Electrical stimulation appears to reverse some of the brain damage caused by Alzheimer’s disease in people with early symptoms of the degenerative disorder, new research suggests.

Deep brain stimulation, which has been used successfully in the treatment of Parkinson’s disease, has produced results that researchers from Toronto Western Hospital in Ontario describe as “astonishing.”

Investigators, led by Andres M. Lozano, M.D., a neurosurgeon at Toronto Western Hospital, implanted six people in the early stages of Alzheimer’s with a device that applies electrical impulses to the fornix, an area of the brain that causes shrinkage to the hippocampus as the disease progresses. The hippocampus can shrink by 5% every year on average in people with Alzheimer’s.

After a year with the device, four of the six patients exhibited the expected volume of shrinkage, but two patients experienced modest growth of the hippocampus region. These participants also demonstrated improved cognition. Lozano told the BBC that a patient whose hippocampus had an 8% increase “was an amazing find for all of us.”

These findings were presented at the Society for Neuroscience annual meeting in Washington D.C. earlier this month.