The vast majority of PD patients may experience some form of cognitive impairment over time with perhaps 75% or more developing PD dementia in advanced disease. Cognitive deficits tend to be worse for patients with predominant symptoms of bradykinesia and rigidity. Being male and having visual hallucinations are strong predictors of developing dementia in PD.
The following cognitive functions are usually affected in PD:
Note: all individuals with cognitive impairment should undergo a driving evaluation to assess driving skills and safety.
Miyasaki JM, Shannon K, Voon V, et al; Quality Standards Subcommittee of the American Academy of Neurology. Practice parameter: evaluation and treatment of depression, psychosis, and dementia in Parkinson disease (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2006;66(7):996-1002.
Goldman Gross R, Siderowf A, Hurtig HI. Cognitive impairment in Parkinson’s disease and dementia with Lewy bodies: a spectrum of disease. Neurosignals. 2008;16(1):24-34.