Types of dementia
The most common cause of dementia is Alzheimer’s Disease, which accounts for about around 62% of all cases. In Alzheimer's Disease the brain progressively shrinks due to the death of brain cells. The area of the brain associated with memory, the hippocampus, is the first area to be damaged and problems with memory is typically the first symptom to appear. However, later on, all parts of the brain can be affected. Alzheimer's Disease is also associated with two hallmark changes to the brain. The first is a build up of the β-amyloid peptide, which forms plaques in the brain. The second change is in a protein called tau, which clumps together forming tangles in the brain cells. The biggest risk factor for Alzheimer's Disease is old age.
The second most common form of dementia is Vascular Dementia, which consitutes around 17% of cases. It is caused by damage to the blood vessels that supply oxygen to the brain. If the blood is no longer able to circulate properly, then the brain cells will eventually die. Vascular dementia can be triggered by a single event, such as a stroke, or more chronic conditions such as high blood pressure, heart problems, high cholesterol or diabetes. The first symptoms to appear depend on which part of the brain have been damaged.
Other, less common, forms of dementia include dementia with Lewy bodies (4%) and fronto-temporal dementia (2%).
Find out more about how to reduce your risks of dementia and the genes linked to late- and early-onset Alzheimer's disease.