BDNF and Mental deterioration: The administration of aged microbiota from aged rats (through fecal microbiota transplantation; FMT) to younger rats resulted in the reduced expression of brain-derived neurotrophic factor (BDNF), exacerbated oxidative stress and the increased expression of AGEs, RAGE and pro-inflammatory cytokines, showing a correlation with bacterial aging and the cognitive decline of the host [81].