Emerging research suggests Parkinson's disease may encompass two distinct forms—one originating in the gut and the other in the brain. These findings could explain varying symptoms and disease progression among patients, paving the way for more targeted treatments.
Parkinson's disease involves the progressive loss of dopamine-producing neurons, which regulate movement. Common symptoms include muscle stiffness, bradykinesia, and resting tremors. Globally, it affects an estimated 6.3 million people, including about 200,000 in France.
While the core mechanisms are understood, the underlying causes remain elusive. Researchers from Aarhus University and Aarhus University Hospital in Denmark used advanced PET and MRI scans to study patients at various disease stages, including those with REM sleep behavior disorder—a known precursor to Parkinson's.
The scans revealed key differences: in some patients, dopamine pathways in the brain were impacted before gut or cardiac nerves; in others, enteric and cardiac nervous systems showed damage prior to brain involvement.
These insights challenge our current model of Parkinson's progression, Professor Per Borghammer of Aarhus University explains: "Until now, Parkinson's has been seen as a uniform condition defined by motor symptoms. Yet, patient differences prompted us to investigate further. Advanced imaging now confirms two variants starting in different body regions."
The team classified them as "body-first" (gut-origin) and "brain-first" (brain-origin).
For body-first cases, exploring the gut microbiome holds promise. "Parkinson's patients often have altered microbiomes compared to healthy individuals, but the implications are unclear," says Borghammer. "Identifying these subtypes allows us to probe distinct risk factors and genetics, potentially unlocking new therapies."
Brain-first cases pose challenges, as symptoms emerge later, complicating early diagnosis and intervention to halt progression.
