Dementia explained

Expert reviewer Rahul Bhattacharya, Consultant Psychiatrist
Next review due August 2022

Dementia is a set of symptoms, including certain problems with thinking and memory, that get worse over time.

These symptoms can be caused by a range of underlying medical conditions that affect the brain, including Alzheimer’s disease and vascular dementia. While there is no cure for dementia, there are treatments and therapies that can help people affected by it to live as well as possible.

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About dementia

The term ‘dementia’ is not just used to describe one particular medical condition. Dementia is really a set of symptoms. These include problems with:

  • thinking
  • reasoning
  • solving problems
  • learning
  • memory
  • language
  • daily activities

These problems can be caused by a number of different underlying conditions, which cause dementia by damaging the brain in certain ways. Although technically these conditions are causes of dementia, they are often referred to as different ‘types’ of dementia. You may have heard of some of the most common ones below.

Types of dementia

Alzheimer’s disease is the most common type of dementia. Parts of the brain shrink and proteins build up in the brain. The early signs are usually memory lapses, and the condition steadily gets worse over time.

Vascular dementia is the second most common type of dementia. The first symptoms often appear after a stroke or ‘mini-stroke’. Vascular dementia usually gets worse in big noticeable ‘steps’, rather than gradually. So symptoms may worsen quickly and unexpectedly.

Dementia with Lewy bodies is the third commonest type of dementia, caused by proteins building up in nerve cells. As well as common dementia symptoms, people with this type of dementia may have hallucinations, or movement problems similar to Parkinson’s disease.

Frontotemporal dementia is a rare type of dementia overall; but it's one of the commonest affecting people under 65. It is really a group of conditions that cause cells to die in specific parts of the brain. Unlike other forms of dementia, it usually starts with personality and behavioural symptoms, rather than memory difficulties.

Rarer causes of dementia symptoms are also possible.

Dementia and age

Dementia is closely linked to age. It is very unusual to have any dementia symptoms before the age of 65 – when this does happen, it is known as ‘early-onset’ or ‘young-onset’ dementia.

After the age of 65, the risk of dementia increases steadily as you get older. It can be frightening to hear dementia explained in this way, but you should know that dementia is not inevitable when you get older. Half of those aged 85 do not have dementia.

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

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Symptoms of dementia

Dementia has many possible symptoms. These will depend on the person and the type of dementia.

Remembering, thinking and language

Often the earliest signs of dementia are memory problems such as forgetfulness, repeating questions and difficulty finding the right words. As mentioned in the ‘Dementia and age’ section above, this is different from the milder memory loss that occurs as you age.

As dementia progresses, people are likely to have difficulty reading or following a conversation, understanding instructions and telling the time. They may become disorientated and get lost in familiar places.

Difficulty with daily activities

As memory problems worsen, people with dementia often have increasing difficulty with domestic routines. They may begin to neglect chores and their appearance. They may also develop unhygienic habits.

Emotional and behavioural difficulties

People with dementia often feel low or anxious. They may gradually become more withdrawn or apathetic. Sometimes they can appear to be suspicious and become irritable or even aggressive with those caring for them. They are also often restless and have trouble sleeping.

Differences between types of dementia

Different types of dementia tend to cause different symptoms and emotional reactions, particularly in the early stages. For example, in Alzheimer’s disease the early symptoms tend to involve memory problems, whereas in dementia with Lewy bodies someone may have hallucinations or physical symptoms. 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 the above symptoms, no matter what type of dementia they have.

How dementia affects people

Dementia has a significant effect on people who have the condition, and those who need to care for and support them.

Other health problems

Depending on the type of dementia someone has, they may be at risk of developing other health problems, for example infections or pneumonia.


Dementia has a major impact on a person’s ability to look after themselves. Basic activities of daily living, such as preparing food, looking after the home, personal hygiene, and going to the toilet become more difficult. This often means that they become dependent on others to support them in these activities. Some may be able to get support from friends or relatives in their home, or from a paid carer who comes in to see them. But for many, the level of dependency eventually means they have to move into residential care. In fact, in the UK around one in three people with dementia live in care homes.

Financial problems

Dementia usually affects people after retirement age. But if someone gets early-onset dementia, it may affect their ability to carry on with their work. This can obviously lead to financial problems if they have to leave their job. Whether working or not, people with dementia can have difficulty managing money. Finding that an older relative’s finances are in a bit of a mess can sometimes be the first sign that something is not quite right.

Someone who cares full-time for a relative or friend with dementia will probably have to give up their job as well, leading to even more financial problems. Around two-thirds of the total financial cost of dementia is paid by people with dementia and their loved ones.

How dementia affects loved ones

Caring for a person with dementia can cause significant changes in someone’s life, potentially affecting employment, education and social life, among other things. Ultimately, it can have a serious impact on the carer’s physical and mental health. That’s why looking after yourself as a dementia carer is really important. You may also find it helpful to learn more about dementia, for example, by exploring books, TV programmes and films about dementia.

Can someone live well with dementia?

Because dementia is progressive and can profoundly affect someone’s daily life, it’s easy to think that it’s not possible to live well with the condition. People can be very scared by the thought of dementia.

It’s true that living with dementia can be challenging and frustrating. But it’s important to remember that there are ways to help a person to live well with dementia.

Medical support

Doctors may prescribe certain medicines to help with dementia. There are some treatments that can slow down the progression of symptoms in the early and middle stages of Alzheimer’s disease. For other types of dementia, medicines may help with managing certain 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, over email and in person.

Environment, activities and relationships

As with any illnesses that affect the brain and ability to think, the difficulties that someone faces are not just to do with physical changes in the brain. You also have to take into account the person’s environment. This includes their physical surroundings, relationships, and the way people communicate with them.

The person with dementia – and those around them – can adjust this environment to take account of the condition. This may make the experience of living with dementia considerably less challenging. This might include some of the following steps.

  • Communication – changing the way you speak and communicate with a person with dementia can help them to understand you.
  • Staying active – staying physically and mentally active, and engaging in meaningful leisure or social activities, can have great benefits for a person with dementia.
  • Coping strategies – taking simple steps like making lists, labels and reminders can lessen the impact of memory loss.
  • The physical environment – adjusting the surroundings to suit the person with dementia can help to avoid accidents. For example, removing trip or slip hazards in the home, installing grab rails or making changes that help people with visual problems or hallucinations.
  • The community – communities that are ‘dementia-friendly’ and inclusive enable people with dementia to participate confidently in public life. This can help to keep them active and independent, and reduce isolation. Organisations such as Alzheimer’s Society can help you find out about local support. Our dementia information hub includes more tips and details about other aspects of dementia.

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Related information

    • Practical Dementia Care (3rd ed). Oxford Medicine Online., published 2016
    • Dementia. NICE Clinical Knowledge Summaries., last updated May 2017
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    • Dementia with Lewy bodies. BMJ Best Practice., last updated March 2019
    • Dementia with Lewy Bodies Clinical Presentation. Medscape., last updated June 2018
    • Frontotemporal dementia. PatientPlus., last updated September 2014
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  • Reviewed by Graham Pembrey, Lead Editor, Bupa Health Content Team, August 2019
    Expert reviewer Dr Rahul Bhattacharya, Consultant Psychiatrist
    Next review due August 2022