About this factsheet

This factsheet provides key information about dementia, its symptoms and causes, and how it can be diagnosed. It also describes key types of dementia.
Download a pdf version of the ‘What is dementia?’ factsheet


What is dementia?

Dementia is a term used to describe a set of symptoms linked with progressive neurological (brain) disorders and may include memory loss, difficulties with thinking, problem-solving or language.

Some of these symptoms might be small to start off with, but as dementia progresses they may affect someone’s daily life and tasks.

As a result of changes in the brain, a person with dementia may also experience changes in their mood or behaviour.

A common cause of dementia is Alzheimer’s disease, but it’s not the only cause.  See: Causes of dementia.

Although there are a few common symptoms of dementia such as memory loss, the specific symptoms the person with dementia experiences will depend on the part of the brain which was damaged and the type of disease which has caused the dementia.

Symptoms of dementia

As each person is unique, their experience of dementia especially at early stages will be different from other people.

However some of the cognitive symptoms (linked with thinking or memory) are quite common for someone who lives with dementia. They may experience difficulty with the following:

day-to-day memory – such as difficulty recalling events that happened recently, for example what someone had for breakfast

concentrating, planning or organising – that may include a difficulty with making decisions, solving problems or carrying out a sequence of tasks (for example cooking a meal or making a cup of tea),

language – such as difficulty in following a conversation or finding the right word for something

visuospatial skills – this may include problems judging distances (such as on stairs) and seeing objects, such as patterns on a carpet, in three dimensions

orientation – such as getting confused about where they are, if for example they have left the house, or losing track of the day.

A person with dementia will often experience changes in their mood. They may become frustrated or irritable, easily upset or anxious, or show withdrawal symptoms. Some types of dementia may bring hallucinations (seeing things that are not really there) or delusions (believing in things which are not real).

As dementia is progressive, the symptoms will get worse with time. How quickly dementia progresses will vary from person to person.  The person might develop certain behaviours which may seem unusual or out of character such as pacing or agitation. These changes in behaviour may cause distress to family or friends.

In the later stages of dementia, a person may develop physical symptoms such as muscle weakness, weight loss, changes in sleep pattern or appetite.

Causes of dementia

There are many diseases that result in dementia. We are listing the most common illnesses below:

Alzheimer’s disease is the most common cause of dementia.  Alzheimer’s disease is caused by an abnormal protein which surrounds brain cells and another protein that damages their internal structure. In time, chemical connections between brain cells are lost and cells begin to die. The reduced connections between brain cells affect day-to-day memory, difficulties in finding the right words, solving problems, making decisions, or perceiving things in three dimensions.

Vascular dementia occurs if the oxygen supply to the brain is reduced because of narrowing or blockage of blood vessels. It causes some brain cells become damaged or die. The symptoms can occur suddenly (after a large stroke) or they can develop over time as a result of a series of small strokes. The symptoms of vascular dementia vary and may be similar to the symptoms of Alzheimer’s disease. Many people have difficulties with problem-solving or planning, concentrating and thinking quickly. They may also experience short periods when they get very confused.

Mixed dementia – describes when someone has more than one type of dementia, and a mixture of the symptoms of those types. It is common for someone to have both Alzheimer’s disease and vascular dementia.

Dementia with Lewy bodies – this type of dementia is caused by tiny abnormal structures (Lewy bodies) forming inside brain cells. They disrupt the chemistry of the brain and lead to the death of brain cells. Early symptoms can include alertness that varies over the course of the day, hallucinations, and difficulties judging distances. A person’s day-to-day memory is usually affected less than in the early stages of Alzheimer’s disease. Dementia with Lewy bodies is closely related to Parkinson’s disease and often has some of the same symptoms, including difficulty with movement.

Frontotemporal dementia (including Pick’s disease) – in this type of dementia, the front and side parts of the brain are damaged. Clumps of abnormal proteins form inside brain cells, causing them to die. Initially, changes in personality and behaviour may be the most obvious signs. Depending on which areas of the brain are damaged, the person may have difficulties with fluent speech or forget the meaning of words.

While the symptoms of the above mentioned dementia types vary in the early stages, in the later stages of an illness the symptoms are becoming quite similar. In the later stages of dementia, the person will need more and more support to carry out everyday tasks.

Many people with dementia live well for years after their diagnosis. There is a lot of information, advice and support available for the person with dementia and their support network (family, friends, carers) can help them live well with dementia.

Who gets dementia?

There are currently around 850,000 people in the UK with dementia. This is projected to rise to 1.6 million by 2040.

Dementia 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, dementia can affect younger people too. There are currently more than 42,000 people in the UK under 65 with dementia.

What are the risk factors for dementia?

If your older family member has developed dementia, it is only natural to wonder what the risk of developing dementia is.  Although it is not possible to say for certain, a doctor may outline the factor(s) which might contribute to developing dementia. In most cases, it will be a mixture of risk factors, some of them potentially avoidable and some of them not.

How can I tell if I have dementia?

If you are becoming a bit more forgetful, it doesn’t necessarily mean that you have dementia.

