Monday, October 21, 2013

Lewy Body Dementia (LBD) and how it is different from Alzheimer’s?


Overview

Lewy body dementia (LBD), a progressive brain disease, is the second leading cause of degenerative dementia in the elderly after Alzheimer ’s disease. Although symptoms vary, hallucinations and fluctuating cognition are usually present, along with other features of Alzheimer’s disease, Parkinson’s disease or both.

At times the disease is referred to as dementia with Lewy body’s (DLB) or Parkinson’s disease dementia (PDD). 

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Symptoms

Like Parkinson Disease, people with LBD get slowed movements, stooped unsteady shuffling gait, loss of facial expression, and tendency to fall. Additionally, people with LBD also develop significant changes to memory and thinking. Commonly, they will have major fluctuations in their attention and awareness, which can last for significant periods of the day, or can be momentary. This may manifest as staring spells, spending most of the day sitting or sleeping, or difficulty following events. Oftentimes, the types of thinking changes will look like psychiatric disease like major depression, odd false beliefs (delusions) or seeing things that are not there (visual hallucinations).

Parkinson’s symptoms in LBD:
* loss of spontaneous movement (bradykinesia)
* rigidity (muscles feel stiff and resist movement)
* tremor (less common in LBD than in Parkinson’s disease)
* shuffling walk
* face has a flat, unexpressive look

Alzheimer's disease symptoms in LBD:
* memory loss
* confusion
* decision making capacity declines

Other common symptoms:
* confusion & memory loss fluctuate more than in Alzheimer’s disease
* visual hallucinations and/or delusions are common
* depression
* Rapid Eye Movement (REM) sleep behavior disorder

Causes

In the early 1900s, the scientist Friederich H. Lewy discovered abnormal protein deposits that disrupt the brain’s normal functioning. These Lewy body proteins are found in an area of the brain stem where they deplete the neurotransmitter dopamine, causing Parkinsonian symptoms. In Lewy body dementia, these abnormal proteins are diffuse throughout other areas of the brain, including the cerebral cortex, causing disruption of perception, thinking and behavior. Advanced age is considered to be the greatest risk factor, although some cases have been reported much earlier. Having a family member with Lewy body dementia may increase a person’s risk.

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Lewy bodies are also found in other brain disorders, including Alzheimer's disease and Parkinson's disease dementia. Many people with Parkinson's eventually develop problems with thinking and reasoning, and many people with DLB experience movement symptoms, such as hunched posture, rigid muscles, a shuffling walk and trouble initiating movement.

This overlap in symptoms and other evidence suggest that DLB, Parkinson's disease and Parkinson's disease dementia may be linked to the same underlying abnormalities in how the brain processes the protein alpha-synuclein. Many people with both DLB and Parkinson's dementia also have plaques and tangles — hallmark brain changes linked to Alzheimer's disease.

Progression

Over time, both the movement and cognitive symptoms get worse. These symptoms tend to develop slowly, but somewhat quicker than in dementia of the Alzheimer type. Rarely, the symptoms may develop extremely rapidly.

Late in the course, people may develop problems with injuries from falls, immobility, or swallowing problems.

Diagnosis

The diagnostic workup for Lewy body dementia is the same as for Alzheimer’s disease and generally includes the following elements:
* The history of the onset of cognitive and movement problems are gathered from the patient as well as from their family
* Neuropsychological testing is completed
* Bloodwork is done to look for reversible causes of dementia
* Neurological exam is completed
* Medical history is gathered
* MRI scan is completed

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Medications

There is no cure or definitive treatment for Lewy body dementia. Medical management is complex because of increased sensitivity to many drugs. Clinically proven medications are cholinesterase inhibitors (medications for Alzheimer’s disease) and drugs for Parkinsonian symptoms. However, some medications prescribed for Alzheimer’s disease and Parkinson’s disease can adversely affect people with Lewy body dementia. All prescription and over-the-counter drugs should be initiated at the lowest effective dose and managed by a Lewy body dementia-experienced physician.

Neuroleptics are strong tranquillizers usually given to people with severe mental health problems. They are sometimes also prescribed for people with dementia. However, if taken by people with LBD, neuroleptics may be particularly dangerous. This class of drugs induce Parkinson-like side-effects, including rigidity, immobility, and an inability to perform tasks or to communicate. Studies have shown that they may even cause sudden death in people with LBD. If a person with LBD must be prescribed a neuroleptic, this should be done with the utmost care, under constant supervision, and should be monitored carefully and regularly.

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Non-pharmacological interventions

Supportive treatment for problems with behavior, swallowing, speech and communication, falls and mobility are available. Many people with LBD benefit immensely from occupational therapy, physical therapy, and speech therapy.

Key differences between Alzheimer's and DLB

* Memory loss tends to be a more prominent symptom in early Alzheimer's than in early DLB, although advanced DLB may cause memory problems in addition to its more typical effects on judgment, planning and visual perception. 
* Movement symptoms are more likely to be an important cause of disability early in DLB than in Alzheimer's, although Alzheimer's can cause problems with walking, balance and getting around as it progresses to moderate and severe stages.
* Hallucinations, delusions, and misidentification of familiar people are significantly more frequent in early-stage DLB than in Alzheimer's.
* REM sleep disorder is more common in early DLB than in Alzheimer's.
* Disruption of the autonomic nervous system, causing a blood pressure drop on standing, dizziness, falls and urinary incontinence, is much more common in early DLB than in Alzheimer's.



Sources and Additional Information:
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