Fear response and contingency learning in adolescents with chronic pain
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INTRODUCTION: Chronic pain is a debilitating condition that affects many aspects of individual’s lives. Particularly, it has important consequences on the growth and development of adolescents. Pain-related fear and avoidance are thought to play vital roles in the transformation of acute to chronic pain. Abhorrent fear learning is thought to contribute to the development and maintenance of fear and avoidance behaviors. In this study, we utilized a fear conditioning paradigm to examine fear acquisition and extinction as well as contingency learning in adolescents with chronic pain. METHODS: Thirty-two chronic pain patients (Mean age = 16.5 years, SD 2.2) were recruited from the Pain Treatment Service at Boston Children’s Hospital. Eight healthy controls (Mean age = 16.87 years, SD 2.53) were recruited from the local Boston community. Fear conditioning procedures were implemented according to the ‘screaming lady paradigm’. Two faces were displayed on a computer screen. One was paired with a 95dB scream (80% reinforcement; CS+) whilst the other was not paired with a scream (CS-). Fear was subsequently extinguished by displaying the two faces without any scream. Fear levels were determined via skin conductance response (SCR). RESULTS: Adolescents with chronic pain acquired fear to the CS+ more slowly and their fear response towards the CS- was elevated when compared with healthy controls. Furthermore, unlike the healthy controls, adolescents with chronic pain failed to extinguish fear to the conditioned stimulus when the aversive scream was removed. CONCLUSIONS: These results suggest that adolescents with chronic pain demonstrate slow acquisition of fear, deficits in inhibitory responses towards non-threatening stimuli, and resistance to fear extinction when the threat is no longer present. These altered fear learning processes may be key to our understanding of pain persistence in youth and suggest potential mechanistic targets for future treatment.