Which statement best defines delirium?

• A. Sudden onset of fluctuating mental status changes and inattention with disorganized thinking and/or altered level of consciousness
• B. Slow memory loss with stable attention
• C. Chronic confusion with normal consciousness
• D. Progressive motor weakness

Answer: (A)

Delirium is an acute, fluctuating disturbance of mental status characterized by inattention, often with disorganized thinking and an altered level of consciousness. It comes on suddenly and varies over hours to days, which is why attention is muffled and thinking can spiral into confusion or fragmentation. This combination of a rapid onset and a fluctuating course sets delirium apart from chronic cognitive disorders like dementia, where attention is typically preserved early on and changes progress gradually. The statement described reflects these key features: abrupt onset, fluctuating mental status, inattention, and possible disorganized thinking or altered consciousness. In contrast, slow memory loss with stable attention points to dementia, chronic confusion with normal consciousness isn’t delirium, and progressive motor weakness signals a neuromuscular or other noncognitive issue rather than an acute confusional state.