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).
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.
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
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.
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:
