Dementia with Lewy bodies

12 min read

What is dementia with Lewy bodies?

'Dementia with Lewy bodies' is a common form of dementia, affecting over 100,000 people in the UK.

The term 'dementia' describes a loss of mental ability associated with gradual death of brain cells.

In dementia with Lewy bodies, tiny clumps of abnormal protein – called Lewy bodies – form in the brain. These are also present in the brains of people with

Parkinson’s disease

Symptoms usually develop gradually and become more severe over the course of many years.

What are the symptoms?

People with this form of dementia not only experience problems with memory and judgement, like those with

Alzheimer's disease
, but are also likely to experience difficulty with concentration and visual perception (recognising objects and making judgements about where they are in space).

They may also have:

  • slowed movement, stiff limbs and tremors (as seen in Parkinson’s disease)
  • recurrent visual hallucinations (seeing things that aren't there)
  • sleep disturbances, including sleepiness during the day
  • fainting, unsteadiness and falls

They tend to swing from a state of alertness to drowsiness or staring into space. These extreme changes may be unpredictable and happen from hour to hour or day to day.

It's these extra symptoms that distinguish dementia with Lewy bodies from other types of dementia.

Learn more about the

symptoms of dementia with Lewy bodies

Why do Lewy bodies form, and how do they cause damage?

It's not understood why Lewy bodies build up in people with dementia and Parkinson's disease.

The protein deposits build up in certain areas of the brain. It's thought they disrupt the brain's normal functioning by interfering with chemical signals transmitted from one brain cell to another. For example, they affect the nerve cells responsible for initiating muscle movement.

Find out more about the

causes of dementia with Lewy bodies

How is dementia with Lewy bodies diagnosed?

If your doctor thinks you may have dementia, you may be referred to a memory clinic or another specialist clinic, where you'll be asked about your symptoms and have a physical check-up and memory test. You may also have blood tests and brain scans.

A diagnosis of dementia with Lewy bodies can be made if you have significant mental decline, plus at at least 2 of the main features of the disease, such as fluctuating states of alertness, frequent visual hallucinations or slowed movements.

Learn more about the

diagnosis of dementia with Lewy bodies

How is it managed?

There's no cure for dementia with Lewy bodies, nor any drugs that will slow the disease.

However, a few different medications can be effective in controlling some of the symptoms. In particular, cholinesterase inhibitors (used to treat Alzheimer's disease) have been shown to improve the symptoms of mental decline and the hallucinations for some people.

Rehabilitative support, such as

occupational therapy
and speech therapy aim to help with regaining lost functions, and dementia activities such as 'memory cafes' and some psychological therapies can help with managing the symptoms.

If you have dementia, your future health and social care needs will need to be assessed and a care plan will be drawn up.

For more information, read about the

treatment of dementia with Lewy bodies

What is the outlook?

The progression of symptoms will depend to an extent on the person's personality and general health. Home-based help will be needed, and some people will eventually need residential care in a nursing home.

The average survival after time of diagnosis is similar to that of Alzheimer's disease, about 8 years. However, as with Alzheimer's disease, this can be highly variable in different people.

If you or a loved one has been diagnosed with dementia, remember that you're not alone. The NHS, social services and voluntary organisations will be able to provide advice and support to help you and your family.

Symptoms of dementia with Lewy bodies

The symptoms of dementia with Lewy bodies usually develop gradually and become more severe over the course of many years.

Like other forms of dementia, the disease causes problems with:

  • thinking speed
  • language
  • understanding
  • judgement
  • memory (although significant memory loss may not occur until later)

People affected by dementia with Lewy bodies may become less interested in things and have problems controlling their emotions.

In addition, dementia with Lewy bodies can also cause the following symptoms:

  • extreme swings from alertness to confusion or drowsiness, which may happen unexpectedly and change from hour to hour or day to day
  • slow movement, stiff limbs and tremors (as seen in Parkinson's disease), which cause shuffling when walking
  • recurrent visual hallucinations, which can range from pleasant to distressing
  • fainting, unsteadiness and
  • sleep disturbances, which can cause talking in your sleep or acting out dreams
  • severe sensitivity to antipsychotic drugs
  • loss of sense of smell
  • loss of facial expression
  • dysphagia
    (problems with swallowing)
  • losing control of the bowels and bladder
  • depression

What causes dementia with Lewy bodies?

