Which of the following is a hallmark of delirium?

• A. Inattention with disorganized thinking
• B. Progressive memory loss without fluctuations
• C. Consistent orientation
• D. Stable level of consciousness

Answer: (A)

Delirium is an abrupt, fluctuating disturbance in attention and awareness, with cognitive impairment that often includes disorganized thinking. The defining feature is inattention—the patient has trouble focusing, sustaining, or shifting attention—and this is usually paired with disorganized or incoherent thinking and often a change in level of consciousness. This combination helps distinguish delirium from other cognitive disorders. The other options reflect patterns more typical of dementia (a gradual memory loss without fluctuations), someone who remains consistently oriented, or a person with a stable level of consciousness; delirium, by contrast, commonly involves impaired attention, altered orientation, and a fluctuating level of consciousness.