Behavioral persistence deficit in Parkinson's disease patients

The present study was performed to examine the degree to which decreased task persistence may contribute to deficits in the ability of Parkinson's disease (PD) patients to perform a problem solving task. Patients with mild/moderate PD performed a computerized Tower of Hanoi task in which they planned and verbalized moves to solve the puzzle but did not need to produce a limb motor response. All patients were tested at least 14 h off medication. As expected from previous studies of planning abilities in PD, patients had significant problems performing this task and accuracy decreased specifically when patients were presented with the most difficult puzzles in the sequence. PD patients solved fewer of the most difficult puzzles than did control subjects, but also made significantly fewer attempts to solve those puzzles than controls. These results suggest that PD patients not only have planning and problem solving deficits as have been documented previously, but that at least part of this and perhaps other cognitive performance problems may result from difficulty in maintaining adequate mental effort to successfully complete difficult tasks.