Alzheimer’s disease is a progressive, degenerative disease of the brain, in which build-up of abnormal proteins causes nerve cells to die. This disrupts the transmitters that carry messages, and causes the brain to shrink.As brain cells die, the functions they provide are lost.
That includes memory, orientation and the ability to think and reason. The progress of the disease is slow and gradual.
Scientists have found for the first time that bacteria which cause bleeding gums can get from the mouth into the brain.
Signs of this gum disease bacteria were found in the brains of 51 out of 53 people with Alzheimer’s disease. The findings suggest that people who brush their teeth properly could lower their risk of dementia.
However, it raises concerns for the 45 per cent of people in Britain who already have gum disease and may be at greater risk.A study found that Porphyromonas gingivalis, a major cause of gum disease, is able to reach the brains of mice after just six weeks. The damage found in the brain memory centres of these mice could explain previous evidence that people with long-term gum disease are 70 per cent more likely to get dementia.
Scientists now believe the bacteria could trigger Alzheimer’s in humans, having found the toxic enzymes it produces in the brains, spinal fluid and saliva of people diagnosed with the disease. However there is hope after they discovered a drug which can block the enzymes and save the brain cells of mice. It will be tested on people with Alzheimer’s disease later this year.
Bleeding gums, has been linked to chronic health problems including heart disease. It had been suspected bacteria from the mouth can travel through the bloodstream, breaching cells supposed to protect the brain and spreading through it over several years. Scientists have now shown that P. gingivalis can indeed get from the mouth to the brain in mice.
Once infected with gum disease, these animals showed damage to brain cells in the hippocampus, which is the region of the brain important for memory.
The mice also showed a build-up of beta amyloid, one of the damaging proteins in the brain thought to cause dementia. Experts are divided, but some now believe amyloid forms to fight off the bacteria from gum disease. The scientists tested the brains of 53 people with Alzheimer’s disease, finding enzymes from P. gingivalis in 51 of them. However the study, published in the journal Science Advances, suggests a treatment is in sight.
A drug they gave to mice prevented the loss of memory brain cells, by blocking the enzymes from P. gingivalis. They have developed a more efficient version of that drug, which better penetrates the central nervous system and has already been found to be safe in people. Following encouraging signs that it may improve the memories of people with Alzheimer’s disease, larger clinical trials will be held this year.
Dr Tiago Outeiro, professor of neurodegeneration at Newcastle University, said: ‘The present study is particularly interesting, as it identifies a common pathogen and suggests it may play a role in Alzheimer’s disease. ‘One question that will require a lot of additional work is whether this pathogen is specific for Alzheimer’s disease, or whether it is a signal of more general alterations taking place during neurodegeneration.’
Professor Damien Walmsley, scientific adviser to the British Dental Association, said: ‘This study offers a welcome reminder that oral health can’t remain an optional extra in our health service. ‘Everyone’s life can be improved by regular appointments and good oral hygiene, reducing the bacterial load that’s ever present in our mouths to a level that’s unlikely to cause tooth decay, gum disease or tooth loss.
‘ Dr David Reynolds, chief scientific officer at Alzheimer’s Research UK, said: ‘We know diseases like Alzheimer’s are complex and have several different causes. ‘But strong genetic evidence indicates that factors other than bacterial infections are central to the development of Alzheimer’s, so these new findings need to be taken in the context of this existing research.’
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