Brain signatures of threat-safety discrimination in adolescent chronic pain

Emotional memory bias in adolescents with chronic pain: examining the relationship with neural, stress, and psychological factors

ABSTRACT

Memory biases for pain-related information may contribute to the development and maintenance of chronic pain; however, evidence for when (and for whom) these biases occur is mixed. Therefore, we examined neural, stress, and psychological factors that could influence memory bias, focusing on memories that motivate disabling behaviors: pain perception, conditioned responses to threat-and-safety cues, and responses to aversive nonnoxious stimuli. Two studies were conducted with adolescents with and without chronic pain. Data from 58 participants were included in study 1 (chronic pain n = 34, pain free n = 24, mean age = 16 years), and 39 participants were included in study 2 (chronic pain n = 26, pain free n = 13, mean age = 16 years). Both studies used a threat-safety learning paradigm with memory recall (≈1 month later). Participants completed structural and functional (resting-state) magnetic resonance imaging, salivary cortisol measurements, and self-report measures. Adolescents with pain and pain-free peers consistently recalled being more afraid of safety cues (CS-) and, during heightened stress at encoding (higher cortisol levels), also reported being more afraid of threat cues (CS+). However, no memory bias was present for the emotional response to an aversive stimulus (US; loud scream) or for the recall of pain intensity. Functional connectivity of the amygdala and hippocampus with memory circuits related to the degree of memory bias, but the specific connections varied between the studies, and we observed no relationship between memory bias and brain morphology. Our findings highlight the value of considering the interaction between implicit and explicit memory systems, contributing to a more comprehensive understanding of emotional memory biases in the context of chronic pain.

Anxiety and Depression in Youth With Chronic Pain: A Systematic Review and Meta-Analysis

Importance

For youth with chronic pain, anxiety and depression are reported as consequences of experiencing pain and maintaining factors of ongoing pain and disability. However, prevalence estimates of anxiety and depression remain unclear.

Objective

To report the prevalence of clinical anxiety and depression for youth with chronic pain and compare symptoms of anxiety and depression between youth with and without chronic pain.

Data Sources

MEDLINE, PsycINFO, CENTRAL, and Embase from inception to April 30, 2023.

Study Selection

Included studies that reported prevalence data or symptom scores for anxiety and/or depression in individuals younger than 25 years (mean, ≤18 years) with chronic pain and were published in English.

Data Extraction and Synthesis

From 9648 nonduplicate records, 801 full-text articles were screened. Screening and data extraction occurred in duplicate. Prevalence was determined using event rate calculations. Between-group symptom differences were calculated using Hedges g. Analyses were conducted using the random-effects model. Reporting bias and Grading of Recommendation, Assessment, Development, and Evaluation assessments were conducted.

Main Outcomes and Measures

Prevalence of anxiety and depression (based on diagnosis and clinical cutoff scores) and differences in anxiety and depression symptoms. Moderators of prevalence and symptom differences were analyzed when data allowed.

Results

A total of 79 studies were included with a total sample of 22 956 youth (n = 12 614 with chronic pain). Most youth were female (mean, 74%), with an age range of 4 to 24 (mean [SD], 13.7 [2.10]) years. The prevalence estimate of anxiety diagnoses was 34.6% (95% CI, 24.0%-47.0%) and the portion that exceeded clinical cutoff scores was 23.9% (95% CI, 18.3%-30.6%). The prevalence of depression diagnoses was 12.2% (95% CI, 7.8%-18.7%) and the portion that exceeded clinical cutoff scores was 23.5% (95% CI, 18.7%-29.2%). Youth with chronic pain had greater symptoms of anxiety (g = 0.61; 95% CI, 0.46-0.77) and depression (g = 0.74; 95% CI, 0.63-0.85) compared with controls. Sex, age, pain location, and recruitment sample may moderate anxiety and depression. Considerable heterogeneity was reported for all outcomes. Studies had a low reporting bias, and outcomes were moderate to high quality.

Conclusions and Relevance

The findings of this meta-analysis suggest that 1 in 3 youth with chronic pain meet criteria for anxiety disorder, and 1 in 8 meet criteria for a depressive disorder. This represents a major clinical comorbidity. Moving forward, screening, prevention, and treatment of mental health should be important health care priorities for youth with chronic pain.

