The relation between catastrophizing and facial responsiveness to pain.

Pain catastrophizing has recently been suggested to have a social function based on a positive association observed with facial responsiveness to noxious stimulation. However, this assumption is based on studies applying nociceptive stimuli of fixed intensity, such that high catastrophizers not only displayed increased pain behavior but also rated the stimulation as being more painful. The aim of this study was to investigate the relation between catastrophizing and facial responsiveness while controlling for individual differences in pain sensitivity. The facial expression of pain was investigated in 44 young and pain-free individuals in response to painful and non-painful phasic heat stimuli. Painful temperatures were tailored to the individual sensitivity to produce moderate pain. Facial responses were videotaped and objectively examined using the Facial Action Coding System. We also assessed skin conductance activity as an autonomic indicator of pain-related responses. Catastrophizing was assessed using the Pain Catastrophizing Scale (PCS). In accordance with previous findings, subjects scoring higher on pain catastrophizing required lower thermal intensities to induce a moderately painful sensation (r=-0.40, p=0.007). However, catastrophizing did not correlate with facial responsiveness to perceptually controlled painful stimulation (r=-0.02, p=0.88). Moreover, correlation analyses revealed no significant associations between catastrophizing and skin conductance responses. The present findings provide further support for the impact of pain catastophizing on pain sensitivity. However, our finding of no relation between catastrophizing and facial responsiveness when participants are experiencing comparable psychophysical pain intensities, challenges previous assumptions that high catastrophizers display amplified pain behavior; at least in young and pain-free individuals.