What causes dementia?

We do not know yet exactly what causes dementia. Medical researchers all over the world are working to find causes and develop treatments but as a general principle dementia develops when cells in the parts of your brain involved with mental ability become damaged. Damage to these cells can be caused by:

  • diseases and infections that affect the brain, such as Alzheimer`s disease or meningitis
  • pressure on the brain, for example a brain tumour lack of blood and oxygen supply to the brain, for example due to a stroke
  • head injury

Who is affected?

Alzheimer Scotland estimate that, in 2010, there will be around 71,000 people with dementia in Scotland. Dementia is most common among older people, but can also affect younger people, even (very rarely) those in their thirties. Some forms of dementia (such as fronto-temporal dementias, and alcohol-related dementias) are more likely to affect those who are younge. Around 2,300 people with dementia in Scotland are under 65.

Overall, 67% of people with dementia are female. However, the proportion varies with age group: women account for 45% of people with dementia between 65 and 69, but 79% of people with dementia aged 90 and above. This is due to a combination of higher dementia prevalence rates for men up until the age of 75, and the longer life expectancy of women.

The number of people with dementia is increasing, because the population is getting older; the number of people with dementia is set to double within the next 25 years.

Who is most at risk ...

Some people are more at risk of developing dementia than others.

People with Down`s syndrome are more likely than people in the general population to develop Alzheimer`s disease, and the onset of the illness is likely to be earlier.

There are some rare forms of dementia which are hereditary, caused by inheriting a faulty gene, but there are only a few families affected by these. All of these hereditary types of Alzheimer`s disease are "early onset", which means that they occur before the age of 65.

For anyone not in these few families, having a close relative with Alzheimer`s disease increases your own risk of developing the disease only slightly.

The main risk factor for dementia is age - it is more common in older people and the risk increases with age. But most people over 90 will not develop dementia.