Lewy body dementia (also known as Dementia with Lewy Bodies) is the second most frequent cause of dementia in adults (Alzheimer's Disease is the most common cause).
It was first described in 1961 and has been increasingly recognized over the past 5-10 years.
Lewy dody dementia is a neurodegenerative disorder associated with abnormal structures (Lewy bodies) found in certain areas of the brain. Because these structures and many of the symptoms of dementia with Lewy bodies are associated with Parkinson's and Alzheimer's diseases, researchers do not yet understand whether dementia with Lewy bodies is a distinct clinical entity or perhaps a variant of Alzheimer's or Parkinson's disease.
'Cortical Lewy bodies' are the defining pathological feature of Lewy body dementia. These are abnormal brain cells which are distributed in varying degrees throughout all areas of the brain.
Lewy body dementia is very similar to Alzheimer's disease with progressive loss of memory, language, calculation and reasoning as well as other higher mental functions. However the progress of the illness may be more rapid than seen in Alzheimer's disease.
Lewy body dementia can also be confused with other central nervous system conditions since disease classification is based on the clinical recognition of the grouping of symptoms in any patient under study. Many diseases share some of the same symptoms making diagnosis difficult and not always certain. Progressive supranulear palsy is one of the conditions that may be diagnosed in error as lewy body dementia and of course the reverse is also true.
Recent research has revealed that Lewy bodies contain deposits of a protein called alpha-synuclein that is also linked to Parkinson's disease and multiple system atrophy.
Symptoms can range from traditional parkinsonian effects, such as loss of spontaneous movement (bradykinesia), rigidity (muscles feel stiff and resist movement), tremor, and shuffling gait, to effects similar to those of Alzheimer's disease, such as acute confusion, loss of memory, and loss of, or fluctuating, cognition. Visual hallucinations may be one of the first symptoms noted, and patients may suffer from other psychiatric disturbances such as delusions and depression. Onset of the disorder usually occurs in older adults, although younger people can be affected as well. In 1996 scientists published guidelines for the diagnosis of dementia with Lewy bodies (McKeith IG, et al, Neurology, vol 47, pp 1113-1114, Nov 1996).
Anybody can develop Lewy body dementia. Post mortem studies examining the brains of people with dementia suggest that it is relatively common. However, because there are still questions about the exact nature of Lewy body disease prevalence figures do vary. It appears to affect men and women alike.
As yet risk factors for developing the disease have not been identified. Rare 'familial' cases of Lewy body disease have been described. In these families it is inherited as an 'autosomal dominant' disease which means that if a person carries the gene, he/she will eventually develop the disease. Their children have a 50% chance of inheriting the illness.
At present there is no cure for Lewy body disease. We need to understand more about the disease itself in order to look towards possible treatments. However it is sometimes possible to treat some of the symptoms of this disease. For example if depression accompanies the disease it will usually respond to antidepressant therapy. Occasionally if the hallucinations are unpleasant these may be reduced with medication.