Acute Onset Vascular Dementia is a medical condition that is characterized by visible symptoms like confusion, memory loss, difficulty thinking, and other neurological disorders. However, there are no antonyms for this condition as such since it is a specific medical diagnosis that refers to a condition affecting the brain. Nonetheless, the antonyms for 'acute' and 'dementia' can be obtained from a standard English lexicon. For instance, antonyms for acute range from slow, chronic, gradual, and mild, while antonyms for dementia include sanity, soundness, cognitive well-being, and mental clarity. Overall, it is essential to seek medical attention early when symptoms of such acute onset conditions are noted to help prevent long-term consequences.