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Lewy Body DementiaLewy body dementia (LBD) is one of the most common types of progressive dementia. Lewy body dementia usually occurs sporadically, in people with no known family history of the disease. However, rare familial cases have occasionally been reported. The central feature of Lewy body dementia is progressive cognitive decline, combined with three additional defining features: (1) pronounced "fluctuations" in alertness and attention, such as frequent drowsiness, lethargy, lengthy periods of time spent staring into space, or disorganized speech; (2) recurrent visual hallucinations, and (3) parkinsonian motor symptoms, such as rigidity and the loss of spontaneous movement. People may also suffer from depression. The symptoms of Lewy body dementia are caused by the build-up of Lewy bodies - accumulated bits of alpha-synuclein protein -- inside the nuclei of neurons in areas of the brain that control particular aspects of memory and motor control. Researchers don't know exactly why alpha-synuclein accumulates into Lewy bodies or how Lewy bodies cause the symptoms of Lewy body dementia, but they do know that alpha-synuclein accumulation is also linked to Parkinson's disease, multiple system atrophy, and several other disorders, which are referred to as the "synucleinopathies." The similarity of symptoms between Lewy body dementia and Parkinson's disease, and between Lewy-body dementia and Alzheimer's disease, can often make it difficult for a doctor to make a definitive diagnosis. In addition, Lewy bodies are often also found in the brains of people with Parkinson's and Alzheimer's diseases. These findings suggest that either Lewy body dementia is related to these other causes of dementia or that an individual can have both diseases at the same time. Lewy body dementia usually occurs sporadically, in people with no known family history of the disease. However, rare familial cases have occasionally been reported. In Lewy body dementia, cells die in the brain's cortex, or outer layer, and in a part of the mid-brain called the substantia nigra. Many of the remaining nerve cells in the substantia nigra contain abnormal structures called Lewy bodies that are the hallmark of the disease. Lewy bodies may also appear in the brain's cortex, or outer layer. Lewy bodies contain a protein called alpha-synuclein that has been linked to Parkinson's disease and several other disorders. Researchers, who sometimes refer to these disorders collectively as "synucleinopathies," do not yet know why this protein accumulates inside nerve cells in Lewy body dementia. The symptoms of Lewy body dementia overlap with Lewy body dementia in many ways, and may include memory impairment, poor judgment, and confusion. However, Lewy body dementia typically also includes visual hallucinations, parkinsonian symptoms such as a shuffling gait and flexed posture, and day-to-day fluctuations in the severity of symptoms. Patients with Lewy body dementia live an average of 7 years after symptoms begin. Is there any treatment? There is no cure for Lewy-body dementia. Treatments are aimed at controlling the cognitive, psychiatric, and motor symptoms of the disorder. Acetylcholinesterase inhibitors, such as donepezil and rivastigmine, are primarily used to treat the cognitive symptoms of Lewy body dementia, but they may also be of some benefit in reducing the psychiatric and motor symptoms. Doctors tend to avoid prescribing antipsychotics for hallucinatory symptoms of Lewy body dementia because of the risk that neuroleptic sensitivity could worsen the motor symptoms. Some individuals with Lewy body dementia may benefit from the use of levodopa for their rigidity and loss of spontaneous movement. What is the prognosis? Like Alzheimer's disease and Parkinson's disease, Lewy-body dementia is a neurodegenerative disorder that results in progressive intellectual and functional deterioration. There are no known therapies to stop or slow the progression of Lewy body dementia. Average survival after the time of diagnosis is similar to that in Alzheimer's disease, about 8 years, with progressively increasing disability. What research is being done? The National Institute of Neurological Disorders and Stroke (NINDS) conducts research related to Lewy body dementia in laboratories at the NIH and also supports additional research through grants to major medical institutions across the country. Much of this research focuses on searching for the genetic roots of Lewy body dementia, exploring the molecular mechanisms of alpha-synuclein accumulation, and discovering how Lewy bodies cause the particular symptoms of Lewy body dementia and the other synucleinopathies. The goal of NINDS research is to find better ways to prevent, treat, and ultimately cure disorders such as DLB. Lewy bodies are often found in the brains of people with Parkinson's and AD. These findings suggest that either Lewy body dementia is related to these other causes of dementia or that the diseases sometimes coexist in the same person.
More on DementiaConditions That Are Not Dementia
Sources: National Institutes of Health |
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