What is dementia with Lewy bodies (DLB)? from the Alzhe...

What is dementia with Lewy bodies (DLB)? from the Alzheimer's Society, U.K.

What is dementia with Lewy bodies (DLB)?

Dementia with Lewy bodies (DLB) is a form of dementia that shares characteristics with both Alzheimer's and Parkinson's diseases. It accounts for around four per cent of all cases of dementia in older people. Dementia with Lewy bodies is sometimes referred to by other names, including Lewy body dementia, Lewy body variant of Alzheimer's disease, diffuse Lewy body disease, cortical Lewy body disease and senile dementia of Lewy body type. All these terms refer to the same disorder. This factsheet outlines the symptoms of DLB, how it is diagnosed and how it is treated.

DLB appears to affect men and women equally. As with all forms of dementia, it is more prevalent in people over the age of 65. However, in certain rare cases people under 65 may develop DLB.

What are Lewy bodies?

Lewy bodies, named after the doctor who first identified them in 1912, are tiny, spherical protein deposits found in nerve cells. Their presence in the brain disrupts the brain's normal functioning, interrupting the action of important chemical messengers, including acetylcholine and dopamine. Researchers have yet to understand fully why Lewy bodies occur in the brain and how they cause damage.

Lewy bodies are also found in the brains of people with Parkinson's disease, a progressive neurological disease that affects movement. Some people who are initially diagnosed with Parkinson's disease later go on to develop a dementia that closely resembles DLB.

What are the symptoms?

DLB is a progressive disease. This means that over time the symptoms will become worse. In general, DLB progresses at about the same rate as Alzheimer's disease, typically over several years.

* A person with DLB will typically have some of the symptoms of Alzheimer's and Parkinson's diseases.
* They may experience problems with attention and alertness, often have spatial disorientation and experience difficulty with 'executive function', which includes difficulty in planning ahead and co-ordinating mental activities. Although memory is often affected, it is typically less so than in Alzheimer's disease.
* They may also develop the symptoms of Parkinson's disease, including slowness, muscle stiffness, trembling of the limbs, a tendency to shuffle when walking, loss of facial expression, and changes in the strength and tone of the voice.

There are also symptoms that are characteristic of DLB. In addition to the symptoms above, a person with DLB may:

* experience detailed and convincing visual hallucinations (seeing things that are not there), often of people or animals
* find that their abilities fluctuate daily, or even hourly
* fall asleep very easily by day, and have restless, disturbed nights with confusion, nightmares and hallucinations
* faint, fall, or have 'funny turns'.

How is it diagnosed?

DLB can be difficult to diagnose, and this should usually be done by a specialist. People with DLB are often mistakenly diagnosed as having Alzheimer's disease or vascular dementia instead. The diagnosis of DLB is made on the basis of the symptoms − particularly visual hallucinations, fluctuation and the presence of the stiffness and trembling of Parkinson's. New brain-imaging tests can also help.

It is always important to get an accurate diagnosis of dementia, but a proper diagnosis is particularly important in cases of suspected DLB since people with DLB have been shown to react badly to certain forms of medication (see 'DLB and neuroleptics', below).

How is it treated?

At present, there is no cure for DLB. Symptoms such as hallucinations may diminish if challenged, but it can be unhelpful to try to convince the person that there is nothing there. It is sometimes better to try to provide reassurance and alternative distractions.

Recent research suggests that the cholinesterase inhibitor drugs used to treat Alzheimer's disease may also be useful in treating DLB, although they are not yet licensed for this use. However, recent guidelines from the National Institute of Clinical Evidence (NICE) do suggest that these drugs should be considered for 'people with DLB who have non-cognitive symptoms causing significant distress to the individual, or leading to behaviour that challenges'.

People who are experiencing symptoms such as rigidity and stiffness due to parkinsonism may benefit from anti-Parkinson's disease drugs, although these can make hallucinations and confusion worse. Physiotherapy and mobility aids may also help alleviate these problems.

DLB and neuroleptics

Neuroleptics are strong tranquillisers usually given to people with severe mental health problems. In the past, they have frequently been prescribed to people with dementia. However, it is always preferable to find ways of dealing with a person's distress and disturbance that do not involve medication. Under no circumstances should neuroleptics be prescribed as a substitute for good quality care.

For people with DLB, neuroleptics may be particularly dangerous. This class of drugs induce Parkinson-like side-effects, including rigidity, immobility, and an inability to perform tasks or to communicate. Studies have shown that they may even cause sudden death in people with DLB. If a person with DLB must be prescribed a neuroleptic, this should be done with the utmost care, under constant supervision, and should be monitored regularly.

The names of many of the major neuroleptics available are listed below. New drugs are appearing from time to time. The generic name is given first, followed by some of the common proprietary (drug company) names for that particular compound: aripiprazole (Abilify), chlorpromazine (Largactil), clopenthixol (Clopixol), haloperidol (Haldol, Serenace), olanzapine (Zyprexa), promazine quetiapine (Seroquel), risperidone (Risperdal), sulpiride (Dolmatil, Sulparex, Sulpitil), trifluoperazine (Stelazine).

When caring for someone with DLB, it is important to be as flexible as possible, bearing in mind that the symptoms of DLB will fluctuate.

Your local Alzheimer's Society branch will always be willing to talk to you and offer advice and information to support your needs.

For more information, Dementia Catalogue, our specialist dementia information resource, is available on the website at alzheimers.org.uk/dementiacatalogue

Factsheet 403

Last updated: September 2008
Last reviewed: September 2008

Written and reviewed by: Professor Ian McKeith, Clinical Director, Institute for Ageing and Health, Newcastle University