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(262) Increased Heat Pain Sensitivity and Pain-Related Anxiety in Individuals with Autism
S40 The Journal of Pain examined these competing hypotheses in healthy, pain-free participants using a well-validated picture viewing paradigm (ie, Emotional Controls of Nociception, ECON). ECON is a paradigm in which painful, electrocutaneous stimulations are delivered during and in between pictures of emotional content (mutilation, neutral, and erotica). Pain ratings were assessed in response to electric stimuli. This allows for the assessment of emotional modulation of pain by comparing pain evoked during mutilation and erotic pictures to pain evoked during neutral pictures. Additionally, ECON allows for the assessment of attentional modulation of pain by comparing pain evoked during neutral pictures (distraction) to pain evoked in the absence of pictures (control). Prior to ECON, participants filled out the Anger Expression Inventory to assess their tendency to inhibit anger and 2 groups were formed (high anger-in, N = 71 and low anger-in, N = 27) from their responses (ie, +/- 1SD from the normative mean of anger-in). Results found that both groups demonstrated similar emotional modulation of pain. By contrast, persons in the low anger-in group displayed attentional modulation of pain, whereas persons in the high anger-in group failed to attentionally modulate pain. These findings suggest that cognitive resource deficits in high anger-in individuals may contribute to increased pain risk.
(262) Increased Heat Pain Sensitivity and Pain-Related Anxiety in Individuals with Autism
Abstracts impaired descending pain inhibition. The present study examined whether the efficiency of descending inhibition (as measured by conditioned pain modulation, CPM) predicted future chronic pain onset in a sample of participants who were healthy and pain-free at the time of enrollment in OK-SNAP. Chronic pain onset was determined prospectively from follow-up surveys administered every 6-months following enrollment. Of the 139 Native American (NA) and 147 non-Hispanic white (NHW) participants enrolled, 208 (73%) responded to ≥1 follow-up. Participants were said to have developed chronic pain if they experienced persistent pain for >3 months and the pain did not remit at subsequent follow-ups (N=34, 16%). 174 persons did not develop chronic pain. CPM was assessed from painful electric stimulations delivered before and during hand/forearm submersion in 108C water. Pain ratings and nociceptive flexion reflexes (NFR; correlate of spinal nociception) were assessed in response to electric stimuli. CPM efficiency = change in pain/NFR. CPM of pain and NFR were entered as predictors in a logistic regression that controlled for race (NA vs. NHW), age, BMI, sex, general health, depression, anxiety, and somatization. Interactions between race and CPM efficiency were examined as well. Results found less efficient CPM of NFR (OR=6.53, 95%CI: 1.04, 40.95) and more depressive symptoms (OR=10.22, 95%CI: 1.28, 81.36) at enrollment predicted chronic pain onset. The model explained 34.5% of the variance (Nagelkerke R2=.345). Interactions of CPM variables with race were not significant. These findings imply that impaired descending inhibition of spinal nociception (NFR) may play a role in the development of chronic pain.
M. Failla, S. Davis, M. Gerdes, Z. Williams, D. Moore, and C. Cascio; Vanderbilt University Medical Center, Nashville, TN Pain-related anxiety can contribute to increased pain sensitivity and create a barrier to receiving routine medical care. For individuals with autism spectrum disorders (ASD), behavioral response patterns suggest increased pain sensitivity. Neuroimaging studies in ASD suggest altered evaluation or emotional processing of pain which could contribute to pain-related anxiety. However, the relationship between pain sensitivity and pain-related anxiety is not clear in ASD. We hypothesized that individuals with ASD would report higher pain intensity during supra-threshold pain stimuli and endorse more painrelated anxiety, compared to a typical comparison group. We recruited 29 adults (ASD, n=15; TD, n=14) for a series of heat pain tasks (applied to the calf), including heat pain thresholds using a method of limits approach and two supra-threshold tasks. We examined supra-threshold pain using a pain-rating curve, where 7 temperatures (40-48°C) were presented for 5s (5 trials each), and a sustained heat pain task with alternating low (42°C) and high (46°C) temperatures for 21s (6 trials each, 30s inter-trial rest). Pain-related anxiety was assessed using the Pain Anxiety Symptoms Scale-20 (PASS), Fear of Pain Questionnaire-III (FOP-III), and the Situational Pain Catastrophizing Scale (regarding the sustained pain task). While there were no group differences in pain thresholds, mean pain ratings were higher in the ASD group for all temperatures in the pain rating curve (all p<0.05) and in the sustained heat task (both levels, p<0.05). Pain anxiety (PASSTotal) and pain-related fear (FOP-III-Total) were higher in the ASD group (p<0.05 for both), but there were no group differences in situational pain catastrophizing. Pain anxiety symptoms did not significantly correlate with pain ratings. These data suggest greater pain sensitivity and significant painrelated anxiety in ASD, but the relationship between the two constructs remains unclear. Future studies should evaluate the impact of pain-related anxiety on treatment-seeking and adherence behaviors in ASD.
