Association of serotonin-1A and -2A receptor promoter polymorphisms with depressive symptoms, functional recovery, and pain in patients 6 months after lumbar disc surgery

Mechanisms of pain in aging and age-related conditions: Focus on caregivers

Pain is a complex, subjective experience that can significantly impact quality of life, particularly in aging individuals, by adversely affecting physical and emotional well-being. Whereas acute pain usually serves a protective function, chronic pain is a persistent pathological condition that contributes to functional deficits, cognitive decline, and emotional disturbances in the elderly. Despite substantial progress that has been made in characterizing age-related changes in pain, complete mechanistic details of pain processing mechanisms in the aging patient remain unknown. Pain is particularly under-recognized and under-managed in the elderly, especially among patients with Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other age-related conditions. Furthermore, difficulties in assessing pain in patients with AD/ADRD and other age-related conditions may contribute to the familial caregiver burden. The purpose of this article is to discuss the mechanisms and risk factors for chronic pain development and persistence, with a particular focus on age-related changes. Our article also highlights the importance of caregivers working with aging chronic pain patients, and emphasizes the urgent need for increased legislative awareness and improved pain management in these populations to substantially alleviate caregiver burden.

Patient genetic heterogeneities acting as indicators of post-operative pain and opioid requirement in orthopedic surgery: A systematic review

INTRODUCTION

Orthopedic surgical procedures are expected to increase annually, making it imperative to understand the correlations between patient genetic makeup and post-operative pain levels.

METHODS

We performed a systematic literature review using PubMed and Cochrane databases in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 299 articles were initially selected, 20 articles remained after title and abstract review, and nine articles were selected for inclusion upon full text review.

RESULTS

Genetic risk factors identified included the A allele of the 5HT2A gene single nucleotide polymorphism, the AA genotype of the ADRB2 gene, the CG genotype of the IL6 gene, the genotypes CT and TT of the NTRK1 gene, genotypes AA and GA of the OPRM gene, and the AA and GA genotypes of the COMT gene. Additional studies in the review discuss statistical significance of other variants of the COMT gene.

CONCLUSION

There have been genetic association studies performed on the patient heterogeneity and its relationship on patient pain levels, but more data need to be collected to understand the clinical utility of stratifying patients based on genomic sequence.

Is neuregulin-1 (NRG-1) a potential blood biomarker linking depression to obesity? A case-control study

BACKGROUND AND AIM

No definite biomarker linking depression and obesity has been found yet. Our study aimed to investigate neuregulin-1 (NRG-1) as a potential blood biomarker for this association.

METHODS

A case-control study was conducted on 108 obese subjects assigned for laparoscopic sleeve gastrectomy and 100 non-obese controls. Depression was assessed pre- and post-operatively. Serum NRG-1 was measured.

RESULTS

Pre-operatively depression was significantly higher among obese compared to non-obese patients. After the operation, 1.9% of the severely depressed subjects reported no depression, while 5.6% became moderately depressed; about 6% of the moderately depressed and 16% of the mildly depressed became not depressed. Serum NRG-1 level was significantly lower among obese and severely depressed compared to the controls. It was negatively correlated to the level of depression pre- and post-operative (r = -0.764 and -0.467 respectively). The sensitivity of serum NRG1 as a predictor for depression pre- and post-operative was 92.45% and 52.94% respectively. Specificity was 69.09% and 79.73% respectively at cut-off values of ≤ 3.5 and ≤ 2.5 ng/ml.

CONCLUSION

NRG-1 is a possible biomarker for the diagnosis of depression pre-bariatric surgery and the prediction of its prognosis post-operatively.

Factors Which Predict Adverse Outcomes in Anterior Cervical Discectomy and Fusion Procedures in the Nonelderly Adult Population

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

The largest published cohort of anterior cervical discectomy and fusion (ACDF) patients was queried to better characterize demographic and operative factors that predict 90-day complication and 2-year reoperation risk.

SUMMARY OF BACKGROUND DATA

The MarketScan Database was queried from 2007 to 2016 to identify adult patients until 65 years, who underwent an ACDF procedure using International Classification of Diseases 9th Version (ICD-9) and Current Procedural Terminology (CPT) codes. MarketScan is a national insurance claims database that contains millions of patient records across all 50 states.

METHODS

Multivariate logistic regression was used to identify factors associated with complications until 90 days and reoperations until 2 years.

RESULTS

Of 138,839 ACDF procedures, 8500 patients (6.1%) experienced a complication within 90 days of the ACDF, and 7433 (5.4%) underwent surgical revision by 2 years. While the use of anterior cervical plating did not predict 2-year reoperation, it was associated with dramatically reduced 90-day complication risk (adjusted odds ratio [aOR]: 0.32; 95% confidence interval [CI]: 0.30-0.34; P <0.001). Upon multivariate analysis, female sex (aOR: 0.83; 95% CI: 0.79-0.87; P <0.001) was associated with decreased risk of 2-year reoperation, while depression predicted a 50% increase in reoperation risk (aOR: 1.51; 95% CI: 1.43-1.59; P <0.001). The single largest factor associated with reoperation risk, however, was the presence of a 90-day postoperative complication (aOR: 1.79; 95% CI: 1.66-1.94; P <0.001).

