What type of dementia is characterized by an abrupt onset?

The condition characterized by an abrupt onset is delirium. Delirium is a rapid change in cognitive function that typically develops over hours to days, often due to an underlying medical condition, substance use, or withdrawal. Symptoms can include confusion, disorientation, altered levels of consciousness, and fluctuating cognition, which can provide a contrasting presentation compared to other types of dementia.

In contrast, Alzheimer's disease is a progressive form of dementia that generally has a gradual onset, characterized by slow cognitive decline over months to years. Lewy-body dementia also tends to have a gradual onset and involves fluctuations in attention and alertness, visual hallucinations, and Parkinsonian features. Frontotemporal dementia usually presents with personality changes, behavior issues, and language difficulties, typically developing insidiously rather than abruptly.

Therefore, recognizing that delirium is marked by its rapid development helps differentiate it from other dementia types that present in a slower, more insidious manner.