Bacteria linked to gum disease may also be involved in the development of Alzheimer's disease, according to new UK research.

Researchers tested the brain tissue often people who had died with Alzheimer's as well as ten people of a similar age but but who did not have the disease.

They found that the brains of four of the 10 Alzheimer sufferers showed signs of infection with one of the major periodontal disease bugs.

None of the brains from people without dementia showed any signs of bacteria associated with gum disease.

The researchers believe that the bacteria involved may enter the brain through the bloodstream and help trigger dementia.

The study from the University of Central Lancashire in England is published in the Journal of Alzheimer's Disease.