In distinguishing delirium from dementia, which description best captures onset, course, attention, and consciousness?

• A. Delirium: chronic, stable attention; dementia: sudden fluctuation.
• B. Delirium: no change in consciousness; dementia: fluctuating consciousness.
• C. Delirium and dementia have identical features.
• D. Delirium: acute onset, fluctuating attention and consciousness.

Answer: (D)

Distinguishing delirium from dementia hinges on how quickly symptoms appear and how attention and arousal behave. Delirium shows up suddenly, with a rapid and usually fluctuating course. People have problems sustaining attention, and their level of consciousness or arousal can be altered—yes, they might drift from alert to drowsy or even more confused throughout the day. Dementia, in contrast, unfolds slowly over months to years, with a steady, progressive cognitive decline. Attention tends to be relatively preserved early on, and consciousness remains clear most of the time.

So the description that best fits delirium is an abrupt onset paired with fluctuations in both attention and consciousness. The other options don’t match this pattern: delirium is not a chronic, steadily attentive state; consciousness is typically disrupted in delirium, whereas dementia usually preserves consciousness early on; and the two conditions do not share identical features.