Brain scans of people exposed to certain neurotoxins reveal brain damage identical to that found in people suffering from Parkinson' s disease  This fact shows not only that these neurotoxins cause this type of brain damage, but also that the brain damage itself causes Parkinson' s disease
Thus brain scans can be used to determine who is likely to develop Parkinson' s disease
It overestimates the importance of early diagnosis in determining appropriate treatments for people suffering from Parkinson's disease.