Dementia With Lewy Bodies
By Penelope Roques
What is it?
Dementia with Lewy Bodies (DLB) is a progressive dementia, the hallmarks of which are hallucinations and fluctuating levels of attention. Some rigidity and stiffness may be seen. There may also be a disturbed sleep pattern with nightmares and abnormal behaviour. DLB is thought to be due to a faulty production of a protein, which then builds up within the nerve cells of the brain.
What are the Symptoms?
Cognitive decline is always a feature and memory problems occur in two out of three patients. Characteristically these fluctuate in severity and are associated with various degrees of alertness and attention span. There are increasing problems of daily living. Stiffness is seen which appears similar to that of Parkinsonís disease and repeated falls often occur. Visual hallucinations are present in 80% of patients and appear very detailed and real and are usually related to people or animals. These hallucinations often occur at night. Other behavioural problems similar to those seen in Fronto-temporal dementia may be seen although not usually in the early stages the illness. Neuroleptics should be avoided in view of sensitivity to side effects. The side effects may cause rigidity and confusion and even reported sudden death. In a last resort atypical (newer) neuroleptics may help. DLB is thought to be the second commonest degenerative dementia after AD.
What is the Life Span of the Illness?
DLB may be a fairly rapid illness, lasting approximately 5-7 years although it may be quicker or slower.
Who can get Lewy Body Dementia and is it Genetic?
The cause of this form of neurodegenerative disease is uncertain. There are overlaps between Alzheimer's disease and Parkinson's disease. Genetic studies are making some progress in revealing a matrix of different genes, which may contribute to development of DLB. This appears to be complex but may explain firstly the relationship of DLB to the other primary Lewy body disorders including Parkinson's disease and secondly the association with Alzheimer's disease. It remains to be seen whether genetic testing will be sufficiently simple to help in clinical diagnosis.
As with all dementias careful management and support are vital. Sometimes neuroleptics are given to help control the hallucinations and delusions but these are poorly tolerated. There is now good anecdotal evidence that acetylcholinesterase inhibitors such as donepezil abolish the hallucinations very effectively and are being used increasingly. The outcome of any treatments needs to be carefully balanced with any side effects that may occur. There are conflicting requirements in trying to treat the neuropsychiatric disturbance as well as the parkinsonism. The treatments for hallucinations, delusions and behavioural disturbance tend to make the movement disorder worse and vice versa. Depression is common and should be treated.
Why is it called Dementia with Lewy Bodies?
The illness has had many names and is now known as Dementia with Lewy bodies. The changes in the brain cells (Lewy bodies) were first described by Frederich Lewy a colleague of Alois Alzheimer.
These changes were first recognised in Parkinsonís disease where they are mostly restricted to one area of the brain. In LBD the Lewy bodies are more widely distributed throughout the brain.
Consensus guidelines for the clinical diagnosis of DLB (McKeith et al., 1966)
1. The central feature is progressive cognitive decline amounting to dementia; deficits on tests of attention, fronto-cortical skills and visuospatial ability may be especially significant.
2. Two of the following are required for a probable, and one for a possible, diagnosis of DLB:
a) Fluctuating cognition with pronounced variations in attention and alertness.
b) Recurrent visual hallucinations that are typically well formed and detailed
c) Spontaneous motor features of Parkinsonism.
3. Features supportive of the diagnosis are:
a) Repeated falls
b) Syncope or transient loss of consciousness
c) Neuroleptic hypersensitivity
d) Systematized delusions
e) Hallucinations in other modalities
4. DLB is less likely in the presence of:
a) Stroke disease, revealed by focal neurological signs or brain imaging
b) Evidence of any other physical or brain illness that may account for the clinical picture.
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