One could only speculate. And then there are those studies that say:
Does a vegan diet reduce risk for Parkinson's... [Med Hypotheses. 2001] - PubMed - NCBI"Three recent case-control studies conclude that diets high in animal fat or cholesterol are associated with a substantial increase in risk for Parkinson's disease..."
I dislike articles like the one you posted because they serve to spread anti-carb propaganda. The Paleo community really needs to stop demonizing macronutrients. It will come back to haunt the pioneers.