Sucrose consumption enhances the analgesic effects of cigarette smoking in male and female smokers

Acute analgesic effect of nicotine vaping using three experimental pain induction tasks: a randomized, placebo-controlled laboratory study

RATIONALE

Pain and nicotine use are co-occurring conditions with a significant impact on health. Experimental evidence supports an acute analgesic effect of nicotine which may reinforce nicotine use among those with chronic pain. Evidence for nicotine analgesia have primarily been gathered in combustible cigarette users and have not been extended to electronic nicotine delivery systems (ENDS or vaping). Furthermore, the mechanisms of nicotine analgesia in humans are not well understood.

OBJECTIVES

Assess the effect of acute vaped nicotine on subjective and behavioral indices of pain sensitivity using three tasks designed to probe distinct mechanisms of analgesia.

METHODS

This study recruited ENDS users (N = 86) to undergo a paced vaping protocol followed by pain tasks in counterbalanced order. Across four sessions, participants vaped e-liquid containing nicotine or placebo, and flavor or no-flavor in a 2 × 2 within-subject design. Assessments included cold pressor, submaximal effort tourniquet to induce ischemic pain, and temporal summation of heat pain, an index of central sensitization.

RESULTS

Compared to placebo, nicotine increased cold pressor pain tolerance (ηp2 = 0.031), ischemic pain threshold (ηp2 = 0.073) and tolerance (ηp2 = 0.056) but had no effect on temporal summation of pain. Flavor did not affect pain sensitivity. Females reported greater ischemic pain sensitivity (ηp2 = 0.027) and greater reductions in craving (ηp2 = 0.086).

CONCLUSIONS

Consistent with research from tobacco smoking, analgesia may be reinforcing and contribute to nicotine dependence among ENDS users. More research on sex differences is warranted.

The effects of smoking on pain scores, vital signs, and analgesic consumption in patients undergoing tympanomastoidectomy surgery

INTRODUCTION

In this study, we investigate the effects of smoking on pain scores, vital signs, and analgesic consumption in the intraoperative and postoperative period in patients undergoing tympanomastoidectomy surgery.

METHODS

A total of 100 patients with American Society of Anesthesiologists I-II status, aged 18-55 years, and who were planned to undergo tympanomastoidectomy surgery were divided into two groups: smokers (Group 1) and non-smokers (Group 2). The patients were compared for preoperative, intraoperative, and 24-hour postoperative carboxyhemoglobin, blood pressure, oxygen saturation, respiratory rate, heart rate, pain intensity and verbal numerical rating scales, the extent of patient-controlled tramadol dose, nausea, and vomiting.

RESULTS

There were 50 individuals in each group. Postoperative analgesic consumption and pain scores were higher in Group 1, and the first postoperative pain was felt earlier. Furthermore, in Group 1, preoperative carboxyhemoglobin levels and postoperative nausea were statistically higher before, after, and at the tenth minute after induction, whereas oxygen saturation was lower. The two groups had no statistical difference regarding intraoperative and postoperative vital signs. Postoperative analgesic consumption was not affected by age or gender.

CONCLUSIONS

Smoking changes postoperative pain management, especially for this kind of operation, and these patients feel more pain and need more postoperative analgesic doses. Therefore, effective postoperative pain control should take account of smoking behavior, and analgesic doses may need to be adjusted for patients who smoke.

The Anti-Nociceptive Effects of Nicotine in Humans: A Systematic Review and Meta-Analysis

BACKGROUND

Pain can have a serious impact on a patient's physical, mental, and social health, often causing their quality of life to decline. Various nicotine dosage forms, such as nicotine patches and nasal spray, have been developed and used as analgesics in clinical settings. However, there is controversy over the anti-nociceptive effects of nicotine among different clinical trials. The purpose of this meta-analysis is to quantify the analgesic effect of nicotine patches, nicotine nasal spray, and tobacco smoking on pain in humans.

METHODS

Relevant articles published in English prior to July 2023 were identified using the PubMed, Cochrane Library, and Embase online databases in accordance with PRISMA (2020) guidelines. Two reviewers independently screened and selected studies, extracted data, and assessed the quality of the included studies using version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2). RStudio was used for data synthesis, heterogeneity assessment, sensitivity analysis, publication bias assessment, trim-and-fill analyses, and generating forest plots.

