Cognitive contributions to differences in learning after moderate to severe traumatic brain injury

Deficits in learning and memory are commonly observed after traumatic brain injury (TBI); however, the mechanisms underlying such deficits are poorly understood. This study examines the contribution of other cognitive processes in verbal learning after moderate to severe TBI. Adults with TBI who have verbal learning deficits were predicted to perform worse on executive measures than adults who are able to learn.

Participants were 51 community-dwelling adult volunteers (age 18-59) with moderate to severe TBI. Injury severity was determined by Glasgow Coma Scale score ≤12 and corroborating information from medical records. Group membership (TBI-learners or TBI-nonlearners) was determined by a learning criterion of perfect recall on 2 consecutive trials within 15 trials on the open-trial Selective Reminding Test. All participants completed a comprehensive neuropsychological test battery. Group differences were examined using independent-samples t tests, and logistic regression was used to determine significant predictors of learning ability.

The TBI-learner group performed better than the TBI-nonlearner group most consistently on tasks of executive control and working memory. Results of a logistic regression showed that working memory capacity was the most significant predictor of learning ability after TBI.

Working memory significantly influences the ability to learn verbal information after TBI. The documented relationship between working memory and learning will guide the development of more efficacious treatments to rehabilitate learning and memory deficits after TBI.