Mental fatigue and impaired cognitive function after an acquired brain injury.

OBJECTIVE: Mental fatigue is a common subjective symptom following an acquired brain injury. In many cases, this is long-lasting with a considerable negative impact on work, studies, social activities, and quality of life. No objective test for mental fatigue exists today. The aim of this study was to investigate whether mental fatigue can be objectively measured.

MATERIALS AND METHODS: This study included 32 controls with no mental fatigue and 42 well-rehabilitated participants who suffered from long-term mental fatigue following stroke, traumatic brain injury, encephalitis or meningitis, and late effects after brain tumor. Attention, processing speed and working memory were assessed using a test and retest design following a demanding reading exercise.

RESULTS: Significant interactions were found for tests measuring processing speed, working memory, and attention. The control group improved at the second test, while those who suffered from mental fatigue did not.

CONCLUSIONS: This study indicates impaired cognitive performance over time after cognitive activity for individuals suffering from mental fatigue after an acquired brain injury.