Acute organic brain syndrome is a medical condition that affects the functioning of the brain and can result in a wide variety of symptoms. There are several synonyms that are commonly used to describe this condition, including delirium, confusion, and dementia. Delirium is a sudden onset of confusion that can be caused by a variety of factors, including drug interactions and infections. Confusion is a state of disorientation and difficulty in understanding that can be caused by many factors, including trauma, infection, and metabolic disturbances. Dementia is a progressive decline in cognitive function that can be caused by a variety of brain disorders, including Alzheimer's disease and Parkinson's disease.