Dementia with Lewy bodies (DLB), one of the most common forms of dementia, has no cure. Now, a group has identified three bacteria involved in DLB—Collinsella, Ruminococcus, and Bifidobacterium. Their findings suggest new avenues for diagnosis and treatment. The onset of DLB is associated with abnormal deposits of alpha-synuclein, a protein in the brain. A research group discovered that three intestinal bacteria, Collinsella, Ruminococcus, and Bifidobacterium, were associated with patients with DLB. The bacteria Akkermansia, which degrades the intestinal mucosa, increased. On the other hand, the bacteria that produce short-chain fatty acids (SCFA) in the gut decreased. On the other...