Probing white matter microstructure in youth with chronic pain and its relation to catastrophizing using neurite orientation dispersion and density imaging

ABSTRACT

Chronic pain is common in young people and can have a major life impact. Despite the burden of chronic pain, mechanisms underlying chronic pain development and persistence are still poorly understood. Specifically, white matter (WM) connectivity has remained largely unexplored in pediatric chronic pain. Using diffusion-weighted imaging, this study examined WM microstructure in adolescents (age M = 15.8 years, SD = 2.8 years) with chronic pain (n = 44) compared with healthy controls (n = 24). Neurite orientation dispersion and density imaging modeling was applied, and voxel-based whole-white-matter analyses were used to obtain an overview of potential alterations in youth with chronic pain and tract-specific profile analyses to evaluate microstructural profiles of tracts of interest more closely. Our main findings are that (1) youth with chronic pain showed widespread elevated orientation dispersion compared with controls in several tracts, indicative of less coherence; (2) signs of neurite density tract-profile alterations were observed in several tracts of interest, with mainly higher density levels in patients; and (3) several WM microstructural alterations were associated with pain catastrophizing in the patient group. Implicated tracts include both those connecting cortical and limbic structures (uncinate fasciculus, cingulum, anterior thalamic radiation), which were associated with pain catastrophizing, as well as sensorimotor tracts (corticospinal tract). By identifying alterations in the biologically informative WM microstructural metrics orientation dispersion and neurite density, our findings provide important and novel mechanistic insights for understanding the pathophysiology underlying chronic pain. Taken together, the data support alterations in fiber organization as a meaningful characteristic, contributing process to the chronic pain state.

Top-down threat bias in pain perception is predicted by higher segregation between resting-state networks

Top-down processes such as expectations have a strong influence on pain perception. Predicted threat of impending pain can affect perceived pain even more than the actual intensity of a noxious event. This type of threat bias in pain perception is associated with fear of pain and low pain tolerance, and hence the extent of bias varies between individuals. Large-scale patterns of functional brain connectivity are important for integrating expectations with sensory data. Greater integration is necessary for sensory integration; therefore, here we investigate the association between system segregation and top-down threat bias in healthy individuals. We show that top-down threat bias is predicted by less functional connectivity between resting-state networks. This effect was significant at a wide range of network thresholds and specifically in predefined parcellations of resting-state networks. Greater system segregation in brain networks also predicted higher anxiety and pain catastrophizing. These findings highlight the role of integration in brain networks in mediating threat bias in pain perception.

Application of PainDETECT in pediatric chronic pain: how well does it identify neuropathic pain and its characteristics?

Introduction

Neuropathic pain (NP) arises from nerve damage or disease, and when not defined, it can impair function and quality of life. Early detection allows for interventions that can enhance outcomes. Diagnosis of NP can be difficult if not properly evaluated. PainDETECT is a NP screening tool developed and successfully used in adults.

Objectives

We evaluated the validity of painDETECT in a pediatric population.

Methods

Adolescents and young adults (10-19 years old) completed painDETECT and quantitative sensory testing (QST), which assessed mechanical allodynia and hyperalgesia, common symptoms of NP. Pain diagnoses, including neuropathic pain (n = 10), were collected through documentation in the medical chart. Descriptive statistics were used to examine age, gender, pain diagnoses, and painDETECT scores. Kruskal-Wallis H tests were conducted to examine differences in QST results across painDETECT categorizations.

Results

Youth with chronic pain (N = 110, Mage = 15.08 ± 2.4 years, Nfemale = 88) and peers without pain (N = 55, Mage = 15.84 ± 3.9 years, Nfemale = 39) completed the painDETECT. The painDETECT scores for youth with pain (M = 12.7 ± 6.76) were significantly higher than those for peers without pain (M = 2.05 ± 2.41). PainDETECT demonstrated 80% sensitivity and 33% specificity in a pediatric population. Individuals who screened positively on the PainDETECT had significantly higher mechanical allodynia (M = 0.640 ± 0.994) compared with those who screened negatively (M = 0.186 ± 0.499; P = 0.016).

Conclusion

PainDETECT demonstrated the ability to screen for NP, and QST mechanical allodynia results were consistent with a positive NP screen. Results of the study offer preliminary support for the ongoing assessment of the painDETECT as a brief, inexpensive, and simple-to-use screening tool for pediatric patients with primary pain complaints.

