Rarer causes of dementia

There are many other diseases that can lead to dementia. These are rare: together they account for only about five per cent of all dementia. They tend to be more common among younger people with dementia (under the age of 65).

These rarer causes include alcohol-related brain damage (including Korsakoff's syndrome), corticobasal degeneration, progressive supranuclear palsy, HIV infection, Niemann-Pick disease type C, and Creutzfeldt-Jakob disease (CJD).

Some people with Parkinson's disease or Huntington's disease develop dementia as the illness gets worse. People with Down's syndrome are also at a particular risk of developing Alzheimer's disease as they get older.

Mild cognitive impairment

Some people have problems with their memory or thinking but these are not severe enough to interfere with everyday life. In this case, a doctor may diagnose mild cognitive impairment (MCI). Research shows that people with MCI have an increased risk of developing dementia; about 10-15 per cent of this group will develop dementia each year.

However, MCI can also be caused by other conditions such as anxiety, depression, physical illness and side effects of medication. Because of this, some people with MCI do not go on to develop dementia, and a small number of people will even get better.

Who gets dementia?

It is predicted there will be around 850,000 people in the UK with dementia in 2015. It mainly affects people over the age of 65 (one in 14 people in this age group have dementia), and the likelihood of developing dementia increases significantly with age. However, it can affect younger people: there are more than 40,000 people in the UK under 65 with dementia. Dementia can affect men and women.

Scientists are investigating the ways dementia might run in the family. In a very small number of people, certain types of dementia are inherited as a single gene that causes the disease, usually before age 65. A much larger number of people will inherit a combination of genes that increases or decreases their risk of developing dementia in much less direct ways.

How can I tell if I have dementia?

Becoming a bit more forgetful does not necessarily mean that you have dementia. Many people notice that their memory becomes a bit less reliable as they get older - for example they might forget someone's name. Memory loss can also be a sign of stress, depression or certain physical illnesses.

However, anyone who is worried that their memory is getting noticeably worse, or who has other symptoms such as those listed above, should discuss their concerns with the GP.

Diagnosing dementia

It is very important to get a proper assessment of problems with memory or thinking. They may be caused by a treatable condition such as depression or an infection, rather than dementia.

If the cause is dementia, a diagnosis has many benefits. It provides someone with an explanation for their symptoms, gives access to treatment, advice and support, and allows them to prepare for the future and plan ahead. Knowing the type of dementia (eg Alzheimer's disease, vascular dementia) may allow appropriate drug treatments to be offered.

Dementia will usually be diagnosed by a specialist doctor such as a psychiatrist (a mental health specialist), a geriatrician (a doctor specialising in the physical health of older people) or a neurologist (someone who concentrates on diseases of the nervous system). Occasionally a GP or specialist nurse will make the diagnosis, depending on their expertise and training.

There is no single test for dementia. A diagnosis is based on a combination of things:

• taking a 'history' - by the doctor talking to the person and someone who knows them well about how their problems developed and how they are now affecting their daily life

• cognitive tests of mental abilities (eg memory, thinking) - simpler tests will be carried out by a nurse or doctor, more specialist tests by a psychologist

• physical examination and tests (eg blood tests) - to exclude other possible causes of the symptoms

• a scan of the brain - if this is needed to make the diagnosis.

A common pattern is for the GP to make an initial assessment and then refer the person to a memory clinic or other specialist service for more detailed assessment. A specialist doctor will have more expertise in dementia and will be able to arrange more detailed tests and brain scans if needed. The diagnosis should be communicated clearly to the person and usually also those closest to them, along with a discussion about the next steps.

Source: Alzheimers Society