Final answer:
NMS can be differentiated from serotonin syndrome by symptoms such as mutism, leukocytosis, and myoglobinuria, indicating a severe reaction to neuroleptic drugs that affect dopamine activity in the basal nuclei.
Step-by-step explanation:
The patient being treated for psychosis who develops symptoms of Neuroleptic Malignant Syndrome (NMS) can be distinguished from serotonin syndrome by certain clinical features. Specifically, mutism, leukocytosis, and myoglobinuria are helpful in differentiating NMS from serotonin syndrome. These symptoms are indicative of a severe reaction to neuroleptic drugs, where dopamine activity is reduced affecting the basal nuclei of the brain, leading to severe motor, autonomic, and mental status changes.