At last, researchers are starting to use intranasal delivery , and have also used it for stem cells, rather than drugs. This was proposed years ago on this forum. Using a simple nasal spray, you can deliver drugs, stem cells etc direct to the brain, including substances which don't pass the blood brain barrier. Why therefore has so much money been spent drilling holes in sufferers heads, using trojan horses to get substances across the BBB, etc.
This must be tantamount to a cure, unlike a DBS where it simply puts the clock back a few years, but you continue to degrade.
Ron