Parkinson's disease dementia

Parkinson's disease dementia (PDD) is dementia that is associated with Parkinson's disease (PD). Together with dementia with Lewy bodies (DLB), it is one of the Lewy body dementias characterized by abnormal deposits of Lewy bodies in the brain.

Parkinson's disease starts as a movement disorder, but progresses in most cases to include dementia and changes in mood and behavior. The signs, symptoms and cognitive profile of PDD are similar to those of DLB; DLB and PDD are clinically similar after dementia occurs in Parkinson's disease. Parkinson's disease is a risk factor for PDD; it speeds up decline in cognition leading to PDD. Up to 78% of people with PD have dementia. Delusions in PDD are less common than in DLB, and persons with PD are typically less caught up in their visual hallucinations than those with DLB. There is a higher incidence of tremor at rest in PD than in DLB, and signs of parkinsonism in PDD are less symmetrical than in DLB.