previous studies have suggested that accumulation of free water molecules in the brain could be a potential biomarker for brain changes and damage caused by Parkinson’s. Researchers at the University of Florida (UF) have now provided long-term data analysis that validates free-water accumulation in the posterior substantia nigra – a brain area affected in Parkinson’s – as a progression marker for this illness.

“By finding a new way to detect and track how Parkinson’s affects the brain, this study provides an important tool for assessing whether a drug might slow or stop those changes and keep symptoms from getting worse,” Daofen Chen, program director at the National Institute of Neurological Disorders and Stroke, said in a news release.

The research team evaluated imaging data collected across one to four years during the Parkinson’s Progressive Marker Initiative (PPMI) – a multicenter global study to identify and validate progression markers in Parkinson’s, and sponsored by the Michael J. Fox Foundation.

While the amount of free water in the substantia nigra remained the same throughout one year in healthy volunteers, the same was not true for early-stage Parkinson’s patients. The team found that in those patients, free water increased in the substantia nigra over the course of one year, and kept increasing in the following years.

“The amount of free water doesn’t just change over one year. It keeps progressively increasing, which suggests that it’s tracking the progressive degeneration of neurons,” said David Vaillancourt, a professor of applied physiology and kinesiology at UF.

The team also found that the progressive accumulation of water in the substantia nigra is linked to worsening Parkinson’s symptoms. This finding suggests that water changes in the brain reflect Parkinson’s-related damage to neurons.

“That correlation is encouraging because it pins down the biological relevance of free water,” Vaillancourt said. “The PPMI data is real-world messy data, and when you find the effect in real-world messy data, it makes you think that it has legs.”

Taken together, the findings suggest that measuring free water using imaging methods could be a means to evaluate disease progression, with potential as a clinical trial outcome measure. The team adds that the method is highly reproducible, which could largely facilitate measures of treatment efficacy. Nonetheless, more studies are needed to understand the underlying mechanism of water changes in Parkinson’s.

Currently, the research team is developing new computerized analysis methods to facilitate free water analysis in MRI-based scans.