CONCLUSION

Increased patient comorbidities and the use of bone morphogenic protein were found to increase the risk for postoperative complications, while cervical plating was associated with a strong decline in this risk. In addition, poor patient mental health outweighed the adverse of impact of other comorbidities on 2-year revision risk. The presence of a postoperative complication was the key modifiable risk factor associated with reoperation risk. Conclusions from this study may help surgeons better identify high-risk ACDF patients for more careful patient selection, counseling, informed consent, and management.

Genetic and epigenetic mechanisms influencing acute to chronic postsurgical pain transitions in pediatrics: Preclinical to clinical evidence

Background

Chronic postsurgical pain (CPSP) in children remains an important problem with no effective preventive or therapeutic strategies. Recently, genomic underpinnings explaining additional interindividual risk beyond psychological factors have been proposed.

Aims

We present a comprehensive review of current preclinical and clinical evidence for genetic and epigenetic mechanisms relevant to pediatric CPSP.

Methods

Narrative review.

Results

Animal models are relevant to translational research for unraveling genomic mechanisms. For example, Cacng2, p2rx7, and bdnf mutant mice show altered mechanical hypersensitivity to injury, and variants of the same genes have been associated with CPSP susceptibility in humans; similarly, differential DNA methylation (H1SP) and miRNAs (miR-96/7a) have shown translational implications. Animal studies also suggest that crosstalk between neurons and immune cells may be involved in nociceptive priming observed in neonates. In children, differential DNA methylation in regulatory genomic regions enriching GABAergic, dopaminergic, and immune pathways, as well as polygenic risk scores for enhanced prediction of CPSP, have been described. Genome-wide studies in pediatric CPSP are scarce, but pathways identified by adult gene association studies point to potential common mechanisms.

Conclusions

Bench-to-bedside genomics research in pediatric CPSP is currently limited. Reverse translational approaches, use of other -omics, and inclusion of pediatric/CPSP endophenotypes in large-scale biobanks may be potential solutions. Time of developmental vulnerability and longitudinal genomic changes after surgery warrant further investigation. Emergence of promising precision pain management strategies based on gene editing and epigenetic programing emphasize need for further research in pediatric CPSP-related genomics.

The Role of Sex in Genetic Association Studies of Depression

Depression is the most common mental illness in the U.S. affecting nearly 40 million adults age 18 years and older. Depression has both genetic and environmental influences. In addition, women are more likely to be affected by depression than men. However, the relationship between genes and depression is complex and may be influenced by sex. Understanding the genetic basis of sex-specific differences for depression has the potential to lead to new biological understanding of the etiology of depression in females compared to males and to promote the development of novel and more effective pharmacotherapies. This review examines the role of sex in genetic associations with depression for both genome-wide association and candidate gene studies. While the genetic association signals of depression differ by sex, the role of sex in the heritability of depression is complex and warrants further investigation.

New-onset depression after hip fracture surgery among older patients: Effects on associated clinical outcomes and what can we do?

BACKGROUND

Hip fracture in the elderly is a worldwide medical problem. New-onset depression after hip fracture has also received attention because of its increasing incidence and negative impact on recovery.

AIM

To provide a synthesis of the literature addressing two very important questions arising from postoperative hip fracture depression (PHFD) research: the risk factors and associated clinical outcomes of PHFD, and the optimal options for intervention in PHFD.

METHODS

We searched the PubMed, Web of Science, EMBASE, and PsycINFO databases for English papers published from 2000 to 2021.

RESULTS

Our results showed that PHFD may result in poor clinical outcomes, such as poor physical function and more medical support. In addition, the risk factors for PHFD were summarized, which made it possible to assess patients preoperatively. Moreover, our work preliminarily suggested that comprehensive care may be the optimal treatment option for PHFDs, while interdisciplinary intervention can also be clinically useful.

CONCLUSION

We suggest that clinicians should assess risk factors for PHFDs preoperatively, and future research should further validate current treatment methods in more countries and regions and explore more advanced solutions.

History of depression is associated with worsened postoperative outcomes following colectomy

AIM

Depression is a prevalent disorder that is associated with adverse health outcomes, but an understanding of its effect in colorectal surgery remains limited. The purpose of this study was to examine the impact of history of depression among patients undergoing colectomy.

METHOD

United States patients from Marketscan (2010-2017) who underwent colectomy were included and stratified by whether they had a history of depression within the past year, defined as (1) a diagnosis of depression during the index admission, (2) a diagnosis of depression during any inpatient or (3) outpatient admission within the year, and/or (4) a pharmacy claim for an antidepressant within the year. The primary outcomes were length of stay (LOS) and inpatient hospital charge. Secondary outcomes included in-hospital mortality and postoperative complications. Logistic, negative binomial, and quantile regressions were performed.

