What is dementia?

The word 'dementia' describes a set of symptoms that over time can affect memory, problem-solving, language and behaviour. Alzheimer's disease is the most common type of dementia.

Page contents

  1. About dementia
  2. Types of dementia
  3. Symptoms
  4. Risk and prevention
  5. Diagnosis
  6. Treatments

You can also read our information about dementia in accessible formats, including audio, Easy Read and British Sign Language.

About dementia

Dementia describes a group of symptoms that include problems with memory, thinking or language, and changes in mood, emotions, perception and behaviour.  

Dementia is a progressive disease, which means symptoms may be relatively mild at first, but they get worse over time. There are many types of dementia but Alzheimer’s disease is the most common. The next most common is vascular dementia. 

What causes dementia?

Dementia is not a natural part of aging. It is caused when a disease damages nerve cells in the brain.

Nerve cells carry messages between different parts of the brain, and to other parts of the body. As more nerve cells are damaged, the brain becomes less able to work properly. 

Dementia can be caused by many different diseases. These diseases affect the brain in different ways, resulting in different types of dementia. 

Types of dementia

Around 19 out of 20 people with dementia have one of four main types. Dementia affects everyone differently, however each type has some common early symptoms.  

A person may also have mixed dementia where they have symptoms of more than one type.

Alzheimer’s disease

Alzheimer’s disease is the most common type of dementia. For most people, the first signs of Alzheimer’s are problems with their memory, thinking, language or perception. 

Read our information on Alzheimer’s disease 

Vascular dementia

Vascular dementia is the second most common type of dementia. Common early signs of vascular dementia include problems with planning or organising, making decisions or solving problems. 

Read our information on vascular dementia 

Dementia with Lewy bodies (DLB)

Dementia with Lewy bodies (DLB) is caused by Lewy body disease. Symptoms of DLB include having difficulties staying focused, experiencing delusions, and problems with movement and sleep.

It is closely related to Parkinson’s disease

Read our information on dementia with Lewy bodies (DLB) 

Frontotemporal dementia (FTD)

Frontotemporal dementia (FTD) is one of the less common types of dementia. It is sometimes called Pick's disease or frontal lobe dementia.

Common symptoms of FTD include changes to personality and behaviour and/or difficulties with language. 

Read our information on frontotemporal dementia (FTD) 

Rarer types of dementia

There are many other causes of dementia. Read our information on rarer types of dementia. 

Read about rarer types of dementia

What are the symptoms of dementia?

Each person experiences dementia in their own individual way. Different types of dementia also tend to affect people differently, especially in the early stages.

However, there are some common early signs and symptoms of dementia. These include:

  • memory loss – for example, problems recalling things that happened recently
  • difficulty concentrating, planning or organising – for example, struggling to make decisions, solve problems or follow a series of steps (such as cooking a meal)
  • problems with language and communication – for example, difficulties following a conversation or finding the right word for something
  • misunderstanding what is being seen – for example, problems judging distances (such as on stairs) or perceiving the edges of objects, and misinterpreting patterns or reflections
  • being confused about time or place – for example, losing track of the time or date, or becoming confused about where they are
  • mood changes or difficulty controlling emotions – for example, becoming unusually anxious, irritable, sad or frightened, losing interest in things and personality changes.

With some types of dementia, the person may have difficulty knowing what is real and what isn’t. They may see or hear things that are not really there (hallucinations), or strongly believe things that are not true (delusions).

However, having symptoms like memory problems does not always mean a person has dementia. Dementia-like symptoms can be caused by other conditions, such as:

      The later stages of dementia

      Dementia is progressive, which means symptoms may be relatively mild at first, but they get worse over time. A person may also experience new symptoms as their dementia progresses.

      Read about the later stages of dementia

      Who gets dementia?

      There are currently around 900,000 people in the UK living with dementia. It mainly affects people over the age of 65.

      The likelihood of developing dementia increases significantly with age. One in 14 people aged over 65 has dementia. This rises to 1 in 6 for people aged over 80.   

      Dementia can affect younger people too. This is often called young-onset dementia. Around 1 in 20 people with dementia are younger than 65. There are more than 42,000 people in the UK under 65 with dementia.  

      Dementia is also more common among women than men. 

      Why do some people get dementia and not others?   

      It is not always clear why some people get dementia while others don’t. It can depend on a combination of age, genes, lifestyle and other health conditions.  

      Most types of dementia are not passed down (inherited) from a parent to a child. There are a few genes that will cause dementia if they are passed from a parent to a child – known as ‘familial’ genes. However, familial genes are rare.

      Some things can increase your chances of developing dementia, including:

      However, evidence shows there are things a person can do to reduce their risk of getting dementia, especially if they do them mid-life (aged 40–65).

      Diagnosing dementia 

      It is very important for anyone who has regular problems with their memory or thinking to be assessed by a health professional.

      If these problems are because of dementia, getting an early diagnosis has many benefits.

      It gives the person an explanation for their symptoms, gives them access to treatment, advice and support, and allows them to plan for the future. 

      How to get a dementia diagnosis

      The dementia diagnosis process can vary for everyone. Read more about the typical steps involved in getting a diagnosis, including what might happen if you are referred to a specialist.

      Read more

      Treatments for dementia

      Knowing the type of dementia (for example, Alzheimer’s disease or vascular dementia) is also important. This is because it may allow the person to get the right treatment, such as:

      There is no cure for dementia yet. However, the right care and treatment can help a person with dementia live well for as long as possible.

      A combination of both drug and non-drug treatments can help a person with dementia to keep doing things for themselves.

      Download or order a copy of our factsheet

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