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What is Dementia?

If you, or a friend or relative, have been diagnosed with dementia, you may be feeling anxious or confused. You may not know what dementia is. This factsheet should help answer some of your questions about dementia, including what causes it and how it is diagnosed. The term ‘dementia ‘ describes a set of symptoms which include loss of memory, mood changes and problems with communication and reasoning. These symptoms occur when the brain is damaged by certain diseases, including Alzheimer’s Disease and damage caused by a series of small strokes.

Dementia is progressive, which means that the symptoms will gradually get worse. How fast dementia progresses will depend on the individual person and what type of dementia they have. Each person is unique and will experience dementia in their own way. It is often the case that carers, family and friends struggle to cope.


  • Loss of memory – this particularly affects short term memory, for example forgetting what happened earlier in the day, not being able to recall conversations, being repetitive or forgetting the way home from the shops. Long term memory is usually still quite good.
  • Mood changes – people with dementia may be withdrawn, sad, frightened or angry about what is happening to them.
  • Communication problems – including problems finding the right words for things, for example describing the function instead of naming it.


There are several diseases and conditions that result in dementia. These include:

Alzheimer’s Disease

The most common cause of dementia. During the course of the disease the chemistry and structure of the brain change, leading to the death of brain cells. Problems of short-term memory are usually the first noticeable sign.

Vascular Dementia

If the oxygen supply to the brain falls due to vascular disease, brain cells are likely to die and this can cause the symptoms of vascular dementia. These symptoms can occur either suddenly, following a stroke, or over time through a series of small strokes.

Dementia with Lewy Bodies

This form of dementia gets its name from tiny abnormal structures that develop inside nerve cells. Their presence in the brain leads to the degeneration of brain tissue. Symptoms can include disorientation and hallucinations, as well as problems with planning, reasoning and problem solving. Memory can be affected to a lesser degree. This form of dementia shares some of the characteristics with Parkinson’s Disease.

Fronto-temporal dementia (including Pick’s Disease)

There are about 850,000 people in the UK with dementia. Dementia mainly affects people over the age of 65 and the likelihood increases with age. However, it can affect younger people: there are over 40,000 people in the UK under the age of 65 who have dementia. Dementia can affect men and women. Scientists are investigating the genetic background to dementia.


Most forms of dementia cannot be cured, although research is continuing into developing drugs, vaccines and other treatments. Drugs have been developed that can temporarily alleviate some of the symptoms of some types of dementia.


Many people fear they have dementia, particularly if they think that their memory is getting worse or if they have known someone who has had the illness. Becoming forgetful does not necessarily mean that you have dementia; memory loss can be an effect of aging, and it can also be a sign of stress or depression. In rare cases, dementia like symptoms can be caused by vitamin deficiencies and/or a brain tumour.


It is very important to get a proper diagnosis. A diagnosis will help the doctor rule out any illnesses that might have similar symptoms to dementia, including depression. Having a diagnosis may also mean it is possible to be prescribed drugs to alleviate symptoms. Whether you are someone with dementia or a carer, a diagnosis can help with preparing and planning for the future.

Dementia can be diagnoses by a doctor – either a GP or a specialist. The specialist may be a geriatrician (a doctor specialising in the care of older people), a neurologist (someone who concentrates on diseases of the nervous system) or a psychiatrist (a mental health specialist). The doctor may carry out a number of tests to check basic thinking processes and the ability to perform daily tasks. They may request further tests, such as a brain scan or more in-depth assessment of memory, concentration and thinking skills.


Please help yourself to our free download of the Purple Angel Guide for Care and Knowledge paper which goes with it.

Written by Chantelle Merritt an activity co-ordinator and carer and Norman McNamara, a person living with dementia, this pamphlet gives an insight into the support which staff and families can give both within a care home and family setting together with an activity list.

Dementia Guide (.pdf)

Understanding Dementia Questionnaire (.pdf)


Alzheimer’s Society National Helpline number: 0300 222 1122