Impaired Higher-Order Executive Function in Transitive Inference Task Among Individuals With a History of Concussion

OBJECTIVE: To examine the impact of mild traumatic brain injury (mTBI) on transitive inference (TI) task performance in subjects with concussion history. TI relies on brain executive function, which may be vulnerable to concussion-induced axonal disruption and impairment in inter-regional communication. DESIGN: Analytical cross-sectional comparison. SETTING: Institutional study in a university setting. PARTICIPANTS: University students with and without a history of concussion. INDEPENDENT VARIABLES: Participants with and without a history of concussion. MAIN OUTCOME MEASURES: Assessment of participants' learning and transitive inference abilities using a 5-item TI test that provided performance scores on learning premise pairs and transitive inference pairs. RESULTS: In a 5-item TI task consisting of training in premise pairs and a test, participants with a history of 1 or more concussions performed as well as controls on the premise pairs. However, although performance was similar on 1 transitive pair, the final transitive pair was strongly compromised in those with a history of concussion (47% and 71%, respectively). CONCLUSIONS: Previously unreported in the literature, our data demonstrated a specific impairment of executive function in participants with a history of concussion despite their normal learning ability. The pattern of the impaired TI task performance indicates the collapse of the TI symbolic distance effect and may reflect disrupted inter-regional communication because of concussion-related axonal damage.