An exploration of verbal concept formation in Parkinson's disease

Literature suggests that Parkinson's disease patients are impaired on neuropsychological tests measuring executive function; yet verbal, as opposed to visuospatial, concept formation has hardly been evaluated in PD patients. Ten PD patients and 10 individually matched Normal Controls (NCs) were given a seldomly used verbal concept formation task known as the Verbal Concept Attainment Test (VCAT), with additional executive function tests administered for comparison. NCs took less time to complete the VCAT than PD patients, obtained a higher percentage of correct answers on the difficult/more abstract VCAT items, and tended to score higher on the test overall. Differences in performance between the two groups were also found for other executive function tests. It was concluded that PD patients likely suffer from a deficit in verbal concept formation past a certain threshold of conceptual difficulty, and that this deficit probably fits into a hypothesized "frontal lobe syndrome" for PD patients.