Trait anger and blood pressure recovery following acute pain: evidence for opioid-mediated effects

Previous work has suggested that positive associations between trait anger (TRANG) and pain sensitivity are due to dysfunctional endogenous opioid analgesic systems. In this study, we examined whether TRANG is associated with impaired opioid modulation of blood pressure (BP) recovery. A total of 46 pain-free normotensive controls and 69 normotensive chronic low back pain (LBP) sufferers received opioid blockade (8mg naloxone IV) or placebo in randomized, counterbalanced order in separate sessions. During each, participants underwent a 1-min finger pressure pain task followed by an ischemic forearm pain task. Opioid blockade impaired post-pain BP recovery in controls but not LBP participants (ps < .001). In controls, low TRANG was associated with blockade-induced recovery impairments, with no blockade effect in high TRANG participants. In LBP participants, blockade did not alter recovery regardless of TRANG (interaction ps < .05). Results support dysfunctional opioid modulation of BP recovery in healthy high TRANG controls and further suggest chronic pain-related impairments in opioid-mediated cardiovascular recovery.     

Psychological coping with acute pain: An examination of the role of endogenous opioid mechanisms

This study examined the relationship among endogenous opioids, Monitoring and Blunting coping styles, and acute pain responses. Fifty-eight male subjects underwent a 1-min pressure pain stimulus during two laboratory sessions. Subjects experienced this pain stimulus once under endogenous opioid blockade with naltrexone and once in a placebo condition. Blunting was found to be negatively correlated with pain ratings, but this relationship was significantly more prominent under opioid blockade. Results for coping behaviors subjects used to manage the experimental pain were generally consistent with the Blunting results, indicating that cognitive coping was related more strongly to decreased pain ratings and cardiovascular stress responsiveness under opioid blockade. Overall, the beneficial effects of Blunting and cognitive coping on pain responses did not depend upon endogenous opioids and, in fact, became stronger when opioid receptors were blocked. The relationship between endogenous opioids and coping appears to be dependent upon situational and stimulus characteristics.     

Experiences of patients requiring strong opioid drugs for chronic non-cancer pain: a patient-initiated study

BACKGROUND: Chronic non-cancer pain is an increasing problem in health care. This study was initiated by a patient wanting to discover more about the experiences of other patients requiring strong opioid analgesia for such pain. AIM: To determine the attitudes and experiences of patients receiving long-term strong opioid medication for chronic non-cancer pain in primary care. Design of study: Qualitative study using interpretative phenomenological analysis. SETTING: A semi-rural general practice in southwest England. METHOD: The study data came from a focus group and 10 individual patient interviews. A patient researcher was involved in the design, conduct, and analysis of the project. RESULTS: The impact of pain affected participants in every aspect of their daily lives. Attitudes to strong opioid medication were both positive and negative. Concerns about starting medication usually centred on fears of addiction, being seen as an addict, or that the patients may have a more serious condition than they had previously thought. However, these fears were tempered by an appreciation of the benefits that strong opioids brought in terms of pain relief and consequent gains in a nearer-to-normal existence. The data did not produce any evidence of addictive behaviour or of tolerance despite these initial fears. Patients adopted a trade-off approach, balancing pain relief with medication side effects, accepting more pain for a reduction in sedation and nausea. All patients described coping strategies they developed themselves and learned from outside influences, such as pain clinic courses and support from the GP. There was realism that total pain relief was not possible, but that a balance could be struck. CONCLUSION: Chronic non-cancer pain is associated with high levels of distress and psychosocial impairment. Patients in this study appreciated the benefits of strong opioid medication, having come to terms with fears of addiction and learned coping strategies. These findings should encourage GPs to consider strong opioid medication for patients with severe chronic pain in line with published evidence-based guidelines.     