RESULTS

Among 88 981 patients, 21 878 (24.6%) had a history of depression. Compared to those without, patients with a history of depression had significantly longer LOS (IRR = 1.06, 95% CI [1.05, 1.07]), increased inpatient charge (β = 467, 95% CI [167, 767]), and increased odds of in-hospital mortality (OR = 1.37, 95% CI [1.08, 1.73]) after adjustment. History of depression was also independently associated with increased odds of respiratory complication, pneumonia, and delirium (all P < 0.05).

CONCLUSION

History of depression was prevalent among individuals undergoing colectomy, and associated with greater mortality and inpatient charge, longer LOS, and higher odds of postoperative complication. These findings highlight the impact of depression in colorectal surgery patients and suggest that proper identification and treatment may reduce postoperative morbidity.

Does human serotonin-1A receptor polymorphism (rs6295) code for pain and associated symptoms in fibromyalgia syndrome?

Genetic predisposition may play an important role in the development of fibromyalgia syndrome (FMS). Serotonin is known to be involved in pain modulation and serotonin-1A receptor plays a considerable role in determining the central 5-HT tone. Consequently, variation in 5-HT1A receptor gene (HTR1A) may be responsible for inter-individual variability in pain sensitivity and other clinical symptoms of FMS. Therefore, the objectives of this research work were to study the gene polymorphism of 5-HTR1A gene and to explore the correlation between rs6295 genotype (-1019C/G HTR1A) and duration of pain, pain intensity and pain related depression and anxiety, if any, in FMS. 5-HTR1A genotype for the C(-1019)G polymorphism was typed in 62 patients with FMS and 42 healthy subjects. Present pain intensity, components of pain and pain related depression and anxiety were assessed using the numerical pain rating scale, McGill pain questionnaire and Hamilton depression and anxiety rating scale respectively. 5-HTR1A gene was represented by three different genotypes, homozygous C/C, heterozygous C/G and homozygous G/G. Analysis of the 5-HTR1A gene showed a frequency of 58%, 31% and 11% for the C/C, C/G and G/G genotypes, respectively in FMS group. This proportion was 69%, 23% and 8% in healthy subjects. No significant correlation was observed between 5-HTR1A gene polymorphism and pain and related symptoms in FMS patients. To the best of our knowledge this is the first study which investigated the correlation between the 5-HTR1A gene polymorphism and pain intensity, the affective component of pain, pain related depression and anxiety in FMS.

Pivotal mental states

This paper introduces a new construct, the 'pivotal mental state', which is defined as a hyper-plastic state aiding rapid and deep learning that can mediate psychological transformation. We believe this new construct bears relevance to a broad range of psychological and psychiatric phenomena. We argue that pivotal mental states serve an important evolutionary function, that is, to aid psychological transformation when actual or perceived environmental pressures demand this. We cite evidence that chronic stress and neurotic traits are primers for a pivotal mental state, whereas acute stress can be a trigger. Inspired by research with serotonin 2A receptor agonist psychedelics, we highlight how activity at this particular receptor can robustly and reliably induce pivotal mental states, but we argue that the capacity for pivotal mental states is an inherent property of the human brain itself. Moreover, we hypothesize that serotonergic psychedelics hijack a system that has evolved to mediate rapid and deep learning when its need is sensed. We cite a breadth of evidences linking stress via a variety of inducers, with an upregulated serotonin 2A receptor system (e.g. upregulated availability of and/or binding to the receptor) and acute stress with 5-HT release, which we argue can activate this primed system to induce a pivotal mental state. The pivotal mental state model is multi-level, linking a specific molecular gateway (increased serotonin 2A receptor signaling) with the inception of a hyper-plastic brain and mind state, enhanced rate of associative learning and the potential mediation of a psychological transformation.

A functional polymorphism in the ATP-Binding Cassette B1 transporter predicts pharmacologic response to combination of nortriptyline and morphine in neuropathic pain patients

Many genetic markers have been associated with variations in treatment response to analgesics, but none have been assessed in the context of combination therapies. In this study, the treatment effects of nortriptyline and morphine were tested for an association with genetic markers relevant to pain pathways. Treatment effects were determined for single and combination therapies. A total of 24 functional single nucleotide polymorphisms were tested within the gene loci of mu-opioid receptor (OPRM1) gene locus, ATP-Binding Cassette B1 Transporter (ABCB1), Cytochrome P450 gene family (CYP2C19 and CYP2D6), catecholamine inactivator Catechol-O-Methyl Transferase (COMT), and serotonin receptor 2A (HTR2A). Genotyping was performed in a population of neuropathic pain patients who previously participated in a clinical trial. For monotherapy, neither nortriptyline nor morphine responses were associated with single nucleotide polymorphisms. However, for nortriptyline + morphine combination therapy, the single nucleotide polymorphism rs1045642 within the drug efflux pump ABCB1 transporter significantly predicted analgesic response. The presence of the C allele accounted for 51% of pain variance in this subgroup in response to combination treatment. The T-allele homozygotes demonstrated only 20% improvement in pain scores, whereas the C-allele homozygotes 88%. There was no significant contribution of rs1045642 to the medication side effects under all treatment conditions. The UK Biobank data set was then used to validate this genetic association. Here, patients receiving similar combination therapy (opioid + tricyclic antidepressant) carrying the C allele of rs1045642 displayed 33% fewer body pain sites than patients without that allele, suggesting better pain control. In all, our results show a robust effect of the rs1045642 polymorphism in response to chronic pain treatment with a nortriptyline + morphine combination.

