Original sentence: 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.This association may not be universal
Edited sentence: However, a systematic review on personality and CFS concludes that any association is not definitive.The involvement of psychological factors within CFS as a whole is unclear but according to some research, a lack of support or the reinforcement of illness behavior from social networks can be associated with delayed recovery