Cognitive impairment in incident, untreated Parkinson disease

Little is known regarding the cognitive impairment in subjects with early, drug-naïve Parkinson disease (PD). The aim of this study was to explore the proportion with mild cognitive impairment (MCI) and subtypes in an incidence cohort of untreated PD in Southern and Western Norway.

A total of 196 non-demented, drug-naive patients who were recruited after an extensive search of all new cases of PD in the area and 201 healthy control subjects completed a battery of neuropsychological tests of verbal memory, visuospatial, and attentional-executive functioning. Subjects were classified as MCI if the age- and education-corrected z-score was falling 1.5 standard deviations below the mean for at least one of the cognitive domains.