The Theory Long-lasting fatigue

The Theory
How could brain fatigue become long-lasting?
Brain fatigue immediately after a head injury, stroke, or other nervous system disease is understandable, but why does it persist for some people even after visible healing? Currently, there is no clear explanation.
The extent or location of the brain injury, or the age or sex of the person, does not seem to significantly affect the risk of long-term brain fatigue. However, there may be pre-existing risk factors. Studies suggest that individuals with depression and anxiety before the injury are more likely to suffer long-term problems. Hereditary factors also play a role. People with a specific gene set of the apolipoprotein epsilon 4 allele are at greater risk of developing long-term neuropsychological impairment following brain injury. Multiple head injuries also increase the risk of developing brain fatigue.