Brain imaging reveals that engagement of descending inhibitory pain pathways in healthy women in a low endogenous estradiol state varies with testosterone

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Associations between the severity of menopausal symptoms and musculoskeletal pain in postmenopausal Portuguese women

OBJECTIVE

To analyze the association of the severity of the menopausal symptoms with musculoskeletal pain in Portuguese postmenopausal women.

METHODS

A cross-sectional, observational study was conducted on 167 women (63.85 ± 9.36 years). The Menopause Rating Scale was used to evaluate the menopausal symptoms severity, while the Nordic Musculoskeletal Questionnaire was employed to assess the localization of the musculoskeletal pain, and multi-located pain was determined if two or more body regions were affected. Depression (Hospital Anxiety and Depression Scale), age, body mass index (BMI) and physical activity level were considered as potential confounders.

RESULTS

A greater severity of the somato-vegetative menopausal symptoms was related to the prevention from usual activities because of pain in the neck, shoulders, elbows, wrists/hands and knees (R2 of Nagelkerke = 0.064, 0.043, 0.074, 0.045 and 0.045, respectively). Associations were also observed between greater age and pain in the knees, ankles and feet (R2 of Nagelkerke = 0.036 and 0.034, respectively), and being physically inactive with upper back pain (R2 of Nagelkerke = 0.060). Higher depressive symptoms were linked to pain in the hip/thighs and knees (R2 of Nagelkerke = 0.067 and 0.085, respectively), as well as being physically inactive was related ton in the neck (R2 of Nagelkerke = 0.053). Only a greater BMI was related to multi-located pain in the last 7 days (R2 of Nagelkerke = 0.041).

CONCLUSIONS

The findings of our study showed that, taking into account possible confounders, greater severity of the menopausal symptoms at a somatic-vegetative level was associated with more anatomical regions with musculoskeletal pain.

Pain mechanisms in the transgender individual: a review

Specific Aim

Provide an overview of the literature addressing major areas pertinent to pain in transgender persons and to identify areas of primary relevance for future research.

Methods

A team of scholars that have previously published on different areas of related research met periodically though zoom conferencing between April 2021 and February 2023 to discuss relevant literature with the goal of providing an overview on the incidence, phenotype, and mechanisms of pain in transgender patients. Review sections were written after gathering information from systematic literature searches of published or publicly available electronic literature to be compiled for publication as part of a topical series on gender and pain in the Frontiers in Pain Research.

Results

While transgender individuals represent a significant and increasingly visible component of the population, many researchers and clinicians are not well informed about the diversity in gender identity, physiology, hormonal status, and gender-affirming medical procedures utilized by transgender and other gender diverse patients. Transgender and cisgender people present with many of the same medical concerns, but research and treatment of these medical needs must reflect an appreciation of how differences in sex, gender, gender-affirming medical procedures, and minoritized status impact pain.

Conclusions

While significant advances have occurred in our appreciation of pain, the review indicates the need to support more targeted research on treatment and prevention of pain in transgender individuals. This is particularly relevant both for gender-affirming medical interventions and related medical care. Of particular importance is the need for large long-term follow-up studies to ascertain best practices for such procedures. A multi-disciplinary approach with personalized interventions is of particular importance to move forward.

Could sex-specific subtypes of hand osteoarthritis exist? A retrospective study in women presenting to secondary care

Introduction

Hand osteoarthritis is more common in women, and its risk increases around the time of the menopause. We set out to describe the timing between menopause and the onset of symptomatic hand osteoarthritis (OA), and associations with the use of hormone replacement therapy (HRT) or its discontinuation, describing any identifiable subgroups of women.

Methods

Retrospective healthcare-records study of sequential women referred to a specialist hand OA clinic, 2007-2015. Confirmation of hand OA diagnosis was by clinican, by accepted criteria. Demographics and clinical variables were from healthcare-records, recorded by standardised proforma. Outcomes of interest were reported age of onset of hand symptoms, reported age at final menstrual period (FMP), time from FMP to reported onset of hand symptoms and time from cessation of HRT to reported onset of hand symptoms. Exposure categories for systemic HRT use were never users, current users, previous users. Analysis of Variance compared groups; linear regression analysed associations of exposure with outcome.

Results

82/92(89%) of eligible women were post-menopausal, mean age at FMP 49.9 years (SD5.4). In these post-menopausal women, median time from FMP to hand symptom onset was 3 years. 48/82 (59%) developed hand symptoms within the defined peri-menopausal period (FMP ± 4 years), whilst some women developed their symptoms before or after (range -25, 30 years). In women who discontinued HRT prior to symptom onset, the median time from HRT cessation to onset of hand symptoms was 6 months. Past HRT users were older at hand symptom onset than women who had not taken HRT [coeff.4.7 years (0.92, 8.39); P = 0.015].

Conclusions

This study adds to evidence associating the menopause/sex hormone deficiency with hand OA symptom onset in a sizeable subgroup of women (but not all). HRT use/cessation appears to influence the timing of onset of hand OA symptoms. It is not possible to interpret from this type of study whether sex hormone deficiency is causative of disease or modulates its symptoms. It is also not possible to judge whether painful hand osteoarthritis in post-menopausal women is a subtype of disease. Further investigation is indicated of sex-specific subtypes and potential for personalised medicine for post-menopausal women with hand osteoarthritis, as a clearly definable high-risk subgroup.

Selective androgen receptor modulator microparticle formulation reverses muscle hyperalgesia in a mouse model of widespread muscle pain

ABSTRACT

Chronic pain is a significant health problem associated with disability and reduced quality of life. Current management of chronic pain is inadequate with only modest effects of pharmacological interventions. Thus, there is a need for the generation of analgesics for treating chronic pain. Although preclinical and clinical studies demonstrate the analgesic effects of testosterone, clinical use of testosterone is limited by adverse androgenic effects. Selective androgen receptor modulators (SARMs) activate androgen receptors and overcome treatment limitations by minimizing androgenic side effects. Thus, we tested whether daily soluble SARMs or a SARM-loaded microparticle formulation alleviated muscle hyperalgesia in a mouse-model of widespread pain (male and female C57BL/6J mice). We tested whether the analgesic effects of the SARM-loaded microparticle formulation was mediated through androgen receptors by blocking androgen receptors with flutamide pellets. In vitro and in vivo release kinetics were determined for SARM-loaded microparticles. Safety and toxicity of SARM treatment was determined using serum cardiac and liver toxicity panels, heart histology, and conditioned place preference testing. Subcutaneous daily SARM administration, and 2 injections, 1 week apart, of SARM-loaded microparticles alleviated muscle hyperalgesia in both sexes and was prevented with flutamide treatment. Sustained release of SARM, from the microparticle formulation, was observed both in vitro and in vivo for 4 weeks. Selective androgen receptor modulator treatment produced no cardiac or liver toxicity and did not produce rewarding behaviors. These studies demonstrate that SARM-loaded microparticles, which release drug for a sustained period, alleviate muscle pain, are safe, and may serve as a potential therapeutic for chronic muscle pain.

Early life factors associated with the experiences of pain in later life: evidence from a population based study in India

BACKGROUND

The influence of early life factors is becoming increasingly apparent as studies investigate how experiences, resources, and constraints in childhood affect health and well-being later in life. The present study contributes to this literature by examining the association between several early life factors and self-reported pain among older adults in India.

