By comparing scans of people affected by the disease and healthy counterparts, a new study has mapped the early stages of Parkinson's disease progress in the brain.
The results should increase our understanding of how Parkinson's disease spreads, say researchers from McGill University in Montreal, Canada, who report their findings in the journal eLife.
The map is the first to show the extent and distribution of the atrophy that Parkinson's disease causes as it spreads through brain regions.
Previous studies have not been able to consistently show regional atrophy in the early stages of Parkinson's disease because the data sets and sample sizes have been too small and the methods were not sensitive enough, says senior author Dr. Alain Dagher.
For their study, the team used the open source Parkinson's Progression Markers Initiative database.
This gave them access to more MRI scans and clinical data than had ever been used on such a study before. This, together with their more sensitive methods, is what allowed them to pick out the brain regions that atrophy in the early stages of Parkinson's disease.
The scans and data allowed them to compare the brain structure of 232 patients in the early stages of Parkinson's disease (PD) with 117 healthy individuals of similar ages.
They found that the disease progresses from cell to cell through the brain along networks, as Dr. Dagher - a neurologist specializing in movement disorders and functional brain imaging - explains:
"The atrophy pattern on MRI is compatible with a disease process that spreads via brain networks - something that had never been shown in human patients before, and would support the hypothesis that PD is caused by a 'toxic agent' that spreads trans-neuronally."
This adds weight to the idea that Parkinson's is a prion-like disease caused by a toxic, misfolded protein called alpha-synuclein. The protein copies itself and travels along brain networks, clogging up cells on its way.
Similar mechanisms have been proposed for Alzheimer's disease and Bovine Spongiform Encephalopathy (BSE - commonly known as mad cow disease).
Mapping will continue as disease progresses in the participants
Monitoring of the patients in the study will continue, with yearly evaluations expected to yield a wealth of data so researchers can continue to map disease progression through the brain.
Treatments for the symptoms exist, but there is no cure for Parkinson's - a disease that affects an estimated 7-10 million people worldwide. The disease kills brain cells that release dopamine, a chemical messenger that helps to regulate movement, emotional responses and other functions.
As the disease progresses, the brain's supply of dopamine dwindles, giving rise to a range of symptoms such as tremor, stiffness, slowness of movement and impaired balance. The symptoms gradually get worse and everyday aspects of life that most of us take for granted - like walking, talking and taking care of oneself - become increasingly difficult.
The team behind the current study hopes the map will help develop new tests for drugs that target the culprit protein, an avenue that may lead to treatments that prevent, slow or even reverse Parkinson's disease.
The findings follow other research Medical News Today learned about that proposes Parkinson's may be a consequence of brain cell burnout. A study led by the University of Montreal suggests Parkinson's disease may be the result of an energy crisis in brain cells that have unusually high energy needs in order to control movement.