RESULTS

Sixteen eligible articles, including k = 5 studies of pain tolerance (n = 210), k = 5 studies of pain threshold (n = 210), and k = 12 studies of pain scores (N = 1249), were included for meta-analysis. Meta-analytic integration for pain threshold (Hedges' g = 0.28, 95% CI = 0-0.55, Z = 1.99, p = 0.05) and pain tolerance (Hedges' g = 0.32, 95% CI = 0.05-0.59, Z = 2.30, p = 0.02) revealed that nicotine administered via tobacco smoke generated acute analgesic effects to thermal stimuli. Meta-analytic integration for pain scores revealed that nicotine had a weak anti-nociceptive effect on postoperative pain of -0.37 (95% CI = -0.77 to 0.03, Z = -1.80) but with no statistical significance (p = 0.07). In addition, a limited number of included studies revealed that long-term smoking produced hyperalgesia that may be characterized as small to medium in magnitude (Hedges' g = 0.37, 95% CI = 0.29-0.64, Z = 5.33, p < 0.01).

CONCLUSION

These results help to clarify the mixed outcomes of trials and may ultimately inform the treatment of pain. We observed that acute nicotine administration prolonged the laboratory-induced pain threshold and tolerance time and may mildly relieve postoperative pain. In addition, long-term tobacco smoking may have a nociceptive effect on different types of chronic pain. More research is needed to determine the anti-nociceptive effects of nicotine in humans, and to understand the optimal timing, dose, and method of delivery of nicotine.

Microglia sustain anterior cingulate cortex neuronal hyperactivity in nicotine-induced pain

BACKGROUND

Long-term smoking is a risk factor for chronic pain, and chronic nicotine exposure induces pain-like effects in rodents. The anterior cingulate cortex (ACC) has been demonstrated to be associated with pain and substance abuse. This study aims to investigate whether ACC microglia are altered in response to chronic nicotine exposure and their interaction with ACC neurons and subsequent nicotine-induced allodynia in mice.

METHODS

We utilized a mouse model that was fed nicotine water for 28 days. Brain slices of the ACC were collected for morphological analysis to evaluate the impacts of chronic nicotine on microglia. In vivo calcium imaging and whole-cell patch clamp were used to record the excitability of ACC glutamatergic neurons.

RESULTS

Compared to the vehicle control, the branch endpoints and the length of ACC microglial processes decreased in nicotine-treated mice, coinciding with the hyperactivity of glutamatergic neurons in the ACC. Inhibition of ACC glutamatergic neurons alleviated nicotine-induced allodynia and reduced microglial activation. On the other hand, reactive microglia sustain ACC neuronal excitability in response to chronic nicotine, and pharmacological inhibition of microglia by minocycline or liposome-clodronate reduces nicotine-induced allodynia. The neuron-microglia interaction in chronic nicotine-induced allodynia is mediated by increased expression of neuronal CX3CL1, which activates microglia by acting on CX3CR1 receptors on microglial cells.

CONCLUSION

Together, these findings underlie a critical role of ACC microglia in the maintenance of ACC neuronal hyperactivity and resulting nociceptive hypersensitivity in chronic nicotine-treated mice.

The analgesic effect of nostalgia elicited by idiographic and nomothetic approaches on thermal stimulus

Nostalgia is shown to relieve an individual's perception of pain evoked by cold water, pressure, and thermal stimuli. However, there is no direct evidence to show the analgesic effects of different nostalgia-inducing methods on various stimulus intensities. We conducted two studies to examine the analgesic effect, at different pain intensities, after inducing nostalgia either idiographically or nomothetically. Study 1 (N = 118) induced nostalgia through an idiographic approach (i.e., event reflection task) and found that nostalgia relieved both high and low thermal pain. Study 2 (N = 66) induced nostalgia through a nomothetic approach (i.e., viewing nostalgic pictures) and found that nostalgia relieved low but not high thermal pain. The findings verify the analgesic effect of nostalgia on thermal pain and suggest the potential moderating role of the nostalgia induction approach and pain intensity. Practically, these findings have implications for using nostalgia as a nonpharmacological treatment for pain.

Gender discrimination facilitates fMRI responses and connectivity to thermal pain

Gender discrimination is a serious social issue that has been shown to increase negative consequences, especially in females when accompanied by acute or chronic pain. Experiencing social pain through discrimination can increase an individual's evaluation of evoked physical pain. However, few studies have explored the mechanism underlying how gender discrimination modulates brain responses when individuals experience physical pain evoked by noxious stimuli. In this study, we addressed this issue using a gender discrimination fMRI paradigm with thermal pain stimulation. We found that discrimination indeed affected participants' own behavioral self-evaluation of noxious stimuli. Discrimination-encoded brain activations were identified in the temporopolar cortex, while brain activations to thermal stimuli after viewing pictures of discrimination were found in the dorsal anterior cingulate cortex (dACC). Brain activations in the temporopolar cortex and the dACC were correlated. Furthermore, pain perception-specific functional connectivity of the dACC-SII in the cue stage and the dACC-frontal in the pain stage were identified, suggesting a facilitative effect of gender discrimination on females' experience of physical pain. Our results indicate that the dACC may play a central role in mediating the affective aspect of physical pain after experiencing discrimination. These findings provide novel insights into the underlying mechanism of how gender discrimination facilitates females' experience of physical pain.

