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 communication between nerve cells and play a significant role in learning and memory. When these antibodies bind to the receptors, they can disrupt normal brain function, leading to various neurological and psychiatric symptoms. The presence of anti-NMDA receptor antibodies is associated with a condition known as anti-NMDA receptor encephalitis, which can cause symptoms such as seizures, confusion, and changes in behavior. This condition is often treated with immunotherapy to reduce antibody levels and restore normal brain function. Early diagnosis and treatment are essential for better outcomes.