Science doesn’t always proceed linearly straight-forward. Quite often, it zigs and zags between competing hypotheses which can even be contradictory. Evidence is beginning to accumulate that this may indeed be the case with Alzheimer’s research. For over thirty years, from the early 1980’s, the dominant hypothesis has been that the accumulations of amyloid and tau protein plaques found in the brains of Alzheimer’s patients are abnormal and are the cause of the mental decline of those patients. So research focused on how to directly halt or mitigate the growth of those plaques, and that work has been strikingly disappointing. Quite large amounts of money have been invested in attempting to develop drugs which function directly against the plaque accumulation, yet none have been successful in human trials.

The hypothesis that there might be an external physical cause for the plaque accumulation, that there might be a bacterial or viral agent prompting the amyloid and tau accumulations, that the plaque accumulations might actually be a way the brain fights back against certain invaders, was regarded a heresy. But now there is developing evidence that there might be one or two or even more invading agents against which the brain attempts to fight back with the amyloid and tau plaques. (For the story of one of the herpes researchers, see How an outsider in Alzheimer’s research bucked the prevailing theory — and clawed for validation.)

We posted earlier (Herpes & Alzheimer’s and Herpes & Alzheimer’s — More) about studies strongly suggesting that the Herpes virus may be one of the causative agents. Separately, other studies (Periodontitis is associated with cognitive impairment among older adults: analysis of NHANES-III and

Inflammation and Alzheimer’s disease: Possible role of periodontal diseases) have suggested Periodontal diseases as similar agents. Now a new study strongly suggests that this may indeed be the case.

Here are four media articles about the newest work:

We may finally know what causes Alzheimer’s – and how to stop it

DEMENTIA AND GUM DISEASE: ALZHEIMER’S LINKED TO GINGIVITIS

Gum Disease Bacteria Found in Alzheimer’s Brains

How gum disease could lead to Alzheimer’s

And here is the research report on the work:

Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors

All links have been added to Alzheimer’s > Risk Factors and Neuro-Psych