Genetic and Epigenetic Consequence of Early-Life Social Stress on Depression: Role of Serotonin-Associated Genes

Early-life adversity caused by poor social bonding and deprived maternal care is known to affect mental wellbeing and physical health. It is a form of chronic social stress that persists because of a negative environment, and the consequences are long-lasting on mental health. The presence of social stress during early life can have an epigenetic effect on the body, possibly resulting in many complex mental disorders, including depression in later life. Here, we review the evidence for early-life social stress-induced epigenetic changes that modulate juvenile and adult social behavior (depression and anxiety). This review has a particular emphasis on the interaction between early-life social stress and genetic variation of serotonin associate genes including the serotonin transporter gene (5-HTT; also known as SLC6A4), which are key molecules involved in depression.

The serotonin receptor 2A (HTR2A) rs6313 variant is associated with higher ongoing pain and signs of central sensitization in neuropathic pain patients

BACKGROUND

The serotonin receptor 2A (HTR2A) has been described as an important facilitation mediator of spinal nociceptive processing leading to central sensitization (CS) in animal models of chronic pain. However, whether HTR2A single nucleotide variants (SNVs) modulate neuropathic pain states in patients has not been investigated so far. The aim of this study was to elucidate the potential association of HTR2A variants with sensory abnormalities or ongoing pain in neuropathic pain patients.

METHODS

At total of 240 neuropathic pain patients and 253 healthy volunteers were included. Patients were phenotypically characterized using standardized quantitative sensory testing (QST). Patients and controls were genotyped for HTR2A g.-1438G > A (rs6311) and c.102C > T (rs6313). Genotype-related differences in QST parameters were assessed considering QST profile clusters, principal somatosensory components and sex.

RESULTS

There was an equal distribution of rs6313 and linked rs6311 between patients and controls. However, the rs6313 variant was significantly associated with a principal component of pinprick hyperalgesia and dynamic mechanical allodynia, indicating enhanced CS in patients with sensory loss (-0.34 ± 0.15 vs. +0.31 ± 0.11 vs., p < .001). In this cluster, the variant allele was also associated with single QST parameters of pinprick hyperalgesia (MPT, +0.64 ± 0.18 vs. -0.34 ± 0.23 p = .002; MPS, +0.66 ± 0.17 vs. -0.09 ± 0.23, p = .009) and ongoing pain was increased by 30%.

CONCLUSIONS

The specific association of the rs6313 variant with pinprick hyperalgesia and increased levels of ongoing pain suggests that the HTR2A receptor might be an important modulator in the development of CS in neuropathic pain.

SIGNIFICANCE

This article presents new insights into serotonin receptor 2A-mediating mechanisms of central sensitization in neuropathic pain patients. The rs6313 variant allele was associated with increased mechanical pinprick sensitivity and increased levels of ongoing pain supporting a contribution of central sensitization in the genesis of ongoing pain providing a possible route for mechanism-based therapies.

Effect of change in preoperative depression/anxiety on patient outcomes following lumbar spine surgery

OBJECTIVE

The purpose of this study was to investigate the association between positive change in depression or anxiety within three months post-operation and clinically meaningful changes in long-term clinical outcomes after lumbar spine surgery.

METHODS

This study included adults with preoperative diagnosis of depression or anxiety who underwent lumbar spine surgery in the Quality Outcomes Database (QOD) from 2012 to 2018 with either a 12- or 24-month follow-up. Positive change in depression and anxiety was assessed three months after surgery. Clinical outcomes measured included Numeric Rating Scale (NRS) score for back pain (BP) and leg pain (LP), Oswestry Disability Index score (ODI) for disability, EuroQol Visual Analog Scale score (EQ-VAS) for health-related quality of life (HRQOL), and North American Spine Surgery (NASS) index score for patient satiaction measured at 12- and 24 months after surgery.

RESULTS

Of the 9,656 and 1,393 patients who were included in the 12- and 24-month cohort, respectively, 7,277 patients (75.4 %) and 1,089 (78.2 %) experienced a positive change in depression or anxiety within three months after surgery. At both 12- and 24-month follow-up, patients who had positive change in depression or anxiety were more likely to achieve minimal clinically important changes in NRS-BP/LP, ODI, EQ-VAS, and NASS (all p < 0.01) compared to those who did not experience improvement in depression or anxiety.

CONCLUSION

Depression and anxiety are important comorbidities to consider in patients undergoing lumbar spine surgery. Positive change in depression and anxiety are associated with improvements in pain, disability, satisfaction, and overall functioning.