Predictors of severe postoperative pain after orthopedic surgery in the immediate postoperative period

AIM

Severe pain in the immediate postoperative period can negatively affect patients' quality of recovery, prolong hospital stay, and increase the risk of developing persistent pain. This study aimed to examine the predictors of severe postoperative pain in the immediate postoperative period among orthopedic trauma patients.

METHODS

A prospective observational study design was used. Data were collected from 153 patients that underwent orthopedic surgery procedures. Pain scores were assessed by a numeric pain scale at 45 min in the Post Anesthesia Care Unit. Physical health status was measured by the American Society of Anesthesiologists Status Classification System, and total dose of opioids (converted to morphine equivalents) and other demographic and clinical characteristics were recorded from medical records.

RESULTS

Preoperative smoking and physical health status were statistically significant predictors of severe postoperative pain in the immediate postoperative period. The odds of severe postoperative pain for smokers were 2.42 times the odds of nonsmokers. Patients with severe systemic disease showed 4.27 times lower odds of severe pain than more healthy patients.

CONCLUSION

Preoperative predictors of severe postoperative pain should be considered when assessing and treating orthopedic patients postoperatively to assure adequate pain relief.

Nicotine withdrawal induces hyperalgesia via downregulation of descending serotonergic pathway in the nucleus raphe magnus

Patients deprived of cigarettes exhibit increased pain sensitivity during perioperative periods, yet the underlying neuroanatomical and molecular bases of this hypersensitivity are unclear. The present study showed that both the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were significantly decreased in a rat model of nicotine withdrawal. These rats showed less tryptophan hydroxylase 2 (TPH2) positive neurons and reduced TPH2 expression in the nucleus raphe magnus (NRM), and thus resulted in decreased 5-hydroxytryptamine (5-HT) levels in cerebrospinal fluid. Intrathecal injection of 5-HT or NRM microinjection of TPH-overexpression adeno-associated virus alleviated nicotine withdrawal-induced hyperalgesia, whereas 5-HT receptor pharmacological blockade by methysergide (a 5-HT receptor antagonist) exacerbated hypersensitivity and diminished the difference between the two groups. Together, these data indicate that hyperalgesia after nicotine withdrawal is mediated by declined descending serotonergic pathways in the NRM. This provides a new perspective to improve the postoperative pain management of patients, especially the smokers.

Genetic Underpinnings of Musculoskeletal Pain During Treatment With Aromatase Inhibitors for Breast Cancer: A Biological Pathway Analysis

BACKGROUND

Musculoskeletal pain (MSKP) is the most reported symptom during treatment with aromatase inhibitors (AIs) for breast cancer. The mechanisms underlying MSKP are multidimensional and not well understood. The goals of this biological pathway analysis were to (1) gain an understanding of the genetic variation and biological mechanisms underlying MSKP with AI therapy and (2) identify plausible biological pathways and candidate genes for future investigation.

METHOD

Genes associated with MSKP during AI therapy or genes involved in drug metabolism of and response to AIs were identified from the literature. Studies published through February 2019 were queried in PubMed®. The genes identified from the literature were entered into QIAGEN's Ingenuity® Pathway Analysis (IPA) software to generate canonical pathways, upstream regulators, and networks through a core analysis.

RESULTS

The 17 genes identified were ABCB1, ABCG1, CYP17A1, CYP19A1, CYP27B1, CYP2A6, CYP3A4, CYP3A5, ESR1, OATP1B1, OPG, RANKL, SLCO3A1, TCL1A, UGT2A1, UGT2B17, and VDR. These genes are involved in encoding bone-remodeling regulators, drug-metabolizing enzymes (cytochrome P450 family, UDP-glucuronosyltransferases family), or drug transporters (ATP-binding cassette transporters, organic anion transporters). Multiple plausible biological pathways (e.g., nicotine degradation, melatonin degradation) and candidate genes (e.g., NFKB, HSP90, AKT, ERK1/2, FOXA2) are proposed for future investigation based on the IPA results.

CONCLUSION

Multiple genes and molecular-level etiologies may contribute to MSKP with AI therapy in women with breast cancer. Our innovative combination of gene identification from the literature plus biological pathway analysis allowed for the emergence of novel candidate genes and biological pathways for future investigations.

Lifestyle and Chronic Pain across the Lifespan: An Inconvenient Truth?

