Parkinson's disease dementia is a dementia associated with Parkinson's disease. It is a type of Lewy body dementia, characterized by abnormal deposits of Lewy bodies in the brain, along with dementia with Lewy bodies. Parkinson's disease begins as a movement disorder, but in most cases progresses to include dementia and changes in mood and behavior. The signs, symptoms, and cognitive profile of Parkinson's disease dementia are similar to those of Lewy body dementia. Parkinson's disease is a risk factor for dementia, accelerating the decline of cognitive function leading to Parkinson's disease dementia. Up to 78% of people with Parkinson's disease have dementia. Delusions are less common in Parkinson's disease dementia than in dementia with Lewy bodies. Public awareness of Lewy body dementia varies greatly from that of Parkinson's disease and Alzheimer's disease, although Lewy body dementia is the second most common type of dementia after Alzheimer's disease. Information about Parkinson's disease dementia from the Parkinson's Foundation