When Distress Becomes Somatic: Dementia Family Caregivers' Distress and Genetic Vulnerability to Pain and Sleep Problems

BACKGROUND AND OBJECTIVES

Stress can trigger physical pain and disturb sleep. Whether dementia family caregivers experience heightened pain is unknown. Cycles of unwanted thoughts about caregiving stressors and avoidance of these thoughts-that is, caregiving-related distress-may exacerbate both pain and sleep disturbances, and genetic susceptibility to stress may further modulate these associations.

RESEARCH DESIGN AND METHODS

Dementia caregivers (72 spouses, 58 adult children, ages 34-89) rated the extent to which they experienced unintended thoughts about caregiving and tried to suppress such thoughts. They also reported their pain levels, sleep problems, and depressive symptoms. Peripheral blood leukocytes were genotyped for 5-HTTLPR (serotonin-transporter-linked polymorphic region) and 5-HT1A receptor polymorphism rs6295 on the 5HTR1A locus.

RESULTS

Short-allele carriers for 5-HTTLPR experienced more pain and sleep problems in association with greater caregiving-related distress than those with other genotypes. For rs6295, C carriers also showed the strongest links between distress and sleep problems. Those who experienced more avoidance and intrusive thoughts about caregiving had more severe depressive symptoms, consistent with past work.

DISCUSSION AND IMPLICATIONS

Caregivers' genetic profiles helped to explain whether caregiving-related distress predicted worse pain and sleep problems. These data reveal new somatic risks of caregiver distress and provide targets for intervention. According to plasticity theories, caregivers genetically predisposed to greater stress reactivity may also respond particularly well to interventions, and many brief treatments may effectively address caregivers' intrusions and avoidance.

Qualitative sex differences in pain processing: emerging evidence of a biased literature

Although most patients with chronic pain are women, the preclinical literature regarding pain processing and the pathophysiology of chronic pain has historically been derived overwhelmingly from the study of male rodents. This Review describes how the recent adoption by a number of funding agencies of policies mandating the incorporation of sex as a biological variable into preclinical research has correlated with an increase in the number of studies investigating sex differences in pain and analgesia. Trends in the field are analysed, with a focus on newly published findings of qualitative sex differences: that is, those findings that are suggestive of differential processing mechanisms in each sex. It is becoming increasingly clear that robust differences exist in the genetic, molecular, cellular and systems-level mechanisms of acute and chronic pain processing in male and female rodents and humans.

A metabolomic study on the gender-dependent effects of maternal exposure to fenvalerate on neurodevelopment in offspring mice

BACKGROUND

The general population is widely exposed to fenvalerate. However, the effects of maternal exposure to fenvalerate on neurodevelopment in offspring and the underlying metabolic mechanism are largely unknown.

METHODS

Pregnant mice were exposed to fenvalerate for 11 consecutive days. The forced swimming test (FST) was performed in 35 day-old offspring to investigate the effects of fenvalerate on neurobehavioral responses. Blood serum free T4 and free T3 concentrations were measured using commercial ELISA. Blood and thyroid samples were used for metabolomic analyses with UPLC Q-Exactive. The expression levels of neurotransmitter metaolite receptors were determined in the frontal cortex of offspring using real-time PCR.

RESULTS

The immobility time, free T4 and free T3, and expression levels of Htr1a and Htr2a were statistically changed in offspring male mice. Metabolomic analysis revealed that the pentose phosphate pathway, starch and sucrose metabolism, glutamic acid metabolism were the key changed pathways in the blood, and thiamine metabolism was the key changed pathway in the thyroid.

CONCLUSION

Prenatal exposure to fenvalerate affected neurodevelopment in male offspring mice both via the changed abundances of metabolites involved in glycolysis related metabolism and medium-chain fatty acid metabolism, and the changes in 5-HT receptor expression.

Systematic Review and Meta-Analysis of Genetic Risk of Developing Chronic Postsurgical Pain

Chronic postsurgical pain (CPSP) is a significant detriment to postsurgical recovery and a risk factor for prolonged opioid use. Emerging evidence suggests the estimated heritability for chronic pain is 45% and that genetic factors partially explain individual susceptibility to CPSP. The aim of this study was to systematically review, assess quality, and summarize the studies in humans that have investigated genetic factors associated with CPSP. We also conducted a meta-analysis to derive a single effect size for evaluable genetic associations with CPSP. Our comprehensive literature search included review of 21 full-text articles evaluating variants of 69 genes for association with CPSP. We found significant gene variant associations reported for variants/haplotypes of 26 genes involved in neurotransmission, pain signaling, immune responses and neuroactive ligand-receptor interaction, with CPSP. Six variants of 5 genes (COMT: rs4680 and rs6269, OPRM1: rs1799971, GCH1: rs3783641, KCNS1: rs734784 and TNFA: rs1800629), were evaluated by more than one study and were included in the meta-analysis. At rs734784 (A>G) of KCNS1, presence of G allele marginally increased risk of CPSP (Additive genetic model; Odds ratio: 1.511; 95% CI 1-2.284; P value: .050), while the other variants did not withstand meta-analyses criteria. Our findings demonstrate the role of genetic factors with different functions in CPSP, and also emphasize that single genetic factors have small effect sizes in explaining complex conditions like CPSP. Heterogeneity in surgical cohorts, population structure, and outcome definitions, as well as small number of available studies evaluating same variants, limit the meta-analysis. There is a need for large-scale, homogenous, replication studies to validate candidate genes, and understand the underlying biological networks underpinning CPSP. PERSPECTIVE: Our systematic review comprehensively describes 21 studies evaluating genetic association with CPSP, and limitations thereof. A meta-analysis of 6 variants (5 genes) found marginally increased risk for CPSP associated with rs734784 A>G of the potassium voltage-gated channel gene (KCNS1). Understanding genetic predisposition for CPSP will enable prediction and personalized management.

