Laboratory Pain Responses Research Articles

Prediction of pain responses to subsequent cold pressor test via baseline heart rate variability in healthy adults.

Baseline heart rate variability (HRV) that reflects parasympathetic nervous system (PNS) activity may serve as an objective, physiological index of pain assessment, but more research is warranted to examine the link between HRV and laboratory pain responses. This study examined whether baseline HRV would predict pain responses to subsequent cold pressor test (CPT) in healthy adults. One hundred twenty-three participants completed resting HRV assessment and CPT consisting of immersing their right hand into a cold-water bath for a maximum of 2min. Pain threshold and pain rating were assessed during CPT. Completion status of CPT, defined as completing CPT or terminating CPT before 2 min, was recorded as an additional laboratory pain measure. Pearson's correlation analysis was performed to examine the link between HRV and pain responses, whereas regression analysis was performed to test the prediction of pain responses via baseline HRV. HF-HRVlog , which reflects PNS activity, was significantly associated with the CPT completion status (r=0.23, p=0.01), but not significantly associated with pain threshold (r=0.17, p=0.06) or pain rating (r=-0.11, p=0.24). HF- HRVlog was found to be a significant predictor of CPT completion status (B=0.53, p=0.013). Baseline HF- HRVlog may serve as an objective, physiological index to predict laboratory pain responses, and the completion status of laboratory pain tests, such as CPT, may be used as a laboratory pain measure to capture important individual differences in pain processing. A better understanding of how psychophysiology relates to human pain is important. We examined the association of baseline heart rate variability (HRV) with pain response to subsequently-administered cold pressor test (CPT) in healthy adults. We found that HF-HRVlog , which reflects parasympathetic nervous system activity, predicted the completion status (completion or termination) of CPT. Baseline HF-HRVlog may serve as an objective, physiological index of pain and the completion status of CPT may help assess the important individual differences in pain processing.

Pubertal Status Moderates the Association between Mother and Child Laboratory Pain Tolerance

There is limited information regarding the relationship between parent and child responses to laboratory pain induction in the absence of experimental manipulation. To assess the association between responses to cold and pressure pain tasks in 133 nonclinical mothers and children (mean age 13.0 years; 70 girls), and the moderating effects of child sex and pubertal status on these mother-child relationships. Mothers and children independently completed the cold and pressure pain tasks. Multiple linear regression analyses examined the association between mothers' and children's laboratory pain responses. The moderating effects of child sex and pubertal status were tested in the linear models by examining the interaction among mother laboratory pain responses, and child sex and pubertal status. Mothers' cold pain anticipatory anxiety and pressure pain intensity were associated with children's pressure pain anticipatory anxiety. Mothers' pressure pain tolerance was associated with children's pain tolerance for both the cold and pressure pain tasks. Mothers' cold pain tolerance was associated with children's pressure pain tolerance. Pubertal status moderated two of the three significant mother-child pain tolerance relationships, such that the associations held for early pubertal but not for late pubertal children. Sex did not moderate mother-child pain associations. The results indicate that mother-child pain relationships are centred primarily on pain avoidance behaviour, particularly among prepubertal children. These findings may inform interventions focused on pain behaviours, with a particular emphasis on mothers of prepubertal children, to reduce acute pain responses in their children.

Situational catastrophizing mediates laboratory pain responses in sickle cell disease patients

Situational catastrophizing mediates laboratory pain responses in sickle cell disease patients

Experimental Pain Responses in Children with Chronic Pain and in Healthy Children: How Do They Differ?

