The role of psychological factors in chronic pain.

The traditional view conceptualizes pain as being directly associated with the extent of physical pathology. The observations that there are a number of patients who report pain in the absence of physical pathology, the converse, asymptomatic individuals who evidence objective physical pathology, the inconsistency in response of patients with identical diagnoses, and the low association between impairments and disability suggest that factors other than physical pathology contribute to the reports of pain. The role of behavioral, cognitive, and affective factors have each been shown to have direct effects on the report of pain, adaptation, and response to treatment, as well as indirect effects by influencing sympathetic nervous system and neurochemical factors associated with nociception. The direct and indirect effects of behavioral (operant), cognitive, and affective factors in chronic pain are described.