Genetic, epigenetic and posttranscriptional mechanisms for treatment of major depression: the 5-HT1A receptor gene as a paradigm

Major depression and anxiety are highly prevalent and involve chronic dysregulation of serotonin, but they remain poorly understood. Here, we review novel transcriptional (genetic, epigenetic) and posttranscriptional (microRNA, alternative splicing) mechanisms implicated in mental illness, focusing on a key serotonin-related regulator, the serotonin 1A (5-HT1A) receptor. Functional single-nucleotide polymorphisms and stress-induced DNA methylation of the 5-HT1A promoter converge to differentially alter pre- and postsynaptic 5-HT1A receptor expression associated with major depression and reduced therapeutic response to serotonergic antidepressants. Major depression is also associated with altered levels of splice factors and microRNA, posttranscriptional mechanisms that regulate RNA stability. The human 5-HT1A 3′-untranslated region is alternatively spliced, removing microRNA sites and increasing 5-HT1A expression, which is reduced in major depression and may be genotype-dependent. Thus, the 5-HT1A receptor gene illustrates the convergence of genetic, epigenetic and posttranscriptional mechanisms in gene expression, neurodevelopment and neuroplasticity, and major depression. Understanding gene regulatory mechanisms could enhance the detection, categorization and personalized treatment of major depression.

The molecular neurobiology of chronic pain-induced depression

The increasing number of individuals with comorbidities poses an urgent need to improve the management of patients with multiple co-existing diseases. Among these comorbidities, chronic pain and mood disorders, two long-lasting disabling conditions that significantly reduce the quality of life, could be cited first. The recent development of animal models accelerated the studies focusing on the underlying mechanisms of the chronic pain and depression/anxiety comorbidity. This review provides an overview of clinical and pre-clinical studies performed over the past two decades addressing the molecular aspects of the comorbid relationship of chronic pain and depression. We thus focused on the studies that investigated the molecular characteristics of the comorbid relationship between chronic pain and mood disorders, especially major depressive disorders, from the genetic and epigenetic point of view to key neuromodulators which have been shown to play an important role in this comorbidity.

Genetics of perioperative pain management

PURPOSE OF REVIEW

The current review will discuss the current literature on genetics of pain and analgesia, with special emphasis on perioperative setting. We will also discuss pharmacogenetics-based management guidelines, current clinical status and future perspectives.

RECENT FINDINGS

Recent literature suggests that the interindividual variability in pain and postoperative analgesic response is at least in part because of one's genetic make-up. Some of the well characterized polymorphisms that are associated with surgical pain and opioid-related postoperative adverse outcomes are described in catechol-O-methyl transferase, CYP2D6 and μ-opioid receptor (OPRM1), ATP-binding cassette subfamily B member 1, ABCC3, organic cation transporter 1 genes. Clinical Pharmacogenetics Implementation Consortium has put forth recommendations on CYP2D6 genotype-based opioid selection and dosing. The list of drug-gene pairs studied continue to expand.

SUMMARY

Pharmacogenetic approach marks the dawn of personalized pain medicine both in perioperative and chronic pain settings.

Mild Depression in Low Back Pain: the Interaction of Thought Suppression and Stress Plays a Role, Especially in Female Patients

PURPOSE

Mild depression has been shown as a precursor and as a consequence of low back pain, even in early phases of acute or subacute pain. Chronic daily life stress as well as dysfunctional pain-related cognitions such as thought suppression (TS) seem to play a role in the pain-depression cycle; however, the mechanisms of these associations are less understood. Experimentally induced TS, conceived as the attempt to directly suppress sensations such as pain, has been shown to paradoxically cause a delayed and non-volitional return of the suppressed thoughts and sensations and to increase affective distress. These dysfunctional processes are supposed to increase under high cognitive load, such as high stress.

METHOD

In the present cross-sectional study, we for the first time sought to examine a possible interaction between habitual TS and stress on depression in N = 177 patients with subacute low back pain (SLBP), using the following questionnaires: Subscale Thought Suppression from Avoidance-Endurance Questionnaire, Beck Depression Inventory, and Kiel Interview of Subjective Situation. A three-way ANOVA was conducted with two groups of TS (high/low), stress (high/low) and sex as independent factors and depression as dependent.