Extant research comparing laboratory pain responses of children with chronic pain with healthy controls is mixed, with some studies indicating lower pain responsivity for controls and others showing no differences. Few studies have included different pain modalities or assessment protocols. To compare pain responses among 26 children (18 girls) with chronic pain and matched controls (mean age 14.8 years), to laboratory tasks involving thermal heat, pressure and cold pain. Responses to cold pain were assessed using two different protocols: an initial trial of unspecified duration and a second trial of specified duration. Four trials of pressure pain and of thermal heat pain stimuli, all of unspecified duration, were administered, as well as the two cold pain trials. Heart rate and blood pressure were assessed at baseline and after completion of the pain tasks. Pain tolerance and pain intensity did not differ between children with chronic pain and controls for the unspecified trials. For the specified cold pressor trial, 92% of children with chronic pain completed the entire trial compared with only 61.5% of controls. Children with chronic pain exhibited a trend toward higher baseline and postsession heart rate and reported more anxiety and depression symptoms compared with control children. Contextual factors related to the fixed trial may have exerted a greater influence on pain tolerance in children with chronic pain relative to controls. Children with chronic pain demonstrated a tendency toward increased arousal in anticipation of and following pain induction compared with controls.

Healthcare utilization for pain in children and adolescents: a prospective study of laboratory and non-laboratory predictors of care-seeking

Few studies have focused on identifying predictors of medical consultation for pain in healthy children and adolescents. This investigation sought to identify parent and child laboratory and non-laboratory predictors of pediatric healthcare utilization for pain problems. Participants were 210 healthy children and adolescents (102 girls), aged 8-17 years who took part in a laboratory pain session. Three months after the laboratory session, participants were contacted by telephone to ascertain whether they had experienced pain and whether they had seen a healthcare professional for pain. Zero-order correlations among sociodemographic status, child laboratory pain responses, parent physical/mental health status and medical consultation for pain were conducted to identify relevant correlates of pediatric healthcare utilization; these correlates were subjected to multivariate analyses. Bivariate analyses indicated that higher anticipated pain and bother for the cold pressor task, as well as poorer parent physical health status, were associated with pediatric medical consultation for pain, but only among girls. Sequential logistic regression analyses controlling for child age indicated that only parent physical health status, not the laboratory indicators, significantly predicted healthcare consultation for pain among girls. No parent or child correlates of care-seeking for pain emerged for boys. The findings suggest that parents' perceived physical health plays a role in determining whether medical care is sought for pain complaints in healthy girls. These results suggest that interventions to assist parents in managing their own physical health problems could lead to reductions in medical consultation for girls' pain.

Sex differences in the associations among laboratory pain reactivity, parent health status, and health care utilization for pain in healthy children

Although women report more pain and are more likely to seek health care than men, such sex differences are less clear among children. We examined the relationships among laboratory pain responses, parent self-reported health status, and health care utilization (HCU) for pain in 167 healthy children (51.5% girls) aged 8-17 years (mean age = 12.5). Children participated in a laboratory pain session that included the cold pressor task (CPT), a heat task, and a pressure task. Children were subsequently telephoned and asked whether they had experienced any pain in the past 3 months and whether they had seen a health care professional for this pain.

Sex Differences in the Relationship Between Maternal Negative Life Events and Children's Laboratory Pain Responsivity

Previous research has demonstrated links between psychosocial factors, including negative life events (NLE) and pain in children. This study examined sex differences in the relationship among mother-reported NLE, child NLE, mother somatization, and children's laboratory pain responses for heat, cold, and pressure pain tasks. We predicted that maternal NLE would be moderately associated with girls' pain responses but would not be associated with boys' pain responses. Participants were 176 nonclinical children (89 boys) aged 8 to 18 years (mean = 12.2, SD = 2.7) and their mothers. Mothers and children completed questionnaires assessing their perceptions of NLE experienced in the previous 12 months. Contrary to predictions, maternal NLE were related to pain responses in both boys and girls, although in opposite directions. Thus, increased maternal stress was associated with increased pain responses in girls but with decreased pain responses in boys. In addition, the impact of maternal NLE was only apparent for heat and pain tasks, indicating differential effects for various types of pain. The current findings underscore the importance of family variables in understanding sex differences in children's pain. Future research is needed to examine the mechanisms within the parent-child relationship that contribute to sex-differentiated pain outcomes, particularly under conditions of exacerbated parental stress.

