Artificially boosting its levels completely removed the symptoms of Alzheimer's affected mice and the US findings offer an entirely new approach to tackling the disease in humans.
Rebecca Wood, chief executive of the Alzheimer's Research Trust, said: "Our brains are hugely complex and understanding how they work and become damaged by diseases like Alzheimer's is a massive task.
"This research adds a piece to the Alzheimer's puzzle and provides new leads for researchers. It suggests a way to keep nerve cells in the brain communicating, which is vital for thinking and memory.
"We don't know yet if these findings will lead to a new treatment for Alzheimer's - that's some way off. It's critical we invest in research now to build understanding."