Intestinal microbial community assessment in patients with different forms of epilepsy and autoimmune encephalitis: An exploratory study.

Despite the availability of antiseizure medications (ASMs), approximately one-third of patients with epilepsy remain refractory to treatment. Evidence suggests that the gut microbiota modulates central nervous system function through neuroimmune and metabolic pathways. We characterized the fecal microbiome of patients with epilepsy and autoimmune encephalitis (AE) using 16S rRNA sequencing. Ninety-six participants from a tertiary hospital in Brazil were included: mesial temporal lobe epilepsy (MTLE; n = 38), genetic generalized epilepsy (GGE; n = 11), AE (n = 10), and healthy controls (n = 37). Microbial community composition differed between treatment-responsive and refractory patients. Compared with responsive individuals (n = 16), refractory patients (n = 43) showed lower relative abundances of Agathobaculum, Bacteroides, Bilophila, and Coprobacter, and higher abundance of Guopingia. Dietary fiber intake was negatively associated with Enterocloster and Frisingicoccus. Riboflavin (vitamin B2) and niacin (vitamin B3) were positively associated with Schaalia and Hominimerdicola, respectively. Functional predictions indicated that valproic acid use and treatment responsiveness were associated with increased microbial potential for GABA synthesis and tryptophan degradation, and reduced potential for dopamine and histamine degradation. These findings link the gut microbiome to epilepsy subtype and treatment response.