Lewy body dementia

Lewy body dementia is a progressive, complex and challenging condition which is thought to account for 10- 15% of all those with dementia. Around 10% of younger people with dementia have dementia with Lewy bodies. In the early stages it is often mistaken for Alzheimer’s disease and can be diagnosed wrongly.

Lewy body dementia includes two subtypes; dementia with Lewy bodies and Parkinson’s disease dementia. It particularly affects the person’s ability to think and move and can cause hallucinations, fluctuations in alertness and sleep disturbances which can be extremely distressing for the person and their family.

The main difference between the two types of Lewy body dementia is when certain symptoms first occur:

  • Dementia with Lewy bodies – changes in thinking, visual perception (cognitive symptoms) and sleep may be experienced first and difficulty with movement (Parkinsonian symptoms) – occur at the same time or later
  • Parkinson’s disease dementia  – Parkinsonian symptoms are experienced first followed by cognitive changes. Not everyone with Parkinson’s disease will go onto develop dementia but the risk of developing dementia is increased

As the condition progresses both people with dementia with Lewy bodies and Parkinson’s disease dementia tend to have similar symptoms and will have increasing difficulty with managing everyday tasks.

What causes Lewy body dementia?

Lewy body dementia is caused by abnormal clumps of protein (called Lewy bodies) gathering inside brain cells. These Lewy bodies can build up in many parts of the brain but particularly in the areas responsible for thought, movement, visual perception and regulating sleep and alertness.

Managing the effects of dementia with Lewy bodies

A person with dementia with Lewy bodies might:

  • have recurring visual hallucinations – see things that are not there (these can be pleasant or upsetting)
  • experience disturbed sleep– known as Rapid Eye Movement (REM) sleep disorder, in which people are restless and can experience intense dreams/nightmares
  • experience sudden changes and fluctuations in alertness – people may stare blankly into space for periods of time, seem drowsy and lethargic and spend a lot of time sleeping
  • have slowed movement, difficulty walking, shuffling or appear rigid (as in Parkinson’s disease)
  • experience tremors – usually in the hands whilst at rest
  • have problems with balance and be prone to falls
  • bladder and bowel problems
  • difficulties with swallowing

Memory is often less affected than with other types of dementia but people may be at more risk of mood and behaviour changes such as apathy, anxiety, depression, delusions and paranoia. One type of delusion, known as Capgras syndrome, in which the person believes that a friend or relation has been replaced by an imposter can be particularly difficult for families. Other symptoms may include changes in blood pressure, body temperature and impaired sense of smell.

Treatment and support

It is important for someone with Lewy body dementia to get an accurate diagnosis so they get the right treatment and support. Diagnosis should include gathering information on the person’s symptoms and a specific scan called a SPECT (single photon emission computed tomography) scan may help support a diagnosis of Lewy body dementia.

People with Lewy body dementia may be offered medication and other interventions to help with their symptoms. These will not stop or reverse the course of the disease but can improve the quality of life for them and their families and carers.

Some of the medications used to treat Alzheimer’s disease can help with the cognitive symptoms of Lewy body dementia and can help reduce distressing hallucinations, concentration and memory problems. These are usually most effective in early or moderate phases but do not help everyone.

Importantly many people with Lewy body dementia are particularly sensitive to medications used to treat hallucinations and only certain types should be used with extreme caution.

Medications used for Parkinson symptoms may be helpful but again caution is required as they may make hallucinations worse.

Other interventions focus on symptom control and include; physiotherapy, occupational therapy, counselling, groups, cognitive stimulation therapy, music and activities.

For more information visit lewybody.org. You can also phone our free Helpline to speak to a dementia specialist Admiral Nurse about Lewy body dementia on 0800 888 6678 (Monday-Friday 9am-9pm, Saturday and Sunday 9am-5pm) or email helpline@dementiauk.org. If you would prefer a pre-booked appointment by phone or video call, visit Closer to home.

Understanding Lewy body dementia

In collaboration with The Lewy Body Society, our Admiral Nurses have put together a leaflet to give a deeper understanding into this type of dementia

Download the leaflet

Dementia Helpline

We know that living with dementia can be overwhelming. Our dementia specialist Helpline nurses can help you take back control and face the future with confidence

Find out more

What is dementia?

Dementia is an umbrella term used to describe a range of progressive neurological disorders, that is, conditions affecting the brain

Find out more

Publication date: March 2023
Review date: March 2025