What are the characteristic features of delirium?

Delirium is defined by specific features that help differentiate it from other cognitive disorders, such as dementia. The characteristic features of delirium include an acute onset and a fluctuating course, meaning that the symptoms can vary in intensity throughout the day. Patients often experience inattention, which is a hallmark of delirium, indicating difficulty in focusing or sustaining attention. Additionally, there is typically an altered level of consciousness, which can range from hyperalertness to drowsiness or confusion.

The acute onset emphasizes that the symptoms develop relatively quickly, often over hours to days, contrasting with conditions like dementia that present gradually. The fluctuating nature of symptoms can lead to periods of lucidity followed by confusion, further complicating the clinical picture.

These features are critical for diagnosis and management because they highlight the transient and reversible nature of delirium, distinguishing it from chronic cognitive impairments. Understanding these core characteristics is essential for effective assessment and intervention in patients.