This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Symptoms and signs in psychiatry and classification, Subject name: Psychiatry
True about delirium are all except 
Select and explain. 
A. Preserved attention, B. Disturbed sleep, C. Disorientation, D. Hallucination
A: Preserved attention
Answer: A: Preserved attention 
Explanation: Delirium is characterized by an acute decline in both the level of consciousness and cognition with paicular impairment in attention. A life threatening, yet potentially reversible disorder of the central nervous system (CNS), delirium often involves perceptual disturbances, abnormal psychomotor activity, and sleep cycle impairment. Reference: Kaplan & Sadock's Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry, 11th Edition, page 697.