Editorial. Parkinson disease dementia (PDD) is one of the nonmotor complications of Parkinson disease, characterized by impairment of visuospatial and executive functions.1 The yearly incidence of PDD among patients with Parkinson disease is estimated at approximately 10%, but is widely variable in different reports.1,2 The risk of PDD increases with disease duration and patient age.3 Parkinson disease dementia is often complicated by many neuropsychiatric symptoms such as mood disturbances, apathy, and psychosis.. Please contact the library to request a copy of this article - http://bit.ly/1Xyazai