People who fail to keep their teeth clean could be at greater risk of Alzheimer’s disease, according to a new study.
A study of brain samples from deceased dementia patients found that they contained unusually high levels of Porphyromonas gingivalis, a type of bacteria which causes gum disease.
Although the bacteria live in the mouth, they can enter the bloodstream during eating, chewing, tooth brushing or dental surgery, and potentially reach the brain, experts explained.
Inflammation caused by gum disease-related bacteria has already been linked to various health problems including diabetes, heart disease and stroke.
Their arrival in the brain could prompt the immune system to release chemicals which kill brain cells, resulting in the type of changes seen in the brains of Alzheimer’s patients and causing symptoms like memory loss and confusion, experts said.
The new findings, by researchers from the University of Central Lancashire (UCLan), back up a previous study by US researchers which showed that failing to brush your teeth at least daily significantly increases the risk of dementia.
Dr Sim Singhrao, one of the authors of the study published in the Journal of Alzheimer’s Disease, said: “We are working on the theory that when the brain is repeatedly exposed to bacteria and/or their debris from our gums, subsequent immune responses may lead to nerve cell death and possibly memory loss.
“Thus, continued visits to dental hygiene professionals throughout one’s life may be more important than currently envisaged with inferences for health outside of the mouth only.”
Prof StJohn Crean, dean of the school of medicine and dentistry at UCLan, added: “Our hypothesis is that this is a chronic assault. It is not happening overnight, it is a build-up over years.
“But all we have shown so far is that bacteria from the gum region get into the brain. We haven’t proven that they cause Alzheimer’s disease.”
The researchers studied brain tissue from ten deceased dementia patients, and compared them against samples from ten patients who died without dementia.
Significant signs of the gum disease virus were found in the dementia patients’ brains but not the controls, the researchers reported.
Previous studies had linked dementia to other bacteria and viruses, such as the Herpes simplex virus type 1, but the new study is the first to identify Porphyromonas gingivalis in the brains of dementia patients.
Dr Simon Ridley, of Alzheimer’s Research UK, said: “We don’t know whether the presence of these bacteria in the brain contributes to the disease and further research will be needed to investigate this.
“We know that there are likely to be many risk factors for Alzheimer’s and we need to investigate these in more detail to help develop new preventions or treatments.”