Decision making after traumatic brain injury: a temporal discounting paradigm

A temporal discounting paradigm was used to examine decision making for hypothetical monetary reward following traumatic brain injury (TBI). A case-control design compared individuals following moderate or severe TBI with a healthy control group matched for age and gender. The impact of intelligence, impulsivity, and mood on temporal discounting performance was examined. A within-subjects design for the TBI group determined the influence of a range of neuropsychological tests on temporal discounting performance. Both patients and controls demonstrated temporal discounting. However, the TBI group discounted more than controls, suggesting that their decision making was more impulsive, consistent with ratings on the impulsiveness questionnaire. Discounting performance was independent of neuropsychological measures of intelligence, memory, and executive function. There was no relationship between temporal discounting and ratings of everyday executive function made by patients' relatives. Low mood did not account for discounting performance. The results of this study suggest that temporal discounting may be a useful neuropsychological paradigm to assess decision making linked to monetary reward following TBI. Performance was relatively independent of intelligence, memory and standard tests of executive ability and may therefore assist when assessing a patient's mental capacity to manage their financial affairs.