June 3, 2026

@michaelokun

Can a brain MRI reveal the biology behind Parkinson’s disease? Diffusion MRI is a specialized MRI technique that measures microscopic changes in brain tissue and may provide clues about neurodegeneration before major structural damage is visible. Shannon Chiu and colleagues describe in a new paper in Annals of Neurology how diffusion MRI findings relate to α-synuclein seed amplification assay (SAA) status in early Parkinson’s disease. Key points: - Most folks w/ Parkinson’s disease who were SAA positive showed MRI patterns consistent w/ Parkinson’s disease using the Automated Imaging Differentiation for Parkinsonism (AIDP) approach. - SAA positive participants had worse smell function and a shorter duration of motor symptoms prior to imaging. - Only limited MRI differences were observed between SAA positive and SAA negative groups, suggesting that α-synuclein positivity alone may not explain the broader patterns of neurodegeneration detected by diffusion MRI. My take: This study highlights an important lesson in Parkinson’s disease research. Biomarkers and imaging may each be measuring different pieces of the same puzzle. A positive α-synuclein test tells us that abnormal protein aggregation is present, however diffusion MRI may be capturing downstream effects on brain structure and circuitry. The future will likely require combining molecular biomarkers, imaging and clinical features to fully understand the biology of Parkinson’s disease. I was biased as an author so please read and decide for yourself. Here are 5 points that resonated w/ me: 1- A positive α-synuclein seed amplification assay does not necessarily mean a person will show widespread MRI changes early in the disease. 2- Smell loss continues to emerge as one of the strongest clinical clues linked to underlying α-synuclein pathology. 3- Advanced MRI techniques such as free-water imaging may provide information different from biomarker testing and the two approaches may be complementary. 4- Artificial intelligence tools such as AIDP continue to show promise in identifying Parkinson-related patterns of neurodegeneration from routine MRI scans. 5- Image plus may be important!