METHODS

Data come from the 2017-18 wave 1 of the Longitudinal Ageing Study of India (LASI). The sample size includes 28,050 older adults aged 60 and above (13,509 men and 14,541 women). Pain is a self-reported, dichotomous measure where participants responded to whether they were often troubled with pain and whether this experience interfered with their ability to carry out daily household chores. Early life factors, which are retrospective accounts of experiences, included the respondent's position in birth order, their health status, school absenteeism, being bedridden, family socioeconomic status (SES), and their parent's experience with chronic disease. Logistic regression analysis is employed to examine the unadjusted and adjusted average marginal effects (AME) of selected domains of early life factors associated with the probability of experiencing pain.

RESULTS

22.8% of men and 32.3% of women reported pain that interfered with daily activities. Pain was higher among men (AME: 0.01, confidence interval (CI): 0.01-0.03) and women (AME: 0.02, CI: 0.01-0.04) with third or fourth birth order compared to counterparts with first birth order. Both men (AME: -0.02, CI: -0.04-0.01) and women (AME: -0.07, CI: -0.09 - -0.04) having a fair childhood health status reported a lower probability of pain. The probability of pain was higher among both men (AME: 0.03, CI: 0.01-0.07) and women (AME: 0.07, CI: 0.03-0.13) who were bedridden due to sickness in their childhood. Similarly, the pain likelihood was higher among men who missed school for more than a month due to health problems (AME: 0.04, CI: -0.01-0.09). Men and women with poor financial condition in their childhood reported (AME: 0.04, CI: 0.01-0.07) a higher probability of experiencing pain relative to their peers who reported a more financially advantaged early life.

CONCLUSIONS

Findings of the present study add to the empirical literature on the association between early life factors and later life health and well-being. They also are pertinent to health care providers and practitioners working in pain management, as this knowledge better positions them to identify older adults most susceptible to pain. Moreover, findings of our study underscore that the interventions to ensure health and well-being in later life must start far earlier in the life course.

Differences in chronic pain prevalence between men and women at mid-life: a systematic review protocol

INTRODUCTION

Epidemiological literature shows differences in chronic pain (CP) prevalence in men and women. Women are more likely to develop CP at different points of the life course, such as adolescence and old age. Less is known about the prevalence of CP by sex and the difference in prevalence during mid-life, when changes may predispose to an earlier differentiation in CP distribution. The aim of this study is to describe the difference in prevalence of CP at mid-life (ages 40-60) in men and women in the general population.

METHODS AND ANALYSIS

This systematic review follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Appropriate studies will be identified in the following databases: MEDLINE, EMBASE, AMED and PsycINFO. Two reviewers will independently screen each title and abstract. Studies eligible for data extraction will report estimates of CP prevalence for each sex, and/or a measure of the difference in prevalence between sexes. The findings will be reported in a narrative synthesis following the Social Research Council Methods Programme guidelines. A random effects meta-analysis will be conducted where the reviewers can justify combining results.

ETHICS AND DISSEMINATION

This review will summarise the prevalence of CP in men and women at mid-life, based on existing evidence. It is expected that the results will identify gaps in knowledge and areas for further research. The review will be submitted for publication in topic specific journals and disseminated to professional networks. Individual patient data are not included, so ethical approval is not required.

PROSPERO REGISTRATION NUMBER

CRD42021295895.

The influence of sex hormones on musculoskeletal pain and osteoarthritis

The association of female sex with certain rheumatic symptoms and diseases is now indisputable. Some of the most striking examples of this association occur in individuals with musculoskeletal pain and osteoarthritis, in whom sex-dependent changes in incidence and prevalence of disease are seen throughout the lifecourse. Joint and muscle pain are some of the most common symptoms of menopause, and there is increasingly compelling evidence that changes in or loss of sex hormones (be it natural, autoimmune, pharmacological, or surgical) influence musculoskeletal pain propensity and perhaps disease. However, the effects of modulation or replacement of sex hormones in this context are far less established, particularly whether these approaches could represent a preventative or therapeutic opportunity once symptoms have developed. In this Review, we present evidence for the association of changes in sex hormones with musculoskeletal pain and painful osteoarthritis, discussing data from diverse natural, therapeutic, and experimental settings in humans and relevant animal models relating to hormone loss or replacement and the consequent effects on health, pain, and disease. We also postulate mechanisms by which sex hormones could mediate these effects. Further research is needed; however, increased scientific understanding of this complex area could lead to real benefits in musculoskeletal and women's health.

Testosterone administration enhances the expectation and perception of painful and non-painful somatosensory stimuli

The influence of testosterone on pain perception remains inconsistent in the literature. This randomized, placebo-controlled, double-blind, crossover study investigated the effect of testosterone administration on perception and expectation of electrocutaneous stimulus. Thirty healthy male participants received a single dose of testosterone in one session and a placebo in the other session. For each session, they completed a pain-rating task in which a predictability cue was inserted before a painful or non-painful electocutaneous stimulus delivery, while neural activity was simultaneously recorded by a 64-channel electroencephalographic (EEG) system. Expected and perceived pain ratings, as well as event-related potentials (ERPs) to electocutaneous stimuli and prestimulus EEG oscillatory activities while expecting upcoming electocutaneous stimuli were comprehensively compared between testosterone and placebo sessions. Compared with the placebo session, participants in the testosterone session reported greater pain rating and exhibited greater amplitude of N1 component on ERPs when perceiving both painful and non-painful electrocutaneous stimuli. Mediation analysis revealed that testosterone enhanced the pain-intensity ratings via the N1 response to the electrocutaneous stimulus. Upon viewing the predictability cues after testosterone administration, expected pain intensity increased and spontaneous low-frequency α-oscillation power in the frontal region decreased. These results provide evidence that testosterone enhanced perception and expectation of somatosensory events, and that this was a general effect rather than pain-specific. A plausible explanation for these findings is that testosterone acts to increase vigilance and sustained attention levels, as evidenced by the decreased α-oscillation power. Thus, our findings support a causal role for testosterone in heightening the biological salience of incoming somatosensory information.

Metabolomic study combined with the low-level light therapy of Chinese acupuncture points and combined oral contraceptives in treatment of primary dysmenorrhea: A prospective, multicenter, randomized controlled study

Objective

To compare the changes of metabolites between Low-level light therapy (LLLT) and combined oral contraceptive (COC) after treatment of primary dysmenorrhea (PD), and to compare and analyze the biological and biochemical effects of the two treatments by analyzing the differences in metabolite profiles.

Methods

A multicenter, double-blind, prospective, parallel, randomized controlled study was conducted on 69 women aged 16-35 years old with PD who were randomly divided into COC treatment group or LLLT treatment group. Low-level light therapy with light-emitting diodes (LED) was applied on two acupoints named "Guanyuan" (CV4) and "Qihai" (CV6). After 12 weeks of treatment intervention, blood samples were collected before and after treatment for metabolomic analysis. We used UPLC-MS/MS analysis to compare the differences in metabolite changes between LLLT and COC before and after treatment.