It's not currently understood why some people develop dementia with Lewy bodies.

The disease is caused by the build-up of protein deposits, called Lewy bodies, inside brain cells.

Lewy bodies are tiny clumps of alpha-synuclein protein found in the brains of people with this form of dementia, and also in people with Parkinson’s disease.

They build up in areas of the brain responsible for memory and muscle movement, although it's not understood why. It's also uncertain how Lewy bodies damage brain cells.


One theory is that Lewy bodies interfere with the effects of 2 neurotransmitters called dopamine and acetylcholine. Neurotransmitters are messenger chemicals that send information from 1 brain cell to another.

Dopamine and acetylcholine are thought to play an important role in regulating brain functions, such as memory, learning, mood and attention.

Dementia with Lewy bodies is closely related to Parkinson’s disease, a condition where part of the brain becomes progressively damaged over a number of years, leading to physical symptoms, such as involuntary shaking (

), muscle stiffness and slowness of movement. A person with this form of dementia may also develop these symptoms.

Learn more about the

symptoms of dementia with Lewy bodies

Diagnosing dementia with Lewy bodies

Confirming a diagnosis of dementia can be difficult, particularly when the condition is in its early stages. This is because many of the symptoms of dementia can also be caused by other conditions.

It can be helpful if you and a close relative or friend are seen together, because they can help you remember what's happening.

For dementia with Lewy bodies to be diagnosed correctly, you'll have a number of tests and assessments, including:

  • an assessment of your symptoms – for example, how long you have had memory problems
  • a full assessment of your mental abilities
  • a physical examination
  • a review of the medication you're taking in relation to your symptoms
  • a range of tests, including
    blood tests
    , to rule out other possible causes of your symptoms, such as a
    vitamin B deficiency
  • brain scans, such as a
    computerised tomography (CT) scan
    or a
    magnetic resonance imaging (MRI) scan
    , which can check for signs of a
    brain tumour
    or brain shrinkage. A type of single photon emission tomography (SPECT) scan, which looks at the dopamine system in the brain, can sometimes be helpful for diagnosis

Some of these tests can be carried out by your doctor. Some will be carried out by other specialists, such as a neurologist (an expert in treating conditions that affect the brain and nervous system), an elderly care physician, or a psychiatrist with experience in treating dementia.

Generally, a diagnosis of dementia with Lewy bodies is made if you have significant mental decline, plus at at least 2 of the following features:

  • extreme swings from alertness to confusion or drowsiness, which may happen unexpectedly and change from hour to hour or day to day
  • recurrent visual hallucinations, which can be pleasant or distressing
  • slow movement, stiff limbs and tremors (as seen in Parkinson's disease), which cause shuffling when walking
  • repeated falls
  • fainting
  • severe sensitivity to antipsychotic drugs
  • delusions (believing things that, when examined rationally, are obviously untrue)

Read more about the typical

symptoms of dementia with Lewy bodies

Assessing your mental abilities

There are some questionnaires that can be used to help test your mental abilities and how severe your symptoms are. A widely used questionnaire is the Mini Mental State Examination (MMSE).

The MMSE can be used to assess a number of different mental abilities, including:

  • short and long-term memory
  • attention span
  • concentration
  • language and communication skills
  • ability to plan
  • ability to understand instructions

The MMSE is a series of questions, each carrying a score with a maximum of 30 points. Example questions include:

  • memorising a short list of objects and then repeating the list back
  • correctly identifying the current day of the week, followed by the date, the month, the season and the year

The MMSE is not a test to diagnose dementia. However, it's useful for assessing the level of mental impairment that a person with dementia may have. For people with dementia, the scoring system works as follows:

  • a score of above 20 indicates mild impairment
  • a score of 10-19 indicates moderate impairment
  • a score of less than 10 indicates severe impairment

People without dementia will often score 28-30, but these scores are not set in stone and may be influenced by a person’s level of education. For example, someone who cannot read or write very well may score less than 28, but not have dementia. Similarly, someone with a higher level of education may achieve a higher score but still have dementia.

