In a breakthrough that will give drug developers a target for creating medicine to treat patients with dementia, researchers have for the first time identified a substance in the brain that is proven to cause memory loss.

In the past, scientists thought that plaques and tangles, unnatural accumulations of two naturally occurring proteins in the brain, caused Alzheimer’s disease. But a research team, which included members from the Johns Hopkins University and the University of Minnesota Medical School, hypothesised that there was a specific substance in the brain that causes memory decline that is present even before nerve cells begin to die.