PERSEVERATIVE MOTOR BEHAVIOR IN PARKINSONS-DISEASE

Difficulties in shifting of cognitive sets and perseverative behaviour have been shown to be part of the neuropsychology of Parkinson's dise ase, possibly due to frontal dysfunction. We have tested perseverative motor behaviour by assessing ability to generate random movement sequ ences in 15 patients with Parkinson's disease using the Breidt Perseve ration Test Device (PTD). In this experiment subjects are instructed t o press one of nine buttons arranged randomly on a metal board without use of systematic or repetitive strategies. The speed of this task th at comprises 150 consecutive presses is determined by an acoustic go-s ignal appearing at 1 Hz frequency. Results were compared with 14 age-m atched controls. Patients performance was impaired with intrusion of u nwanted systematic strategies suggesting a decreased ability of Parkin son patients to generate random movement sequences.