Altered anterior insula functional connectivity in adolescent and young women with endometriosis-associated pain: Pilot resting-state fMRI study

BACKGROUND

Endometriosis is the leading cause of chronic pelvic pain. Alterations in brain functional connectivity have been reported in adult women with endometriosis-associated pain (EAP), however, it is still unknown if similar patterns of changes exist in adolescents.

METHODS

In this pilot study, resting-state fMRI scans were obtained from 11 adolescent and young women with EAP and 14 healthy female controls. Using a seed-to-voxel approach, we investigated functional connectivity between the anterior insula, medial prefrontal cortex, and the rest of the brain. Furthermore, we explored whether potential functional connectivity differences were correlated with clinical characteristics including disease duration, pain intensity, and different psychosocial factors (pain catastrophizing, fear of pain, functional disability, anxiety, and depression).

RESULTS

Our findings revealed that patients with EAP demonstrated significantly decreased connectivity between the right anterior insula and two clusters: one in the right cerebellum, and one in the left middle frontal gyrus compared to controls. Additionally, functional connectivity between the right anterior insula and the right cerebellum was positively associated with pain intensity levels. In patients with EAP, brain changes were also correlated with state anxiety and fear of pain.

CONCLUSIONS

Our results are relevant not only for understanding the brain characteristics underlying EAP at a younger age, but also in enhancing future pain treatment efforts by supporting the involvement of the central nervous system in endometriosis.

Top-down threat bias in pain perception is predicted by intrinsic structural and functional connections of the brain

Top-down processes such as expectations play a key role in pain perception. In specific contexts, inferred threat of impending pain can affect perceived pain more than the noxious intensity. This biasing effect of top-down threats can affect some individuals more strongly than others due to differences in fear of pain. The specific characteristics of intrinsic brain characteristics that mediate the effects of top-down threat bias are mainly unknown. In this study, we examined whether threat bias is associated with structural and functional brain connectivity. The variability in the top-down bias was mapped to the microstructure of white matter in diffusion weighted images (DWI) using MRTrix3. Mean functional connectivity of five canonical resting state networks was tested for association with bias scores and with the identified DWI metrics. We found that the fiber density of the splenium of the corpus callosum was significantly low in individuals with high top-down threat bias (FWE corrected with 5000 permutations, p < 0.05). The mean functional connectivity within the language/memory and between language/memory and default mode networks predicted the bias scores. Functional connectivity within language memory networks predicted the splenium fiber density, higher pain catastrophizing and lower mindful awareness. Probabilistic tractography showed that the identified region in the splenium connected several sensory regions and high-order parietal regions between the two hemispheres, indicating the splenium's role in sensory integration. These findings demonstrate that individuals who show more change in pain with changes in the threat of receiving a stronger noxious stimulus have lower structural connectivity in the pathway necessary for integrating top-down cue information with bottom-up sensory information. Conversely, systems involved in memory recall, semantic and self-referential processing are more strongly connected in people with top-down threat bias.

Processing of pain by the developing brain: evidence of differences between adolescent and adult females

ABSTRACT

Adolescence is a sensitive period for both brain development and the emergence of chronic pain particularly in females. However, the brain mechanisms supporting pain perception during adolescence remain unclear. This study compares perceptual and brain responses to pain in female adolescents and adults to characterize pain processing in the developing brain. Thirty adolescent (ages 13-17 years) and 30 adult (ages 35-55 years) females underwent a functional magnetic resonance imaging scan involving acute pain. Participants received 12 ten-second noxious pressure stimuli that were applied to the left thumbnail at 2.5 and 4 kg/cm 2 , and rated pain intensity and unpleasantness on a visual analogue scale. We found a significant group-by-stimulus intensity interaction on pain ratings. Compared with adults, adolescents reported greater pain intensity and unpleasantness in response to 2.5 kg/cm 2 but not 4 kg/cm 2 . Adolescents showed greater medial-lateral prefrontal cortex and supramarginal gyrus activation in response to 2.5 kg/cm 2 and greater medial prefrontal cortex and rostral anterior cingulate responses to 4 kg/cm 2 . Adolescents showed greater pain-evoked responses in the neurologic pain signature and greater activation in the default mode and ventral attention networks. Also, the amygdala and associated regions played a stronger role in predicting pain intensity in adolescents, and activity in default mode and ventral attention regions more strongly mediated the relationship between stimulus intensity and pain ratings. This study provides first evidence of greater low-pain sensitivity and pain-evoked brain responses in female adolescents (vs adult women) in regions important for nociceptive, affective, and cognitive processing, which may be associated with differences in peripheral nociception.