Association between smoking status and cardiovascular and cortisol stress responsivity in healthy young men

Acutely, cigarette smoking stimulates increases in blood pressure (BP). heart rate (HR), and cortisol, but little evidence is available concerning the impact of habitual smoking status on cardiovascular stress responsivity. This relation was assessed in 86 healthy male firefighters, age 19 to 31, comprising 52 nonsmokers and 34 smokers. Measures of BP, HR, salivary free cortisol, breathing pattern, and self-reported stress and alertness were obtained while subjects performed nonverbal mental arithmetic and a socially evaluative speech task. Systolic and diastolic BP were higher at rest in nonsmokers than smokers, and a consistent difference in stress responsivity was also found. BP, HR, and cortisol responses to mental arithmetic were significantly smaller in smokers than nonsmokers, with mean changes in BP (adjusted for body weight) averaging 19.3/1 l.0 mmHg and 28.5/15.4 mmHg in smokers and nonsmokers, respectively. There were no effects of smoking status on task performance or subjective stress responses and no differences between groups in family health history, health-related behaviors, or psychological characteristics that might account for the reactivity difference. Possible explanations of the results are discussed, and methodological implications for cardiovascular stress reactivity studies are outlined. This study was supported by the Medical Research Council, UK     

Effects of Opioid Blockade with Naltrexone and Distraction on Cold and Ischemic Pain in Hypertension

Essential hypertension is characterised by reduced pain sensitivity. Hypertensive hypoalgesia has been attributed to elevated endogenous opioids and/or increased activation of descending pain modulation systems. A double-blind placebo-controlled design compared the effects of naltrexone and placebo on cold and ischemic pain in unmedicated newly-diagnosed patients with essential hypertension. Patients performed a cold pressor task while resting and while performing a distracting secondary task. They also performed a forearm ischemia task while resting. Although the cold pressor and ischemia tasks elicited significant increases in pain and blood pressure, pain ratings and pressor responses did not differ between naltrexone and placebo. Cold pain was reduced by distraction compared to rest. The finding that opioid blockade with naltrexone did not moderate the pain and pressor responses to cold and ischemia suggests that pain and associated blood pressure responses are not modulated by opioids in hypertension. The finding that the distracting secondary task successfully reduced pain ratings suggests normal supraspinal pain modulation in essential hypertension.     

Sensory effects of baroreceptor activation and perceived stress together predict long-term blood pressure elevations

Activating the arterial baroreceptors in animals has been shown to blunt pain sensation and provide other forms of central nervous system inhibition. This study tested the hypothesis that, among human subjects, a tonic increase in blood pressure (BP) could be a learned response to environmental stressors among subjects in whom the baroreceptor inhibitory mechanism is active. In a sample of 96 healthy, normotensive men and women, amount of pain-reduction produced by baroreceptor stimulation predicted an increase in resting BP 20 months later: the increase was proportional to self-assessed daily life stress. Among the subjects reporting the greatest amount of stress, the pain inhibition effect accounted for more than 80% of the BP variance. These results support the hypothesis that the reduction in perceived stress produced by baroreceptor stimulation may reward learned increases in BP. This research was supported by Deutsche Forschungsgemeinshaft Grant EL 101/3 to Thomas Elbert and National Institutes of Health Grant ROl HL40837 to B. R, Dworkin.     

尼氟酸抑制慢性内脏痛大鼠海马CA1区突触长时程增强

目的:探讨尼氟酸(HCN2特异性阻断剂)对慢性内脏痛大鼠海马CA1(cornu ammonis 1)区突触长时程增强(LTP)的影响。方法:选用新生SD大鼠(雌雄不分)出生后8～14 d内,每天固定时间给予1次60 mmHg压力的结直肠扩张刺激建立慢性内脏痛模型,大鼠成年后通过测量腹外斜肌对结直肠扩张引起的放电反应来评估肠道痛觉的敏感性。采用离体脑片场电位的记录方法,观察慢性内脏痛大鼠海马CA1区场电位LTP的变化,并观察不同浓度(25～75 mg/L)的尼氟酸对慢性内脏痛大鼠海马CA1区场电位LTP的影响。结果:慢性内脏痛大鼠海马基础场电位的幅值及斜率与正常大鼠比较无显著性差异,但高频刺激后模型大鼠诱导出的LTP幅值及斜率的变化率与正常大鼠比较均显著增加(P<0.05);尼氟酸对正常大鼠离体海马场电位LTP的峰值和斜率没有任何影响,但是不同剂量(25～75 mg/L)的尼氟酸可剂量依赖性显著降低慢性内脏痛大鼠离体海马场电位LTP的峰值及斜率。结论:HCN2通道可能参与慢性内脏痛大鼠海马场电位LTP的易化过程。     

