The causes of the various illnesses that result in dementia aren't well understood at present. However, they all result in structural and chemical changes in the brain leading to the death of brain tissue. There are certain conditions that make you more likely to get dementia. You're more likely to develop late-onset dementia as you get older; or to develop vascular dementia if you have high blood pressure, irregular heart rhythms or have had a stroke. Your risk of dementia may be affected if someone else in your family has it. People with learning disabilities are at particular risk.
Attribution: BUPA