For over a century, neurodegenerative diseases like Alzheimer’s and Parkinson’s disease have been considered protein disorders, characterised by the accumulation of amyloid-beta plaques, tau tangles, and Lewy bodies. Research and drug development followed the same logic: target the proteins, slow the disease. The results, after decades of trials and considerable investment, have been largely disappointing. A growing body of research now suggests this framing may be incomplete....

For decades, Parkinson’s disease (PD) has been viewed as a disorder of the brain. This perspective was shaped by the presence of misfolded alpha-synuclein aggregates throughout the brain, combined with the loss of dopamine-producing neurons. Collectively, these dysfunctions drive the devastating motor symptoms, speech difficulties, and cognitive decline that characterise PD. However, recent research challenges this brain-centric view. Alpha-synuclein has been identified to appear in the...