Is the regimen safe in the long-term?: NOT PROVEN. As I understand it, mannitol needs to be taken daily at a dose of 1.5 tablespoons/day for life. The same research group describe mannitol as a BBB disrupter. There must be a concern as to what this lets into the brain. Against that is its successful long-term use as a food agent.

An interesting claim for mannitol is that its effects can be noticed in two months. (I was expecting a disease progression slowing therapy, such as alpha-synuclein cleansing, to take at least a year before having a noticeable effect.) This shortens the test period. It can be made quicker still by testing continuously throughout the trial: stopping early if the initial results make it unlikely that the positive outcome is achievable; reporting early if the initial results are particularly good. The tap-test can be used for this.

John