Dementia is caused by different diseases that affect the brain. Lewy body dementia – also known as dementia with Lewy bodies (DLB) – is caused by Lewy body disease.
In this disease, tiny clumps of proteins known as Lewy bodies appear in the nerve cells of the brain. Lewy bodies are named after FH Lewy, the German doctor who first identified them.
Lewy bodies cause a range of symptoms, some of which are shared by Alzheimer’s disease and some by Parkinson’s disease. For this reason, DLB is often wrongly diagnosed. About 1 in 10 people with dementia has DLB.
It may account for 10-15 per cent of all cases of dementia. DLB can be diagnosed wrongly and is often mistaken for Alzheimer’s disease. This section describes the symptoms of DLB and how it is diagnosed, as well as the treatment and support available.
DLB is sometimes known by other names. These include Lewy body dementia, Lewy body variant of Alzheimer’s disease, diffuse Lewy body disease and cortical Lewy body disease. All these terms refer to the same condition.
It is not yet known why Lewy bodies develop in the brain or exactly how they cause dementia. But we do know that Lewy body disease:
Having Lewy body disease doesn’t mean that a person’s dementia is only caused by the build-up of Lewy bodies in their brain.
Many people with DLB also have a build-up of other proteins that cause Alzheimer’s disease. This is common in people over about 80 years old. For people with both DLB and Alzheimer’s, dementia symptoms are often more severe and progress more quickly.
Parkinson’s disease is also caused by a build-up of Lewy bodies in the brain. DLB has a lot of symptoms in common with Parkinson’s disease. Both cause problems with:
In DLB, the symptoms of dementia begin before or around the same time as the person develops problems with movement.
For people with Parkinson’s disease, symptoms of dementia often develop many years after the movement problems begin.