大鼠开胸术后慢性疼痛的预测指标

目的观察疼痛时弥散性伤害抑制性控制(DNIC)的动态变化,对术前DNIC、术后急性疼痛能否作为术后慢性胸痛的预测指标进行初步研究。方法术前检测大鼠DNIC,建立开胸术后慢性疼痛模型,分组为空白组(n=10)、假手术组(n=10)、模型组(n=20),连续监测术后1、3、6、9、12、15、18和21 d的机械痛阈、冷痛阈及DNIC。结果模型组大鼠中,11只发展为慢性疼痛组(CPTP组),9只在经历急性疼痛后痛觉恢复正常(non-CPTP组)。与CPTP组比较,non-CPTP组术前DNIC减弱(P0.05),术后6 d切口附近机械痛阈值及冷痛阈值更低(P0.05)。与术前DNIC相比,模型组术后急性疼痛时期(术后3 d)DNIC减弱(P0.05),CPTP组术后21 d DNIC持续减弱(P0.05),而non-CPTP组DNIC恢复正常。结论术前DNIC及术后6 d急性疼痛程度是开胸术后慢性疼痛的两项危险因素;疼痛急性期,个体DNIC减弱,痛觉恢复正常时,个体DNIC水平也渐趋恢复正常。     

Predictors of neurocognitive performance in chronic pain patients

In a sample of 70 chronic pain patients, hierarchical multiple regression analyses were utilized to assess the additive and interactive contributions of pain severity and psychological distress variables to neurocognitive performance across attention and concentration, memory, and reasoning ability domains. Although the full model predicting attention and concentration was found to be significant, there was no significant contribution of pain severity, psychological distress, or the Pain Severity x Psychological Distress interaction to the prediction of attention and concentration scores after controlling for the effect of years of formal education. After controlling for the effect of years of formal education, pain severity and psychological distress did make separate and significant contributions to the prediction of memory scores; however, the Pain Severity x Psychological Distress interaction did not significantly affect memory scores. After controlling for the effect of years of formal education, there was no significant contribution of pain severity, psychological distress, or the Pain Severity x Psychological Distress interaction to reasoning ability scores. Results suggest the importance of assessing memory function when managing psychologically distressed chronic pain patients.     

Effects of parental history of hypertension and urbanization on blood pressure in zimbabweans

The increasing prevalence of essential hypertension is a growing public health concern for Zimbabwe and other African countries. Two important risk factors for hypertension are urbanization and parental history of hypertension. The relations among parental history of hypertension, urbanization, and blood pressures (BPs) are poorly understood. The objective of this study is to clarify these relations in a population of urbanized. African, young adults. The relation between parental history of hypertension and urbanization on resting BPs and BP responses to a menial arithmetic stressor was examined in a group of normotensive, Black medical students with (n = 36) and without (n = 34) a parental history of high BP.and with (n = 49) and without (n = 19) a parental history of urbanization. Results indicate that those with a positive parental history of high BP had higher resting BPs and greater systolic blood pressure (SBP) increases in response to laboratory stress, when compared to their negative parental history counterparts. Further, those with parents residing in urban areas had higher resting SBPs than those with parents residing in rural areas. However, no reactivity differences were apparent between the urban and rural parent groups. These data suggest that although parental history for hypertension influences both resting and reactivity BPs, parental history of urbanization may influence only resting BP. This study was supported by NIH/Fogarty International Center Grants 5T37TW3041-02, N1H-HL35195. and NIH-HL32738.     

Parental history of hypertension and cardiovascular response to stress in black and white men

White offspring of hypertensives typically exhibit an elevated cardiovascular response to stress. Studies of Black offspring of hypertensives have been fewer, with inconsistent results. This may be due, in part, to incomplete characterizations of hemodynamic responses. This study examines cardiovascular reactivity in Black and White offspring of hypertensives with a particular focus on vascular resistance responses. A total of 62 healthy normotensive men, 41 with a parental history of hypertension (PH+: 21 Blacks, 20 Whites), and 21 without parental hypertension (PH-: 7 Blacks, 14 Whites) engaged in a series of laboratory tasks. Both Black and White PH+ participants exhibited elevated diastolic blood pressure (DBP) responses, but to different patterns of stressor tasks. Familial differences in total peripheral resistance response were also obtained for Black and White participants in a comparison across all tasks, but were particularly evident in tasks when PH+ participants had elevated DBP responses. These results suggest that a parental history of hypertension is an important moderator of cardiovascular, and in particular peripheral vascular, responses to stress in Black and White individuals. This research was supported in part by National Institutes of Health Grants HL31533 and RR00046. We thank Doris Murrell, Antonia Vincent, Nancy Pettee, and Deborah Jansen for their technical assistance.     

