In delirium, what is a hallmark feature?

• A. Fluctuations in LOC
• B. Hallucinations
• C. Restlessness
• D. Normal orientation

Answer: (A)

Delirium is defined by an acute, fluctuating disturbance in attention and awareness. The defining feature is changes in level of consciousness that come and go, often swinging between drowsy and highly alert over hours to days. This fluctuation in arousal and attentional capacity is what sets delirium apart from other conditions; it shows that consciousness is not stable. Hallucinations or restlessness can occur with delirium but aren’t universal or defining. Normal orientation would not fit, since delirium typically involves disorientation or fluctuating awareness. The key point is that consciousness levels vary in a way that reversible, abrupt changes in thinking, perception, and attention accompany delirium.