A bug about Alzheimer’s

Cortexyme Inc. believes it has connected the dots between Alzheimer’s and gum disease, outlining a path from the bacteria that cause periodontitis to chronic brain infection with hallmarks of AD. But in a field that has struggled for unity on a causal mechanism, skeptics argue the company’s hypothesis leaves too many unanswered questions, and will hit the same clinical hurdles that have confounded β-amyloid inhibitors.

In a Science Advances study published last month, Cortexyme and collaborators from eight academic institutions offered a new explanation for the etiology of AD, suggesting it stems from proteolytic enzymes released in the brain by Porphyromonas gingivalis...