Family history of hypertension,exercise training,and reactivity to stress in rats

In this study we sought to assess the role of exercise training on blood pressure (BP) reactivity to tailshock stress in rats with varying family histories of hypertension. Exercise training consisted of swimming 90 min per day in isothermic water for either 2, 6, or 10 months, beginning at 2 months of age. Control subjects were age-matched and did not exercise daily. Rats with either zero (Wistar-Kyoto), 1 (borderline hypertensive), or 2 (spontaneously hypertensive) hypertensive parents were studied. At the appropriate age, femoral artery catheters were implanted and rats were studied at rest and in response to a 20-min stress session. Exercise training reduced basal BP, especially in rats with a positive family history that were exercised for the longest duration. Reactivity to stress was actually significantly enhanced in trained rats. Thus, these data do not support the reactivity hypothesis, but suggest several reasons why the literature has been so inconsistent. The discussion emphasizes the importance of basal, rather than phasic, BP responses resulting from exercise training. Research for this article was supported by National Institutes of Health (NIH) Grant No. HL19680 to James E. Lawler and NIH Grant No. HL34878 to Ronald H. Cox     

Pain-coping strategies in chronic pain patients: Psychometric characteristics of the pain-coping inventory (PCI)

This article presents a series of studies aimed at validating a comprehensive pain-coping inventory (PCI) that is applicable to various types of patients with chronic pain. Item and scale analyses were performed for patients with rheumatoid arthritis (RA), patients with chronic headache, and pain clinic outpatients. The following 6 scales were derived from a simultaneous component analysis: Pain Transformation, Distraction, Reducing Demands, Retreating, Worrying, and Resting, all of which were internally reliable. A higher order factor analysis grouped the PCI scales into active (transformation, distraction, reducing demands) and passive (retreating, worrying, resting) pain-coping dimensions. Differences in use of strategy found between RA patients and headache patients indicated that the PCI scales were sufficiently sensitive to measure differences between groups. Concurrent validity was assessed for patients with RA and patients with fibromyalgia and predictive validity was assessed for patients with recently diagnosed RA after 1 and 3 years. In both analyses the validity of the scales was supported, in particular the predictive validity of passive coping scales for future outcomes.     

Predictors of disability in patients with chronic low back pain

IntroductionChronic low back pain (CLBP) is a common and disabling health problem. In this study, we aimed to assess the relationship between pain intensity, the components of catastrophizing, depression and disability in patients with chronic low back pain.Material and methodsSeventy-six patients diagnosed with CLBP (age range 25–77 years; 73.7% female) participated in the study. Participants’ socio-demographic data were collected: age, gender, height, weight, and work status (employed or retired). All participants were asked to complete the Pain Catastrophizing Scale (PCS), the visual analogue scale (VAS), the Oswestry Disability Questionnaire (ODQ), and the Beck Depression Inventory (BDI).ResultsThe mean group scores revealed moderate CLBP complaints (VAS – 4 [3–6]), mild depression (BDI – 10 [5–16]), a moderate level of catastrophizing (PCS total score 20.5 [10–34]) and moderate disability (Oswestry Disability Index [ODI] – 31 [14–38]). Positive significant correlations were found between ODI and age, residence, work status, VAS, PCS-rumination, PCS-magnification, PCS-helplessness and BDI, and also between PCS subscales and VAS. Our multivariate linear regression analysis showed that age, pain intensity, PCS-helplessness and depression can predict disability in patients with CLBP, explaining 84% of the variance of disability (R² = 0.851, adjusted R² = 0.843).ConclusionsA multidisciplinary approach is needed for patients with CLBP and should include physical, mental and social evaluation in order to offer an optimal treatment.     