Treatment for dementia with Lewy bodies

If you've been diagnosed with dementia, your future health and social care needs will need to be assessed and a care plan drawn up.

A care plan is a way of ensuring you receive the right treatment for your needs.

There's currently no cure for dementia with Lewy bodies, but medication and psychological therapy can help in managing the symptoms. These are detailed below.

Rehabilitative support such as

occupational therapy
and speech therapy will help you to regain your lost functions as best as possible.


Acetylcholinesterase inhibitors

Acetylcholinesterase inhibitors such as donepezil (Aricept), galantamine (Reminyl) or rivastigmine (Exelon) may be prescribed for you.

These drugs have been shown to improve hallucinations, confusion, and drowsiness in some people with dementia with Lewy bodies. They work by increasing levels of the chemical acetylcholine in the brain. Acetylcholine is a neurotransmitter that sends signals from 1 cell to another, and in dementia with Lewy bodies this becomes reduced.

Nausea and vomiting
are the most common side effects of acetylcholinesterase inhibitors. However, if they occur they usually settle down within the first 2 weeks of taking the medication.

Other drugs

  • levodopa, a drug used to treat Parkinson's disease, may help relieve the movement problems, but it can also worsen hallucinations and other psychotic symptoms, so needs to be carefully monitored by your doctor
  • antidepressants
    may help you cope if you have depression
  • antipsychotics such as haloperidol are to be avoided wherever possible, and only really used for treating severely challenging behaviour that's putting you or others at risk of harm. This is because they can cause a range of serious side effects including rigidity and immobility. If antipsychotics are needed, they will be prescribed at the lowest possible dose and for the shortest possible time, by a specialist experienced in treating dementia with Lewy bodies.

Psychological treatments

Psychological treatments, such as those explained below, can help some people with dementia to cope with the symptoms. However, there's no evidence these are effective for people with dementia with Lewy bodies, specifically.

Cognitive stimulation and reality orientation therapy

Cognitive stimulation involves taking part in activities and exercises designed to improve your memory, problem-solving skills and language ability.

Reality orientation therapy is a type of therapy that reduces feelings of mental disorientation, memory loss and confusion, while improving feelings of self-esteem.

The therapy may involve group work in a classroom, in which a board prominently displays information such as:

  • the current day and date
  • the location of the classroom
  • the names of the people in the group

The group members repeat a series of tasks designed to give mental stimulation. The tasks also reinforce information regarding the time, the place and the people involved in the group. You'll be involved in discussions about a variety of topics, as well as taking part in word and memory games.

Reality orientation may be beneficial in some cases, but the benefits can be small and are often only apparent with continued effort. The technique is also often considered unsuitable for use in care home settings.

Validation therapy

The aim of validation therapy is to explore what things were like for the person in the past and how this relates to the way they are feeling now. It works on the principle that even the most confused behaviour has some meaning for the person.

For example, if a person with dementia talks about wanting to go home to see their husband or wife who has previously died, telling them that their partner is no longer alive may not be the best course of action and may confuse and upset them further.

Validation therapy is sometimes felt to be a better form of psychological therapy than cognitive stimulation and reality orientation therapy for treating dementia. This is because it focuses on the condition from an emotional, rather than factual, perspective. It views ‘confused talk’ as reflecting the emotional meaning of past events.

Behavioural therapy

Behavioural therapy uses a problem-solving approach where possible motivations and reasons for troublesome behaviour are identified. Different strategies are adopted to try to change that behaviour.

Behavioural therapy can be used to treat many of the behavioural problems associated with dementia, such as depression, aggression and delusional thinking. It's usually given by a carer, such as a trained friend or relative, or by an employed carer and it's always supervised by a healthcare professional.

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.