The 'neglected tropical diseases' affect tens of millions of people and claim more than 50,000 lives each year.
The prospect of altering an animal's brain to make it more human alarms some experts.
"This new drug could be a game-changer for future treatment of asthma."
The findings are part of the first completed phase III trial of an anti-tau drug in Alzheimer's.
For more than a century, people have sought to delineate the different brain areas and their function.
The drug that worked best for arthritis, they found, was diclofenac, say researchers.
Scientific studies are considered valid only if they can be reproduced by outside teams of researchers who come to the same conclusions.
Sign up to receive our free newsletter