Chronic pain has a tremendous personal and socioeconomic impact and remains difficult to treat. Therefore, it is important to provide an update on the current understanding regarding lifestyle factors in people with chronic pain across the lifespan. Lifestyle factors such as physical (in)activity, sedentary behavior, stress, poor sleep, unhealthy diet, and smoking are associated with chronic pain severity and sustainment. This applies to all age categories, that is, chronic pain across the lifespan. Yet current treatment options often do not or only partly address the many lifestyle factors associated with chronic pain or attempt to address them in a standard format rather than providing an individually tailored multimodal lifestyle intervention. The evidence regarding lifestyle factors is available in adults, but limited in children and older adults having chronic pain, providing important avenues for future research. In conclusion, it is proposed that treatment approaches for people with chronic pain should address all relevant lifestyle factors concomitantly in an individually-tailored multimodal intervention. Ultimately, this should lead to improved outcomes and decrease the psychological and socioeconomic burden of chronic pain. Level of Evidence: IV.

Factors associated with pain and analgesic consumption following non-surgical periodontal therapy under local anaesthesia and carried out by dental students

AIM

Evaluate factors associated with pain and analgesic consumption following non-surgical periodontal therapy.

MATERIALS AND METHODS

The sample consisted of 218 patients with chronic periodontitis, submitted to non-surgical scaling and root planing under local anaesthesia at a public dental service in southern Brazil. The data collection instruments included a demographic questionnaire, as well as State-Trait Anxiety Inventory, Corah's Dental Anxiety Scale, Visual Analogue Scale, Numerical Rating Scale and Verbal Rating Scale. The presence and intensity of pain were evaluated at 2, 6, 12, 24 and 48 hr after scaling and root planing.

RESULTS

A total of 52.3% of the patients reported mild intensity pain at some point during the 48 hr after scaling and root planing with local anaesthesia. Smoking (PR = 1.47; 95% CI = 1.16-1.65), severe periodontal inflammation (PR = 1.31; 95% CI = 1.09-1.58) and dental anxiety (PR = 1.24; 95% CI = 1.03-1.49) were associated with postoperative pain after adjusting for age, gender and state and trait anxiety scores. Moreover, 46.8% of the subjects used analgesics at some time during the 48-hr follow-up period and dental anxiety was the only factor associated with postoperative analgesic use.

CONCLUSIONS

Smoking, severe periodontal inflammation and dental anxiety were identified as factors associated with pain after non-surgical scaling and root planing with local anaesthesia. Dental anxiety was also a factor associated with postoperative analgesic use.

Acute analgesic effects of nicotine and tobacco in humans: a meta-analysis

Although animal models have consistently demonstrated acute pain inhibitory effects of nicotine and tobacco, human experimental studies have yielded mixed results. The main goal of this meta-analysis was to quantify the effects of nicotine/tobacco administration on human experimental pain threshold and tolerance ratings. A search of PubMed and PsycINFO online databases identified 13 eligible articles, including k = 21 tests of pain tolerance (N = 393) and k = 15 tests of pain threshold (N = 339). Meta-analytic integration for both threshold and tolerance outcomes revealed that nicotine administered through tobacco smoke and other delivery systems (eg, patch, nasal spray) produced acute analgesic effects that may be characterized as small to medium in magnitude (Hedges g = 0.35, 95% confidence interval = 0.21-0.50). Publication bias-corrected estimates remained significant and indicated that these effects may be closer to small. Sex composition was observed to be a significant moderator, such that pain threshold effects were more robust among samples that included more men than women. These results help to clarify a mixed literature and may ultimately help to inform the treatment of both pain and nicotine dependence. Pain and tobacco smoking are both highly prevalent and comorbid conditions. Current smoking has been associated with more severe chronic pain and physical impairment. Acute nicotine-induced analgesia could make smoking more rewarding and harder to give up. Future research should use dynamic measures of experimental pain reactivity and further explore biopsychosocial mechanisms of action.

Interrelations between pain and alcohol: An integrative review

Pain and alcohol use are both highly prevalent in the general population, and pain-alcohol interrelations are of increasing empirical interest. Previous research has identified associations between pain and alcohol dependence, and the current review provides novel contributions to this emerging domain by incorporating studies that have tested relations between pain and low-to-moderate alcohol consumption, and by identifying potential psychosocial mechanisms of action. Specifically, we sought to integrate evidence of pain-alcohol relations derived from two directions of empirical inquiry (i.e., effects of alcohol on pain and effects of pain on alcohol use) across psychological, social, and biological literatures. We observed converging evidence that associations between alcohol consumption and pain may be curvilinear in nature. Whereas moderate alcohol use was observed to be associated with positive pain-related outcomes (e.g., greater quality of life), excessive drinking and alcohol use disorder appear to be associated with deleterious pain-related outcomes (e.g., greater pain severity). We also observed evidence that alcohol administration confers acute pain-inhibitory effects, and that situational pain may motivate alcohol consumption (e.g., drinking for pain-coping). Future research can inform theoretical and clinical applications through examination of temporal relations between pain and alcohol consumption, tests of hypothesized mechanisms, and the development of novel interventions.