Amygdalar Functional Connectivity Differences Associated With Reduced Pain Intensity in Pediatric Peripheral Neuropathic Pain

Background

There is evidence of altered corticolimbic circuitry in adults with chronic pain, but relatively little is known of functional brain mechanisms in adolescents with neuropathic pain (NeuP). Pediatric NeuP is etiologically and phenotypically different from NeuP in adults, highlighting the need for pediatric-focused research. The amygdala is a key limbic region with important roles in the emotional-affective dimension of pain and in pain modulation.

Objective

To investigate amygdalar resting state functional connectivity (rsFC) in adolescents with NeuP.

Methods

This cross-sectional observational cohort study compared resting state functional MRI scans in adolescents aged 11–18 years with clinical features of chronic peripheral NeuP (n = 17), recruited from a tertiary clinic, relative to healthy adolescents (n = 17). We performed seed-to-voxel whole-brain rsFC analysis of the bilateral amygdalae. Next, we performed post hoc exploratory correlations with clinical variables to further explain rsFC differences.

Results

Adolescents with NeuP had stronger negative rsFC between right amygdala and right dorsolateral prefrontal cortex (dlPFC) and stronger positive rsFC between right amygdala and left angular gyrus (AG), compared to controls (P_FDR<0.025). Furthermore, lower pain intensity correlated with stronger negative amygdala-dlPFC rsFC in males (r = 0.67, P = 0.034, n = 10), and with stronger positive amygdala-AG rsFC in females (r = −0.90, P = 0.006, n = 7). These amygdalar rsFC differences may thus be pain inhibitory.

Conclusions

Consistent with the considerable affective and cognitive factors reported in a larger cohort, there are rsFC differences in limbic pain modulatory circuits in adolescents with NeuP. Findings also highlight the need for assessing sex-dependent brain mechanisms in future studies, where possible.

Amygdala functional connectivity mediates the association between catastrophizing and threat-safety learning in youth with chronic pain

ABSTRACT

There is a need to identify brain connectivity alterations predictive of transdiagnostic processes that may confer vulnerability for affective symptomology. Here, we tested whether amygdala resting-state functional connectivity (rsFC) mediated the relationship between catastrophizing (negative threat appraisals and predicting poorer functioning) and altered threat-safety discrimination learning (critical to flexibly adapt to new and changing environments) in adolescents with persistent pain. We examined amygdala rsFC in 46 youth with chronic pain and 29 healthy peers (age M = 15.8, SD = 2.9; 64 females) and its relationship with catastrophizing and threat-safety learning. We used a developmentally appropriate threat-safety learning paradigm and performed amygdala seed-based rsFC and whole-brain mediation analyses. Patients exhibited enhanced connectivity between the left amygdala and right supramarginal gyrus (SMG) (cluster-level P-FDR < 0.05), whereas right amygdala rsFC showed no group differences. Only in patients, elevated catastrophizing was associated with facilitated threat-safety learning (CS+>CS-; rp = 0.49, P = 0.001). Furthermore, in patients, elevated catastrophizing was associated with reduced left amygdala connectivity with SMG / parietal operculum, and increased left amygdala connectivity with hippocampus, dorsal striatum, paracingulate, and motor regions (P < 0.001). In addition, blunted left amygdala rsFC with right SMG/parietal operculum mediated the association between catastrophizing and threat-safety learning (P < 0.001). To conclude, rsFC between the left amygdala (a core emotion hub) and inferior parietal lobe (involved in appraisal and integration of bodily signals and attentional reorienting) explains associations between daily-life relevant catastrophizing and threat-safety learning. Findings provide a putative model for understanding pathophysiology involved in core psychological processes that cut across diagnoses, including disabling pain, and are relevant for their etiology.

