Which statement about delirium's onset is true?

• A. It has sudden onset
• B. It is typically chronic over years
• C. It often presents with unaltered attention
• D. It has sudden onset of fluctuating mental status changes and inattention

Answer: (D)

Delirium shows up as an abrupt, acute change in mental status with fluctuations in consciousness and attention. The statement that describes a sudden onset of fluctuating mental status changes and inattention best captures these core features. Delirium is not a chronic, years-long process like dementia, and attention is typically impaired rather than unaltered. The combination of sudden onset, fluctuating cognition, and inattention is what sets delirium apart and guides urgent assessment for an underlying medical cause.