Scientists have identified a new gene variant that seems to strongly raise the risk for Alzheimer's disease, giving a fresh target for research into treatments for the mind-robbing disorder.

The problem gene is not common – less than 1 percent of people are thought to have it – but it roughly triples the chances of developing Alzheimer's compared to people with the normal version of the gene. It also seems to harm memory and thinking in older people without dementia.

The main reason scientists are excited by the discovery is what this gene does, and how that might reveal what causes Alzheimer's and ways to prevent it. The gene helps the immune system control inflammation in the brain and clear junk such as the sticky deposits that are the hallmark of the disease. Mutations in the gene may impair these tasks, so treatments to restore the gene's function and quell inflammation may help.