Somewhere between 50 and 80% of people who have had a traumatic brain injury will experience disabling fatigue. However, fatigue is also related to other symptoms commonly found after brain injury, such as depression, insomnia, and cognitive deficits. Until recently, it has been unclear whether fatigue has a direct impact on disability, or if it is a side effect of other common symptoms contributing to disability.
A recent study of people with traumatic brain injury found that fatigue uniquely contributed to disability. After controlling for depression, executive function, and injury severity, researchers found that fatigue was a significant independent predictor of disability. There was, however, one factor that was associated with both increased fatigue and disability. Executive function, which is important for problem solving, coping, and decision-making, increased both fatigue and disability when impaired.
Executive function impairment and fatigue produced a cyclical pattern. The more difficult it is for a person to solve problems or to make decisions, the more stressed and irritable he becomes. This stress and irritability leads to greater fatigue, which in turn creates increased executive function impairment.
Juengst S, Skidmore E, Arenth PM, Niyonkuru C, & Raina KD. The unique contribution of fatigue to disability in community dwelling adults with traumatic brain injury. Archives of Physical Medicine and Rehabilitation. (September 2012).