What is Neuroleptic Malignant Syndrome (NMS) and its urgent signs?

• A. A mild, temporary reaction to antidepressants that resolves in a day.
• B. A sleep disorder characterized by trouble falling asleep.
• C. A mood disorder that responds to lithium alone.
• D. A life-threatening reaction to antipsychotics with hyperthermia, severe lead-pipe rigidity, autonomic instability, and altered mental status requiring immediate cessation of antipsychotics and medical support.

Answer: (D)