Alzheimer's sufferers could be offered new hope in the form of a commonly used blood pressure drug, new research has suggested.
Scientists found that the drugs, known as angiotensin receptor blockers (ARBs), both prevented the disease occurring and slowed its progression.
The effect was "striking", according to the US researchers who reported their findings at an Alzheimer's conference in Chicago.
A database at the US Department of Health Systems Veterans Affairs was used to examine the records of about six million patients treated for high blood pressure between 2001 and 2006.
Those taking ARBs were 35% to 40% less likely to develop Alzheimer's disease or other forms of dementia than patients on different medications.
Patients already suffering from Alzheimer's when they started taking ARBs had a 45% reduced chance of developing delirium, being admitted to a nursing home, or dying prematurely.
Those who had experienced strokes before or during the course of their illness appeared to benefit most from the drugs.
Study leader Professor Benjamin Wolozin, from Boston University School of Medicine, said: "For those who already have dementia, use of ARBs might delay deterioration of brain function and help keep patients out of nursing homes."