Assessing the executive function deficits of patients with Parkinson's disease - Utility of the Tower of London-Drexel

The aim of the study was to investigate the utility of the Tower of London-Drexel (TOLDX) in assessing the executive deficits associated with Parkinson's disease (PD). We sought to determine whether the TOLDX would differentiate between (a) patients with PD and healthy control participants (HCP), (b) demented and nondemented patients, and (c) depressed and nondepressed patients. A new TOLDX score, stimulus bound, was introduced to assess utilization behaviors. Furthermore, the convergent and divergent validity of the TOLDX was examined. The TOLDX total move, rule and time violation, and stimulus-bound scores of patients with PD significantly differed from the HCP Demented and nondemented patients also differed significantly in their TOLDX performance, with the stimulus-bound score being the most significantly differentiating score. However, the depressed and nondepressed patients did not differ in their TOLDX performance. Support was found for the convergent and divergent validity of the TOLDX. The clinical and theoretical implications of the findings are discussed.