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Dementia with Lewy bodies


Expert reviewer, Professor Graham Stokes, psychologist and dementia specialist
Next review due December 2019

Dementia with Lewy bodies is the third commonest type of dementia. It probably makes up around one in 10 cases (10%).

An older couple looking at a computer

About dementia with Lewy bodies

Doctors don’t know exactly what causes dementia with Lewy bodies. There are some family ‘clusters’, but most of the time it doesn’t run in the family. Mostly it’s diagnosed in people over 60, but it does sometimes occur in people in their 50s. Doctors don’t know much about what increases your risk of dementia with Lewy bodies. This may be because dementia with Lewy bodies was only recognised as a separate condition relatively recently. It may be more common in men. There are some known changes in genes that have been found in affected families, but we don’t know how much these contribute to the majority of cases that don’t run in families.

Some symptoms of dementia with Lewy bodies are similar to other types of dementia, such as Alzheimer's disease. These dementia signs can include difficulty managing and memory loss, which may come on later in the course of the disease. Typical symptoms of dementia with Lewy bodies include seeing things (visual hallucinations), fluctuation in attention and awareness, sleep disturbance and a movement disorder similar to Parkinson’s disease.

Symptoms of dementia with Lewy bodies

Dementia with Lewy bodies has symptoms in common with Parkinson’s disease. In both conditions, protein deposits called Lewy bodies are seen in brain cells.

Doctors look for three typical signs to diagnose dementia with Lewy bodies:

  • fluctuations in mental ability, attention and alertness
  • seeing things – visual hallucinations happen in up to two-thirds of people with the condition
  • physical symptoms similar to those of Parkinson’s disease

If someone shows two of these signs, their doctor will say that dementia with Lewy bodies is likely. If they have one, their doctor may say that dementia with Lewy bodies is possible, but they can’t make a definite diagnosis.


Mental state

The brain’s function tends to get worse over time in dementia with Lewy bodies. As it worsens the person will become less able to look after themselves and need more and more help.

A particular symptom of dementia with Lewy bodies is a fluctuation in mental ability, attention and level of alertness. This can cause someone to be silent and unresponsive for several minutes at a time.

Around two-thirds of people with dementia with Lewy bodies see things that are not there (have hallucinations). About one in five hear things that are not there. These are called auditory hallucinations.

Hallucinations may happen at night, making them difficult to distinguish from dreams. This is made more difficult to cope with by another symptom called rapid eye movement (REM) sleep disturbance. This causes vivid dreams, meaning someone may call out and act out their dreams in their sleep.

Depression can occur in around four out of every 10 people diagnosed with dementia with Lewy bodies. They may also have anxiety.

Find out more about depression and its treatment.


Parkinson’s disease symptoms

The symptoms of dementia with Lewy bodies are similar to those experienced by people with Parkinson's disease. These symptoms gradually worsen over a number of years.

People may move very slowly and develop a very particular way of walking: in a shuffling way, taking very small steps while leaning forwards.

Another common Parkinson’s disease symptom that is also a symptom of dementia with Lewy bodies is having an expressionless face. People sometimes describe this as ‘mask-like’.

One common Parkinson’s disease symptom that people with dementia with Lewy bodies don’t generally have is shaking (tremor), but it can sometimes occur.

Find out more about Parkinson’s disease.

How dementia with Lewy bodies develops

Dementia with Lewy bodies is a long-term condition that gets worse over time. Generally, dementia with Lewy bodies gets worse quite gradually. On average, people live for between five and eight years after diagnosis.

Hallucinations can be one of the first signs that something is wrong. The varying mental state and attention span are also often early signs of the disease.

Memory problems may not show up straightaway but can become a problem later in the course of the disease. Parkinson’s symptoms may also not show up at first but develop later on.

As the condition develops, the person will have more difficulty managing day-to-day life. They’re likely to need help with more basic daily tasks such as washing and dressing. Because the condition worsens over time, eventually many people need to be looked after continually, which is often only possible in residential care.

As with many long-term illnesses, there can be complications with dementia with Lewy bodies. People are more likely to have frequent falls than with other types of dementia. This is due to the Parkinson’s symptoms that people with dementia with Lewy bodies have. These also cause difficulty swallowing, which means that people with dementia with Lewy bodies are at risk of inhaling food or drinks. This increases their risk of pneumonia.

Causes of dementia with Lewy bodies

Doctors don’t fully understand what causes dementia with Lewy bodies. Brain cells taken from people who have had dementia with Lewy bodies show the typical clumps of protein (Lewy bodies) that form inside nerve cells in Parkinson’s disease. Doctors think that these are toxic to brain cells.

Other theories about the causes of dementia with Lewy bodies are that a key chemical process in cells gets interrupted and brain cells are then unable to work properly. Or the cells may be affected by other abnormal processes, such as inflammation. A few changes in genes have been found in families where dementia with Lewy bodies is more common. But most cases of dementia with Lewy bodies do not run in families and it is not clear how important these changes in genes are generally.


Image of a part of the brain under a microscope, showing a Lewy body 

A close-up of part of the brain under a microscope. A chemical has been added to show up
a certain protein. The black ring shows a clump of this protein. This is a Lewy body.

Medicines for dementia with Lewy bodies

Unfortunately, there is no cure for dementia with Lewy bodies as yet. A number of different medicines can be prescribed as treatments for dementia with Lewy bodies. Your doctor is likely to prescribe one of the three medicines available:

  • donepezil (Aricept)
  • galantamine (Reminyl)
  • rivastigmine (Exelon)

The names in brackets are the brand names. These are all the same type of drug, called acetylcholinesterase inhibitors. They may help with hallucinations, delusions and agitation, which are common symptoms of dementia with Lewy bodies. Rivastigmine may also help people to sleep better. All these medicines have to be prescribed by a specialist and are either tablets or capsules. You take Aricept once daily and the other two medicines twice daily. Exelon also comes as a stick-on patch that you change once every 24 hours. This can be easier for some families to manage than tablets, but people who are underweight may be more likely to have side-effects. Common side-effects with acetylcholinesterase inhibitors include feeling sick, vomiting, sleepiness and vivid dreaming. If you take them for a long time, they can cause muscle cramps, runny nose and weight loss.

When someone has delusions and hallucinations, a doctor would usually prescribe medicines called anti-psychotics. However, they don’t generally prescribe these for someone with dementia with Lewy bodies as they can make Parkinson’s symptoms worse. They may also make the person’s dementia and their physical health considerably worse. Around half of people with dementia with Lewy bodies have severe adverse reactions to anti-psychotics. So, doctors may prescribe acetylcholinesterase inhibitors instead. Sometimes people with dementia with Lewy bodies can be very anxious and agitated. If this is the case, the doctor may prescribe a medicine for anxiety, such as lorazepam. This will only be for a short time, though, as these medicines can make memory problems worse. As around four out of 10 people with dementia with Lewy bodies have depression, doctors often prescribe anti-depressants. Many people have disturbed sleep and this can be treated with a medicine called clonazepam. You take it about half an hour before going to bed and it is helpful in nine out of 10 people with dementia with Lewy bodies.


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    Image from Su B, Liu H, Wang X. Ectopic localization of FOXO3a protein in Lewy bodies in Lewy body dementia and Parkinson's disease. Mol Neurodegener. 2009 Jul 23;4:32. Reproduced under Creative Commons licence.

  • Produced by Nick Ridgman, Lead Health Editor, Bupa UK Health Content Team, December 2016
    Expert reviewer, Professor Graham Stokes, psychologist and dementia specialist
    Next review due December 2019



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