Incremental utility of an extended stroop task for identifying subtle differences in cognitive performance among healthy older adults.

The Stroop Color and Word Test is a test of processing speed, response inhibition, and executive functioning (EF). This project examined whether extending the Stroop Color-Word trial beyond the standard time limit could more accurately assess performance on EF measures. Cognitively healthy older individuals (n = 198) enrolled in a study of cardiovascular health completed the Stroop as part of a neuropsychological battery. Two scores were computed for the Color-Word trial: the number of items completed within the first 45 seconds (traditional Color-Word score) and the speed of page completion beyond the first 45 seconds (Stroop-Extended score). Criterion measures included the Trail-Making Test Part B (TMT-B), Digit Span Backward, Symbol Digit Modalities Test, Short Category Test, and measures of verbal fluency. Results from hierarchical linear regression analyses indicated that the extended Stroop score accounted for small but statistically significant variance in TMT-B (additional 2.6%) and Digit Span Backwards (additional 2.6%) beyond the standard Color-Word score. These findings suggest that extending the Stroop Color-Word trial beyond the first 45 seconds provides a limited increase in predictive power within a healthy sample with restricted range of performance. The extended Stroop requires additional examination in heterogeneous samples, including clinical populations, to determine its predictive utility.