Neurofilament light
 

This is being looked at as a marker/way to measure disease across all neurodegenerative illnesses. I'm no scientist but this seems as good as anything else research has got right now, and I hope it's used to speed up the search for a cure. Here's the link:

ALS Research Forum | Neurofilament Light: A Universal Mark of Neurodegeneration

If you've got a scientific/medical background, please chime in with your thoughts.