Performance at the clock drawing test of individuals affected by Parkinson's disease and healthy subjects: a retrospective study.

Clock drawing test (CDT) is a screening tool used in neuropsychological assessment for evaluating comprehensively multiple cognitive functions. Aberrant performance at CDT was observed in Parkinson's disease, due to impaired executive functioning as well as visuospatial difficulties. However, previous studies suffered from different limitations, such as reduced sample size as well as no comparison with healthy individuals. This retrospective study aimed to verify CDT accuracy in discriminating between 240 patients with idiopathic Parkinson's disease and 205 healthy subjects. We verified CDT accuracy in discriminating patients when classified according to their global cognitive functioning measured through the Mini-Mental State Examination and the Frontal Assessment Battery. Our results showed that affected individuals reported a worse performance in CDT than healthy controls. Instead, no difference was found between patients when categorized according to their performance at the Mini-Mental State Examination or Frontal Assessment Battery. We confirmed that patients with Parkinson's disease reported low performance at the CDT. We encouraged the use of CDT for early detection of possible cognitive difficulties in Parkinson's disease for clinical and research purposes.