Does gum disease play a key role in the development of Alzheimer's?
Scientists believe this may be the case after their study found further evidence of the link between bacteria in a common type of gum disease and people with dementia, the BBC reports.
Researchers say their findings offer hope for a new way of tackling the illness, for which there is no cure and no effective treatments.
But does it mean people should be more worried about their oral health?
Scientists analysed brain tissue, spinal fluid, and saliva from dead and living patients with diagnosed and suspected Alzheimer's.
Their study, published in the journal Science Advances, found bacteria associated with chronic gum disease, Porphyromonas gingivalis, in the brains of people with Alzheimer's.
Tests on mice confirmed the bacteria could travel from the mouth to the brain and showed the toxic protein they secrete, called gingipain, destroyed brain neurons.
The bacteria also increased production of amyloid beta, a component of the amyloid plaques commonly associated with Alzheimer's.