Dementia or other cognitive problems. Some people with PD may develop memory problems and slow thinking. Cognitive problems become more severe in late stages of PD, and a diagnosis of Parkinson’s disease dementia (PDD) may be given. Memory, social judgment, language, reasoning, or other mental skills may be affected. There is currently no way to halt PD dementia, but drugs such as rivastigmine, donepezil, or memantine may help. The medications used to treat the motor symptoms of PD may cause confusion and hallucinations.