What is dementia?



   Oxford Dementia Centre

   Institute of Public Care

   Roosevelt Drive

   Oxford OX3 7XR

   Tel: 0845 120 4048


   email: info@disc.org.uk





This fact sheet offers information for carers about dementia.  It covers who is most likely to have dementia, the causes of dementia and the different types of dementia that exist.


You may also find the following fact sheets helpful:


·            Assessment and diagnosis

·            Treatment and therapy for people with dementia

·            Making your home dementia friendly


What is dementia?


Dementia is an illness and is different from normal ageing, although some of the features or symptoms of dementia are similar to the changes that happen as people age.


Dementia is caused by physical damage to the brain. It is a progressive illness which is a term used by doctors to mean that the illness advances and gets worse.  Dementia affects a person’s ability to think rationally and remember.  These abilities usually enable us to carry out a vast range of different activities, such as writing a shopping list, dressing, going to the toilet, driving and having conversations. When these abilities are affected, the range of activities that a person can perform safely becomes quite limited.


Symptoms such as forgetfulness usually develop slowly, although on occasions, a person may suddenly deteriorate after a physical illness or trauma, such as the loss of a partner.  The speed of decline depends on the type of dementia it is, the age at which the person begins to be affected and individual characteristics such as personality, background and the kind of support and care available.


Over time, as more damage occurs in the brain, both physical health and mental health decline. Doctors and other professionals sometimes refer to this decline in mental health as affecting ‘cognitive (thinking) abilities’, or ‘deterioration in cognitive ability’.


People often talk about dementia as though there is only one illness or disease.  It is in fact an umbrella term for over 70 different diseases or conditions.



The most common form of dementia is Alzheimer’s disease and this and other forms of dementia are described later in this fact sheet.


Who gets dementia?


Almost a million people in the UK are estimated to have dementia and numbers are expected to rise steeply in the next two decades.  It is uncommon for anyone under 60 to have dementia.  Old age is the biggest risk factor for dementia, and the older a person is, the more at risk they are.  Whilst 1 in 25 people aged 65 and over will be affected by dementia, this ratio increases to 1 in 4 people aged 80 and over.


Both men and women are affected but because more women survive beyond 75 years and over, dementia affects more women then men.


Some people may be more susceptible to the development of dementia because they have, or have had:


·          Previous head injuries

·          Clinical depression

·          Untreated high blood pressure

·          A family history of diseases, which are linked to the development of dementia

·          Downs syndrome


What sorts of changes take place in dementia?


Each person is different and they will experience dementia in their own individual way.  Some symptoms or features are very common, but others, such as causing physical harm to others or constantly shouting out, are not.


It assists everyone concerned with support and care for the person with dementia, to see dementia as a disability.  This helps us to understand that the feelings and behaviours that a person with dementia expresses are almost certainly a response to the stress, frustration and sadness that they are experiencing.  Most importantly carers should always remember that the person with dementia still has their ability to feel.  The illness has not taken away the ability to feel emotions and the way they are cared for, addressed or spoken to will undoubtedly affect them.


Early in the illness (sometimes called mild dementia) a person with dementia may experience:


·          A decline in recent memory such as forgetting the way home from the shops, being unable to name objects or remember names and places and repeating themselves.


·          A loss in the ability to take the initiative or plan anything. This erodes their independence.  They may seem apathetic and show less interest in hobbies or activities.


·          Mood swings and personality changes blaming others for ‘stealing’ mislaid items, becoming self centred and less concerned about the feeling of others, feeling sad, afraid or more angry.  These are common reactions to anxiety and stress related to memory loss and these may well be out of character.


·          Difficulties in making themselves understood and a decline in the ability to talk, read and write.


·          A decline in social skills and withdrawal from contact with other people and the outside environment which may be too much to cope with.


Later on in the illness (sometimes referred to as moderate dementia) many of the difficulties are more marked and people with dementia often experience:


·          Reduction in ability to carry out tasks associated with daily living such as putting on clothes in the correct order, forgetting the pans on the stove, and to light a gas ring or gas fire, not remembering to wash or bathe and possibly hiding soiled clothes if they have had ‘an accident’.


·          Sleep problems as anxiety increases and people find it hard to respond to ‘feeling tired’ and ‘going to bed’ at night time.  They may ‘wander’ at night or try to go to the post office or shops in the early hours of the morning.


·          Losses of appetite as psychological triggers for eating are affected by brain damage.  The person could be losing weight but saying they are eating.


As the illness progresses and a person has ‘severe dementia’, they may exhibit:


·        Behaviour that offends or is hurtful including verbal and physical aggression or behaviour, which goes beyond the bounds of acceptable social behaviour and sometimes sexual decency including removal of clothes or inappropriate physical contact.


·        Incontinence of urine and sometimes of faeces.


·        Constant repetition of words and phrases.


·        Inability to recognise family and friends and thinking that their child is their spouse.


·        Behaviour such as hallucinations.


·        Total inability to wash, dress, eat and drink without assistance.



Towards the end of the illness, people with dementia are likely to be:


·          Physically frail and weak as their mental health is deteriorating and their body systems gradually shut down.


·          Prone to breathing difficulties because of respiratory infections and other health problems, such as pneumonia, as they will have reduced immunity to illness.






This fact sheet can be made available in large print.


We are constantly looking to improve our information.  It helps if you let us know whether the information in this fact sheet was/was not useful and if there are other fact sheets that you would have found helpful that we have not yet provided.


While the information contained in this fact sheet is believed to be correct, DISC does not accept liability for any error/s it may contain.