Sex differences in the association between cortisol concentrations and laboratory pain responses in healthy children

Research in adult populations has highlighted sex differences in cortisol concentrations and laboratory pain responses, with men exhibiting higher cortisol concentrations and reduced pain responses compared with women. Yet, less is known about the relationship of cortisol concentrations to pain in children. This study examined associations between sex, cortisol, and pain responses to laboratory pain tasks in children. Salivary cortisol samples from subjects aged 8 to 18 years were obtained at baseline after entering the laboratory (SCb), after the completion of all pain tasks (SC1), and at the end of the session (SC2), 20 minutes later. Blood cortisol samples were also taken after completion of the pain tasks (BC1) and at the end of the session (BC2), 20 minutes later. Subjects completed 3 counterbalanced laboratory pain tasks: pressure, heat, and cold pressor tasks. Pain measures included pain tolerance, and self-reported pain intensity and unpleasantness for all 3 tasks. The study included 235 healthy children and adolescents (119 boys, 116 girls; mean age, 12.7 years; range, 8-18 years; 109 [46.4%] were in early puberty; 94 [40.0%] white). Salivary and blood cortisol levels were highly correlated with each other. Salivary cortisol levels for the total sample and for boys and girls declined significantly from SCb to SC1 (P < 0.01), although there were no significant changes from SC1 to SC2. No significant sex differences in salivary or blood cortisol levels were evident at any assessment point. Separate examination of the cortisol-laboratory pain response relationships by sex (controlling for age and time of day) suggested different sex-specific patterns. Higher cortisol levels were associated with lower pain reactivity (ie, increased pressure tolerance) among boys compared with girls at SC1, SC2, and BC1 (SC1: r = 0.338, P = 0.003; SC2: r = 0.271, P = 0.020; and BC1: r = 0.261, P = 0.026). However, higher cortisol levels were related to higher pain response (ie, increased cold intensity [BC2: r = 0.229, P = 0.048] and unpleasantness [BC1: r = 0.237, P = 0.041]) in girls compared with boys. These findings suggest important sex differences in cortisol-pain relationships in children and adolescents. Cortisol levels were positively associated with increased pain tolerance in boys and increased pain sensitivity in girls.

Maternal Negative Life Events (NLE) and somatization: Relationship to children’s laboratory pain responses

Prior research has demonstrated that a number of psychosocial factors have been associated with the experience of pain in children. Such factors include the family system as a context within which NLE experienced by a family member may impact other family members through the transmission of stress as well as by modeling of responses to stressors. Additionally, characteristics and behaviors of a family member, such as somatization, may be transmitted to other members through similar processes. This study examined mother-experienced NLE, mother somatization, child age and child sex in relation to children’s responses to heat and pressure laboratory pain tasks in 165 healthy mother-child dyads [84 male; 8–17 years old (M=12.1, SD=2.6)].

Ethnic differences in responses to multiple experimental pain stimuli

A growing body of literature suggests that the experience of clinical pain differs across ethnocultural groups. Additionally, some evidence indicates greater sensitivity to experimentally induced pain among African Americans; however, most studies have included only one pain modality. This study examined ethnic differences in responses to multiple experimental pain stimuli, including heat pain, cold pressor pain, and ischemic pain. Heat pain threshold and tolerance, ratings of repetitive suprathreshold heat, and ischemic and cold pressor pain threshold and tolerance were assessed in 120 (62 African American, 58 white) healthy young adults. Also, several psychological instruments were administered. No ethnic group differences emerged for threshold measures, but African Americans had lower tolerances for heat pain, cold pressor pain and ischemic pain compared to whites. Ratings of intensity and unpleasantness for suprathreshold heat stimuli were significantly higher among African Americans. African Americans reported greater use of passive pain coping strategies and higher levels of hypervigilance. Controlling for passive pain coping did not account for group differences in pain responses, while controlling for hypervigilance rendered group differences in heat pain tolerance and ischemic pain tolerance non-significant. These findings demonstrate differences in laboratory pain responses between African Americans and whites across multiple stimulus modalities, and effect sizes for these differences in pain tolerance were moderate to large for suprathreshold measures. Hypervigilance partly accounted for group differences. Additional research to determine the mechanisms underlying these effects is warranted.

