Dementia is a syndrome (a group of related symptoms) that is associated with an ongoing decline of the brain and its abilities. These include:

  • thinking,
  • language,
  • memory,  
  • understanding, and
  • judgement.

People with dementia may also have problems controlling their emotions or behaving appropriately in social situations. Aspects of their personality may change. Most cases of dementia are caused by damage to the structure of the brain.

How common is dementia?

Dementia is a common condition. Usually dementia occurs in people who are 65 or over. The older you get, the more likely you are to develop it.

It is estimated that dementia occurs in:

  • 1.4% of men and 1.5% of women aged between 65 and 69,
  • 3.1% of men and 2.2% of women aged between 70 and 74,
  • 5.6% of men and 7.1% of women aged between 75 and 79,
  • 10.2 % of men and 14.1% of women aged between 80 and 84, and
  • 19.6% of men and 27.5% of women aged 85 or over.

Types of dementia

Listed below are the different types of dementia.

  • Alzheimer's disease, where small clumps of protein, known as plaques, begin to develop around brain cells. This disrupts the normal workings of the brain.
  • Vascular dementia, where problems with blood circulation result in parts of the brain not receiving enough blood and oxygen.
  • Dementia with Lewy bodies, where abnormal structures, known as Lewy bodies, develop inside the brain.
  • Frontotemporal dementia, where the frontal and temporal lobes (two parts of the brain) begin to shrink. Unlike other types of dementia, frontotemporal dementia usually develops in people who are under 65. It is much rarer than other types of dementia.

This section focuses on vascular dementia, dementia with Lewy bodies and frontotemporal dementia.


In clinical terms, the outlook for dementia is not good. In most cases, there is no cure and symptoms will get worse over time.

However, even if a person’s dementia cannot be cured, there are a number of effective treatments that can help them to cope better with their symptoms and improve their quality of life.

If you have dementia, it may affect your ability to drive.

Last updated: 04 October 2011

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