I'm wondering what effect does parkinson's disease have on intelligence and cognitive functions?

Parkinson dementia: Parkinson disease can be associated with cognitive impairment including problems with memory, judging and problem solving, decreased ability to deal with finances, and sometimes increased napping during the day, visual hallucinations. This is called parkinson disease dementia (pdd) and looks a lot like lewy body dementia to the point that they are considered a spectrum.