Why does dementia develop?

There are likely to be a number of factors, rather than one single cause of dementia. Age, genetic inheritance, vascular risks such as diabetes and high blood pressure, and diet are all thought to have an influence.  

Age

The likelihood of developing dementia increases significantly with age.  1 in 1000 people under the age of 65 have dementia compared to 1 in 14 people over the age of 65 with dementia.

Genetic Inheritance

A small number of people with Alzheimer’s disease have a faulty gene which is passed down through families and usually affects people in their 40s and 50s.  Although these faulty genes are rare you can be referred for genetic testing (which involves giving consent, discussion with the whole family and having a blood test).

Frontotemporal dementia which mainly affects people under 65.  There are different forms which probably have different causes.  Several faulty genes have been discovered which are sometimes passed down through families.

CADASIL is a rare genetic disorder which can cause damage to blood vessels in the brain.  It can be passed down through families.  It is very rare and affects around 1200 people in the UK.  

People with Down’s syndrome are more likely to develop Alzheimer’s disease in their 40s and 50s.  

Diet

Studies have shown that a diet high in fruit, vegetables, oily fish and foods low in sugars appear to reduce the risk of dementia.  However, the design of these studies means that definite conclusions about the effect of diet on the risk of dementia cannot be drawn.

Other Factors

People who have had a severe head injury or received repeated blows to the head e.g. boxers, are at higher risk of developing dementia.  People who smoke, or have high blood pressure and cholesterol levels, are also more at risk.