Stress effects on mood, HPA axis, and autonomic response: comparison of three psychosocial stress paradigms

Extensive experimental psychology research has attempted to parse the complex relationship between psychosocial stress, mood, cognitive performance, and physiological changes. To do so, it is necessary to have effective, validated methods to experimentally induce psychosocial stress. The Trier Social Stress Test (TSST) is the most commonly used method of experimentally inducing psychosocial stress, but it is resource intensive. Less resource intense psychosocial stress tasks include the Socially Evaluative Cold Pressor Task (SECPT) and a computerized mental arithmetic task (MAT). These tasks effectively produce a physiological and psychological stress response and have the benefits of requiring fewer experimenters and affording data collection from multiple participants simultaneously. The objective of this study was to compare the magnitude and duration of these three experimental psychosocial stress induction paradigms. On each of four separate days, participants completed either a control non-stressful task or one of the three experimental stressors: the TSST, SECPT, or MAT. We measured mood, working memory performance, salivary cortisol and alpha-amylase (AA), and heart rate. The TSST and SECPT exerted the most robust effects on mood and physiological measures. TSST effects were generally evident immediately post-stress as well as 10- and 20-minutes after stress cessation, whereas SECPT effects were generally limited to the duration of the stressor. The stress duration is a key determinant when planning a study that utilizes an experimental stressor, as researchers may be interested in collecting dependent measures prior to stress cessation. In this way, the TSST would allow the investigator a longer window to administer tasks of interest.

Ecological momentary assessment of smoking behavior in persistent pain patients

OBJECTIVES

Smoking is associated with chronic pain and pain-related functional impairment. Some studies suggest that pain activates smoking urges and others suggest that smoking is analgesic. We evaluated these associations using ecological momentary assessment, a method for real-time measurement of health-related phenomena.

METHODS

For 1 week, 36 chronic pain patients who smoked a mean of 17.5 (SD=9.4) cigarettes per day completed multiple daily assessments on a handheld computer.

RESULTS

The sample included 67% women and 39% whites; 67% had back pain, with an average (SD) worst pain severity during the past week of 8.6 (1.5) on a 0 to 10 numeric rating scale. Patients completed an average (SD) of 44 (24) random assessments. At each assessment, the patient recorded pain "right now" on a 0 to 10 scale, whether he/she was "about to smoke," and if he/she had "just smoked in the past 30 minutes," pain before smoking. After controlling for other significant correlates of pain, patients who were about to smoke had more pain than at other times (M [SD]=6.5 [2.3] vs. 5.2 [2.4]; P<0.01), but pain before and after smoking was not different (M [SD]=6.1 [2.2] vs. 5.9 [2.3]; P=0.18).

DISCUSSION

These findings support the hypothesis that smoking behavior is triggered by pain, but smoking is not analgesic. Future studies should clarify potential explanatory mechanisms for this pain-related trigger and evaluate tailored cessation strategies for pain patients.

[Effects of smoking on venous cannulation pain: a randomized prospective trial]

BACKGROUND AND OBJECTIVES

It has been demonstrated that smoking increases pain perception; however the effect of smoking on perception of pain during venous cannulation is not known. The purpose of this study is to determine whether or not smoking has an effect on pain perception due to peripheral venous cannulation.

METHODS

220 patients scheduled to have elective surgery were enrolled in the study and were divided into two groups (Group S and C, n=110 for each) according to their smoking habits. Numerical rating scale was introduced to the patients and then peripheral venous cannulation at the dorsum of the hand was made with a 20G intracath. Pain perception of the patients was scored by subsequent numerical rating scale questioning.

RESULTS

The demographic characteristics of the groups were identical. Numerical rating scale scores in Group S and C were 3.31±1.56 and 1.65±1.23, respectively (p<0.001).

CONCLUSION

Pain perception due to peripheral venous cannulation is higher in smokers. Future studies on pain treatment should consider the smoking habits of patients.

Prevalence of neck and low back pain in community-dwelling adults in Spain: an updated population-based national study (2009/10-2011/12)

PURPOSE

To estimate time trends in the prevalence of neck (NP) and low back pain (LBP) from 2009 to 2012; and to determine the socio-demographic features, self-rated health status, co-morbidity, lifestyle-related habits, and health care service associated with NP and LBP in Spanish adults.