Exposure in Vivo as a Treatment Approach to Target Pain-Related Fear: Theory and New Insights From Research and Clinical Practice

Pain-related fear (PRF) can be a significant factor contributing to the development and maintenance of pain-related disability in individuals with persistent pain. One treatment approach to target PRF and related avoidance behavior is exposure in vivo (EXP). EXP has a long history in the field of anxiety, a field that is constantly evolving. This Perspective outlines recent theoretical advancements and how they apply to EXP for PRF, including suggestions for how to optimize inhibitory learning during EXP; reviews mechanistic work from neuroimaging supporting the targeting of PRF in people with chronic pain; and focuses on clinical applications of EXP for PRF, as EXP is moving into new directions regarding who is receiving EXP (eg, EXP in chronic secondary pain) and how treatment is provided (EXP in primary care with a crucial role for physical therapists). Considerations are provided regarding challenges, remaining questions, and promising future perspectives.

IMPACT

For patients with chronic pain who have elevated pain-related fear (PRF), exposure is the treatment of choice. This Perspective highlights the inhibitory learning approach, summarizes mechanistic work from experimental psychology and neuroimaging regarding PRF in chronic pain, and describes possible clinical applications of EXP in chronic secondary pain as well as in primary care.

Safety learning during development: Implications for development of psychopathology

Fear and safety learning are necessary adaptive behaviors that develop over the course of maturation. While there is a large body of literature regarding the neurobiology of fear and safety learning in adults, less is known regarding safety learning during development. Given developmental changes in the brain, there are corresponding changes in safety learning that are quantifiable; these may serve to predict risk and point to treatment targets for fear and anxiety-related disorders in children and adolescents. For healthy, typically developing youth, the main developmental variation observed is reduced discrimination between threat and safety cues in children compared to adolescents and adults, while lower expression of extinction learning is exhibited in adolescents compared to adults. Such distinctions may be related to faster maturation of the amygdala relative to the prefrontal cortex, as well as incompletely developed functional circuits between the two. Fear and anxiety-related disorders, childhood maltreatment, and behavioral problems are all associated with alterations in safety learning for youth, and this dysfunction may proceed into adulthood with corresponding abnormalities in brain structure and function-including amygdala hypertrophy and hyperreactivity. As impaired inhibition of fear to safety may reflect abnormalities in the developing brain and subsequent psychopathology, impaired safety learning may be considered as both a predictor of risk and a treatment target. Longitudinal neuroimaging studies over the course of development, and studies that query change with interventions are needed in order to improve outcomes for individuals and reduce long-term impact of developmental psychopathology.

Do Parental Pain Knowledge, Catastrophizing, and Hypervigilance Improve Following Pain Neuroscience Education in Healthy Children?

Pediatric chronic pain is a challenging problem for children and their families, although it is still under-recognized and under-treated. The aim of this study was to investigate whether a pain neuroscience education program for children (PNE4Kids) delivered to healthy children aged 8 to 12 years old and attended by their parents would result in improved parental knowledge about pain neurophysiology, decreased parental pain catastrophizing about their own pain and their children's, decreased parental pain vigilance and awareness, and decreased fear of pain in children. Twenty-seven healthy child-parent dyads received a 45 min PNE4Kids session. Demographic data were collected, and the Neurophysiology of Pain Questionnaire (NPQ), Fear of Pain Questionnaire-Parent Proxy Report (FOPQ-P), Pain Catastrophizing Scale (PCS), Pain Catastrophizing Scale for Parents (PCS-P), and the Pain Vigilance and Awareness Questionnaire (PVAQ) were completed by the parents before and after the PNE4Kids session. Twenty-six dyads completed study participation. In response to the PNE4Kids session, significant short-term (1 week) improvements were shown in the NPQ (p < 0.001) and the FOPQ-P (p = 0.002). Parents' level of pain knowledge and children's fear of pain, reported by their parents, improved after a 45 min PNE4Kids session. Thus, PNE4Kids should likewise be further investigated in healthy child-parent dyads as it might be useful to target parental and children's pain cognitions at a young age.

Neuropathic pain in children: Steps towards improved recognition and management

Neuropathic pain in children can be severe and persistent, difficult to recognise and manage, and associated with significant pain-related disability. Recognition based on clinical history and sensory descriptors is challenging in young children, and screening tools require further validation at older ages. Confirmatory tests can identify the disease or lesion of the somatosensory nervous system resulting in neuropathic pain, but feasibility and interpretation may be influenced by age- and sex-dependent changes throughout development. Quantitative sensory testing identifies specific mechanism-related sensory profiles; brain imaging is a potential biomarker of alterations in central processing and modulation of both sensory and affective components of pain; and genetic analysis can reveal known and new causes of neuropathic pain. Alongside existing patient- and parent-reported outcome measures, somatosensory system research methodologies and validation of mechanism-based standardised end-points may inform individualised therapy and stratification for clinical trials that will improve evidence-based management of neuropathic pain in children.

