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.
The most recent estimates of incidence of DLB relate to an elderly French population assessed over 15 years. Incidence was estimated to be 112/ 100,000 person-years and increased continuously with age even in the oldest individuals.