D-Serine: The anti-ketamine?

The science of biology has a long, proud history of progressing by breaking things. For example, a chemical that knocks out brain function is now starting to tell us about how the brain functions.

Ketamine was first used as a high-dose dissociative anesthetic, first tested in a prison population in the mid-1960s^[1]. Thirty years later^[2], it was used at lower doses to uncover some interesting information about how the brain works. Ketamine binds to a glutamate receptor in the brain known as the N-methyl-D-aspartate receptor (NMDAR), and reduces its activity. When the receptor was blocked with ketamine in the brains of healthy people, symptoms related to schizophrenia were observed, in addition to impaired cognition, which implies that the NMDAR may play a role in psychiatric and cognitive disorders.

If blocking the NMDAR induced schizophrenia-like symptoms, then perhaps stimulating it could help reduce symptoms of schizophrenics. This hypothesis has been tested, and a recent meta-analysis^[3] found that several compounds that increase the function of the NMDAR show promise in helping to treat schizophrenia. One of these compounds is D-serine, an enantiomer (mirror image) of L-serine, one of the amino acids used as a building block of proteins.