The epigenetic changes happen mostly in the later stages of the disease, when patients are unable to retain recently learned information and suffer dramatic cognitive decline, Yan says a key reason for the cognitive decline is the loss of glutamate receptors, which play a key role in learning and short-term memory. And when mice that had been genetically engineered to have Alzheimer's were infected with gum disease, their dementia symptoms worsen. Most scientists think it is likely to be down to a combination of factors, including your genes and lifestyle.
The team also examined the cerebrospinal fluid and saliva of 10 patients believed to have Alzheimer's disease, and found the P. gingivalis gene hmuY in seven, and P. gingivalis itself in all of them.
Those concerned that poor dental health could increase their risk of Alzheimer's disease are advised to practice good oral hygiene to preclude the prevalence of P. gingivalis in the mouth, said Dominy.
"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", Dr. David Reynolds, Chief Scientific Officer from Alzheimer's Research UK, said in a statement. In more than 90% of the more than 50 Alzheimer's brain samples, they also spotted toxic enzymes produced by the bacteria called gingipains.
Singhrao, who has also conducted research into the cause of Alzheimer's, had earlier discovered that the bacteria invade the brains of mice which had gum infections.
A large-scale clinical trial that will involve giving the drug to patients with mild to moderate Alzheimer's is planned for later this year. P. gingivalis causes periodontitis, an infection that destroys the gums and can lead to tooth loss.
Where did the story come from?
The DIAN study, which has been running since 2008, involves a global network of researchers, led by Professors John Morris and Randall Bateman at Washington University, St Louis, Missouri with study sites in the USA, England, Germany and three research teams in Australia - NeuRA, The Florey Institute and the Edith Cowen University in WA.
What kind of research was this?
What did the research involve?
The bacteria assaults the brain cells with a hostile protein while also promoting the formation of plagues in brain tissue that are found in Alzheimer's patients.
And in an experiment on mice, those dosed with gingipains had higher levels of the hallmark Alzheimer's protein, amyloid beta, and greater damage to their neurons than those who didn't.
What were the basic results?They found 96 percent of 53 patients with the condition had RgpB, or a form of the gingipains enzyme known as arginine-gingipain.
The mouse studies found that blocking gingipains effectively protected the hippocampus, a part of the brain vital to memory, from P. gingivalis infection.
How did the researchers interpret the results?
A new study has found that sleep deprivation worsens brain damage from Alzheimer's and increases the risk of Parkinson's disease.
She was diagnosed in 2003 after her husband noticed she forgot her cell phone one day even though she had just called him from it.
Researchers say their findings offer hope for a new way of tackling the illness, for which there is no cure and no effective treatments.
If the findings hold up, do they mean that everyone with a P. gingipains infection-nearly 50% of the USA adult population-will develop Alzheimer's? "If there are leaky blood vessels in the brain ... then we should work to fix it ... and acting on the vascular system may have important effects on delaying or even stopping cognitive decay".
The researchers say they have also begun "new drug application-enabling studies" with the gingipain-inhibiting substance tested here.