Study Rationale:
This study builds on two recent discoveries in neuroscience: first, the brain is organized in large-scale networks of nerve cells; and second, the clumps of alpha-synuclein, amyloid and tau -- proteins implicated in Parkinson's disease (PD) and Alzheimer's disease (AD) -- can spread from nerve cell to nerve cell, like infection.
Hypothesis:
Parkinson's and Alzheimer's affect different brain networks, and over the period of time, the disease spreads through these networks.
Study Design:
We will use magnetic resonance imaging (MRI) data -- brain scans -- from the databases of the Parkinson's Progression Markers Initiative (PPMI), our large-scale, international biomarker study, and the Alzheimer's Disease Neuroimaging Initiative (ADNI) to measure the extent and distribution of brain damage in both diseases. We will then search for correlation between the imaging results and clinical severity of disease. Next, we will use MRI scans of healthy volunteers to establish networks in a healthy brain, which will allow us to test the theory that Parkinson's and Alzheimer's spread through these networks.
Impact on Diagnosis/Treatment of Parkinson's Disease:
Proving that alpha-synuclein clumps spread through networks of neurons would greatly advance our understanding of PD. If this is how alpha-synuclein spreads in the brain, preventing the spread of protein clumps from cell to cell could halt disease progression.
Next Steps for Development:
This study may facilitate the development of MRI methods to assess the success of future therapies in stopping the spread of neurodegeneration. It may also be valuable in predicting the development of complications of Parkinson's disease.