Alzheimer’s is one of the biggest mysteries in medicine. As populations have aged, dementia has skyrocketed to become the fifth biggest cause of death worldwide. Alzheimer’s constitutes some 70 per cent of these cases and yet, we don’t know what causes it. Recent studies are pointing to a new theory though. Let’s see what we now know.
We wonder how many of us actually consider going to the doctor’s office when our gums are bleeding after brushing our teeth in the morning. Not many, statistics have shown us… But, recent research tells us that you might want to get that checked out. We may finally have found the long-elusive cause of Alzheimer’s disease. It’s called Porphyromonas gingivalis, the key bacteria in chronic gum disease.
That’s some really harsh news considering that gum disease affects around a third of all people. But the good news is that a drug that blocks the main toxins of P. gingivalis is entering major clinical trials this year, and research published today shows it might stop and even reverse Alzheimer’s. There could even be a vaccine.
Does bacteria build up in the brain cause dementia?
This certain gum disease often involves the accumulation of proteins called amyloid and tau in the brain, and the leading hypothesis has been that the disease arises from the inefficient control of these two proteins.
But research in recent years has revealed that people can have amyloid plaques without actually having to suffer eventually from dementia . There have been so many failed attempts to treat Alzheimer’s by moderating these proteins have failed that this hypothesis is starting to get ruled out.
Evidence has been growing on the facts that the bacteria involved in gum disease and other illnesses have been found after death in the brains of people who had Alzheimer’s, but until now, it hasn’t been clear whether these bacteria caused the disease or simply got in via brain damage caused by the condition.
A study tested whether the purpose of beta-amyloid is also to kill microbes in the brain, not only in the gum area. When they injected bacteria into the brains of mice bred to be able to develop plaques much as humans do, the mice developed amyloid plaques overnight.
This suggests that microbial infection could be triggering the formation of plaques that cause Alzheimer’s disease. Somehow, bacteria, viruses or other pathogens may be crossing the blood-brain barrier and getting into the brain. The brain may be responding by using beta-amyloid to trap and kill them. But if these plaques aren’t cleared away fast enough, they may then lead to inflammation and tangles of another protein, the tau ones, mentioned earlier, that eventually cause neurons to die and so the progression towards Alzheimer’s disease occurs.
What is the link between gum disease and Alzheimer’s?
Multiple research teams have been investigating P. gingivalis, and have so far found that it invades and inflames the regions in the brain that have been affected by Alzheimer’s. Studies on mice with induces Alzheimer’s have shown that gum infections can worsen the symptoms of the brain disease, and that it can cause Alzheimer’s-like brain inflammation, neural damage, and the amyloid plaque mentioned earlier.
“When science converges from multiple independent laboratories like this, it is very compelling,” says Casey Lynch of Cortexyme, a pharmaceutical firm in San Francisco, California.
In the new study, Cortexyme have now reported finding the toxic enzymes – called gingipains – that P. gingivalis uses to feed on human tissue in 96% of the 54 Alzheimer’s brain samples they looked at, and found the bacteria themselves in all three Alzheimer’s brains whose DNA they examined.
