Dementia is a term used to describe the symptoms of many disorders that affect the brain. It is not therefore one specific disease.


Because there are so many causes of dementia which affect people differently, and which change over time, no two people will experience dementia in the same way.

There are more than 55 million people world-wide with dementia, and about 1,600 in Jersey.

Because dementia mainly affects older people and because we can now expect to live well into our 80s or 90s, it is more common than even 100 years ago. This rise in numbers is also in part due to people having better access to medical care and there being better ways of diagnosing this. There is also significant evidence that life-style factors may be influencing the increase in the number of people with dementia, so there is a renewed focus on brain health and risk reduction strategies.

Although the risk of dementia increases with age, younger people in their 30s – 60s can also have dementia. The term ‘younger onset dementia’ is used for any form of dementia under the age of 65.

What causes dementia?

There are many different conditions that can cause dementia, which we sometimes think of as the types of dementia.

The most common types are, Alzheimer’s disease, vascular dementia, Lewy body disease, frontotemporal dementia, and alcohol acquired dementia (sometimes called Korsakoff’s syndrome). While quite a lot is known about the changes that are happening in the brain with these conditions, why people develop dementia is mostly unknown, apart from some types of vascular dementia and alcohol related dementia.

Anyone can get dementia but the likelihood of having dementia increases with age. We also know that our health and lifestyles, and for a very small number of people diagnosed, genes may be a cause.

Dementia occurs when nerve cells in the brain are damaged. These cells carry messages between different parts of the brain and to other parts of the body and as more nerve cells are damaged the brain becomes less able to work properly.