I agree with soccertese. I think you should be very careful here before you start ingesting significant doses of mannitol. Besides any BBB issues is the fact that the research was done on fruit flies. I believe there're is some mice research also, but they were given the mannitol intravenously.

Laura is correct that mannitol is used for a number of medical conditions (surgery, diuretic, renal problems). However, it also has many undesirable side effects. You may find one of those side effects does cure PD related constipation as you're running to the restroom.

Hopefully, something good develops as this research moves forward. But be careful if you try to dose yourself now without any additional info.