(263) Less Efficient Endogenous Inhibition of Spinal Nociception Predicts Chronic Pain Onset: A Prospective Analysis from the Oklahoma Study of Native American Pain Risk (OK-SNAP) F. Huber, B. Kuhn, E. Lannon, C. Sturycz, M. Payne, N. Hellman, T. Toledo, Y. Gu€ereca, M. Demuth, S. Palit, J. Shadlow, and J. Rhudy; University of Tulsa, Tulsa, OK Chronic pain results in tremendous economic and psychological burden. Thus, an ability to identify individuals at risk for chronic pain onset could be an important first step in reducing this burden. One mechanism that may contribute to pain onset is
(264) Altered Brain Network Topology in Chronic Low Back Pain Patients on Prescription Opioid Analgesics B. Jarrahi and S. Mackey; Stanford University School of Medicine, Stanford, CA Opioid prescribing for chronic pain conditions such as Chronic Low Back Pain (CLBP) in the United States has increased substantially in the past two decades. However, the effects of opioid analgesics on the brain network topology in CLBP remains unknown. The present study therefore provides the first test of the hypothesis that opioid status impacts the activity of the whole-brain network using graph theory methods. Resting state fMRI data were collected on a 3T scanner from 10 CLBP patients on long-term opioid regimens (CLBP+; 5 males, mean age § SD = 48.5 § 14.8 years) and 10 matched opioid-na€ıve CLBP patients (CLBP-, 5 males, mean age § SD = 43.6 § 12.6 years) according to a protocol approved by the Stanford IRB. Following image quality assurance in MRIQC, and preprocessing in SPM12, we performed graph theoretical network analysis using CONN toolbox. For each participant, global network efficiency — a graph theory measure for integrative capacity of complex systems, was calculated and correlated with individual differences in sensory pain scores from Short Form McGill Pain Questionnaire (SF-MPQ). We focused on global efficiency as it reflects effective information transfer (i.e., small-worldness) within a network of nodes (i.e., regions of interests) and edges (i.e., correlation). Results revealed that the global efficiency values were positively correlated with pain in CLBP- but not in CLBP+ (r = 0.49 vs r = - 0.06, p = 0.05). This suggests that as sensory dimension of the pain intensity increased, CLBP- exhibited more efficient information transfer across a network of brain regions, including the core nodes of the salience network (anterior insula), frontoparietal central executive network (dorsolateral prefrontal cortices), and bilateral sensorimotor networks. Follow up studies with larger sample size are required to corroborate these observations and to formulate appropriate strategies for opioid prescribing guidelines, accordingly. Supported by NIH P01AT006651, and NIH T32DA035165.
(265) The Relationship between Discrimination and Pain Tolerance and its Potential Mediation by Stress: Results from the Oklahoma Study of Native American Pain Risk (OK-SNAP)
Y. Gu€ereca, B. Kuhn, E. Lannon, S. Palit, C. Sturycz, M. Payne, N. Hellman, T. Toledo, F. Huber, M. Demuth, J. Shadlow, and J. Rhudy; University of Tulsa, Tulsa, OK Compared to other racial/ethnic minority groups, Native Americans (NAs) are more likely to report experiences of discrimination and also have the highest prevalence of pain conditions.
(262) Increased Heat Pain Sensitivity and Pain-Related Anxiety in Individuals with Autism
Abstracts impaired descending pain inhibition. The present study examined whether the efficiency of descending inhibition (as measured by conditioned pain modulation, CPM) predicted future chronic pain onset in a sample of participants who were healthy and pain-free at the time of enrollment in OK-SNAP. Chronic pain onset was determined prospectively from follow-up surveys administered every 6-months following enrollment. Of the 139 Native American (NA) and 147 non-Hispanic white (NHW) participants enrolled, 208 (73%) responded to ≥1 follow-up. Participants were said to have developed chronic pain if they experienced persistent pain for >3 months and the pain did not remit at subsequent follow-ups (N=34, 16%). 174 persons did not develop chronic pain. CPM was assessed from painful electric stimulations delivered before and during hand/forearm submersion in 108C water. Pain ratings and nociceptive flexion reflexes (NFR; correlate of spinal nociception) were assessed in response to electric stimuli. CPM efficiency = change in pain/NFR. CPM of pain and NFR were entered as predictors in a logistic regression that controlled for race (NA vs. NHW), age, BMI, sex, general health, depression, anxiety, and somatization. Interactions between race and CPM efficiency were examined as well. Results found less efficient CPM of NFR (OR=6.53, 95%CI: 1.04, 40.95) and more depressive symptoms (OR=10.22, 95%CI: 1.28, 81.36) at enrollment predicted chronic pain onset. The model explained 34.5% of the variance (Nagelkerke R2=.345). Interactions of CPM variables with race were not significant. These findings imply that impaired descending inhibition of spinal nociception (NFR) may play a role in the development of chronic pain.
