Alzheimer’s disease is the leading cause of dementia. It progressively worsens multiple aspects of health over time, from short-term memory loss to behavioral changes to loss of bodily functions. The actual cause of Alzheimer’s is currently unknown. One widely-accepted hypothesis proposes that Alzheimer’s is caused by the accumulation of misfolded proteins in the brain. Unfortunately, many drugs targeting misfolded proteins perform poorly in clinical trials, hinting that this hypothesis might be wrong. Misfolded proteins might be another side effect, not the cause.

Researchers recently published a new line of evidence supporting a hypothesis that Alzheimer’s might be a result of an infection by oral bacteria P. gingivalis. The bacteria produces toxins called gingipains that are found to accumulate in the brain of Alzheimer’s patients. The gingipains degrade human proteins, giving rise to the infamous misfolded proteins. The researchers also developed chemical compounds that could neutralize gingipains. Mice injected with gingipains developed degenerate brain cells, while mice that were pretreated with neutralizing compounds beforehand maintained healthy brain cells.

Although this new work might be the much-needed breakthrough in curing Alzheimer’s disease, the hypothesis is not conclusively proven and many questions still remain. Is P. gingivalis actually the cause of Alzheimer’s? Some experts still believe the disease could be caused by a fungal or viral infection. How does the bacteria get from the gum to the brain? What else does the gingipain toxin interact with in the brain? Are the neutralizing compounds safe or even effective in humans? 

Managing Correspondent: Veerasak (Jeep) Srisuknimit

Original Paper: Science Advance

Press article: Science, ScienceNews

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