Original sentence: High scores of neuroticism and introversion on psychological tests has previously been associated with a greater risk of developing CFS.However, a systematic review on personality and CFS concludes that any association is not definitive.The success of psychiatric treatments suggests CFS may be perpetuated when patients fixate on a physical cause of illness or their symptoms and when exercise is avoided, and a lack of support or the reinforcement of illness behavior from social networks can be associated with delayed recovery
Edited sentence: A review by Prins et al stated that CFS may be perpetuated when patients fixate on a physical cause of illness or their symptoms and when exercise is avoided.Although  neuroticism and introversion have previously been reported as risk factors for developing CFS, a systematic review of personality factors concludes that while personality often seems to play a role in CFS, it is difficult to draw general conclusions and an association is not definitive.The review also cited research indicating that a lack of support or the reinforcement of illness behavior from social networks may be associated with delayed recovery for certain groups