The influence of the glutamatergic system on cognition in schizophrenia: A systematic review

- The glutamatergic pathway is proposed to be involved in cognition in schizophrenia.
- Gene, neuroimaging, pharmacological and amino acid studies were reviewed.
- Most influenced domains are memory, working memory and executive function.
- Different domains are associated with different parts of the glutamatergic pathway.
- Cognition should be looked at by domain, not through global scores.

Previous literature showing the role of the glutamatergic system on cognition in schizophrenia has been inconclusive. 44 relevant pharmacological, candidate gene and neuroimaging studies were identified through systematic search following PRISMA guidelines. To be included, studies must have observed at least one objective measure of cognitive performance in patients with schizophrenia and either manipulated or measured the glutamatergic system. Of the cognitive domains observed, memory, working memory and executive functions appear to be most influenced by the glutamatergic pathway. In addition, evidence from the literature suggests that presynaptic components synthesis and uptake of glutamate is involved in memory, while postsynaptic signalling appears to be involved in working memory. In addition, it appears that the glutamatergic pathway is particularly involved in cognitive flexibility and learning potential in regards to executive functioning. The glutamatergic system appears to contribute to the cognitive deficits in schizophrenia, whereby different parts of the pathway are associated with different cognitive domains. This review demonstrates the necessity for cognition to be examined by domain as opposed to globally.