Dementia is caused by different diseases. Dementia with Lewy bodies is the third most common disease that causes dementia.

What is dementia with Lewy bodies?

The word dementia is used to describe a group of symptoms. These include:

  • memory loss
  • confusion
  • changes to communication
  • mood and behaviour.

These symptoms affect day-to-day life.

Dementia is caused by different diseases. Dementia with Lewy bodies is the third most common disease that causes dementia after Alzheimer’s disease and vascular dementia.

For every 100 people who have dementia, about 10-15 will have dementia with Lewy bodies.

This means that around 100,000 people in the UK have this type of dementia.

Dementia with Lewy bodies is often shortened to DLB.

What causes dementia with Lewy bodies?

In DLB, small round clumps of protein build up inside nerve cells in the brain. One of these proteins is called alpha-synuclein, and the clumps it forms are called Lewy bodies.

As DLB progresses, Lewy bodies build up and this accumulation is accompanied by damage to nerve cells. This damage affects the way that our brain cells communicate.

In DLB, the nerve cells that are affected are in areas of the brain that control our thinking, memory, and body movement.

Is dementia with Lewy bodies related to Parkinson's disease and Parkinson's disease dementia?

Dementia with Lewy bodies is closely related to Parkinson’s disease (PD).

The build-up of Lewy bodies is also found in Parkinson’s and leads to symptoms like movement problems and tremors.

People who have Parkinson’s disease are more likely to go on to develop dementia. This is known as Parkinson’s disease dementia (PDD).

Dementia with Lewy bodies and Parkinson’s disease dementia can affect people in very similar ways, and people will receive a diagnosis of one or the other dependent on the timing of certain symptoms.

  • If memory problems and dementia symptoms appear before or at the same time as movement problems and symptoms, then a diagnosis of dementia with Lewy bodies is likely to be given.
  • If Parkinson’s movement problems are experienced for a year or more before memory and thinking symptoms appear, a diagnosis of PDD is likely to be given.

It is not always easy to tell if a person has DLB or PDD, as the timing of the start of memory and thinking symptoms is not always clear.

Umbrella with the word "Lewy bodies" in. Underneath, the first row says Lewy body dementia and Parkinson's disease. Underneath Lewy body dementia is dementia with Lewy bodies, and Parkinson's disease dementia falls under both Parkinson's disease and Lewy body dementia

Lewy Body Dementia is a term that describes both DLB and PDD and can be useful in these situations. It can also be useful to group these conditions as there are many similarities, both in symptoms and in the needs of people with the conditions and their families.

Dementia with Lewy bodies

This booklet is for anyone who wants to know more about dementia with Lewy bodies (DLB). This includes people living with DLB, their carers, families and friends.

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This information was updated in December 2023 and is due to be reviewed in December 2025. It was written by Alzheimer’s Research UK’s Information Services team with input from lay and expert reviewers. Please get in touch if you’d like a version with references or in a different format.

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