DAO and schizophrenia: For instance, serine deficiency syndromes include epilepsy, spasticity, and neurocognitive symptoms; these symptoms may partially be ameliorated by serine supplementation [51] In addition, d-serine deregulation is involved in the positive, negative, and cognitive symptoms of schizophrenia [52] and the inhibition of DAO appears to be a viable strategy to increase d-serine level and to have therapeutic potential in schizophrenia [53].