Problem-solving abilities in Parkinson's disease.

Abstract

Anatomic, physiologic and pathologic findings suggest that the integrity of frontal lobe functioning may be compromised in people with Parkinson's disease. This disruption has been proposed to result in neuropsychological deficits similar to those seen in people with cortical frontal lobe lesions. In a number of studies, investigators report evidence of "frontal lobe" deficits (also termed problem solving deficits) in people with the disease. The exact nature of the impairment is as yet unclear. This study employs the Wisconsin Card Sorting Test (WCST) and the Controlled Oral Word Association Test, previously reported as sensitive measures of problem solving deficits in Parkinson's disease. It also uses the California Sorting Test, previously administered to people with cortical frontal lobe lesions and leading to reports of perseverative errors. As yet, there has been no reported use of this test with PD subjects to the best of my knowledge. The three tests were administered to 19 subjects with Parkinson's disease and 19 demographically matched control subjects. Results of analyses of the WCST scores appeared similar to previous reports, that is, there was a significant difference between PD subjects and controls. Scores on the Controlled Word Association Test were similar between groups on semantic categories and significantly different when letters only were used. Scores on the California Sorting Test were similar between groups on all measures of correct responses, but significantly different in measures of perseverations on the free sorting condition. These results were interpreted as showing further evidence for the Brown and Marsden model of "internal cue" deficit. When sorting under varying degrees of structure and external cues, it was found that the more outside-imposed structure and the more external cues, the more the two groups scored alike. By contrast, the more unstructured the condition, the more the PD group showed impairment.