A meta-analysis of response inhibition and Stroop interference control deficits in adults with traumatic brain injury (TBI).

The prominent clinical feature of behavioral impulsivity following traumatic brain injury (TBI) suggests impairment of frontal inhibitory control processes. This meta-analysis consolidates the recent surge in studies across two forms of "effortful" inhibition, employing well-defined paradigms of response inhibition (N = 20; i.e., go/no-go, sustained attention to response, stop-signal, Conners' continuous performance tasks) and response interference control (N = 21, i.e., Stroop color word tasks). Across 41 effect sizes involving 989 adults with mild to severe TBI and 969 controls, the overall effect of TBI on reduced inhibitory control was small to moderate (d = 0.3) and significant. The effect was larger in studies measuring response inhibition performance (d = 0.5), while Stroop interference control yielded a nonsignificant overall effect size (d = 0.05). Further analysis of the latter finding revealed a large effect size when Stroop task studies used the outcome measure "total time on task" (d = 1.4), but not "RT per trial" or "number of stimuli" (d = -0.8 and -0.9). Response speed in these tasks was impaired to a large degree (d = 0.96). Together these findings support a response inhibition deficit following TBI but suggest factors other than interference control, such as poor processing speed, fatigue, and underarousal, may underlie poor performance in Stroop tasks.