What is dementia?

Expert reviewers, Dr Daniel Edward Anderson, Psychiatrist and Dr Adrian Raby, General Practitioner
Next review due December 2024

Dementia is a set of symptoms that includes difficulties with daily living and with thinking, solving problems and memory, It usually gets worse over time. There is no cure for most causes of dementia. But there are treatments and therapies that can help people affected by it to live as full a life as possible.

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About dementia

Dementia isn’t a specific medical condition. It’s a set of symptoms caused by one or more brain conditions. These can affect:

  • the way the brain works – for example, thinking, reasoning, concentrating and remembering things
  • mood and behaviour including personality and control over emotions
  • managing day-to-day activities such as driving and shopping


Dementia is usually progressive, which means it gradually gets worse over time. It’s also irreversible. That means once symptoms start, their development can be slowed down but cannot be reversed.

Dementia becomes more common with older age. By the time people reach their 80s, around one in 10 will have dementia.

There are many health conditions which cause dementia by damaging the brain in different ways. Although these conditions are causes, they are sometimes called types of dementia. You may have heard of some of the most common ones.

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Types of dementia

There are four main types of dementia.

Alzheimer’s disease is the most common type of dementia. – around half of people with dementia will have it. Abnormal proteins in the brain damage the cells and over time these start to die. The early symptoms are usually memory lapses.

Vascular dementia is the second most common type of dementia. The brain is damaged when the blood supply to it is reduced. This may happen after a stroke or mini-stroke. Symptoms of vascular dementia can get worse in big or small steps.

Dementia with Lewy bodies is the third most common type of dementia. It’s caused by proteins building up in nerve cells. People with this type of dementia may see things that aren’t there. It can also cause movement problems similar to Parkinson’s disease.

Frontotemporal dementia is one of the commonest types affecting people under 65. It’s a group of conditions that cause cells to die in specific parts of the brain. It usually starts with changes to personality, language and behaviour rather than changes to memory.

Some people have more than one type of dementia. This is sometimes called mixed dementia. Other, rarer causes of dementia symptoms are also known.

Dementia and age

Dementia is closely linked to age. It is unusual to have any dementia symptoms before the age of 65. When this happens, it's sometimes called young-onset dementia.

After the age of 65, the chances of developing of dementia increase steadily. It can be frightening to hear that, but dementia isn’t something that will definitely happen when you get older. Fewer than one in 10 people over 65 have dementia.

There’s a difference between dementia and the more common mild memory loss that occurs as you age. If you occasionally have trouble remembering things, it’s unlikely to mean you have dementia.

Symptoms of dementia

Dementia symptoms can sometimes be difficult to spot because they often start and develop slowly. People are also good at finding ways to manage the symptoms so that they’re not obvious.

There are many possible symptoms. These will be different for each person and will depend on the type of dementia.

Different types of dementia tend to cause different symptoms, particularly in the early stages. However, as the conditions progress, all dementia types tend to ‘converge’ in terms of symptoms. So, someone in the later stages will have a wider range of symptoms, no matter what type of dementia they have.

Remembering, thinking and language

Often, the earliest signs of dementia are memory problems. It can be difficult to learn and remember new things or appointments and dates. Some people repeat questions and have difficulty finding the right words.

Dementia also affects lots of the things we routinely do, such as planning, making decisions and solving problems. Someone might have problems judging whether something is a good idea or not, or difficulty showing initiative when something goes wrong.

As dementia progresses, people may have difficulty reading and writing or following a conversation. They may become disorientated and get lost in familiar places.

Difficulty with daily activities

People with dementia often have increasing difficulty managing at home with day-to-day tasks. That can include:

  • managing money and paying bills
  • shopping and cooking
  • using the telephone
  • cleaning and doing housework
  • taking medicines properly


As the dementia gets worse, basic tasks such as washing, dressing and going to the toilet become more challenging.

Emotional and behavioural difficulties

Dementia can affect someone’s personality, emotional responses and behaviour. For many people with the condition and their carers, this is one of the most difficult things to come to terms with.

These are some of the common symptoms:

  • low mood, anxiety and depression
  • mood swings
  • feeling agitated and restless, including wandering about
  • disturbed sleep
  • being withdrawn or lacking energy or enthusiasm to do things
  • losing inhibitions and doing things they wouldn’t usually do – for example, swearing
  • change in personality


Dementia stages

How dementia develops is often talked about in term of three different stages – early, middle and late. How long someone is in each stage and thus how quickly the condition progresses vary. It can be upsetting to read but understanding what to expect can help with planning care. And it’s important to remember that everyone is different.

