The four most common types of dementia are: Alzheimer’s disease: This is the most common type of dementia, characterized by the buildup of abnormal proteins in the brain that lead to the death of brain cells and progressive cognitive decline. Vascular dementia: This type of dementia is caused by reduced blood flow to the brain, often due to conditions such as stroke or hypertension, and can result in a decline in cognitive function. Lewy body dementia: This type of dementia is caused by abnormal protein deposits in the brain and can cause changes in mood and behavior, as well as movement difficulties and cognitive impairment. Frontotemporal dementia: This type of dementia is characterized by the degeneration of nerve cells in the front and side areas of the brain, leading to changes in behavior, personality, and language abilities.