A 28-year-old man is brought tothe ER of a local hospital by the police,who found him wandering withouta coat in subzero weather, mutteringabout being persecuted by asecret organization. During the evaluationhe is disorganized, distractible,and from time to time dozesoff in the middle of a sentence. Family members deny previous psychiatricor substance abuse history, but they add that lately the patient hadcomplained of fatigue and increased thirst. The toxic screen is negativeand glucose level is 4.5.Choose the most likely diagnosis:
b. Psychotic depression
c. Brief psychotic episode
d. Paranoid schizophrenia
The answer is a. (Yudofsky, 3/e, pp 455–459.) The patient’s persecutorydelusions and disorganized thinking could suggest a psychotic disordersuch as schizophrenia or brief reactive psychosis, but fluctuations inconsciousness and disorientation are typically found in delirium. Memory,language, and sleep-wake cycle disturbances are also typical of delirium.Delusions, hallucinations, illusions, and misperceptions are also common.The causes of delirium are many and include metabolic encephalopathies,such as the hyperglycemic encephalopathy experienced by the patient inthe vignette; intoxications with drugs and poisons; withdrawal syndromes;head trauma; epilepsy; neoplasms; vascular disorders; allergic reactions andinjuries caused by physical agents (heat, cold, radiation).