Chronic pain is associated with deficits in information processing

Beginning with the theoretical premise that pain stimuli are liable to perturb the ordinary dynamical state of the brain, we hypothesized that individuals in pain may experience impaired information processing. A sample of 19 persons complaining of chronic pain and a comparison sample of 25 persons having sustained head trauma were obtained by retrospective chart review. The chronic-pain group consisted of 19 persons whose primary complaint was significant chronic pain, with no known history of head trauma or neurologic disorder. The comparison group consisted of 25 persons who had sustained mild to moderate head traumas. All subjects were administered information processing and motor subtests of the Human Performance Measurement System, a computerized set of measures. Both groups obtained mean z scores below the normative mean on all measures except visual digit span. There were no differences between groups on motor measures, visual digit span, and visual-spatial memory. On 2 of 6 information-processing tests, pain patients performed more poorly than head-trauma patients. The results suggest that pain may disrupt cognitive performances which depend on intact speed and capacity of information processing.