OUTCOME MEASURES

The European Health Interview Survey for Spain (2009) and the Spanish National Health Survey (2011).

METHODS

A total of 43,072 subjects were included. We analyzed data collected from the European Health Interview Survey for Spain conducted in 2009 (n = 22,188), and the Spanish National Health Survey in 2011 (n = 20,884). We considered the presence of isolated NP, LBP and both (NP&LBP). We analyzed socio-demographic features; self-perceived health status; lifestyle habits; comorbid diseases, and professional treatment using logistic regression models.

RESULTS

The prevalence of isolated NP, LBP and NP&LBP increased from 2008/9 to 2011/12 (7.86 vs. 8.56 %; 5.18 vs.5.44 %; 10.61 vs.11.12 %, respectively). Being female, increased the probability of isolated NP and NP&LBP, but decreased the probability of LBP. The prevalence of all pain localizations increased with older age, lower education level, poor self-rated health, smoker, comorbidities, psychological distress (anxiety or depression), hospital and physiotherapist visits and consumed drugs for pain, in 2008/9 as compared to 2011/12. Moreover, LBP, and NP&LBP were associated with obesity, whereas NP&LBP was associated with being married.

CONCLUSIONS

The prevalence of LBP, NP and NP&LBP had increased in the last 3 years in Spain.

Nicotine withdrawal and stress-induced changes in pain sensitivity: a cross-sectional investigation between abstinent smokers and nonsmokers

Chronic smoking has been linked with alterations in endogenous pain regulation. These alterations may be pronounced when individuals quit smoking because nicotine withdrawal produces a variety of psychological and physiological symptoms. Smokers interested in quitting (n = 98) and nonsmokers (n = 37) completed a laboratory session including cold pressor test (CPT) and heat thermal pain. Smokers set a quit date and completed the session after 48 h of abstinence. Participants completed the pain assessments once after rest and once after stress. Cardiovascular and nicotine withdrawal measures were collected. Smokers showed blunted cardiovascular responses to stress relative to nonsmokers. Only nonsmokers had greater pain tolerance to CPT after stress than after rest. Lower systolic blood pressure was related to lower pain tolerance. These findings suggest that smoking withdrawal is associated with blunted stress response and increased pain sensitivity.

Passive smoking increases pain perception in children undergoing venous catheterization

AIM

To establish whether there is any association between passive smoking and pain perception in children, in the absence of existing studies into possible links.

METHODS

This single-centre study focused on 100 children - 50 who had been exposed to passive smoking and 50 who had not - who were admitted to general polyclinics from September 2012 to December 2012 and needed venous catheterization. Patients with chronic diseases, neurologic and psychiatric illnesses, communication problems and analgesic use in the last 24 h were excluded. The passive smoking group had a mean age of 7.3 years (56% male) and the nonpassive smoking group had a mean age of 7.7 years (44% male). The main study parameter was the Wong-Baker faces pain rating scale (WBFPS) score during catheterization.

RESULTS

There was a statistically significant difference between the pain perceptions of the 100 children studied and smoke exposure. The WBFPS scores of the 50 children who were passive smokers were significantly higher than the scores of the 50 who were not passive smokers (p = 0.00).

CONCLUSION

Passive smoking increases pain perception in children during invasive medical procedures.

Nature and nurture of human pain

Humans are very different when it comes to pain. Some get painful piercings and tattoos; others can not stand even a flu shot. Interindividual variability is one of the main characteristics of human pain on every level including the processing of nociceptive impulses at the periphery, modification of pain signal in the central nervous system, perception of pain, and response to analgesic strategies. As for many other complex behaviors, the sources of this variability come from both nurture (environment) and nature (genes). Here, I will discuss how these factors contribute to human pain separately and via interplay and how epigenetic mechanisms add to the complexity of their effects.

Pain, nicotine, and smoking: research findings and mechanistic considerations

Tobacco addiction and chronic pain represent 2 highly prevalent and comorbid conditions that engender substantial burdens upon individuals and systems. Interrelations between pain and smoking have been of clinical and empirical interest for decades, and research in this area has increased dramatically over the past 5 years. We conceptualize the interaction of pain and smoking as a prototypical example of the biopsychosocial model. Accordingly, we extrapolated from behavioral, cognitive, affective, biomedical, and social perspectives to propose causal mechanisms that may contribute to the observed comorbidity between these 2 conditions. The extant literature was 1st dichotomized into investigations of either effects of smoking on pain or effects of pain on smoking. We then integrated these findings to present a reciprocal model of pain and smoking that is hypothesized to interact in the manner of a positive feedback loop, resulting in greater pain and increased smoking. Finally, we proposed directions for future research and discussed clinical implications for smokers with comorbid pain disorders. We observed modest evidence that smoking may be a risk factor in the multifactorial etiology of some chronically painful conditions and that pain may come to serve as a potent motivator of smoking. We also found that whereas animal studies yielded consistent support for direct pain-inhibitory effects of nicotine and tobacco, results from human studies were much less consistent. Future research in the emerging area of pain and smoking has the potential to inform theoretical and clinical applications with respect to tobacco smoking, chronic pain, and their comorbid presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

