What is a key characteristic of delirium?

Delirium is characterized primarily by a rapid change in cognitive function, attention, and awareness, often presenting with symptoms such as restlessness and hallucinations. It typically develops over a short period, often hours to days, and is frequently associated with underlying medical conditions, such as infections, metabolic imbalances, or substance withdrawal. The presence of restlessness and hallucinations signifies the acute nature of delirium, indicating a significant and sudden alteration in cognitive state that distinguishes it from other conditions like dementia or chronic mood disorders.

In contrast, persistent memory loss suggests a more chronic condition like dementia rather than the fluctuating and often reversible state associated with delirium. A gradual cognitive decline is also indicative of dementia, where cognitive functions slowly deteriorate over time rather than abruptly. Consistent mood swings, while they may present in various psychological disorders, do not define the fluctuating level of consciousness and cognitive disruption seen in delirium. Thus, the key characteristic of restlessness and hallucinations points directly to the nature of delirium.