Results

76 differential metabolites were detected in the LLLT group, and 92 differential metabolites were detected in the COC group, which were up-regulated or down-regulated (p < 0.001). Prostaglandin D2 (PG D2) was down-regulated and biliverdin was up-regulated after LLLT treatment, 4a-Hydroxytetrahydrobiopterin, Prostaglandin D2, 5-Hydroxy-l-tryptophan, Cholic acid were down-regulated and cortisol was up-regulated after COC treatment, and the differences were statistically significant. Cortisol and testosterone glucuronide in LLLT group were significantly lower than those in COC group. The metabolic pathways affected were glycerophospholipid metabolism, linoleic acid metabolism and arachidonic acid metabolism in the LLLT group, and glycerophospholipid metabolism, folate biosynthesis, arachidonic-acid-metabolism, and tryptophan metabolism in the COC group. The differential metabolic pathway were linoleic acid metabolism, steroid hormone biosynthesis, and alpha-Linolenic acid metabolism after the comparison of LLLT with COC.

Conclusion

LLLT and COC might relieve dysmenorrhea by down-regulating PGD2, and LLLT might also relieve dysmenorrhea by up-regulating biliverdin. The level of cortisol and testosterone glucuronide after LLLT treatment was lower than that after COC treatment, which might lead to the difference in the clinical efficacy of the two treatments for dysmenorrhea.

Neuroimaging reveals a potential brain-based pre-existing mechanism that confers vulnerability to development of chronic painful chemotherapy-induced peripheral neuropathy

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating condition impacting 30% of cancer survivors. This study is the first to explore whether a brain-based vulnerability to chronic sensory CIPN exists.

METHODS

This prospective, multicentre cohort study recruited from three sites across Scotland. Brain functional MRI (fMRI) scans (3 Tesla) were carried out on chemotherapy naïve patients at a single fMRI centre in Edinburgh, Scotland. Nociceptive stimuli (with a 256 mN monofilament) were administered during the fMRI. Development of chronic sensory/painful CIPN (CIPN+) was determined based upon European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Chemotherapy-Induced Peripheral Neuropathy 20 changes conducted 9 months after chemotherapy, and imaging data analysed using standard software.

RESULTS

Of 30 patients recruited (two lung, nine gynaecological, and 19 colorectal malignancies), data from 20 patients at 9 months after chemotherapy was available for analysis. Twelve were classified as CIPN+ (mean age, 63.2[9.6] yr, 9.6; six female), eight as CIPN- (mean age 62.9 [SD 5.5] yr, four female). In response to punctate stimulation, group contrast analysis showed that CIPN+ compared with CIPN- had robust activity in sensory, motor, attentional, and affective brain regions. An a priori chosen region-of-interest analysis focusing on the periaqueductal grey, an area hypothesised as relevant for developing CIPN+, showed significantly increased responses in CIPN- compared with CIPN+ patients. No difference in subcortical volumes between CIPN+ and CIPN- patients was detected.

CONCLUSIONS

Before administration of any chemotherapy or appearance of CIPN symptoms, we observed altered patterns of brain activity in response to nociceptive stimulation in patients who later developed chronic sensory CIPN. This suggests the possibility of a pre-existing vulnerability to developing CIPN centred on brainstem regions of the descending pain modulatory system.

Hormonal contraceptives and the brain: A systematic review on 60 years of neuroimaging, EEG, and biochemical studies in humans and animals

Hormonal contraception has been widely prescribed for decades. Although safety and efficacy are well-established, much uncertainty remains regarding brain effects of hormonal contraception. We systematically review human and animal studies on the brain effects of hormonal contraception which employed neuroimaging techniques such as MRI, PET and EEG, as well as animal studies which reported on neurotransmitter and other brain biochemical effects. We screened 1001 articles and ultimately extracted data from 70, comprising 51 human and 19 animal studies. Of note, there were no animal studies which employed structural or functional MRI, MRS or PET. In summary, our review shows hormonal contraceptive associations with changes in the brain have been documented. Many questions remain and more studies are needed to describe the effects of hormonal contraception on the brain.

Resistance training protects against muscle pain through activation of androgen receptors in male and female mice

ABSTRACT

Resistance training-based exercise is commonly prescribed in the clinic for the treatment of chronic pain. Mechanisms of aerobic exercise for analgesia are frequently studied, while little is known regarding resistance training mechanisms. We developed a resistance training model in mice and hypothesized resistance training would protect against development of muscle pain, mediated through the activation of androgen receptors. Activity-induced muscle hyperalgesia was produced by 2 injections of pH 5.0 stimuli with fatiguing muscle contractions. Resistance training was performed by having mice climb a ladder with attached weights, 3 times per week. Resistance training acutely increased blood lactate and prolonged training increased strength measured via forepaw grip strength and 1 repetition maximum, validating the exercise program as a resistance training model. Eight weeks of resistance training prior to induction of the pain model blocked the development of muscle hyperalgesia in both sexes. Resistance training initiated after induction of the pain model reversed muscle hyperalgesia in male mice only. A single resistance training bout acutely increased testosterone in male but not female mice. Administration of the androgen receptor antagonist flutamide (200 mg pellets) throughout the 8-week training program blocked the exercise-induced protection against muscle pain in both sexes. However, single administration of flutamide (1, 3, 10 mg/kg) in resistance-trained animals had no effect on existing exercise-induced protection against muscle pain. Therefore, resistance training acutely increases lactate and testosterone and strength overtime. Eight weeks of resistance training prevents the development of hyperalgesia through the activation of androgen receptors in an animal model of muscle pain.

Conditioned pain modulation and offset analgesia: Influence of sex, sex hormone levels and menstrual cycle on the magnitude and retest reliability in healthy participants

BACKGROUND

Conditioned Pain Modulation (CPM) and offset analgesia quantify impairment of endogenous pain modulation, but magnitude and reliability vary broadly between studies, indicating influencing factors that are not currently controlled for. The aim of this study was to quantify magnitude and retest reliability of CPM and offset analgesia in healthy participants, whilst investigating the influence of sex and sex hormone levels.

METHODS

62 participants (30 female) completed the study. We tested CPM (heat-cold paradigm) and offset analgesia on six days within two menstrual cycles (tests were performed in each phase of two subsequent menstrual cycles, with similar time-points for men).

RESULTS

Median offset effect was -29.4% in female and -22.5% in male participants (as change from initial stimulus). Median early CPM effects were -16.7% for women versus -13.3% for men. Reliability (intra-class correlation coefficient (ICC)) was similar between the main measures, offset effect (female: 0.48, male: 0.47) and early CPM effect (female: 0.49, male: 0.43). There was significant variance between individual experimental parameters within protocols but not between sexes or menstrual phases. While oestradiol and progesterone did not correlate with the magnitude of effect within sexes, we found that testosterone levels explained an estimated 5-10% of variance within individual responses in all sexes.

CONCLUSIONS

Our results show that the reliability of both CPM effect and offset analgesia were independent of sex and menstrual cycle phase. The magnitude of CPM and offset effects were weakly influenced by sex and testosterone levels, indicating an area for future research, rather than clinical significance.

SIGNIFICANCE STATEMENT

This study investigated CPM and offset analgesia in parallel, across sexes and during two menstrual cycles while assessing the impact of sex hormones. Reliability seems to depend on experimental parameters rather than participant characteristics, while the magnitude of effect could be weakly linked to sex hormones and sex.

Can fibromyalgia be considered a characteristic symptom of climacterium?

