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Lewy body dementia, or LBD, is a common cause of dementia. According to the Lewy Body Dementia Association, 1.3 million Americans have LBD. Like Alzheimer disease, LBD causes intellectual and physical deterioration due to progressive damage of brain cells. People diagnosed with LBD survive an average of about eight years according to the National Institute of Neurological Disorders and Stroke. People with late-stage LBD often lose their ability to communicate, care for themselves and even swallow.

Cause and Effect of LBD

Lewy bodies are clumps of protein found in the nerve cells of the brain. They build up in areas of the brain that control memory and movement, damaging the cells and disrupting function. Lewy bodies are not detectable by any test. Doctors diagnose LBD based on specific symptoms. People with LBD and those with Parkinson disease often show similar late-stage symptoms. People with LBD typically exhibit signs and symptoms of dementia up to a year before movement problems develop. Movement problems with LBD occur earlier and are more severe than with Alzheimer disease.

Mental Symptoms

With LBD, attention and visual symptoms come and go but in later stages, memory loss is clearly evident. People with LBD often have delusions. For example, they may believe that someone close to them has been replaced by an impostor. They also commonly have visual and auditory hallucinations -- that is, they see and hear things that are not present. Initially, these periods of confusion come and go. However, these delusions and hallucinations become more frequent as the disease progresses. Anxiety, depression, emotional lability and aggression are common in late-stage LBD.

Movement Symptoms

In later stages of the disease, people with LBD have poor movement control and coordination. Falls and bizarre movements are common. The muscles do not relax normally, making them extremely tense. People with advanced LBD appear rigid and usually have difficulty with daily tasks, including bathing, self-feeding and toileting. They also have difficulty speaking and swallowing. They may have a vacant stare and extreme sensitivity to touch. Injuries related to falls may cause broken bones or infections that could eventually contribute to death.

Caring for Someone With LBD

Someone with LBD may be helped by making her environment more soothing. Speaking reassuringly and avoiding conflict can be helpful. Acquiescing rather than arguing or trying to reason with someone who has LBD is often the best choice, as long as safety is not an issue. Providing a routine and allowing the person to perform simple tasks can help reduce agitation and anxiety. In the final stages of LBD, when the ability to control movements results in the loss of self-care functions and eating, full or part-time hospice care may be an option.