I think that this can be the answer
I heard about this thing long time ago.
http://www.consumerhealth.org/books/index.cfm?ID=2675
Cure for the disease is vitamin E. Vitamin E is is impossible to produce, synthesize artificially.
Real vitamin E you can only find in the butter made from the fresh milk made from the cows which are eating fresh green grass not other artificial food.
Only in the fresh grass you have active natural active antioxidant.
Butter made from the milk of these cows is very yellow.
You can buy the active component on the internet also , but I would go with the natural staff always.

Problem here is the transport of blood through the capillaries feeding the neuron cells. Sterol from the milk is giving back the elasticity to the capillaries and the circulations is improving.
When circulation is back disease is gone.
This disease is totally artificial and the answer how and why is in the book from the link I posted in the beginning .