Nitric oxide and pro-inflammatory cytokines correlate with pain intensity in chronic pain patients

Objective: Inflammatory cytokines as well as nitric oxide (NO) play a key role in the pathogenesis of persistent and exaggerated pain states. To document this, we investigated whether a range of cytokines and NO were detectable in the plasma of chronic pain patients and whether cytokine and NO levels correlated with pain severity. Methods: Plasma samples of 94 chronic pain patients and 6 healthy volunteers were obtained. Average pain intensity during the last 24h was assessed on a 11-point numeric rating scale and patients were distributed to three groups: light, moderate and severe pain. The concentrations of TNF-α, GM-CSF, interleukin (IL)-1β, IL-6, IL-8, interferon (IFN)-γ, IL-2, IL-4, IL-5, IL-10 and nitrate/nitrite were determined. Results: Patients with light pain demonstrated significantly increased levels of IL-6 compared to controls. In the severe pain group IL-6 and nitrate/nitrite were significantly increased. Serum concentrations of IL-1β, TNF-α, IL-2 and IL-4 were increased but as we adjusted the level of significance at p = 0.0045, most cytokine plasma levels failed to reach statistical significance. Conclusions: Pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IFN-γ, TNF-α) in the plasma correlate with increasing pain intensity. Chronic pain patients show a significant increase in plasma levels of NO in comparison to healthy controls. Received 30 May 2006; returned for revision 17 July 2006; accepted by G. Geisslinger 7 August 2006     

Factors affecting body awareness in older adults with chronic musculoskeletal pain

IntroductionChronic musculoskeletal pain (CMP) and cognitive impairment (CI) may reduce body awareness in older adults. The first aim of this study was to determine the impact of CMP and CI on body awareness in older adults. The second was to search for the factors most affecting body awareness using logistic regression analysis.Material and methodsTwo hundred and 65 older adults (males: 138 and females: 127) aged 65 and over (mean age; 72.27 ±6.42 years) living in their own homes were included. We used the following evaluation methods: CMP intensity (Visual Analog Scale – VAS), cognitive status (Hodkinson’s Abbreviated Mental Test – HAMT), and body awareness (Body Awareness Questionnaire – BAQ). Logistic regression analysis was used to determine the factor most affecting the BAQ score.ResultsEighty-five point two percent of participants (n = 265) reported CMP (lower extremity pain: 74.6%; spinal pain: 66.6%; upper extremities pain: 44.4%). CMP intensity was higher in lower extremities (mean VAS: 5.73 ±1.86 cm). Gender differences in terms of CMP were found in favor of males (p = 0.0001). Mean HAMT score was 8.16±1.65. Gender difference in favor of males was significant (p = 0.0001). Mean BAQ score was 77.61±20.90; there was no significant difference between the gender (p = 0.142). There was a significant moderate positive correlation between body awareness and cognitive status (r = 0.382, p = 0.0001). However, a weak negative correlation was found between body awareness and pain intensity (r = –0.234, p = 0.0001). Regression analysis showed that living environment (rural area), low education level, low cognition level and increased CMP intensity significantly predicted body awareness.ConclusionsThe results obtained from this study indicate that cognitive impairment and pain should be reduced by improving body awareness among older adults. That is why health professionals should evaluate all related factors affecting body awareness before planning the most suitable rehabilitation program.     

The Psychosomatic Symptom Checklist revisited: Reliability and validity in a chronic pain population

A psychometric evaluation of the SUNYA Revision of the Psychosomatic Symptom Checklist (PSC) was conducted with 405 chronic pain patients who completed the PSC as part of a diagnostic battery. Several properties of the measure were examined, including its reliability, internal consistency, discriminant validity, and factor structure. Contrary to a previous study, the measure demonstrated a modest reliability, a poor discriminant validity, and a multifactor structure that accounted for only a small proportion of the variance in the measure. Thus, the PSC did not appear to be an adequate measure of general psychosomatic distress when used with chronic pain patients. For these patients, the PSC may measure symptom clusters rather than general psychosomatic symptomatology. Since the PSC is used in various clinical populations, the results underscore the importance of investigating the properties of the measure in these populations.