A Parkinson's biomarker, or measure to track disease activity, could help researchers and doctors diagnose the disease at early stages, predict symptoms and test new treatments.
Two recent papers point to potential Parkinson's biomarkers after analysis of data from The Michael J. Fox Foundation's (MJFF) Parkinson's Progression Markers Initiative (PPMI).
PPMI is a landmark study following more than 1,500 volunteers at 33 clinical sites around the world, and provides its vast database of clinical, imaging, and biological data to researchers for greater discovery. The PPMI dataset has been downloaded more than 1 million times.
Measuring Fluid in the Brain
In one study, published in the journal Brain, University of Florida researchers reviewed PPMI brain scans and found people with newly diagnosed PD had increased fluid in the substantia nigra brain region, where dopamine cells die in Parkinson's. This fluid buildup continued to increase across four years. PPMI volunteers without PD did not have these changes.
These findings echo similar results from an earlier study.
"To evaluate and validate an imaging marker, it is important to confirm results across data collection sites, and The Michael J. Fox Foundation database provides a unique opportunity to do that," said lead author Roxana G. Burciu, PhD, in a press release.
Researchers may use this noninvasive marker to track the effects of treatments to slow the progression of PD.
"If the measurement in the substantia nigra is increasing year after year after year, and if you can stop that from occurring, you're likely to slow or possibly stop the progression of the disease," senior author David Vaillancourt, PhD, said.
In addition, this increase in fluid over one year predicted progression of motor symptoms over four years.
"It suggests if you were able to control that measurement with medication as early as possible, then you could control long-term clinical progression," Dr. Vaillancourt said.
Tracking Dopamine Loss
Another recent paper, this one from the Critical Path for Parkinson's Consortium -- of which MJFF is part -- showed dopamine transporter imaging (DaTscan) could be used as a biomarker to select participants for clinical trials.
Some people show Parkinson's motor symptoms but do not have dopamine loss on DaTscans.
These authors published in the journal Clinical Translational Science that people who did show dopamine loss on DaTscans saw greater progression of motor symptoms over time compared to those without dopamine loss. They reviewed data from PPMI and the Parkinson Research Examination of CEP-1347 Trial (PRECEPT) clinical trial.
The authors say, then, researchers could use DaTscan to choose people for trials who would more likely benefit from the therapy, which cuts trial size, time and cost.
Some disease-modifying studies already are using this tool: SURE-PD3 study of raising urate levels and PASADENA trial of an alpha-synuclein antibody. Both are recruiting people with early-stage PD.