Lewy body disease is caused by the degeneration and death of nerve cells in the brain. The name comes from the presence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells. It is thought that these may contribute to the death of the brain cells. They are named after the doctor who first wrote about them. It is sometimes referred to as Diffuse Lewy body disease.

What is the cause?
At present there is no known cause of Lewy body disease, and no known risk factors have been identified. There is no evidence that it is an inherited disease.

How is Lewy body disease diagnosed?
This type of dementia is diagnosed by taking a careful history of the pattern of symptoms, and by excluding other possible causes such as Vascular dementia and Alzheimer’s disease. A brain scan may reveal brain degeneration, but the Lewy bodies can only be identified by examination of brain tissue after death.

Lewy body disease is similar to Alzheimer’s disease in many ways, and in the past it has sometimes been difficult to distinguish the two. It has only recently been accepted as a disease in its own right. It can occur by itself or together with Alzheimer’s disease and/or Vascular dementia. It may be hard to distinguish Lewy body disease from Parkinson’s disease, and some people with Parkinson’s disease develop a dementia which is similar to that seen in Lewy body disease.

What are the symptoms?
The symptoms of dementia with Lewy body disease include:

Difficulty with concentration and attention
Extreme confusion
Difficulties judging distances, often resulting in falls.
There are also three cardinal symptoms, two of which must be present in order to make the diagnosis:

Visual hallucinations
Parkinsonism (tremors and stiffness similar to that seen in Parkinson’s disease)
Fluctuation in mental state so that the person may be lucid and clear at one time and confused, disoriented and bewildered at other times. Typically this fluctuation occurs over a period of hours or even minutes and is not due to any underlying acute physical illness.
Some people who have Lewy body disease may also experience delusions and/or depression.

Who gets Lewy body disease?
Both men and women can develop this disease, although it is more common in men.

How does Lewy body disease progress?
Lewy body disease differs from Alzheimer’s disease in that the progression of the disease is usually more rapid. However, like Alzheimer’s disease it is a degenerative condition, eventually leading to complete dependence. Death is usually a result of another illness, such as pneumonia or an infection. The average lifespan after the onset of symptoms is about seven years.

Is there treatment available?
At present there is no cure for Lewy body disease. Symptoms such as depression and disturbing hallucinations can usually be reduced by medication. However, medications to relieve hallucinations may increase muscle tremors and stiffness. Conversely, anti-Parkinson drugs may make hallucinations worse.

Emerging evidence suggests that cholinesterase inhibitor drugs may be quite helpful for some people with this condition.

People with this form of dementia are very sensitive to the side effects of neuroleptic drugs such as antipsychotic medications. It is essential all medications are supervised by a specialist to avoid these severe side effects.