Whether agreeableness and conscientiousness decrease after onset of the chronic fatigue or are risk factors for chronic fatigue is unclear.
The study, published in , found that chronic fatigue syndrome victims scored higher in neuroticism, a measure of vulnerability to negative emotional states such as anxiety or depression, than both people without fatigue and people with medically unexplainable fatigue.
Victims of medically unexplainable fatigue, however, still scored higher in neuroticism scores than people without fatigue.
Although these results were solely correlational, in another study, chronic fatigue syndrome patients rated themselves as higher on neuroticism and lower in extraversion when they were ill then when they were well.
The reduced levels of extraversion may indeed be a result of fatigue rather than a risk factor for fatigue.
The researchers also found a reverse pattern with extraversion, one’s level of activity and sociability.
Chronic fatigue syndrome victims were the least extraverted, and people without fatigue were the most extraverted.
It is possible that neuroticism is also either a result of the fatigue itself or a result of the same factors which are causing the fatigue.
On a psychological level, chronic fatigue may lead to greater emotional burden due to feelings such as worry, frustration, and aloneness that victims of chronic unexplainable fatigue often experience.
Interestingly, another study examined patients with multiple sclerosis, a fatiguing illness which, like chronic fatigue syndrome, has an unknown cause, and found that the multiple sclerosis patients had about as many personality disorders as the chronic fatigue syndrome patients.