Butyric acid-producing bacteria, such as Clostridium butyricum, have shown to improve cognitive decline and histopathological changes in the CA1 area of the hippocampus in vascular dementia (VaD) mice, which was associated with a significant increase in BDNF levels and an increase in fecal butyrate (Liu et al., 2015). The gene discussed is BDNF; the disease is Mental deterioration.