Dementia with Lewy Bodies (DLB) by
Dr Jonathan Schott, Dementia Research Centre
Dementia with Lewy Bodies (DLB) is the third most common cause of dementia in people over 65 but is rare before this age. Like other dementias it is caused by an accumulation of abnormal proteins within the brain, which subsequently leads to death of brain cells and brain shrinkage. In DLB, the abnormal protein is something called “alpha-synuclein” and this is what is found in the “Lewy bodies” that are seen under the microscope in the brains of people with DLB at post-mortem.
The disease may also be called:
- Diffuse Lewy Body Disease.
- Dementia associated with cortical Lewy Bodies.
- Lewy Body variant of Alzheimer’s disease.
- Lewy Body Dementia.
It is unclear why certain people get DLB and it is currently not possible to predict who will develop the disease. Men appear to be slightly more at risk than women. It is likely that the disease is caused by a combination of factors, both genetic and environmental. However, DLB is not thought to run in families and there is no specific gene test for it.
There is overlap between DLB and Parkinson’s disease and many patient’s who have had Parkinson’s disease for many years will develop a similar dementia (sometimes called Parkinson’s disease dementia or PDD).
Symptoms
There are four major features of DLB:
- Thinking problems such as memory difficulties or slower speed of thought.
- Visual hallucinations.
- Features similar to Parkinson’s disease such as slower movements, stiffness and tremor.
- Fluctuation in symptoms.
The thinking problems may well be similar to Alzheimer’s disease and in the early stages of disease these two diseases can look very similar. (In some instances DLB and Alzheimer’s disease can in fact both occur in the same person.) People may have difficulties in remembering day-to-day events and the memory may seem worse for recent events than events in the distant past. These memory problems get worse over time. Some people have problems with a slowing up of their ability to think.
Visual hallucinations are very common in DLB. They are often of silent people or animals and appear very vivid and real. People do not find these hallucinations threatening but can find them disturbing. In addition, patients may experience problems with identifying objects or people, and in some cases even their own spouse.
Patients with DLB to “slow up” and develop symptoms that look like Parkinson’s disease. Thus they tend to walk more slowly, have a change in their facial expression, become more stiff or rigid, notice a change in their handwriting, and may develop a tremor of their hands.
There are often very noticeable fluctuations in symptoms in DLB. On some days patients may be very active, whilst on others they may be very slow and forgetful.
Other symptoms may include:
- Increased tendency to fall.
- Faints.
- Delusions (having fixed abnormal beliefs).
- Confusion.
- Vivid dreams which they may “act out” e.g. kicking out in the night.
Medical tests
The diagnosis of DLB is based on the presence of the features mentioned above, after exclusion of other forms of dementia. In order to make the diagnosis, the doctor will generally take a detailed account of the problems from the patient and someone who knows them well, and perform an examination. Some tests may be performed (although there is no one test that will accurately diagnose DLB). These may include blood tests, a CT or MRI brain scan, a brain wave test (EEG) and some detailed memory tests (neuropsychology tests). You may also be sent for a special brain scan called a “DAT scan” which can help in the diagnosis.
Treatment
There are no curative treatments for DLB. There is good evidence that some of the drugs used for Alzheimer’s disease such as Exelon (Rivastigmine) may be useful in DLB. Some patients with DLB can become depressed, and may respond well to antidepressants. Sometimes treatments for Parkinson’s disease may be useful if patients get very rigid, although this can make confusion worse.
It is important to note that many prescription drugs commonly given for hallucinations can make DLB much worse. It is important that these drugs (“neuroleptics”) are not given to patients with DLB except in certain circumstances by a specialist. It is essential that if a patient with DLB is admitted to a hospital or sees a new doctor, that you inform the medical staff of the diagnosis , so that these drugs are not prescribed.
Prognosis
The progression of DLB is very variable, but the normal life expectancy is similar to Alzheimer’s disease.
The Alzheimer’s Society has useful information on DLB. An information sheet can be requested via their helpline or downloaded from the internet.
back to list
|
