NMDA (N-methyl-D-aspartate) receptors are located in the brain and activated by the neurotransmitters glutamate, glycine, aspartate, and D-serine. NMDA receptors are believed to be associated with learning and memory. It is also thought that NMDA receptors become less functional as we age.

Research indicates that decreased NMDA receptor function may be associated with the learning and memory challenges facing people with Alzheimer’s disease.

Other conditions linked to NMDA receptor impairment include depression, schizophrenia, ischemic brain injury, and neurodegenerative diseases.

NMDA Receptor Antagonists

An antagonist is a chemical that interacts with a receptor in the brain and blocks the receptor from interacting with an agonist. An agonist is a chemical that binds with a receptor and increases the effects of certain neurotransmitters.

NMDA receptor antagonists help to block neurotransmitters from interacting with NMDA receptors. In this way, certain medications hope to treat neurodegenerative diseases by blocking access to the NMDA receptors.

Since excess glutamate is associated with mood disorders like depression, NMDA receptor antagonists like the anesthetic ketamine have caught the attention of scientists looking to develop treatments for depression.

It’s believed that ketamine blocks glutamate from reacting with the NMDA receptor. In 2019, a nasal spray called Esketamine (a form of ketamine) was approved for treatment-resistant depression.