Learning to predict pain: differences in people with persistent neck pain and pain-free controls

Background

Learning to predict threatening events enables an organism to engage in protective behavior and prevent harm. Failure to differentiate between cues that truly predict danger and those that do not, however, may lead to indiscriminate fear and avoidance behaviors, which in turn may contribute to disability in people with persistent pain. We aimed to test whether people with persistent neck pain exhibit contingency learning deficits in predicting pain relative to pain-free, gender-and age-matched controls.

Method

We developed a differential predictive learning task with a neck pain-relevant scenario. During the acquisition phase, images displaying two distinct neck positions were presented and participants were asked to predict whether these neck positions would lead to pain in a fictive patient with persistent neck pain (see fictive patient scenario details in Appendix A). After participants gave their pain-expectancy judgment in the hypothetical scenario, the verbal outcome (PAIN or NO PAIN) was shown on the screen. One image (CS+) was followed by the outcome “PAIN”, while another image (CS−) was followed by the outcome “NO PAIN”. During the generalization phase, novel but related images depicting neck positions along a continuum between the CS+ and CS− images (generalization stimuli; GSs) were introduced to assess the generalization of acquired predictive learning to the novel images; the GSs were always followed by the verbal outcome “NOTES UNREADABLE” to prevent extinction learning. Finally, an extinction phase was included in which all images were followed by “NO PAIN” assessing the persistence of pain-expectancy judgments following disconfirming information.

Results

Differential pain-expectancy learning was reduced in people with neck pain relative to controls, resulting from patients giving significantly lower pain-expectancy judgments for the CS+, and significantly higher pain-expectancy judgments for the CS−. People with neck pain also demonstrated flatter generalization gradients relative to controls. No differences in extinction were noted.

Discussion

The results support the hypothesis that people with persistent neck pain exhibit reduced differential pain-expectancy learning and flatter generalization gradients, reflecting deficits in predictive learning. Contrary to our hypothesis, no differences in extinction were found. These findings may be relevant to understanding behavioral aspects of chronic pain.

Stuck on pain? Assessing children's vigilance and awareness of pain sensations

BACKGROUND

Attending towards pain is proposed as a key mechanism influencing the experience and chronification of pain. Persistent attention towards pain is proposed to drive poor outcomes in both adults and children with chronic pain. However, there are no validated self-report measures of pain-related attention for children.

METHODS

The goals of this study were to adapt the Pain Vigilance and Awareness Questionnaire (PVAQ) for use in a child sample, to preliminary examine its psychometric properties, and to assess its utility over and above a measure of general attentional capacities. We adapted the language of the PVAQ to be more easily understood by children as young as 8 years. In a sample of 160 children (8-18 years) with chronic pain, we examined the factor structure, internal consistency and criterion validity of the PVAQ-C.

RESULTS

The PVAQ-C demonstrated excellent internal consistency (α = 0.92) and moderate-to-strong criterion validity. A one-factor structure best fit the data. Children who reported greater attention to pain also reported greater pain catastrophizing, fear of pain, avoidance of activities and poorer physical functioning. Pain-related attention remained a significant predictor of functioning while controlling for demographics, catastrophizing and fear-avoidance. Pain-related attention also significantly predicted child outcomes independent of the child's general attention control capacities, indicating added value of a pain-specific measure of attention.

CONCLUSIONS

The PVAQ-C shows strong indices of internal reliability and criterion validity, and indicates unique predictive utility. It will be important to study the role of pain-related attention in youth within developmental and functional-motivational frameworks.

SIGNIFICANCE

Pain-related attention is proposed as a key factor influencing fear-avoidance outcomes in both adults and youth with chronic pain, yet no self-report measures of pain-related attention have been validated for children. This paper presents a child version of the Pain Vigilance and Awareness Questionnaire (PVAQ-C), which indicates strong internal consistency, criterion validity and unique predictive validity, and provides evidence to support the Fear-Avoidance Model in youth with chronic pain.