Distractibility When Suffering from Mental Fatigue after a Mild Traumatic Brain Injury

Most Traumatic Brain Injuries are mild (mTBI) yet many people suffer from long-term mental fatigue and cognitive impairment. Despite comments from patients, cognitive difficulties can go undetected. Distractibility is commonly reported but is seldom included in standard neuropsychological assessment. This study was designed to investigate the effect distraction may induce in topdown and bottom-up attention among people who suffer from mental fatigue after mTBI. Thirty mTBI patients suffering from mental fatigue and 30 healthy controls performed a computerized test, including Simple Reaction Time, Choice Reaction Time and Attentional Capture tasks with a salient distractor. A slower processing speed was found in all subtests for the mTBI group and was particularly noticeable for the decision-making task. The distraction stimulus reduced processing speed for both groups, while the mTBI group made more omissions when a distractor emerged, indicating increased distractibility. However, no effect in top-down and bottom-up attention was found. Response time in the presence of a distractor was a predictor for mental fatigue, while depression and anxiety were not, showing the importance to carefully distinguish between emotional distress and mental fatigue. In conclusion, it is suggested that people suffering from mental fatigue after mTBI are slower at processing information, and this is more pronounced when a cognitive demand is added to the task. Distractibility was indicated with more omissions during distraction, but a distinction between top-down and bottom-up systems was not found. Further research is needed to better understand the link between distractibility and mental fatigue after a brain injury.