Role of anticipatory anxiety and anxiety sensitivity in children's and adolescents' laboratory pain responses.

To examine relationships among trait anxiety sensitivity, state task-specific anticipatory anxiety, and laboratory pain responses in healthy children and adolescents. Participants (N=118, 49.2% female, ages 8-18 years) completed a measure of anxiety sensitivity and rated anticipatory anxiety prior to undergoing thermal, pressure, and cold pain tasks. Linear and logistic regressions were used to test the hypothesis that anxiety sensitivity and anticipatory anxiety would predict incremental variance in pain response after controlling for sex, age, and anxious symptoms. Anticipatory anxiety accounted for 35-38% of unique variance in pain report across tasks, and 10% of unique variance in thermal tolerance. Anxiety sensitivity was unrelated to pain responses. Task-specific anxiety is an important predictor of pain report and, in certain cases, pain tolerance. Interventions designed to reduce task-specific anticipatory anxiety may help reduce pain responses in children and adolescents.

Assessment in nonverbal populations (infants, mentally impaired, etc.): The relationship of parents' negative life events to children's laboratory pain responses

Assessment in nonverbal populations (infants, mentally impaired, etc.): The relationship of parents' negative life events to children's laboratory pain responses

Individual differences in diffuse noxious inhibitory controls (DNIC): association with clinical variables

Laboratory pain research has been criticized as being irrelevant to the clinical experience of pain. Previous findings have been inconsistent with some studies suggesting that experimental pain responses may be related to the reported presence or severity of chronic pain, while others report no such associations. However, few of these studies assess a variety of laboratory pain responses, and none has assessed relationships between clinical pain and diffuse noxious inhibitory controls (DNIC) in healthy subjects. We administered questionnaire measures of pain, quality of life, and psychological variables to a sample of healthy adults participating in a laboratory study of age differences in pain responses. DNIC was not related to other laboratory pain responses, psychological variables, or physiological variables measured in the present study. Regression models predicting health-related quality of life (e.g. pain, physical functioning) revealed that age, sex, and DNIC responses explained between 10 and 25% of the variance in these dependent measures. Of the laboratory pain variables, only DNIC was the sole consistent predictor of clinical pain and physical health, with greater DNIC responses related to less pain, better physical functioning, and better self-rated health. In addition, age differences in DNIC appeared to partially mediate age differences in physical functioning. These findings highlight the potential clinical relevance of experimental pain procedures and suggest that DNIC may be the laboratory pain response most closely associated with clinical pain and health-related variables.

Sex-dependent effects of reported familial pain history on recent pain complaints and experimental pain responses

Previous research has demonstrated that both sex and familial pain history can influence clinical pain, and sex is known to affect experimental pain responses. However, the potential interactive effects of sex and family history on pain-related symptoms and experimental pain have not been investigated. This experiment examined recent pain complaints and laboratory pain responses as a function of sex and reported family history of pain in 212 (122 female, 90 male) young adults. All subjects completed questionnaires regarding family history of pain, recent pain experiences, and psychological measures of hypervigilance. Then, warmth detection thresholds, heat pain thresholds and heat pain tolerances were determined. Results revealed sex-dependent influences of familial pain history on recent pain complaints and experimental pain responses. Specifically, a positive family history of pain was associated with increased reports of pain over the previous month and poorer general health as well as enhanced sensitivity to thermal stimuli among females but not males. Higher levels of hypervigilance accounted for some of the family history effects on recent pain complaints but not experimental pain measures. Potential mechanisms underlying these effects of family history among females are discussed.