An experimental drug has been shown to halt memory loss in mice with a rodent version of Alzheimer's disease.
The molecule, called MW108, curbed the activity of an enzyme that is over-active in patients with Alzheimer's and promotes brain inflammation.
As well as stopping the progression of memory loss, it repaired broken communication links between brain cells.
"This is the starting point for the development of a new class of drugs," said study leader Professor Martin Watterson, from Northwestern University in Chicago, US.
"It's possible someday this class of drugs could be given early on to people to arrest certain aspects of Alzheimer's.
"I'm not aware of any other drug that has this effect on the central nervous system."
Changes in the brain start to occur 10 to 15 years before an Alzheimer's patient starts to suffer serious memory problems.
The findings are published in the online journal Public Library of Science ONE.
US co-author Dr Linda Van Eldik, from the University of Kentucky, said: "This class of drugs could be beneficial when the nerve cells are just beginning to become impaired."
The team now plans to refine the drug so it is stable and safe enough to be given to patients in a clinical trial.