Table 1.

Main dysbiotic events that occur in GM during the onset and progression of neurological disorders.

Neurodegenerative Disease	Main Dysbiotic Events in GM	Reference
Autism spectrum disorder (ASD)	-Higher abundances of Bacteroides, Parabacteroides, Clostridium, Faecalibacterium, and Phascolarctobacterium and a lower relative abundance of Streptococcus and Bifidobacterium in ASD patients -Dysbiosis in ASD children may influence the development and severity of ASD symptomatology	[15,26,29]
Parkinson’s disease (PD)	-Enrichment of the genera Lactobacillus, Akkermansia, and Bifidobacterium and depletion of bacteria belonging to the Lachnospiraceae family and the Faecalibacterium genus in PD patients	[39,40]
Amyotrophic lateral sclerosis (ALS)	-Reduced ratio of Firmicutes/Bacteroidetes, decreased abundance of butyrate-producing Oscillibacter, Anaerostipes, Lachnospira counts, and Prevotella, increased abundance of glucose-metabolizing Dorea in ALS patients -GM composition alters during the course of the ALS	[52,54]
Schizophrenia	-In the schizophrenia group, an enhanced count of bacterial families like Prevotellaceae, Veillonellaceae, Bacteroidaceae, and Coriobacteriaceae was observed compared to healthy controls, while Ruminococcus and Roseburia abundances were significantly lower in patients with schizophrenia -Specific bacteria may function as biomarkers to differentiate schizophrenia from healthy individuals -Differences in GM between remission and acute schizophrenia as well as between first-episode drug-naïve and chronically medicated schizophrenia patients	[61,63,64,65]