Introduction

Dementia is a syndrome consisting of a number of symptoms that include loss of memory, judgment and reasoning, and changes in mood and behaviour. These symptoms may affect a person's ability to function at work, in social relationships or in day-to-day activities. Sometimes symptoms of dementia can be caused by conditions that may be treatable, such as depression, thyroid disease, infections or drug interactions. If the symptoms are not treatable and progress over time, they may be due to damage to the nerve cells in the brain.

Alzheimer's disease, the most common form of dementia, accounts for 64% of all dementias in Canada. The features of Alzheimer's disease include a gradual onset and continuing decline of memory, as well as changes in judgment or reasoning, and the inability to perform familiar tasks.

Sometimes a person may have symptoms such as sudden onset of memory loss, early behaviour changes, or difficulties with speech and movement. These symptoms may suggest a dementia other than Alzheimer's disease. Lewy body dementia is one of these dementias.

A person should seek a thorough medical assessment if any of these symptoms are present.

Regardless of the dementia, individuals can obtain information and support from the Alzheimer Society.

What is Lewy body Dementia?

Lewy body Dementia is a form of progressive dementia identified by abnormal structures in the brain cells called "Lewy bodies." These are distributed in various areas of the brain. A major component of Lewy bodies is a protein called alpha synuclein. The mechanism that leads to the formation of Lewy bodies is unknown. Unlike Alzheimer's disease where eventually massive numbers of neurons die, in Lewy body Dementia, only 10-15% of neurons disappear, although function is eventually impaired in the surviving neurons. Certain areas of the brain are affected in Lewy body Dementia that are not usually affected in Alzheimer's disease.

Lewy body Dementia can occur by itself, or together with Alzheimer's or Parkinson's Disease. It accounts for 15-20% 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 and Lewy body variant of Alzheimer's disease.

How does Lewy body Dementia affect the person?

In Lewy body Dementia, there is progressive loss of memory, language, reasoning and toher higher mental functions such as calculation. The person may have difficulty with short- term memory, finding the right word and sustaining a train of thought. An individual may also experience depression and anxiety.

Lewy body Dementia usually has a rapid progression. Memory difficulties may not be an early symptom, but can develop as Lew body Dementia progresses. Marked fluctuations in confusion can vary from hour to hour or week to week. Visual hallucinations (seeing things which are not real) are common and can be worse during times of increased confusion. The visual hallucinations are often recurrent and typically consist of people, children or animals intruding into the home. People with the disease may also make errors in perception, for example, seeing faces in carpet pattern.

Some features of Lewy body Dementia can resemble Parkinson's Disease. These include rigidity (stiffness of muscles), tremors (shaking), stopped posture and slow shuffling movements. Sensitivity to medication, especially some sedatives, may exaggerate these symptoms.

How is Lewy body Dementia assessed?

Assessment should include a neurological exam that emphasizes gait, posture and the degree of rigidity. Blood pressure will also be taken and cognitive functioning should be tested.

Is there a treatment for Lewy body Dementia?

At present, there is no cure for Lewy body Dementia. It is sometimes possible to treat symptoms such as depression, and unpleasant hallucinations can be reduced with medication. Parkinson symptoms can also be treated. However, due to the multiple features of Lewy body Dementia with Parkinson symptoms, management of these diseases can be difficult because treatment of one symptom may be achieved at the expense of another. Treatment is often individualized for each person focusing on treating the symptoms in order of severity to avoid or prevent over-medication.

Source: Alzheimer Society of Canada