There are many types of dementia e. g. Alzheimer's disease the most common type. Alzheimer's disease changes the brain's structure which leads to the death of nerve cells and disrupts the brain's usual activity. People with Alzheimer's also have a shortage of chemicals involved with the transmission of messages within the brain. Vascular dementia is another form of dementia and is triggered by blockages to the blood vessels in the brain. Not enough blood and oxygen reach the nerve cells so they die. Areas of brain tissue that have died in this way are called infarcts, so vascular dementia is also called multi-infarct dementia. Mixed dementia is when you have more than one type of dementia at the same time. A common combination is Alzheimer's disease and vascular dementia.
Attribution: BUPA