Fibromyalgia syndrome (FMS) is a chronic pain syndrome, characterised by diffuse pain in musculoskeletal system and accompanied by stiffness, fatigue, tender points, sleep disturbances and cognitive and gastrointestinal symptoms. It affects middle-aged women (between 40 and 65) predominantly. Climacteric syndrome, which is characterised by vasomotor, somatic (headache, sleep disorders, myalgia and arthralgia) and psychical (mood changes) symptoms, results from the change in brain neurotransmitter concentrations due to gradual decline of ovarian hormone levels. Currently, studies focus on the similarities of FMS and climacteric syndrome in terms of age of occurrence, epidemiology, etiopathogenesis, symptomatology and treatment. Hormonal fluctuation during menopausal transition is likely the triggering factor for both syndromes. Therefore, hormone replacement therapy is a favourable approach in the treatment of FMS due to the antiallodynic, anti-inflammatory and neuroprotective effect of oestrogen. In this review, we emphasise the similarity of FMS and climacteric syndrome and suggested that FMS could be considered as a characteristic symptom of climacterium.

Headache in transgender and gender-diverse patients: A narrative review

OBJECTIVE

To summarize the unique aspects of managing headache in gender minorities and current research in this area including the potential relationship between gender-affirming hormone therapy (GAHT) and headache.

BACKGROUND

The study of headache in gender minorities is intrinsically important. Gender minorities are medically underserved, and their medical care to date has been limited by socioeconomic disadvantages including stigma and an unsupportive clinical environment. Despite the rising population of transgender and gender-diverse adults and youth, headache research has also been limited. Knowledge of hormonal effects on headache in cisgender patients raises the question of possible effects of GAHT on transgender patients.

METHODS/RESULTS

The manuscript is a narrative review of current best practices in treating transgender patients, including the use of appropriate terminology and ways to create a supportive environment. It also contains current guidelines on GAHT and reviews drug-drug interactions and secondary headache related to hormone therapy. We also review transgender headache research and related research on hormonal effects on headache in cisgender individuals.

CONCLUSION

Creating a supportive environment for transgender and gender-diverse patients and being knowledgeable about GAHT are key to providing quality headache care. This review identifies further research needs for this population including the epidemiology of headache disorders in sexual minorities and the potential effects of GAHT on headache disorders in transgender patients.

Testosterone protects against the development of widespread muscle pain in mice

Chronic widespread pain conditions are more prevalent in women than men, suggesting a role for gonadal hormones in the observed differences. Previously, we showed that female mice, compared to male, develop widespread, more severe, and longer-duration hyperalgesia in a model of activity-induced muscle pain. We hypothesized testosterone protects males from developing the female pain phenotype. We tested whether orchiectomy of males before induction of an activity-induced pain model produced a female phenotype and whether testosterone administration produced a male phenotype in females. Orchiectomy produced longer-lasting, more widespread hyperalgesia, similar to females. Administration of testosterone to females or orchiectomized males produced unilateral, shorter-lasting hyperalgesia. Prior studies show that the serotonin transporter (SERT) is increased in the nucleus raphe magnus (NRM) in models of chronic pain, and that blockade of SERT in the NRM reduces hyperalgesia. We examined potential sex differences in the distribution of SERT across brain sites involved in nociceptive processing using immunohistochemistry. A sex difference in SERT was found in the NRM in the activity-induced pain model; females had greater SERT immunoreactivity than males. This suggests that testosterone protects against development of widespread, long-lasting muscle pain and that alterations in SERT may underlie the sex differences.

An update on the management of chronic pelvic pain in women

Chronic pelvic pain represents a major public health problem for women and impacts significantly on their quality of life. Yet it is under-researched and a challenge to manage. Women who suffer from chronic pelvic pain frequently describe their healthcare journey as long, via a variety of specialists and frustrating, with their pain often dismissed. Aetiological factors and associations are best conceptualised using the 'three P's' model of predisposing, precipitating and perpetuating factors. This integrates the numerous biological, psychological and social contributors to the complex, multifactorial nature of chronic pelvic pain. Overall management involves analgesia, hormonal therapies, physiotherapy, psychological approaches and lifestyle advice, which like other chronic pain conditions relies on a multidisciplinary team approach delivered by professionals experienced and trained in managing chronic pelvic pain.

The Relationship Between Androgens and Days per Month of Period Pain, Pelvic Pain, Headache, and TLR4 Responsiveness of Peripheral Blood Mononuclear Cells in Young Women with Dysmenorrhoea

Purpose

Women bear a disproportionate burden of persistent pain conditions when compared to men. To determine whether the hormonal environment affects the clinical experience of pain, as measured by the days per month of pelvic pain (DPelvicPM), period pain (DPeriodPM), headache (DHeadachePM) or the in vitro EC₅₀ for Interleukin-1β (IL-1β) release following TLR4 stimulation with Lipopolysaccharide from Peripheral Blood Mononuclear Cells (PBMCs). Findings were stratified according to use or non-use of the oral contraceptive pill.

Patients and Methods

Fifty-six women aged 16–35 years, with minimal or severe dysmenorrhea, and use or non-use of the OC, were enrolled. Blood was collected on two occasions in a single menstrual cycle: Days 1–2 and Days 7–10. Hormonal analysis for testosterone, dihydrotestosterone, dehydroepiandrosterone, Androstenedione, 3α-Androstanediol, 3β-androstanediol, estradiol, estrone, 17α-hydroxyprogesterone, progesterone, cortisol and sex-hormone binding globulin was undertaken using ultra-sensitive Liquid Chromatography Mass–Spectrometry (LC-MS). PBMCs were exposed to lipopolysaccharide (LPS) and the resulting Interleukin-1β output was determined.

Results

Non-users of the OC showed a strongly inverse correlation between a reducing free androgen index (FAI) and increasing DPelvicPM (p=0.0032), DPeriodPM (p=0.013), DHeadachePM (p=0.041). Non-users of the OC showed a significant increase in DPelvicPM (p=0.049) on Days 7–10. Modestly significant associations were found between reduced androgens and potentiated LPS-induced IL-1β (lower EC₅₀).

Conclusion

This is the first study to investigate the relationship between the hormonal environment and activation of the immune system in young women with dysmenorrhoea-related pain conditions. Low androgen levels were consistently associated with increased pain. Translational implications for the findings are discussed.

The Effects of Hormonal Contraceptives on the Brain: A Systematic Review of Neuroimaging Studies

Background: Hormonal contraceptive drugs are being used by adult and adolescent women all over the world. Convergent evidence from animal research indicates that contraceptive substances can alter both structure and function of the brain, yet such effects are not part of the public discourse or clinical decision-making concerning these drugs. We thus conducted a systematic review of the neuroimaging literature to assess the current evidence of hormonal contraceptive influence on the human brain.

Methods: The review was registered in PROSPERO and conducted in accordance with the PRISMA criteria for systematic reviews. Structural and functional neuroimaging studies concerning the use of hormonal contraceptives, indexed in Embase, PubMed and/or PsycINFO until February 2020 were included, following a comprehensive and systematic search based on predetermined selection criteria.

Results: A total of 33 articles met the inclusion criteria. Ten of these were structural studies, while 23 were functional investigations. Only one study investigated effects on an adolescent sample. The quality of the articles varied as many had methodological challenges as well as partially unfounded theoretical claims. However, most of the included neuroimaging studies found functional and/or structural brain changes associated with the use of hormonal contraceptives.

