Delirium vs dementia: which statement best describes their temporal pattern?

• A. Delirium is an acute, fluctuating disturbance of attention and awareness; dementia is a chronic, progressive cognitive decline
• B. Delirium is chronic; dementia acute fluctuations
• C. Delirium is caused by dehydration
• D. Dementia resolves quickly

Answer: (A)

Temporal pattern differentiates delirium from dementia. Delirium presents abruptly, often over hours to days, and the level of consciousness with attention and awareness fluctuates throughout the day. This acute, fluctuating disturbance is typically triggered by an underlying medical issue, such as infection, metabolic imbalance, medications, or withdrawal. Dementia, on the other hand, evolves slowly over months to years with a steady, progressive decline in cognitive function, most notably memory, and without the characteristic dramatic fluctuations in consciousness seen in delirium. Because of this, the best description is that delirium is an acute, fluctuating disturbance of attention and awareness, while dementia is a chronic, progressive cognitive decline.