The Effect Of Trait Fear Of Pain On Pain Perception And Chronic Pain

Chronic pain is a widespread global health problem,which has caused huge losses to individuals,families and society.Nowadays,a biopsychosocial understanding has come to dominate the professional scientific community's characterization of chronic pain.Collectively,the biopsychosocial approach describes pain and disability as a multidimensional,dynamic interaction among physiological,psychological,and social factors that reciprocally influence each other,resulting in chronic and complex pain syndromes.Under the broad umbrella of the biopsychosocial approach to understanding chronic pain,a number of more specific,mechanism oriented models have been developed to describe the pathways by which particular processes can influence pain related outcomes.Perhaps the most widely known and influential of those models is the Fear Avoidance Model(FAM).The FA model builds on the work of many,all of whom recognized the importance of the beliefs patients holds about their pain and their role in promoting disabling fear and avoidance.The model takes as its starting point the experience of a pain episode,there are two choice,face or escape.The key factor affecting their choice is whether they are fear of pain.When they are not fear of pain,choosing positive coping strategies is beneficial to their physical recovery.If they are afraid of pain and choose to avoid activities that may cause pain,they may aggravate their pain.The FA model has become increasing popular,and a large body of evidences is in line with its assumptions.Research supporting the FA model stems from cross-sectional studies with chronic pain patients,prospective studies in acute pain and studies using structural equation modeling examining the dynamic and sequential relationships among the variables of the FA model.Collectively,these findings underscore the important role of pain related fear in the development of chronic pain syndromes.But pain is a biologically hardwired signal of bodily threat that is designed to capture attention and disrupt ongoing behavior.Therefore,pain is considered an unconditioned stimulus(US)that activates an immediate defensive system.Non-clinical participants vary in the degree to which they are fearful of pain,this is considered a trait difference.The effects of this trait fear of on pain perception and chronic pain are not well studied.In study 1,we explore the effects of trait fear of pain on pain perception.Eighty healthy college students(45 boys and 35 girls)completed the Fear of Pain Questionnaire(FPQ),which measures trait fear of pain,and measured their state anxiety and fear before the experiment with Numerical Rating Scale(NRS).They were then measured for pain perception thresholds under electrical stimulation,pain perception thresholds,pain change detection threshold,and pain tolerance thresholds under cold and hot stimulation.And pain intensity and degree of suffering under electrical stimulation at twice of their pain perception thresholds respectively.And average pain intensity,maximum pain intensity and degree of suffering during cold and hot stimulation respectively.Considering the peak-end law of the pain experience,we use the average pain intensity of cold and hot stimuli as their pain intensity.The results showed that trait fear of pain was only minor related to the state anxiety and fear of participants before the experiment,and not to the pain perception threshold of electrical stimulation.There was a moderate correlation with the pain perception threshold,pain change detection threshold and pain tolerance threshold of cold and hot stimulation.And there was no correlation between trait fear of pain and pain intensity,but there was an upper correlation between trait fear of pain and the degree of suffering that participants experienced.The trait fear of pain and pain intensity together explain the degree of suffering experienced by participants.In study 2,we explored whether this trait fear of pain is indicative of brain activity without pain stimulation.Thirty three participants in study one(14 boys and 29 girls)participated in our study two,in which we scanned resting state functional magnetic resonance images(fMRI)of the brain in the absence of pain stimulation.According to previous studies,we selected anterior cingulate cortex(ACC)and posterior cingulate cortex(PCC)as seed points.The results showed that trait fear of pain was related to the functional connection strength of the left anterior cingulate gyrus and the right supplementary motor area(SMA),and the functional connection strength of the left posterior cingulate gyrus and the left anterior cingulate gyrus and the middle cingulate gyrus.However,the strength of these two functional connections was not correlated with those pain measures in study one.In study 3,we explore the influence of trait fear of pain on chronic pain.307 patients with chronic musculoskeletal pain(118 men and 189 women)completed some scales related to their pain symptoms,trait fear of pain and pain related fear.We use structural equation model to verify the path model of trait fear of pain as a predisposing factor that influences pain symptoms and depression in patients through mediation of pain catastrophizing and pain vigilance.The results showed that trait fear of pain was confirmed by the pathway of mediating effects of pain catastrophizing on the severity of chronic pain,affective distress and depression symptoms in patients..Through these three studies,we can draw a conclusion: In general,trait fear of pain is related to the individual's pain sensitivity,not only the sensitivity of perception,but also the sensitivity of emotion.This kind of individual's trait like difference may be related to the synchrony of individual's brain activity in some regions of the brain in the resting state.And the trait fear of pain affects the cognition and behavior of patients with chronic pain,and ultimately affects their pain and syndrome.