Conclusion: The included studies identified structural and functional changes in areas involved in affective and cognitive processing, such as the amygdala, hippocampus, prefrontal cortex and cingulate gyrus. However, only one study reported primary research on a purely adolescent sample. Thus, there is a need for further investigation of the implications of these findings, especially with regard to adolescent girls.

Sex differences in pain and opioid mediated antinociception: Modulatory role of gonadal hormones

Sex-related differences in pain and opioids has been the focus of many researches. It is demonstrated that women experience greater clinical pain, lower pain threshold and tolerance, more sensitivity and distress to experimentally induced pain compared to men. Sex differences in response to opioid treatment revealed inconsistent results. However, the etiology of these disparities is not fully elucidated. It is, therefore, conceivable now that this literature merits to be revisited comprehensively. Possible multifaceted factors seem to be associated. These include neuroanatomical, hormonal, neuroimmunological, psychological, social and cultural aspects and comorbidities. This review aims at providing an overview of the substantial literature documenting the sex differences in pain and analgesic response to opioids from animal and human studies within the context of the modulatory effects of the aforementioned factors. A detailed and critical discussion of the cellular and molecular signaling pathways underlying the modulatory actions of gonadal hormones in the sexual dimorphism in pain processing and opioid analgesia is extensively presented. It is indicated that sexual dimorphic activation of certain brain regions contributes to differential pain sensitivity between females and males. Plausible crosstalk between sex hormones and neuroimmunological signaling pertinent to toll-like and purinergic receptors is uncovered as causal cues underlying sexually dimorphic pain and opioid analgesia. Conceivably, a thorough understanding of these factors may aid in sex-related advancement in pain therapeutic management.

Role of brain imaging in disorders of brain-gut interaction: a Rome Working Team Report

Imaging of the living human brain is a powerful tool to probe the interactions between brain, gut and microbiome in health and in disorders of brain-gut interactions, in particular IBS. While altered signals from the viscera contribute to clinical symptoms, the brain integrates these interoceptive signals with emotional, cognitive and memory related inputs in a non-linear fashion to produce symptoms. Tremendous progress has occurred in the development of new imaging techniques that look at structural, functional and metabolic properties of brain regions and networks. Standardisation in image acquisition and advances in computational approaches has made it possible to study large data sets of imaging studies, identify network properties and integrate them with non-imaging data. These approaches are beginning to generate brain signatures in IBS that share some features with those obtained in other often overlapping chronic pain disorders such as urological pelvic pain syndromes and vulvodynia, suggesting shared mechanisms. Despite this progress, the identification of preclinical vulnerability factors and outcome predictors has been slow. To overcome current obstacles, the creation of consortia and the generation of standardised multisite repositories for brain imaging and metadata from multisite studies are required.

Neuroimaging of pain in animal models: a review of recent literature

Neuroimaging of pain in animals allows us to better understand mechanisms of pain processing and modulation. In this review, we discuss recently published brain imaging studies in rats, mice, and monkeys, including functional magnetic resonance imaging (MRI), manganese-enhanced MRI, positron emission tomography, and electroencephalography. We provide an overview of innovations and limitations in neuroimaging techniques, as well as results of functional brain imaging studies of pain from January 1, 2016, to October 10, 2018. We then discuss how future investigations can address some bias and gaps in the field. Despite the limitations of neuroimaging techniques, the 28 studies reinforced that transition from acute to chronic pain entails considerable changes in brain function. Brain activations in acute pain were in areas more related to the sensory aspect of noxious stimulation, including primary somatosensory cortex, insula, cingulate cortex, thalamus, retrosplenial cortex, and periaqueductal gray. Pharmacological and nonpharmacological treatments modulated these brain regions in several pain models. On the other hand, in chronic pain models, brain activity was observed in regions commonly associated with emotion and motivation, including prefrontal cortex, anterior cingulate cortex, hippocampus, amygdala, basal ganglia, and nucleus accumbens. Neuroimaging of pain in animals holds great promise for advancing our knowledge of brain function and allowing us to expand human subject research. Additional research is needed to address effects of anesthesia, analysis approaches, sex bias and omission, and potential effects of development and aging.

Gender aspects of the pain syndrome

In recent years, the subject of sex differences in the pain experience attracts a growing interest. The epidemiological and clinical data indicate that women have increased risk of chronic pain, and according to some sources, even experience more intense pain. The hypothetical biological mechanisms underlying sex differences in pain perception consist in the modulating effects produced by sex hormones in relation to the neural substrate. This is confirmed by data on the distribution of gonadal hormones and their receptors in the areas of the peripheral and central nervous system that provide nociceptive transmission. The complexity of the estradiol and progesterone effects on pain sensitivity lies in the fact that, according to various data, both have pre-nociceptive and antinociceptive effects, and testosterone appears to be more characterized by antinociceptive properties. The lion’s share of researches demonstrates the effect of a clinical pain exacerbation during the menstrual cycle. There is irrefutable information about gender differences in responses to drug and non-drug pain treatment, although the results vary depending on a specific therapy and may depend on pain characteristics. Since the recommended dosage of a medication is often based on an “average” male weigh 70 kg, female patients may be facing the risk of increased therapeutic or adverse effects of a drug. The cause is in a higher average percentage of body fat, a lower mean body weight, which contributes to higher median drug concentrations compared with male patients. At present, the available evidence does not allow adapting the methods of pain syndrome treatment to a gender. However, such innovations are quite possible and desirable in the foreseeable future. Additional studies will be required to clarify the mechanisms that determine sex differences in pain responses in order to provide adequate pain relief, according to the patient’s needs.

Gender, genetics, and analgesia: understanding the differences in response to pain relief

Genetic variations and gender contribute significantly to the large interpatient variations in opioid-related serious adverse effects and differences in pain relief with other analgesics. Opioids are the most commonly used analgesics to relieve moderate-to-severe postoperative pain. Narrow therapeutic index and unexplained large interpatient variations in opioid-related serious adverse effects and analgesia negatively affect optimal perioperative outcomes. In surgical, experimental, chronic, and neuropathic pain models, females have been reported to have more pain than males. This review focuses on literature evidence of differences in pain relief due to multiple genetic variations and gender of the patient.

Sex, Gender, and Orofacial Pain

This review examines gender prevalence in orofacial pain to elucidate underlying factors that can explain such differences. This review highlights how gender affects (1) the association of hormonal factors and pain modulation; (2) the genetic aspects influencing pain sensitivity and pain perception; (3) the role of resting blood pressure and pain threshold; and (4) the impact of sociocultural, environmental, and psychological factors on pain.

