A good idea!

My initial reaction was that the BBB would make this impossible, but I was wrong.

Working with mice, Sui et al. report [1]:

"plasma levels of α-Syn are hundreds of times higher than its CSF levels".

"α-Syn is transported across the BBB bidirectionally, in both the brain-to-blood and blood-to-brain directions."

"Inflammation as induced by Lipopolysaccharide increases alpha-synuclein entry into brain, probably because of BBB disruption".

For this approach to be reasonable, we still need to show that PwP can function on lower levels of alpha-synuclein, that lower levels of alpha-synuclein lead to reduced aggregation and, indeed, that these aggregations play a causal role in the pathogenesis of PD. Finally, can such filters be built?

Reference

[1] "Alpha Synuclein is Transported Into and Out of the Brain by the Blood-brain Barrier"
Yu-Ting Sui,1 Kristin M. Bullock,2 Michelle A. Erickson,2 Jing Zhang,1 and W. A. Banks
Peptides, Dec 2014
Alpha Synuclein is Transported Into and Out of the Brain by the Blood-brain Barrier

John