Positive Traits Linked to Less Pain through Lower Pain Catastrophizing

The present study examined the association between positive traits, pain catastrophizing, and pain perceptions. We hypothesized that pain catastrophizing would mediate the relationship between positive traits and pain. First, participants (n = 114) completed the Trait Hope Scale, the Life Orientation Test- Revised, and the Pain Catastrophizing Scale. Participants then completed the experimental pain stimulus, a cold pressor task, by submerging their hand in a circulating water bath (0º Celsius) for as long as tolerable. Immediately following the task, participants completed the Short-Form McGill Pain Questionnaire (MPQ-SF). Pearson correlation found associations between hope and pain catastrophizing (r = -.41, p < .01) and MPQ-SF scores (r = -.20, p < .05). Optimism was significantly associated with pain catastrophizing (r = -.44, p < .01) and MPQ-SF scores (r = -.19, p < .05). Bootstrapping, a non-parametric resampling procedure, tested for mediation and supported our hypothesis that pain catastrophizing mediated the relationship between positive traits and MPQ-SF pain report. To our knowledge, this investigation is the first to establish that the protective link between positive traits and experimental pain operates through lower pain catastrophizing.

Social exclusion and pain sensitivity: why exclusion sometimes hurts and sometimes numbs

Some research indicates that social exclusion leads to increased emotional- and physical-pain sensitivity, whereas other work indicates that exclusion causes emotional- and physical-pain numbing. This research sought to examine what causes these opposing outcomes. In Study 1, the paradigm used to instantiate social exclusion was found to moderate the social exclusion-physical pain relation: Future-life exclusion led to a numbing of physical pain whereas Cyberball exclusion led to hypersensitivity. Study 2 examined the underlying mechanism, which was hypothesized to be the severity of the "social injury." Participants were subjected to either the standard future-life exclusion manipulation (purported to be a highly severe social injury) or a newly created, less-severe version. Supporting our hypothesis, the standard (highly severe) future-life exclusion led to physical-pain numbing, whereas the less-severe future-life exclusion resulted in hypersensitivity. Implications of these results for understanding the exclusion-pain relation and other exclusion effects are discussed.

Enhanced pain perception prior to smoking cessation is associated with early relapse

Accumulated evidence suggests that nicotine induces analgesia, and endogenous pain regulatory mechanisms may be altered by chronic smoking. The extent to which individual differences in pain perception are related to smokers' ability to abstain from smoking has not been directly examined. Seventy-one smokers who were interested in quitting completed a pre-cessation laboratory session which included the cold pressor test (CPT). Pain ratings were collected during and after CPT. Also, mood changes, cardiovascular measures, and salivary cortisol samples were evaluated prior to, during, and after CPT. Participants attended 4 weekly follow-up assessment sessions after their quit day. Cox regression analysis revealed that higher pain ratings during and after CPT predicted greater risk for smoking relapse. These results remained significant after affective and physiological responses to CPT were controlled, suggesting that pain ratings prior to smoking cessation are potentially useful in identifying smokers who are at greater risk of early smoking relapse and may reflect underlying putative risk for nicotine dependence and relapse.

Gender differences in pain modulation by a sweet stimulus in adults: A randomized study

This study aimed to examine whether or not there are gender differences in sweet stimulus-induced analgesia for cold pain in adults. In a randomized cross-over design, twenty men and 20 women held either a 24% sucrose solution or distilled water in their mouth before and while they immersed their hand in cold water and their pain response was examined. Unlike the women, when the men held the sucrose solution in their mouth, the latency of the onset of pain significantly increased, compared with the distilled water. Meanwhile, the level of pain tolerance was not significantly different for both sexes. The findings reveal that the analgesic effect of a sweet stimulus on the pain threshold is influenced by gender differences in human adults, indicating that sweet stimulus-induced analgesia has a brief analgesic effect, particularly for men. Although more research is warranted, the sweet stimulus could be put to practical application as an adjunct to acute pain management for men.

Pain in neonates is different

Pain processing and management in neonates, especially preterm neonates, differs from older populations. In this review, a brief background on pain processing in neonatal life, pain exposure in Neonatal Intensive Care Units (NICU), the consequences of untreated pain, and the difficulties in treating procedural pain pharmacologically will be presented. A more detailed review of non-pharmacological interventions for procedural pain in neonates will include sensory stimulation approaches, oral sweet solutions, and maternal interventions. Some possible mechanisms for the effectiveness of non-pharmacological interventions are offered. Finally, avenues of research into similar interventions as adjuvant therapies or drug-sparing effects in older populations are suggested.

