In this condition, protein deposits of Alpha-synuclein called lewy bodies develop in nerve cells in brain regions involved in memory, reasoning, perception, thinking, behavior and movement. Many people with DLB experience movement symptoms such as hunched posture, rigid muscles, shuffling walk and trouble initiating movement. Lewy body dementia is the second most common kind of dementia after Alzheimer’s disease that gradually causes decline in mental ability. It may sometimes causes visual hallucination and unusual behaviors such as having conversations with deceased loved ones. It sometimes exists in pure form, or with other brain changes, including those commonly observed in Alzheimer's and Parkinson's diseases.
Between 1999 and 2001, the incidence of a diagnosis of DLB among patients attending the Santa Caterina Hospital in Girona, Spain was 26/100,000 cases per year. In addition, incidence increased with age and there was a preponderance of males (63 per cent) in the sample.