Alzheimer’s is a chronic disease with no cure yet and its cause is poorly understood. Research published in the journal ‘Science Advances’ says that poor oral health is a risk factor for Alzheimer’s disease.
Could bacteria that cause gum disease stimulate Alzheimer’s?
A team of researchers examined the potential link between Porphyromonas gingivalis (Pg) – a type of bacteria associated with gum disease – and the effects of Alzheimer’s on the brain. Lab tests in Europe, the United States, New Zealand and Australia using mice demonstrated the potential of the bacteria to travel from a subject’s mouth to its brain. This destroys the neurons. Pg was also found in 51 out of 53 brain autopsies of Alzheimer’s disease patients.
Findings show that Pg is present in the brains of people with Alzheimer’s, not just in their mouths. They also show that in mice, the bacteria trigger brain changes typical of the disease.
Co-lead author Casey Lynch told ‘CNN’ that the “publication sheds light on an unexpected driver of Alzheimer’s pathology – the bacterium commonly associated with chronic gum disease.” She continued by noting that in spite of “significant funding and the best efforts of academic industry and advocacy communities clinical progress against Alzheimer’s has been frustratingly slow.”
The study reveals that toxic enzymes from Pg called gingipains were also found in the brains of Alzheimer’s disease patients. Their levels correlated with levels of neurofibrillary tangles – damaged remains of protein called tau that are required for normal brain function. When the researchers orally infected mice with Pg, an increase of amyloid beta – the plaque associated with Alzheimer’s – was seen in the brain. However, the study explains that the bacteria also exist in low levels in 25 % of healthy people who didn’t have any oral disease.
“Infectious agents have been implicated in the development and progression of Alzheimer’s disease before,” co-lead author Dr Stephen Dominy said. “But the evidence of causation hasn’t been convincing.” He added: “Now, for the first time, we have solid evidence connecting Pg and Alzheimer’s pathogenesis while demonstrating the potential for a class of small molecule therapies to change the trajectory of the disease.”
Is the evidence solid enough?
The scientific community acknowledges that the study adds to the evidence linking gum disease and dementia. Nevertheless some serious questions remain to be answered. It’s still not evident what role gum disease bacteria has in Alzheimer’s development. Speaking to the ‘BBC’ Prof. Tara Spires-Jones from the UK Dementia Research Institute at the University of Edinburgh said that “we will have to await the larger clinical trial to see if it will be beneficial to people living with Alzheimer’s disease.”
Regardless of whether the provocative findings offer hope for a new way of tackling the most common form of dementia, oral hygiene should be a much higher public health priority, particularly for the elderly. Until there’s strong evidence of a link, brushing and flossing is never bad practice, no matter the age.