An Investigation of the Effects of Testosterone and Behavioral Expressions of Pain on Sex/Gender Differences in Pain Perception

Research indicates that women are more susceptible to pain than men, but the reason for this difference is unclear. While estrogen and progesterone have been implicated, testosterone has not received adequate consideration in the literature. Additionally, incorporating behavioral expressions, or exaggerations, of pain as an important aspect of pain perception is receiving increasing attention. The current study examined the role of testosterone in female pain expression and perception via the cold pressor test. Following all participant exclusions, 46 healthy participants (32 women) provided saliva samples for testosterone analysis using enzyme-linked immunosorbent assay before and after rating their pain during the cold pressor test. Participants used a visual analog scale to indicate how the 2℃ water was perceived, ranging from “worst pain imaginable” to “no pain.” The researcher also noted whether a participant displayed overt behavioral expressions of pain such as jumping and cursing. The results revealed that men reported lower visual analog scale scores than women, indicating less perceived pain. A subgroup of women who displayed overt behavioral responses to pain seemed to be driving this sex/gender difference. It was expected that this subgroup of females would have corresponding changes in testosterone that would further explain the observed sex/gender differences, but this was not supported. Collectively, these data add to the previous literature investigating sex/gender differences in pain perception and highlight the importance of studying overt behavioral expressions of pain. Testosterone may alter this behavior and subsequent pain perception, but the contributions of testosterone are likely subtle and were not detected in this study.

Diffuse noxious inhibitory controls and brain networks are modulated in a testosterone-dependent manner in Sprague Dawley rats

Diffuse noxious inhibitory control (DNIC), which involves endogenous pain modulation, has been investigated as a potential mechanism for the differences in pain modulation observed between men and women, though the literature shows contradictory findings. We used a capsaicin-induced DNIC behavioral assay and resting state functional magnetic resonance imaging (rsfMRI) to assess the effect of testosterone on pain modulation and related brain circuitry in rats. We hypothesized that testosterone is required for DNIC that leads to efficient pain inhibition by increasing descending pain modulation. Male, female, and orchidectomized (GDX) male rats had a capsaicin injection into the forepaw to induce DNIC and mechanical thresholds were observed on the hindpaw. rsfMRI scans were acquired before and after capsaicin injection to analyze the effects of DNIC on periaqueductal gray (PAG), anterior cingulate cortex (ACC) and nucleus accumbens (NAc) connectivity to the whole brain. The strength of DNIC was higher in males compared to females and GDX males. PAG connectivity with prelimbic cortex (PrL), ACC and insula was stronger in males compared to females and GDX males, whereas females and GDX males had increased connectivity between the right ACC, hippocampus and thalamus. GDX males also showed a stronger connectivity between right ACC and NAc, and right NAc with PrL, ACC, insula and thalamus. Our findings suggest that testosterone plays a key role in reinforcing the endogenous pain inhibitory system, while circuitries related to reward and emotion are more strongly recruited in the absence of testosterone.

Musculoskeletal pain and menopause

Musculoskeletal pain, arthralgia and arthritis are all more common in women, and their frequency increases with age and in some appears to be associated with the onset of menopause. The clinical assessment, investigation and management of women presenting with musculoskeletal pain, arthralgia or arthritis at the time of menopause are reviewed. Common causes of arthralgia and arthritis in this population are discussed. The epidemiological and trials evidence for the effects of hormone replacement therapy on musculoskeletal pain and arthritis (primarily from RCTs of HRT for other menopausal symptoms) are discussed. Lastly, the possible underlying aetiological roles of sex hormones including estrogen, and their deficiency, in predisposing to musculoskeletal pain and arthritis are overviewed. Although the association appears strong, a causal link between estrogen deficiency and musculoskeletal pain or different types of arthritis is lacking; there have been few studies specifically within this group of symptomatic patients, and there is much still to understand about musculoskeletal pain and arthritis at the time of the menopause, and about how we might prevent or treat this.

Effects of Androgen Deprivation Therapy on Pain Perception, Quality of Life, and Depression in Men With Prostate Cancer

CONTEXT

Previous animal and human research suggests that testosterone has antinociceptive properties. Castration in male rodents increases pain perception which is reversed by testosterone replacement. Pain perception also improves in hypogonadal men with testosterone therapy. However, it remains unclear whether androgen deprivation therapy (ADT) in men with prostate cancer (PCa) is associated with an increase in pain perception.

OBJECTIVES

To evaluate the effects of ADT on pain perception, depression and quality of life (QOL) in men with PCa.

METHODS

Thirty-seven men with PCa about to undergo ADT with leuprolide acetate (ADT group) were followed prospectively for six months to evaluate changes in clinical and experimental pain. Forty men who had previously undergone prostatectomy for localized PCa and were in remission served as controls (non-ADT group). All participants were eugonadal at study entry. Primary outcomes were changes in clinical pain (assessed with Brief Pain Inventory questionnaire) and experimental pain (assessed with quantitative sensory testing). Secondary outcomes included evaluation of depression, anxiety levels, and quality of life.

RESULTS

Serum testosterone levels significantly decreased in the ADT group but remained unchanged in the non-ADT group. There were no significant changes in pain thresholds, ratings, or other responses to quantitative sensory tests over the 6-month course of the study. Clinical pain did not differ between the two groups, and no changes from baseline were observed in either group. Men undergoing ADT did experience worsening of depression (0.93; 95% CI = 0.04-1.82; P = 0.042) and QOL related to physical role limitation (-18.28; 95% CI = -30.18 to -6.37; P = 0.003).

CONCLUSION

ADT in men with PCa is associated with worsening of depression scores and QOL but is not associated with changes in clinical pain or pain sensitivity.

"Luteal Analgesia": Progesterone Dissociates Pain Intensity and Unpleasantness by Influencing Emotion Regulation Networks

Background: Pregnancy-induced analgesia is known to occur in association with the very high levels of estradiol and progesterone circulating during pregnancy. In women with natural ovulatory menstrual cycles, more modest rises in these hormones occur on a monthly basis. We therefore hypothesized that the high estradiol high progesterone state indicative of ovulation would be associated with a reduction in the pain experience. Methods: We used fMRI and a noxious thermal stimulus to explore the relationship between sex steroid hormones and the pain experience. Specifically, we assessed the relationship with stimulus-related activity in key regions of networks involved in emotion regulation, and functional connectivity between these regions. Results: We demonstrate that physiologically high progesterone levels are associated with a reduction in the affective component of the pain experience and a dissociation between pain intensity and unpleasantness. This dissociation is related to decreased functional connectivity between the inferior frontal gyrus and amygdala. Moreover, we have shown that in the pre-ovulatory state, the traditionally "male" sex hormone, testosterone, is the strongest hormonal regulator of pain-related activity and connectivity within the emotional regulation network. However, following ovulation the traditionally "female" sex hormones, estradiol and progesterone, appear to dominate. Conclusions: We propose that a phenomenon of "luteal analgesia" exists with potential reproductive advantages.

Understanding Monitoring Technologies for Adults With Pain: Systematic Literature Review

BACKGROUND

Monitoring of patients may decrease treatment costs and improve quality of care. Pain is the most common health problem that people seek help for in hospitals. Therefore, monitoring patients with pain may have significant impact in improving treatment. Several studies have studied factors affecting pain; however, no previous study has reviewed the contextual information that a monitoring system may capture to characterize a patient's situation.

OBJECTIVE

The objective of this study was to conduct a systematic review to (1) determine what types of technologies have been used to monitor adults with pain, and (2) construct a model of the context information that may be used to implement apps and devices aimed at monitoring adults with pain.

METHODS

A literature search (2005-2015) was conducted in electronic databases pertaining to medical and computer science literature (PubMed, Science Direct, ACM Digital Library, and IEEE Xplore) using a defined search string. Article selection was done through a process of removing duplicates, analyzing title and abstract, and then reviewing the full text of the article.

