Efficacy of Pediococcus Acidilactici as add-on to Antipsychotic Drugs on Metabolic Syndrome Disturbances in First-episode Psychosis and Schizophrenia Spectrum Disorders.

Inclusion Criteria: * Diagnosis of PEP or TEESQ, according to DSM 5 criteria, aged between 18 and 65 years * Having received antipsychotic treatment for at least 8 weeks before starting the study Exclusion Criteria: * Inability to give informed consent, lack of a representative or legal guardian capable of giving consent * Intellectual disability * Clinically significant medical condition (congestive heart failure, liver disease, renal failure, acute pancreatitis, cancer undergoing active treatment, HIV, or other immunodeficiency) * Active substance use in the last 3 months (except nicotine) * Antibiotic medication in the previous 14 days * Celiac disease * Pregnancy or breastfeeding