RESULTS

Results indicated a significant three-way interaction with highest depression scores in female patients showing high TS and high stress. Overall main effects for sex and stress indicated higher depression in women and in highly stressed patients.

CONCLUSION

Our findings support the hypothesis that TS heightens depressive mood under conditions of high cognitive load especially in female patients with SLBP indicating a special vulnerability for depressive mood in women with SLBP.

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.

[Adiponectin: an endogenous molecule with anti-inflammatory and antidepressant properties?]

Adiponectin (ApN) is a hormone produced by adipose tissue, yet the plasma level of ApN is decreased in overweight and obese people, as well as in people with diabetes. In the periphery, this decrease in circulating levels of ApN induces the establishment of a chronic low-grade inflammatory state and is involved in the development of insulin resistance and atheromas. Conversely, "favorable" living conditions, weight loss and regular physical exercise increase ApN blood concentration. Some forms of ApN can reach the brain parenchyma through the cerebrospinal fluid. In the brain, the increase in ApN exerts powerful antidepressant and anxiolytic effects, in particular by fighting against neuroinflammation.

Neural and Genetic Correlates of the Social Sharing of Happiness

Happiness is regarded as one of the most fundamental human goals. Given recent reports that positive feelings are contagious (e.g., the presence of a happy person enhances others' happiness) because of the human ability to empathize (i.e., sharing emotions), empathic ability may be a key factor in increasing one's own subjective level of happiness. Based on previous studies indicating that a single nucleotide polymorphism in the serotonin 2A receptor gene [HTR2A rs6311 guanine (G) vs. adenine (A)] is associated with sensitivity to emotional stimuli and several mental disorders such as depression, we predicted that the polymorphism might be associated with the effect of sharing happiness. To elucidate the neural and genetic correlates of the effect of sharing happiness, we first performed functional magnetic resonance imaging (fMRI) during a “happy feelings” evocation task (emotional event imagination task), during which we manipulated the valence of the imagined event (positive, neutral, or negative), as well as the presence of a friend experiencing a positive-valence event (presence or absence). We recruited young adult women for this fMRI study because empathic ability may be higher in women than in men. Participants felt happier (p < 0.01) and the mentalizing/theory-of-mind network, which spans the medial prefrontal cortex, temporoparietal junction, temporal poles, and precuneus, was significantly more active (p < 0.05) in the presence condition than in the absence condition regardless of event valence. Moreover, participants with the GG (p < 0.01) and AG (p < 0.05) genotypes of HTR2A experienced happier feelings as well as greater activation of a part of the mentalizing/theory-of-mind network (p < 0.05) during empathy for happiness (neutral/presence condition) than those with the AA genotype. In a follow-up study with a vignette-based questionnaire conducted in a relatively large sample, male and female participants were presented with the same imagined events wherein their valence and the presence of a friend were manipulated. Results showed genetic differences in happiness-related empathy regardless of sex (p < 0.05). Findings suggest that HTR2A polymorphisms are associated with the effect of sharing happiness by modulating the activity of the mentalizing/theory-of-mind network.

Genetic variants in 5-HTTLPR, BDNF, HTR1A, COMT, and FKBP5 and risk for treated depression after cancer diagnosis

BACKGROUND

The role of gene-environment interactions in the pathogenesis of depression is unclear. Previous studies addressed vulnerability for depression after childhood adversity and stressful life events among carriers of numerous specific genetic variants; however, the importance of individual genetic variants, the environmental exposures with which they interact, and the magnitude of the risk conveyed by these interactions remain elusive.

METHODS

We included 7,320 people with a first primary cancer identified in the prospective Diet, Cancer and Health study in an exposed-only cohort study. The mean age of the individuals was 68 years (5th, 95th percentiles: 58, 78) at cancer diagnosis. Using Cox regression models and cumulative incidence plots, we analyzed the associations between genetic variants in 5-HTTLPR, BDNF, HTR1A, COMT, and FKBP5 and use of antidepressants as well as hospital contact for depression after diagnosis of cancer.

RESULTS

Overall, we observed no statistically significant associations, with nonsignificant hazard ratio estimates for use of antidepressants of 0.95-1.07.

CONCLUSIONS

This study of elderly people indicates that it is unlikely that the investigated genetic variants are clinically relevantly associated with depression after diagnosis of cancer. The mechanisms for gene-environment interactions in younger individuals are probably different, and we advise caution in extrapolating our results to early life stress. However, conclusion from the present study might be generalizable to elderly persons exposed to other stressful life events.

