Lewy body dementia
Frederick Henry Lewey (born Friedrich Heinrich Lewy on 28 January 1885 in Berlin, died 5 October 1950 in Haverford, Pennsylvania) was a prominent neurologist. He is best known for the discovery of Lewy bodies, which are a characteristic indicator of Parkinson's disease and Dementia with Lewy bodies.
Dementia with Lewy bodies (DLB) is one of the most common types of progressive dementia. The central feature of DLB 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. Patients may also suffer from depression.
The symptoms of DLB 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 DLB 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 DLB and Parkinson’s disease, and between DLB 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 DLB is related to these other causes of dementia or that an individual can have both diseases at the same time. DLB usually occurs sporadically, in people with no known family history of the disease. However, rare familial cases have occasionally been reported.
Lewy body dementia shares characteristics with both Alzheimer's disease and Parkinson's disease. Like Alzheimer's, it causes confusion and like Parkinson's, it can result in rigid muscles, slowed movement and tremors. But the most striking symptom of Lewy body dementia may be its visual hallucinations, which can be one of the first signs of the disorder. Hallucinations may range from abstract shapes or colours to conversations with deceased loved ones.
In Lewy body dementia, these abnormal round structures called Lewy bodies (first seen and linked to Parkinson's disease ("paralysis agitans") in 1912 by Frederic Lewy) develop in regions of the brain involved in thinking and movement.
Lewy body dementia (LBD) signs and symptoms may include visual hallucinations (seeing colours, shapes, animals or people may be one of the first symptoms of LBD), movement disorders (Parkinson's-like signs may include slowed movement, rigid muscles, tremors or a shuffling walk), delusions, cognitive problems (confusion, memory loss and reduced attention span) and sleep difficulties including insomnia and acting out dreams.
The cause of LBD isn't known, but the disorder may be related to Alzheimer's or Parkinson's because Lewy bodies contain a protein associated with Parkinson's, Lewy bodies often are found in the brains of people who have Parkinson's and other rare dementias and people who have Lewy bodies in their brains also often have the plaques and tangles associated with Alzheimer's. Some scientists have suggested that there is a Lewy body variant of Alzheimer's disease. Conversely, LBD and Alzheimer's may just coexist in some people.
Although the cause of LBD isn't clear, several factors appear to increase the risk of developing the disease: most cases occur in adults over 60, it is twice as common in men as in women and there is a slightly higher risk of the disease if there is a family member with it.
After onset, LBD typically causes severe dementia. The Parkinson's-like features and visual hallucinations tend to worsen with time. Average survival is about eight years after symptoms begin.
Treatment can be challenging, and there is no cure; instead, doctors treat the individual symptoms.
* Cholinesterase inhibitors. These Alzheimer's disease medications work by increasing the levels of neurotransmitters — chemical messengers believed to be important for memory, thought and judgment — in the brain. This can help improve alertness and cognition, and may help reduce hallucinations and other behavioural problems.
* Parkinson's disease medications. These medications can help reduce Parkinson's-like muscular symptoms in some people with Lewy body dementia, but they can also cause increased confusion, hallucinations and delusions.
* Antipsychotic medications. These medications may somewhat improve delusions and hallucinations. However, at least a third of the people who have Lewy body dementia have a dangerous sensitivity to some of these types of drugs. Reactions, which are sometimes irreversible, can include severe Parkinson's-like symptoms and a worsening of confusion.
Because antipsychotic drugs can worsen the symptoms of LBD, it might be better to initially try nondrug approaches, such as:
* Modify the environment. Reducing clutter and distracting noise can make it easier for someone with dementia to focus and function.
* Modify the response. A caregiver's response to a behaviour can make the behaviour worse. It's best to avoid correcting and quizzing a person with dementia. Reassuring the person and validating his or her concerns can defuse most situations.
* Modify tasks. Break tasks into easier steps and focus on success, not failure. Structure and routine also help people with dementia feel safe.
* Encourage exercise. Exercise carries many benefits. The fact that these benefits often are the same for people without dementia doesn't lessen their importance. In fact, it just makes exercise a more important activity for caregivers and people with dementia to engage in together. The main benefits of exercise include improved strength and cardiovascular health. Exercise can also lessen symptoms of depression, help retain motor skills and create a calming effect. It can also help sustain strength, flexibility and balance — which may lessen the risk of serious injury from a fall.