M. Failla, S. Davis, M. Gerdes, Z. Williams, D. Moore, and C. Cascio; Vanderbilt University Medical Center, Nashville, TN Pain-related anxiety can contribute to increased pain sensitivity and create a barrier to receiving routine medical care. For individuals with autism spectrum disorders (ASD), behavioral response patterns suggest increased pain sensitivity. Neuroimaging studies in ASD suggest altered evaluation or emotional processing of pain which could contribute to pain-related anxiety. However, the relationship between pain sensitivity and pain-related anxiety is not clear in ASD. We hypothesized that individuals with ASD would report higher pain intensity during supra-threshold pain stimuli and endorse more painrelated anxiety, compared to a typical comparison group. We recruited 29 adults (ASD, n=15; TD, n=14) for a series of heat pain tasks (applied to the calf), including heat pain thresholds using a method of limits approach and two supra-threshold tasks. We examined supra-threshold pain using a pain-rating curve, where 7 temperatures (40-48°C) were presented for 5s (5 trials each), and a sustained heat pain task with alternating low (42°C) and high (46°C) temperatures for 21s (6 trials each, 30s inter-trial rest). Pain-related anxiety was assessed using the Pain Anxiety Symptoms Scale-20 (PASS), Fear of Pain Questionnaire-III (FOP-III), and the Situational Pain Catastrophizing Scale (regarding the sustained pain task). While there were no group differences in pain thresholds, mean pain ratings were higher in the ASD group for all temperatures in the pain rating curve (all p<0.05) and in the sustained heat task (both levels, p<0.05). Pain anxiety (PASSTotal) and pain-related fear (FOP-III-Total) were higher in the ASD group (p<0.05 for both), but there were no group differences in situational pain catastrophizing. Pain anxiety symptoms did not significantly correlate with pain ratings. These data suggest greater pain sensitivity and significant painrelated anxiety in ASD, but the relationship between the two constructs remains unclear. Future studies should evaluate the impact of pain-related anxiety on treatment-seeking and adherence behaviors in ASD.
(263) Less Efficient Endogenous Inhibition of Spinal Nociception Predicts Chronic Pain Onset: A Prospective Analysis from the Oklahoma Study of Native American Pain Risk (OK-SNAP) F. Huber, B. Kuhn, E. Lannon, C. Sturycz, M. Payne, N. Hellman, T. Toledo, Y. Gu€ereca, M. Demuth, S. Palit, J. Shadlow, and J. Rhudy; University of Tulsa, Tulsa, OK Chronic pain results in tremendous economic and psychological burden. Thus, an ability to identify individuals at risk for chronic pain onset could be an important first step in reducing this burden. One mechanism that may contribute to pain onset is
(264) Altered Brain Network Topology in Chronic Low Back Pain Patients on Prescription Opioid Analgesics B. Jarrahi and S. Mackey; Stanford University School of Medicine, Stanford, CA Opioid prescribing for chronic pain conditions such as Chronic Low Back Pain (CLBP) in the United States has increased substantially in the past two decades. However, the effects of opioid analgesics on the brain network topology in CLBP remains unknown. The present study therefore provides the first test of the hypothesis that opioid status impacts the activity of the whole-brain network using graph theory methods. Resting state fMRI data were collected on a 3T scanner from 10 CLBP patients on long-term opioid regimens (CLBP+; 5 males, mean age § SD = 48.5 § 14.8 years) and 10 matched opioid-na€ıve CLBP patients (CLBP-, 5 males, mean age § SD = 43.6 § 12.6 years) according to a protocol approved by the Stanford IRB. Following image quality assurance in MRIQC, and preprocessing in SPM12, we performed graph theoretical network analysis using CONN toolbox. For each participant, global network efficiency — a graph theory measure for integrative capacity of complex systems, was calculated and correlated with individual differences in sensory pain scores from Short Form McGill Pain Questionnaire (SF-MPQ). We focused on global efficiency as it reflects effective information transfer (i.e., small-worldness) within a network of nodes (i.e., regions of interests) and edges (i.e., correlation). Results revealed that the global efficiency values were positively correlated with pain in CLBP- but not in CLBP+ (r = 0.49 vs r = - 0.06, p = 0.05). This suggests that as sensory dimension of the pain intensity increased, CLBP- exhibited more efficient information transfer across a network of brain regions, including the core nodes of the salience network (anterior insula), frontoparietal central executive network (dorsolateral prefrontal cortices), and bilateral sensorimotor networks. Follow up studies with larger sample size are required to corroborate these observations and to formulate appropriate strategies for opioid prescribing guidelines, accordingly. Supported by NIH P01AT006651, and NIH T32DA035165.
(265) The Relationship between Discrimination and Pain Tolerance and its Potential Mediation by Stress: Results from the Oklahoma Study of Native American Pain Risk (OK-SNAP)
Y. Gu€ereca, B. Kuhn, E. Lannon, S. Palit, C. Sturycz, M. Payne, N. Hellman, T. Toledo, F. Huber, M. Demuth, J. Shadlow, and J. Rhudy; University of Tulsa, Tulsa, OK Compared to other racial/ethnic minority groups, Native Americans (NAs) are more likely to report experiences of discrimination and also have the highest prevalence of pain conditions.