Many people notice that their thinking gets a bit slower or their memory becomes a bit less reliable as they get older. They may for example forget a friend’s name occasionally. These symptoms can also be a sign of stress, depression or certain physical illnesses, rather than dementia.

What are the symptoms of dementia?

There are a number of symptoms that may point to dementia if they start affecting your daily life. We list them below.

  • struggle to remember recent events (such as what you have had for breakfast), although you can easily recall things that happened in the past,
  • find it hard to follow conversations or programmes on TV,
  • forget the names of friends or everyday objects,
  • struggle to recall things you have heard, seen or read recently,
  • regularly lose the thread of what you are saying,
  • leave objects in unusual places (eg keys in a bathroom cabinet),
  • have problems thinking and reasoning,
  • feel anxious, depressed or angry,
  • feel confused even when in a familiar environment or get lost on familiar journeys,
  • find that other people start to comment on your forgetfulness.

Is dementia inherited?

Scientists are still investigating how dementia might run in the family. In a small number of people, certain types of dementia are inherited as a single gene that directly causes the disease. People with one of these genes will usually get dementia before the age of 65, classified as early onset dementia.

Everyone else will inherit a combination of genes that increases or decreases their risk of developing dementia in much less direct ways.

What should I do if I am concerned about dementia?

If you are concerned that your or your loved one’s memory is getting noticeably worse, please discuss your concerns with your GP.

Diagnosing dementia

It is very important for anyone who has problems with their memory to contact their GP and get an assessment.

Problems with your memory may be caused by a treatable condition such as depression or an infection, rather than dementia. It’s important therefore to find out the cause to allow the person to get the right treatment.

If the problems with memory are caused by dementia, getting a diagnosis has many benefits. It provides someone with an explanation for their symptoms, gives them access to treatment, advice and support, and allows them to prepare for the future and plan ahead. Knowing the type of dementia (for example, Alzheimer’s disease or vascular dementia) is also important, because it may help the person get an appropriate treatment.

Who can diagnose dementia?

Dementia will normally be diagnosed by a specialist doctor who could be:

  • a psychiatrist – a mental health specialist,
  • a geriatrician – a doctor who specialises in the physical health of older people,
  • a neurologist – someone who specialises in diseases of the nervous system.
  • a GP or specialist nurse may sometimes make the diagnosis, if they have relevant expertise and training.

Treatments for dementia

The large majority of causes of dementia cannot be cured, although research is continuing into developing medicines, vaccines and other medical treatments.  However there are many things we could do to help someone with dementia live well with the condition. Any care and support needs to focus on the individual’s needs and preferences.

Non-prescription treatments and support

There are a range of non-drug treatments available that can help someone to live well with dementia. These include. The GP, memory service or local Alzheimer’s Society are good places to start for more information on what is available.

  • Information, advice, support, therapies and activities – please speak with your local GP or Alzheimer’s Society about any therapies which are available locally. There may be advice and support available both for the person living with dementia and their carer.
  • Talking therapies, which includes counselling, can help someone come to terms with their diagnosis or discuss their feelings.
  • Cognitive behavioural therapy (CBT) may be offered if the person develops depression or anxiety.
  • Cognitive stimulation therapy can be offered to help keep someone’s mind active. It involves doing themed activity sessions over several weeks.
  • Cognitive rehabilitation can help an individual retain their key skills and cope better with the condition. Support devices such as pill boxes and calendar clocks can further support the person living dementia in a practical way.

Some people with dementia enjoy working on their life story book/notes, which encourages them to share their life experiences and memories. As their dementia progresses, they may also enjoy reminiscence work with the support from their family and friends. Such activities can help improve someone’s mood, wellbeing and mental abilities.

Other activities which can stimulate the mood and reminiscence include music, singing or art. It is vital that people with dementia stay as active as they possibly can – not just physically and socially but also mentally. Taking part in meaningful activities that the person enjoys can lead to an increased confidence and self-esteem.

Can dementia be prevented?

It is not often possible to say why a particular person has developed dementia. Although ageing is the biggest factor for dementia, there are a number of things we can do to maintain a healthy life and reduce the chances of getting dementia. These include:

  • Taking a regular physical exercise (for example, cycling, swimming, brisk walking)
  • Maintaining a healthy weight
  • Not smoking
  • Drinking alcohol only in moderation, or not drinking at all
  • Having a healthy balanced diet that is low in saturated fat, does not contain too much salt, sugar or red meat, but contains fish and plenty of fruit, vegetables and grains. The vegetables which are said to be particularly beneficial are raw leafy greens, especially darker greens such as spinach, kale and romaine lettuce, as they have more brain-boosting antioxidants and vitamin K
  • Being mentally active (doing puzzles, reading, or learning a new skill)
  • Being socially active (visiting friends, volunteering)

What risk factors can we change?

There are a number of factors which can lead to narrowing of the arteries thereby increasing the risk of developing Alzheimer’s disease and vascular dementia. These include:

  • Having high blood pressure
  • Lack of physical exercise
  • Smoking