The onset of both classes of disorders is typically related to some stressful experience, and the two classes sometimes co-occur. Psychological problems take a physical form: not under voluntary control, overall dsm-iv categories of somatoform disorder. Thought to be linked to anxiety and all psychologically caused. Individuals are preoccupied with persistent fears of having a serious disease, despite medical reassurance to the contrary: typically beings in early adulthood and tends to have a chronic course, they make catastrophic interpretations of symptoms, prevalence of 5% A previous experience of illness and related medical factors. The presence of inflexible or negative cognitive assumption are always a sign of serious illness. They may experience paralysis of arms or legs; seizures and coordination disturbances; a sensation of prickling, tingling or creeping on the sink, insensitivity to pain; or loss of impairment of sensations (anaesthesias) They appear suddenly in stressful situations (allowing the individual to avoid some activity or responsibility) or receive badly wanted attention.