Assessing Cognitive Impairment in Parkinson's Disease: A Comparison of Two Tower Tasks

Abstract

This study examined whether two tower tasks—the Cambridge Automated Neuropsychological Test Battery “Stockings of Cambridge” (CANTAB-TOL) and the Delis-Kaplan Executive Function System (D-KEFS-TOH), are interchangeable for detecting cognitive deficits in Parkinson's disease (PD) patients. Forty PD patients who met the criteria for this study were assessed with both tasks. The relative contribution of working memory and inhibition was also examined. Relative to controls, PD patients were impaired on the CANTAB-TOL but not the D-KEFS-TOH. Regression analysis which showed that whereas performance on the CANTAB-TOL task was dependent on inhibition and spatial working memory, performance on the D-KEFS-TOH was dependent on spatial working memory only. Only 7% to 24% of the variance between the two tasks was shared. These findings suggest that these tower tasks from two well-established neuropsychological test batteries are not interchangeable.

Key words:

• inhibition
• Parkinson's disease
• planning
• Tower of Hanoi
• Tower of London
• working memory

Notes

¹National Adult Reading Test used to estimate premorbid IQ.

²Total number of years of formal education.

³Mini Mental Status Exam

⁴Beck Depression Inventory-II

⁵Number of years since diagnosis of Parkinson's disease.

∗Significant group difference.

¹Cambridge Automated Neuropsychological Test Battery-Stockings of Cambridge

²Total average number of moves made.

³Delis-Kaplan Executive Function System Tower Task

⁴ctal number of moves; Higher scores indicate greater impairment.

⁵Delis-Kaplan Executive Function System Color-Word Interference Test

∗Significant group difference.

¹Cambridge Automated Neuropsychological Test Battery-Stockings of Cambridge

²Total average number of moves taken.

³Delis-Kaplan Executive Function System Tower Task

⁴Scores for this task were inverted so that a higher score indicated good performance.

⁵Daneman and Carpenter Reading Span Task

⁶Delis-Kaplan Executive Function System Color-Word Interference Task

∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001.

¹Cambridge Automated Neuropsychological Test Battery-Stockings of Cambridge.

²Total average number of moves taken.

³Delis-Kaplan Executive Function System Tower Task.

⁴Scores for this task were inverted so that a higher score indicated good performance.

⁵Daneman and Carpenter Reading Span Task.

⁶Delis-Kaplan Executive Function System Color-Word Interference Task.

∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001.

Disclosure: Audrey McKinlay was sponsored by New Zealand Foundation for Research Science and Technology and by a Claude McCarthy Fellowship. This study has been funded by a grant from the Canterbury Medical Research Foundation.