Although genetic and assessment studies build the foundation, the end goal is safer and more effective treatments. Recently, the two largest and most comprehensive meta-analytic reviews [23▪▪,24▪▪] of NMDA-based treatments were published. Although differing methodology and inclusion criteria were used across studies, both reviews support small-to-medium effect size improvements for total and negative symptoms when used in combination with nonclozapine antipsychotics in chronic schizophrenia, whereas significant effects for positive symptoms were only found by Tsai and Lin [23▪▪]. D-Serine, glycine, sarcosine, and N-acetylcysteine were all significantly effective in subgroup analysis of individual treatments, whereas D-cycloserine was not, in line with earlier meta-analysis.
