Lewy body dementia

Lewy body dementia is a form of dementia that occurs because of abnormal deposits of a protein called alpha-synuclein inside the brain's nerve cells. These deposits are called "Lewy bodies," after the scientist who first described them. The deposits interrupt the brain’s messages. Lewy body dementia usually affects the areas of the brain that involve thinking and movement. Why or how Lewy bodies form is unknown.

Lewy body dementia can occur by itself, or together with Alzheimer's disease or Parkinson's. It accounts for 5-15% of all dementias.

Other names for Lewy body dementia include:

  • Diffuse Lewy body disease
  • Cortical Lewy body disease
  • Lewy body disease
  • Senile Dementia of Lewy Type
  • Dementia with Lewy bodies
  • Lewy body variant of Alzheimer's disease

How does Lewy body dementia affect the person?

A person with Lewy body dementia may have symptoms much like those of both Parkinson's disease and Alzheimer's disease. A progressive loss of memory, language, reasoning and other higher mental functions such as calculating numbers is common. He may have difficulty with short-term memory, finding the right word and keeping a train of thought. He may also experience depression and anxiety. Obvious changes in alertness may also happen. He may be sleepy during the day, but wide awake at night, unable to sleep. Sometimes, he may seem like he does not care about anything. This is called apathy.

Lewy body dementia usually progresses quickly. Problems with memory may not be an early symptom, but can come up as Lewy body dementia progresses. Visual hallucinations (seeing things that are not real) are common and can be worse during times of increased confusion. The visual hallucinations often come back again and again, and typically are of people, children or animals. People with the disease may also make errors in perception, for example, seeing faces in a carpet pattern.

Some features of Lewy body dementia can resemble those in Parkinson's disease. These include rigidity (stiffness of muscles), tremors (shaking), stooped posture, and slow, shuffling movements. Sensitivity to medication, especially some sedatives, may make these symptoms worse.

How is Lewy body dementia assessed?

No single test can diagnose Lewy body dementia. Doctors diagnose the disease by eliminating other diseases and conditions that can cause similar symptoms. Assessment may include a neurological exam that looks at the gait (way of walking), posture and how rigid or stiff the person’s body is.

What are the risk factors for Lewy body dementia?

Doctors do not yet know what causes Lewy body dementia. Risk factors have not been identified. But Lewy bodies have a protein that is also seen in Parkinson's disease and they are often found in the brains of people with Parkinson's disease or Alzheimer's disease. This means that the three conditions may be linked in some way. If a family member has Lewy body dementia, there may be a higher risk of developing Alzheimer’s disease. Lewy body dementia is more common in men than in women.

Is there treatment?

There is no cure yet for Lewy body dementia. Sometimes doctors may prescribe medications to treat symptoms such as those associated with Parkinson's disease, depression, and unpleasant hallucinations.

Medications used to treat Alzheimer’s disease are called cholinesterase inhibitors. They can improve alertness and cognition in some people. They may also reduce hallucinations and other distressing symptoms. Lewy body dementia has so many different features, as well as Parkinson's disease symptoms, that medications may not be an option. One symptom may be treated, but another symptom may get worse at the same time. One way to avoid or prevent this is to treat symptoms according to how severe they are. 

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Last Updated: 08/24/16
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