Gut microbiota in dementia with Lewy bodies

Gut microbiota and fecal bile acids were analyzed in 278 patients with alpha-synucleinopathies, which were comprised of 28 patients with dementia with Lewy bodies (DLB), 224 patients with Parkinson's disease (PD), and 26 patients with idiopathic rapid eye movement sleep behavior disorder (iRBD). Similarly to PD, short-chain fatty acids-producing genera were decreased in DLB. Additionally, Ruminococcus torques and Collinsella were increased in DLB, which were not changed in PD. Random forest models to differentiate DLB and PD showed that high Ruminococcus torques and high Collinsella, which presumably increase intestinal permeability, as well as low Bifidobacterium, which are also observed in Alzheimer's disease, were predictive of DLB. As Ruminococcus torques and Collinsella are also major secondary bile acids-producing bacteria, we quantified fecal bile acids and found that the production of ursodeoxycholic acid (UDCA) was high in DLB. Increased UDCA in DLB may mitigate neuroinflammation at the substantia nigra, whereas neuroinflammation may not be critical at the neocortex. Theraeutic intervention to increase Bifidobacteirum and its metabolites may retard the development and progression of DLB.

Automated summary

Gut microbiota and fecal bile acids analysis in patients with alpha-synucleinopathies revealed decreased short-chain fatty acids-producing genera in dementia with Lewy bodies (DLB) and increased Ruminococcus torques and Collinsella. Random forest models showed that high Ruminococcus torques, high Collinsella, and low Bifidobacterium were predictive of DLB. In DLB, increased production of ursodeoxycholic acid (UDCA) may mitigate neuroinflammation at the substantia nigra.