Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an autoimmune neurological disorder caused by IgG antibodies directed against the GluN1 (NR1) subunit of the NMDA receptor, a glutamate-gated ion channel critical for synaptic transmission, neuronal plasticity, learning, and memory. It is the most common cause of autoimmune encephalitis and the second most common cause of encephalitis overall (after viral encephalitis) in young adults. The disease predominantly affects young women (80% of adult cases are female), often in association with ovarian teratomas, and follows a characteristic clinical progression from psychiatric symptoms to neurological deterioration that can mimic primary psychiatric illness, leading to delayed diagnosis and treatment. The NMDA receptor is a heteromeric glutamate receptor composed of two GluN1 (NR1) obligatory subunits and two GluN2 (NR2A-D) or GluN3 subunits. It functions as a ligand-gated and voltage-gated ion channel that requires both glutamate binding (to GluN2) and glycine/D-serine binding (to GluN1) plus membrane depolarization (to release the magnesium block from the channel pore) for activation. When activated, NMDA receptors allow calcium influx into the postsynaptic neuron, triggering intracellular signaling cascades that mediate long-term potentiation (LTP) --...