Normed neuropsychological tests across multiple cognitive domains consistently detect cognitive deficits in Parkinson disease (PD) when compared with site‐specific healthy control (HC) performance, but relative PD performance was significantly affected by the inclusion and type of HCs vs the use of published norms only. This according to a recent investigation that sought to identify neuropsychological tests that consistently detect cognitive decline in PD across studies. Data from 30 normed neuropsychological tests across 20 international studies in up to 2,908 non-demented PD patients were analyzed. A subset of 17 tests was administered to up to 1,247 HCs. Researchers found:

• Pooled estimates of the differences between PD and site‐specific healthy controls identified significant cognitive deficits in PD patients on 14 test scores across 5 commonly assessed cognitive domains (attention or working memory, executive, language, memory, and visuospatial abilities), but HC performance was statistically above average on 7 of these tests.
• Analyses based on published norms only, as opposed to direct assessment of healthy controls, showed high between‐study variability that could not be accounted for and led to inconclusive results.