Anti-NMDA receptor antibodies are proteins produced by the immune system that mistakenly target and attack the N-methyl-D-aspartate (NMDA) receptors in the brain. These receptors are crucial for various brain functions, including memory and learning. When these antibodies bind to the receptors, they can disrupt normal signaling, leading to neurological symptoms. The presence of anti-NMDA receptor antibodies is associated with a specific type of autoimmune encephalitis, a condition that can cause symptoms such as confusion, seizures, and psychiatric disturbances. Diagnosis typically involves testing for these antibodies in the blood or cerebrospinal fluid, and treatment often includes immunotherapy to reduce antibody levels.