Motor demands of cognitive testing may artificially reduce executive function scores in individuals with spinal cord injury

Abstract

Objective: To determine whether the motor demands of cognitive tests contribute to differences in cognitive function scores in participants with and without spinal cord injury (SCI).Design: Cohort study.Setting: Rehabilitation research laboratory.Participants: 68 individuals without SCI ("NON") and 22 individuals with motor complete SCI ("SCI").Interventions: None.Outcome Measures: NIH Toolbox cognitive assessments, including two with motor demands and reaction-time based scoring (Dimensional Change Card Sort (DCCS), Flanker Inhibitory Control and Attention (Flanker) and two without timed scoring (List Sorting Working Memory (List Sorting), Picture Sequence Memory Test (Picture Sequence). Tests were administered with and without the assistance of a proctor on two randomly-determined days (>24 hr interval). For DCCS and Flanker, the motor-task score offset was estimated as the difference between the proctored and non-proctored scores.Results: For demographically-corrected data, proctoring reduced DCCS and Flanker scores (P < 0.001) but mitigated apparent differences between SCI and NON (all P > 0.403). SCI and NON did not differ for List Sorting (P > 0.072) but did differ significantly for Picture Sequence (P < 0.001). Significant practice effects existed for memory-based tests (List Sorting and Picture Sequence); all P < 0.015, effect size>0.645.Conclusions: DCCS and Flanker scores for individuals with SCI may be artificially reduced consequent to secondary motor demands of the tests. Proctoring and computation of a motor-response score offset enables comparisons to be made between individuals with SCI and a Non-SCI control cohort; however, further work is needed to determine whether offset-adjusted scores can be compared to standardized normative values.

Keywords: Cognition; Executive function; Memory; Spinal cord injuries.

Figures

Figure 1.

Mean (SD) DCCS and Flanker scores for participants with and without SCI. Dashed and dotted lines represent U.S. population normative mean and SD, respectively. *P < 0.05.

Figure 1.

Mean (SD) DCCS and Flanker scores for participants with and without SCI. Dashed and dotted lines represent U.S. population normative mean and SD, respectively. *P < 0.05.

Figure 2.

Mean (SD) List Sorting and Picture Sequence scores for participants with and without SCI. Dashed and dotted lines represent U.S. population normative mean and SD, respectively. *P < 0.05.

Figure 2.

Mean (SD) List Sorting and Picture Sequence scores for participants with and without SCI. Dashed and dotted lines represent U.S. population normative mean and SD, respectively. *P < 0.05.