Cognitive Control Impairments in Traumatic Brain Injury

Abstract

The componential nature of impaired cognitive control following traumatic brain injury (TBI) remains uncertain. We examined regulative and evaluative components of cognitive control in mild and moderate-to-severe (M/S) TBI patients and demographically-matched comparison participants using the AX-CPT task. We also examined relationships of cognitive control impairment to ratings of cognitive, behavioral, and affective symptomatology on the Dysexecutive Questionnaire (DEX). Results revealed that M/S, but not mild TBI patients showed deficits in context-processing and post-error strategic adjustments—extent of impairments correlated with TBI-related symptomatology. Thus, patients with M/S TBI evidence cognitive control dysfunction in the processing and active maintenance of context representations.

Supported by grants from the Evelyn F. McKnight Brain Research Grant Program, the Florida Brain and Spinal Cord Injury Research Trust Fund, and the National Institute of Mental Health (K01 MH01857, R21 MH073076) to W.M.P. We thank Kay Waid-Ebbs for her assistance with patient recruitment and Michael A. Cole, Paul Seignourel, and Diana L. Robins for assistance with data collection.

Notes

Supported by grants from the Evelyn F. McKnight Brain Research Grant Program, the Florida Brain and Spinal Cord Injury Research Trust Fund, and the National Institute of Mental Health (K01 MH01857, R21 MH073076) to W.M.P. We thank Kay Waid-Ebbs for her assistance with patient recruitment and Michael A. Cole, Paul Seignourel, and Diana L. Robins for assistance with data collection.

¹However, see Seignourel et al. (2005) for a discussion of limitations inherent in many Stroop studies of TBI.

²Participants in the current study also participated in previously-reported studies (Perlstein et al., 2004; Seignourel et al., 2005).

³Data for other reports of symptomatology were available for 20 of 24 controls, 13 of 20 mild TBI participants, and 23 of 26 moderate-to-severe TBI participants.

⁴Data for the STAI were available for only 47 participants (15 controls, 18 mild TBI patients, 14 moderate-to-severe TBI patients), as it was employed only after the first 23 participants had been tested in the experimental protocol.

^aOne control and one M/S TBI participant were unable to provide an estimate of father's education.

^bRaw scores.

^cBecause the Digit Symbol was included only later in our protocol, the data for this task include only 22 controls, 20 mild TBI patients, and 18 M/S TBI patients.

^dNRS-self ratings were unavailable for two mild TBI patients.

^eThese measures were introduced after the first 23 participants were run and, therefore, are only available for 15 controls, 18 mild TBI patients, and 14 M/S TBI patients.

^aIncludes data for only 24 of 26 M/S TBI patients, since two patients had 100% errors on at least one condition.

⁵Two M/S TBI participants were excluded from these analyses, as each was missing RTs due to 100% errors on the BX trial type.

⁶Correct-trial RTs before commission of an error included all trials which preceded errors but excluded trials used in calculation of correct post-error trial RTs. Post-error correct-trial RTs were taken from the first correct trial following an error.

⁷The error rate data presented in the Results included both commission and omission errors. It is conceivable that the processes leading to commission errors might reflect a different underlying mechanism than processes reflecting omission errors. Importantly, the statistical pattern of group-related differences did not change when examining only errors of commission.

⁸In the present study, time-since-injury did not significantly correlate with any of the performance measures, suggesting that context maintenance deficits may be present at all stages of TBI.