Disturbance of consciousness with rapid development is a hallmark of which condition?

• A. Dementia
• B. Delirium
• C. Depression
• D. Parkinson's disease

Answer: (B)

Delirium is characterized by an acute disturbance of consciousness and attention that develops over hours to days and often fluctuates during the day. This sudden change in awareness is the hallmark, and it usually signals an underlying medical issue such as infection, metabolic imbalance, dehydration, medication effects, or organ dysfunction, especially in older adults. In contrast, dementia shows a gradual, chronic decline in cognitive function with relatively stable levels of consciousness at the early stages. Depression may cause cognitive complaints, but consciousness remains clear and the changes are tied to mood and motivation rather than an acute global disturbance. Parkinson’s disease involves motor symptoms and may later include cognitive changes, but it does not feature an abrupt disturbance of consciousness as its defining trait.