Scientists in Canada have raised a tantalising prospect - reversing Alzheimer's disease.
Brain shrinkage, declining function and memory loss had been thought to be irreversible.
They used a technique known as deep brain stimulation - applying electricity directly to regions of the brain. In two patients, the brain's memory hub reversed its expected decline and actually grew.
Deep brain stimulation has been used in tens of thousands of patients with Parkinson's as well as having an emerging role in Tourette's Syndrome and depression