Which of the following is NOT a symptom of delirium?

The correct answer is that improved cognitive function is not a symptom of delirium. Delirium is characterized by an acute change in attention and cognition. Patients typically exhibit a range of cognitive deficits, including confusion, disorientation, and a shortened attention span. Delusions, which are false beliefs not based on reality, are also common in individuals experiencing delirium, as are fluctuations in behavior that can result in agitation.

In contrast, improved cognitive function would indicate a return to a baseline level of mental clarity and capacity, which is contrary to the nature of delirium. Individuals with delirium may experience significant cognitive impairment, and any notion of improved cognitive performance would suggest that the acute episode is resolving rather than presenting characteristics typical of delirium.