Coffee drinking enhances the analgesic effect of cigarette smoking

Nicotine (from cigarette smoke) and caffeine (from coffee) have analgesic effects in humans and experimental animals. We investigated the combined effects of coffee drinking and cigarette smoking on pain experience in a group of moderate nicotine-dependent, coffee drinking, young smokers. Pain threshold and pain tolerance were measured during cold pressor test following the habitual nocturnal deprivation of smoking and coffee drinking. Smoking increased pain threshold and pain tolerance in both men and women. Coffee drinking, at a dose that had no independent effect, doubled the increase in pain threshold induced by smoking. The effect could not be explained by a cumulative raise in blood pressure. Our data suggest that caffeine enhances the analgesic effect of nicotine.

Alone but feeling no pain: Effects of social exclusion on physical pain tolerance and pain threshold, affective forecasting, and interpersonal empathy

Prior findings of emotional numbness (rather than distress) among socially excluded persons led the authors to investigate whether exclusion causes a far-reaching insensitivity to both physical and emotional pain. Experiments 1-4 showed that receiving an ostensibly diagnostic forecast of a lonesome future life reduced sensitivity to physical pain, as indicated by both (higher) thresholds and tolerance. Exclusion also caused emotional insensitivity, as indicated by reductions in affective forecasting of joy or woe over a future football outcome (Experiment 3), as well as lesser empathizing with another person's suffering from either romantic breakup (Experiment 4) or a broken leg (Experiment 5). The insensitivities to pain and emotion were highly intercorrelated.

Emotional influences on food choice: sensory, physiological and psychological pathways

Sensory, physiological and psychological mechanisms are reviewed that underlie emotional influences on food choice. Both moods and emotions are considered. Eating a meal will reliably alter mood and emotional predisposition, typically reducing arousal and irritability, and increasing calmness and positive affect. However, this depends on the meal size and composition being close to the eater's habit, expectations and needs. Unusual meals--e.g. too small, unhealthy--may negatively affect mood. Sweetness, and sensory cues to high energy density, such as fatty texture, can improve mood and mitigate effects of stress via brain opioidergic and dopaminergic neurotransmission. However, adaptation in these pathways, perhaps enhanced by inherited sensitivity, with chronic exposure to such sensory qualities, could lead to overeating of energy-dense foods and consequent obesity. Sweet, fatty foods low in protein may also provide alleviation from stress in vulnerable people via enhanced function of the serotonergic system. Moreover, in rats, such foods seem to act as part of a feedback loop, via release of glucocorticoid hormones and insulin, to restrain activity of the hypothalamic pituitary adrenal axis during stress. However, this effect is also associated with abdominal obesity. In humans, a number of psychological characteristics predict the tendency to choose such foods when stressed, such as restrained or emotional eating, neuroticism, depression and premenstrual dysphoria, all of which could indicate neurophysiological sensitivity to reinforcing effects of such foods. Greater understanding of such predictive traits and the underlying mechanisms could lead to tailoring of diet to meet personal emotional needs.

The effects of nicotine and sucrose on spatial memory and attention

Both nicotine and sucrose can enhance performance on cognitive tasks. However, little is known about whether nicotine and sucrose could act jointly to augment mental performance. To investigate if there is an interaction between nicotine and sucrose on cognitive behavior, performance on a continuous performance task (CPT) and a spatial memory task was examined in 14 healthy smokers after they had drunk 8 oz of either a sucrose- or aspartame-containing beverage, and then chewed a piece of gum containing either 2 mg nicotine or no nicotine. To assess changes in mood as a function of nicotine and sucrose intake, the profile of mood states (POMS) test was administered three times during each test session. Participants made significantly more correct responses and significantly fewer incorrect responses on the CPT when they received nicotine than when they received the placebo gum. Closer analysis of the data revealed that there was an interaction between sucrose consumption and nicotine intake. Nicotine increased hits and decreased misses when participants were given the sucrose-containing beverage, but not when they were given the aspartame-containing beverage. Neither nicotine nor sucrose affected spatial memory or mood across experimental sessions. However, when data were analyzed for just the first session, participants who drank the sucrose-containing beverage performed significantly better on the spatial memory task than those who drank the aspartame-containing beverage. No gender differences in the effects of nicotine or sucrose on cognitive performance were detected. The results provide support that both nicotine and sucrose have positive effects on cognitive behavior, and that under some conditions the two variables have additive effects on performance.