RESULTS

In the final analysis, 87 articles were included and 53 of them (61%) used technologies to collect contextual information. A total of 49 types of context information were found and a five-dimension (activity, identity, wellness, environment, physiological) model of context information to monitor adults with pain was proposed, expanding on a previous model. Most technological interfaces for pain monitoring were wearable, possibly because they can be used in more realistic contexts. Few studies focused on older adults, creating a relevant avenue of research on how to create devices for users that may have impaired cognitive skills or low digital literacy.

CONCLUSIONS

The design of monitoring devices and interfaces for adults with pain must deal with the challenge of selecting relevant contextual information to understand the user's situation, and not overburdening or inconveniencing users with information requests. A model of contextual information may be used by researchers to choose possible contextual information that may be monitored during studies on adults with pain.

Experimental and procedural pain responses in primary dysmenorrhea: a systematic review

Primary dysmenorrhea (PD) has been the focus of a number of experimental pain studies. Although a number of reviews exist, few have critically evaluated the existing body of research on PD and experimental and procedural pain. Data from 19 published research articles that include women with PD and responses to an experimental or procedural pain stimulus (or stimuli) suggest that women with PD may have elevated pain reactivity, as compared to women without PD. This pattern appears to be true across different phases of the menstrual cycle. However, there is an abundance of conflicting findings, which may be due to significant methodological issues such as inconsistent definitions of PD, wide variation in experimental pain methodologies, and inaccurate assessment of the menstrual cycle. Future research should focus on identifying specific symptoms (i.e., pain threshold ratings) to more clearly define what constitutes PD, establish reliable and valid laboratory testing protocols, and assess the menstrual cycle with greater precision.

[Pain medicine from intercultural and gender-related perspectives]

Cultural setting and sex and gender of the patient are important factors affecting the occurrence, severity, clinical course and prognosis of pain and pain-related diseases. Intercultural differences in the perception and verbal expression of symptoms and emotional function are fundamental and it is important to realize these differences in order to understand patients with a migration background. A trusting doctor-patient relationship is generally very sensitive and it is even more difficult to establish when differences in the cultural background impair mutual understanding. Regarding sex and gender there is evidence that females are more susceptible to developing chronic pain conditions, experience more severe pain and respond differently to pain therapy; however, results of recent studies indicate that females are not that different to males when comparing several modalities of experimental pain (although some differences exist). Similarly, sex and gender differences in postoperative pain seem to exist but the differences are relatively small when pain scores are compared. Other aspects, such as the response to analgesics and role of psychosocial factors should be addressed when sex and gender aspects are studied. Similarly, sex and gender differences in the prevalence of chronic pain exist but the results of some studies, e.g. those controlling for confounders, are not very clear. Research is needed to delineate the role of specific aspects affecting sex and gender differences and the underlying mechanisms (e.g. reduced inhibitory control, hormones, psychological aspects and social factors). Altogether, we need to open our minds to some intercultural and sex and gender aspects in the clinical setting. For sex and gender differences we may need a more biopsychosocial approach to understand the underlying differences and differentiate between sex and gender and sex and gender-associated aspects for acute and chronic pain.

The OPRM1 A118G polymorphism modulates the descending pain modulatory system for individual pain experience in young women with primary dysmenorrhea

The mu-opioid receptor (OPRM1) A118G polymorphism underpins different pain sensitivity and opioid-analgesic outcome with unclear effect on the descending pain modulatory system (DPMS). Primary dysmenorrhea (PDM), the most prevalent gynecological problem with clear painful and pain free conditions, serves as a good clinical model of spontaneous pain. The objective of this imaging genetics study was therefore to explore if differences in functional connectivity (FC) of the DPMS between the OPRM1 A118G polymorphisms could provide a possible explanation for the differences in pain experience. Sixty-one subjects with PDM and 65 controls participated in the current study of resting-state functional magnetic resonance imaging (fMRI) during the menstruation and peri-ovulatory phases; blood samples were taken for genotyping. We studied 3 aspects of pain experience, namely, mnemonic pain (recalled overall menstrual pain), present pain (spontaneous menstrual pain), and experimental pain (thermal pain) intensities. We report that G allele carriers, in comparison to AA homozygotes, exhibited functional hypo-connectivity between the anterior cingulate cortex (ACC) and periaqueductal gray (PAG). Furthermore, G allele carriers lost the correlation with spontaneous pain experience and exhibited dysfunctional DPMS by means of PAG-seeded FC dynamics. This OPRM1 A118G-DPMS interaction is one plausible neurological mechanism underlying the individual differences in pain experience.

Sex-based differences in brain alterations across chronic pain conditions

Common brain mechanisms are thought to play a significant role across a multitude of chronic pain syndromes. In addition, there is strong evidence for the existence of sex differences in the prevalence of chronic pain and in the neurobiology of pain. Thus, it is important to consider sex when developing general principals of pain neurobiology. The goal of the current Mini-Review is to evaluate what is known about sex-specific brain alterations across multiple chronic pain populations. A total of 15 sex difference and 143 single-sex articles were identified from among 412 chronic pain neuroimaging articles. Results from sex difference studies indicate more prominent primary sensorimotor structural and functional alterations in female chronic pain patients compared with male chronic pain patients: differences in the nature and degree of insula alterations, with greater insula reactivity in male patients; differences in the degree of anterior cingulate structural alterations; and differences in emotional-arousal reactivity. Qualitative comparisons of male-specific and female-specific studies appear to be consistent with the results from sex difference studies. Given these differences, mixed-sex studies of chronic pain risk creating biased data or missing important information and single-sex studies have limited generalizability. The advent of large-scale neuroimaging databases will likely aid in building a more comprehensive understanding of sex differences and commonalities in brain mechanisms underlying chronic pain. © 2016 Wiley Periodicals, Inc.

Pain Severity in Relation to the Final Menstrual Period in a Prospective Multiethnic Observational Cohort: Results From the Study of Women's Health Across the Nation

The development of pain is common in midlife, resulting in increased health care utilization and costs. The aim of this study was to determine the longitudinal trajectory of overall bodily pain among women during the transition between the reproductive years and menopause. We conducted analyses on a community-based, longitudinal cohort of women enrolled in the Study of Women's Health Across the Nation. One thousand four hundred ninety-five women met inclusion criteria, including: 1) defined date of the final menstrual period (FMP), and 2) complete data on Short Form-36 bodily pain. The primary exposure was time to/from the FMP. The primary outcome was the rate of change in Short Form-36 bodily pain, measured on a scale of 0 to 100 with 100 being the most severe pain. We performed within-person trajectory analyses using piecewise regression following nonparametric modeling of functional forms. Mean bodily pain score at the time of the FMP was 29. Mean bodily pain increased at a rate of .26 per year during the transmenopause (the interval spanning 4.5 years before the FMP through .5 years after the FMP), and decreased at a rate of .23 per year after that. Depression and sleep problems were associated with greater increases in pain during the late reproductive years, whereas abdominal cramps at baseline predicted greater decreases in pain during the late reproductive years.

PERSPECTIVE

This article shows that bodily pain increases during the transmenopause and then diminishes during postmenopause. These differences may reflect differences in underlying mechanisms of pain in the 2 periods. Although mean changes were small and unlikely to be clinically meaningful, the magnitude of change varied across subgroups of women.