  • Early (mild). This often lasts a year or two and the symptoms can be mild enough for them to be missed. They include forgetting things, losing track of time and finding it hard to make decisions. People with mild dementia are often able to live independently.
  • Middle (moderate). This is when symptoms get worse and daily tasks become more difficult. Behaviour often changes during this stage as well. Sometimes people start to see and hear things that aren’t there (hallucinations) and believe things that aren’t true (delusions).
  • Late (severe). At this stage, people with dementia become dependent on others for their care. They will need help with eating, drinking and personal care. They may stop recognising family and close friends and be unable to communicate what they want or need.

How dementia affects people

Dementia has a significant effect on people who have the condition, and also on those who care for and support them. It can be challenging to live with and can affect every part of day-to-day life.

Other health problems

Depending on the type of dementia someone has, they may be at risk of developing other health problems. These can include depression, fractures after a fall, infections or pneumonia.


People are generally happier if they can stay in their own homes and remain as independent as possible for as long as possible. There are many ways to support people with dementia to live as independent and full a life as they can at home.

Dementia will eventually have a major impact on a person’s ability to look after themselves. Basic activities of daily living become more difficult. That can include things like preparing food, looking after the home, personal hygiene and going to the toilet. This usually means becoming dependent on others for support with everyday tasks.

Some people with dementia will have friends or relatives who can support them at home. Others will get help from a paid carer who comes in to see them. As symptoms get worse and care at home becomes more difficult or unsafe, the next option is usually moving to residential care. In the UK, around half of people with dementia live in care homes in the later stages.

Financial problems

Dementia can lead to financial difficulties. If someone is young and they develop dementia, it can affect their ability to work as they did before. They may need to reduce their hours or stop work altogether. If someone with dementia needs to pay for care fees or extra help, that will affect their finances.

Someone providing full-time care for someone with dementia will probably need to stop working too. Many people in this situation are entitled to benefits. There are national organisations that support people with dementia and their families. There is a lot of information about these organisations and the support they offer. You can find their details in our section: Other helpful websites.

How dementia affects loved ones

Caring for a person with dementia can cause some significant changes to the carer’s life. It can affect work, social life, relationships and emotions. Without support and regular self-care, it can have a serious impact on a carer’s physical and mental health.

Caring for someone with dementia can be an emotional rollercoaster. There are many positives but there are also challenges and it can also be stressful and hard going. That’s why, if you’re a carer, it’s really important to make sure you look after yourself as well as your loved one. One of the most important things to do is to get a good support network. That can include family and friends, health professionals, organisations and local support groups.

Can someone live well with dementia?

People can be very scared by the thought of dementia and the impact it’s going to have. It’s easy to assume that life will come to a stop or that they won’t be able to carry on doing the things they enjoy. But, with the right support and some practical changes it’s possible to live well with dementia.

Environment, activities and relationships.

When supporting someone with dementia, it is important is to help them stay as well and independent as possible, for as long as possible. That means:

  • helping them stay safe
  • changing the environment to help them manage day-to-day life
  • keeping support and care focused on their needs, abilities and interests – this is called person-centred care


By doing these things, someone with dementia is more likely to enjoy life and to reduce or prevent some of the symptoms. Below are some ideas for actions that may help.

  • Taking part in activities and conversations that help with thinking and using social skills. These should be things that interest the person and use existing skills and abilities.
  • Supporting someone with dementia to be as independent as possible, by making changes to the environment and daily activities. This could include using memory aids, equipment to stay safe in the kitchen and automatic pill dispensers.
  • Taking part in reminiscence therapy. This is talking about a past event or time, often using familiar objects or things from that time. It can help people with dementia to keep a sense of who they are and to feel more confident.
  • Keeping active. Staying physically and mentally active can help people with dementia to manage better, sleep well and improve their general health.
  • Good communication helps to keep relationships going and improves quality of life. Listening and thinking carefully about what is said will help when talking to someone with dementia.


Medical support

Doctors may suggest medicines to help with dementia. For Alzheimer’s disease, there are medicines that can sometimes improve memory in the early or middle stages. These can also slow down or pause the of worsening symptoms for a year or two. For other types of dementia, medicines may help with managing symptoms.

Health and care professionals can also be a great source of support. Admiral Nurses from the charity Dementia UK offer specialist dementia support on the phone, by email and in person.

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Related information


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  • Expert reviewers, Dr Daniel Edward Anderson, Psychiatrist and Dr Adrian Raby, General Practitioner Next review due December 2024