Updated March 16, 2015.

Although you may not be as familiar with Lewy body dementia as you are with Alzheimer's disease, Lewy body dementia is the second most common type of dementia. Lewy body dementia is also referred to as Lewy body disease, diffuse Lewy body disease, cortical Lewy body disease, and dementia with Lewy bodies.

 

Prevalence of Lewy Body Dementia

The Lewy Body Dementia Association reports that up to 20% of all dementia cases are due to Lewy body dementia; that equates to more than 800,000 people in the United States.

However, there are no other clear numbers concerning the prevalence of Lewy body dementia. Part of the problem with estimating an exact number is that Lewy bodies -- the hallmark of Lewy body dementia -- are associated with several diseases. This makes it difficult to distinguish Lewy body dementia from other conditions.

 

Causes of Lewy Body Dementia

Lewy body dementia is associated with deposits of the protein alpha-synuclein inside nerve cells in the brain. People with Lewy body dementia experience impairment in their perception, thinking, and behavior. They also experience visual hallucinations, Parkinson's-like symptoms, and fluctuating alertness.

The deposits are called Lewy bodies, named after Friederich H. Lewy, the researcher who first described the deposits in the early 1900s. Interestingly, Lewy bodies are also found in the brains of those with Parkinson's disease and -- sometimes -- even Alzheimer's disease, making diagnosis much more complicated.

 

Risk Factors for Lewy Body Dementia

Age is the only known risk factor for Lewy body dementia.

Risk increases as age increases, with most cases occurring between the ages 50 and 85. Some cases of Lewy body dementia have been reported within families, but for the most part, the disease occurs with no family history.