Anticipation of thermal pain in diverticular disease

BACKGROUND

The relative importance of peripheral nerve injury or central pain processing in painful diverticular disease (DD) is unclear. Functional magnetic resonance imaging (fMRI) has demonstrated that dysfunctional central pain processing predominates in irritable bowel syndrome (IBS). This study aims to identify anticipatory changes in symptomatic DD (SDD) compared to asymptomatic DD (ADD) and IBS patients.

METHODS

Gastrointestinal symptoms and somatization were evaluated via the Patient Health Question-12 Somatic Symptom and the SDD group divided into low (≤6 [LSDD]) and high (≥7 [HSDD]) somatization. Cued painful cutaneous thermal stimuli were delivered to the left hand and foot during fMRI. Fixed effect group analysis of the 'cued' anticipatory phase was performed.

KEY RESULTS

Within the right posterior insula, greater deactivation was found in the ADD compared to other groups. In emotion processing centers, anterior and middle insula, greater activation was identified in all patient compared to the ADD group, and in LSDD compared to IBS and HSDD groups. In comparison, amygdala deactivation was greater in ADD than the IBS and HSDD groups, and in LSDD vs HSDD groups. Descending nociceptive control centers, such as the superior medial frontal and orbitofrontal cortex, also showed greater deactivation in the ADD and LSDD compared to the HSDD and IBS groups.

CONCLUSIONS & INFERENCES

The HSDD group have altered anticipatory responses to thermal pain, similar to IBS group. The LSDD are similar to ADD group. This suggests underlying differences in pain pathophysiology, and the need for individualized treatment strategies to target the cause of their chronic pain.

The BDNF Val66Met polymorphism is associated with the functional connectivity dynamics of pain modulatory systems in primary dysmenorrhea

Primary dysmenorrhea (PDM), menstrual pain without an organic cause, is a prevailing problem in women of reproductive age. We previously reported alterations of structure and functional connectivity (FC) in the periaqueductal gray (PAG) of PDM subjects. Given that the brain derived neurotrophic factor (BDNF) acts as a pain modulator within the PAG and the BDNF Val66Met polymorphism contributes towards susceptibility to PDM, the present study of imaging genetics set out to investigate the influence of, firstly, the BDNF Val66Met single nucleotide polymorphism and, secondly, the genotype-pain interplays on the descending pain modulatory systems in the context of PAG-seeded FC patterning. Fifty-six subjects with PDM and 60 controls participated in the current study of resting-state functional magnetic resonance imaging (fMRI) during the menstruation and peri-ovulatory phases; in parallel, blood samples were taken for genotyping. Our findings indicate that the BDNF Val66Met polymorphism is associated with the diverse functional expressions of the descending pain modulatory systems. Furthermore, PAG FC patterns in pain-free controls are altered in women with PDM in a genotype-specific manner. Such resilient brain dynamics may underpin the individual differences and shed light on the vulnerability for chronic pain disorders of PDM subjects.

A quantitative and qualitative review of the effects of testosterone on the function and structure of the human social-emotional brain

Social and affective research in humans is increasingly using functional and structural neuroimaging techniques to aid the understanding of how hormones, such as testosterone, modulate a wide range of psychological processes. We conducted a meta-analysis of functional magnetic resonance imaging (fMRI) studies of testosterone administration, and of fMRI studies that measured endogenous levels of the hormone, in relation to social and affective stimuli. Furthermore, we conducted a review of structural MRI i.e. voxel based morphometry (VBM) studies which considered brain volume in relation to testosterone levels in adults and in children. In the included testosterone administration fMRI studies, which consisted of female samples only, bilateral amygdala/parahippocampal regions as well as the right caudate were significantly activated by social-affective stimuli in the testosterone condition. In the studies considering endogenous levels of testosterone, stimuli-invoked activations relating to testosterone levels were noted in the bilateral amygdala/parahippocampal regions and the brainstem. When the endogenous testosterone studies were split by sex, the significant activation of the brain stem was seen in the female samples only. Significant stimuli-invoked deactivations relating to endogenous testosterone levels were also seen in the right and left amygdala/parahippocampal regions studies. The findings of the VBM studies were less consistent. In adults larger volumes in the limbic and temporal regions were associated with higher endogenous testosterone. In children, boys showed a positive correlation between testosterone and brain volume in many regions, including the amygdala, as well as global grey matter volume, while girls showed a neutral or negative association between testosterone levels and many brain volumes. In conclusion, amygdalar and parahippocampal regions appear to be key target regions for the acute actions of testosterone in response to social and affective stimuli, while neurodevelopmentally the volumes of a broader network of brain structures are associated with testosterone levels in a sexually dimorphic manner.

Hand osteoarthritis, menopause and menopausal hormone therapy

Hand osteoarthritis (OA) is one of the commonest musculoskeletal conditions, primarily affecting women over the age of 50, typically around the age of the menopause. Symptomatic disease can give rise to substantial pain, impairment of hand function and quality of life, leading to significant socioeconomic cost. There is currently no disease-modifying therapy, representing a huge unmet clinical need. The evidence for a relationship between hand OA and the menopause is summarised. Whether there is evidence for an effect of menopausal hormonal therapy on the incidence, prevalence or severity of symptomatic hand OA is critically reviewed, and gaps in our knowledge identified. Lastly, the potential mechanisms by which estrogen, or newer agents such as SERMs, might act to interfere with disease pathogenesis are overviewed. The need for specifically designed, controlled trials of agents in cohorts with symptomatic hand OA, refractory to standard symptomatic management is highlighted.

Low-dose progestin-releasing contraceptives are associated with a higher pain threshold in healthy women

OBJECTIVE

To determine the pain thresholds of women taking different formulations of hormonal contraceptives.

DESIGN

Cross-sectional study.

SETTING

Basic health care unit.

PATIENT(S)

Eighty-nine healthy nonusers and 188 users of hormonal contraceptives.

INTERVENTION(S)

Subject interviews were followed by the application of a semistructured questionnaire, including a psychometric assessment with the Beck Depression Inventory and the State-Trait Anxiety Inventory. After the interview, a 10-mL peripheral blood sample was collected. Pain thresholds were obtained by performing pressure algometry.

MAIN OUTCOME MEASURE(S)

Serum concentrations of E2, P, and T (free fraction) were determined via chemoluminescence. The menstrual cycle phase was determined according to hormonal level and identification of an LH surge in urine. Pain threshold was evaluated with a dynamometer applied to the forearm skin of the nondominant limb and abdominal wall.

RESULT(S)

Progestin-only contraceptive users showed a higher pain pressure threshold in the forearm (2.94 ± 0.96 vs. 2.74 ± 0.89 vs. 2.62 ± 0.92) and right (2.11 ± 0.87 vs. 1.83 ± 0.81 vs. 1.78 ± 0.77) and left abdomen (2.12 ± 0.88 vs. 1.79 ± 0.76 vs. 1.73 ± 0.70) than did combined hormonal contraceptive users and nonusers of hormonal contraceptives, respectively. Users of contraceptives that continuously release etonogestrel (subcutaneous implant, vaginal ring) or levonorgestrel (intrauterine devices) had higher pain thresholds.

CONCLUSION(S)

Women who used hormonal contraceptives enabling continuous release of etonogestrel or levonorgestrel tended to have higher pain thresholds than did nonusers of hormonal contraceptives.