Serotonin and brain function: a tale of two receptors

Previous attempts to identify a unified theory of brain serotonin function have largely failed to achieve consensus. In this present synthesis, we integrate previous perspectives with new and older data to create a novel bipartite model centred on the view that serotonin neurotransmission enhances two distinct adaptive responses to adversity, mediated in large part by its two most prevalent and researched brain receptors: the 5-HT1A and 5-HT2A receptors. We propose that passive coping (i.e. tolerating a source of stress) is mediated by postsynaptic 5-HT1AR signalling and characterised by stress moderation. Conversely, we argue that active coping (i.e. actively addressing a source of stress) is mediated by 5-HT2AR signalling and characterised by enhanced plasticity (defined as capacity for change). We propose that 5-HT1AR-mediated stress moderation may be the brain's default response to adversity but that an improved ability to change one's situation and/or relationship to it via 5-HT2AR-mediated plasticity may also be important - and increasingly so as the level of adversity reaches a critical point. We propose that the 5-HT1AR pathway is enhanced by conventional 5-HT reuptake blocking antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), whereas the 5-HT2AR pathway is enhanced by 5-HT2AR-agonist psychedelics. This bipartite model purports to explain how different drugs (SSRIs and psychedelics) that modulate the serotonergic system in different ways, can achieve complementary adaptive and potentially therapeutic outcomes.

Serotonin 2A receptor (5-HT2A) gene promoter variant interacts with chronic perceived stress to modulate resting parasympathetic activity in humans

Decreased resting vagal (parasympathetic) tone is implicated in the development of stress-related disorders, including anxiety and depression. Chronic stress elevates the expression of serotonin 2A receptors (5-HT2A), while activation of 5-HT2A leads to inhibition of parasympathetic synaptic transmission. The T allele of the promoter variant, rs6311 (C>T), of the 5-HT2A gene has been shown to increase the 5-HT2A expression in vitro and to be associated with anxiety and depressive disorders. We thus hypothesized that the 5-HT2A functional polymorphism may influence resting vagal activity among persons with chronically high levels of perceived stress. A total of 1138 well-defined healthy, medication-free Han Chinese were included for 5-HT2A genotyping. The Perceived Stress Scale (PSS) was used to measure the level of perceived stress during the last month and participants were divided into low and high PSS groups. Resting-state heart rate variability (HRV) was used to assess autonomic function. No significant between-genotype difference was found in any HRV variable in the low PSS group (n=610). However, in the high PSS group (n=528), high frequency power and root mean square of successive heartbeat interval differences (both HRV indices of parasympathetic activity) were significantly reduced in T/T genotype carriers compared to C/C homozygotes. Our findings are the first to show that individuals homozygous for the high-expressing 5-HT2A (T) allele exhibit diminished resting vagal tone-an index of stress vulnerability-when experiencing chronically elevated levels of perceived stress. The present results may advance our understanding of the genetic mechanism underlying individual differences in susceptibility to stress.

The pharmacogenomics of pain management: prospects for personalized medicine

Pain is a common symptom that can be complex to treat. Analgesic medications are the mainstay treatment, but there is wide interindividual variability in analgesic response and adverse effects. Pharmacogenomics is the study of inherited genetic traits that result in these individual responses to drugs. This narrative review will attempt to cover the current understanding of the pharmacogenomics of pain, examining common genes affecting metabolism of analgesic medications, their distribution throughout the body, and end organ effects.

Depression and postoperative complications: an overview

BACKGROUND

The interaction of depression and anesthesia and surgery may result in significant increases in morbidity and mortality of patients. Major depressive disorder is a frequent complication of surgery, which may lead to further morbidity and mortality.

LITERATURE SEARCH

Several electronic data bases, including PubMed, were searched pairing "depression" with surgery, postoperative complications, postoperative cognitive impairment, cognition disorder, intensive care unit, mild cognitive impairment and Alzheimer's disease.

REVIEW OF THE LITERATURE

The suppression of the immune system in depressive disorders may expose the patients to increased rates of postoperative infections and increased mortality from cancer. Depression is commonly associated with cognitive impairment, which may be exacerbated postoperatively. There is evidence that acute postoperative pain causes depression and depression lowers the threshold for pain. Depression is also a strong predictor and correlate of chronic post-surgical pain. Many studies have identified depression as an independent risk factor for development of postoperative delirium, which may be a cause for a long and incomplete recovery after surgery. Depression is also frequent in intensive care unit patients and is associated with a lower health-related quality of life and increased mortality. Depression and anxiety have been widely reported soon after coronary artery bypass surgery and remain evident one year after surgery. They may increase the likelihood for new coronary artery events, further hospitalizations and increased mortality. Morbidly obese patients who undergo bariatric surgery have an increased risk of depression. Postoperative depression may also be associated with less weight loss at one year and longer. The extent of preoperative depression in patients scheduled for lumbar discectomy is a predictor of functional outcome and patient's dissatisfaction, especially after revision surgery. General postoperative mortality is increased.

CONCLUSIONS

Depression is a frequent cause of morbidity in surgery patients suffering from a wide range of conditions. Depression may be identified through the use of Patient Health Questionnaire-9 or similar instruments. Counseling interventions may be useful in ameliorating depression, but should be subject to clinical trials.

Interaction between 5-HTTLPR and 5-HT1B genotype status enhances cerebral 5-HT1A receptor binding

Serotonergic neurotransmission is thought to underlie a dynamic interrelation between different key structures of the serotonin system. The serotonin transporter (SERT), which is responsible for the reuptake of serotonin from the synaptic cleft into the neuron, as well as the serotonin-1A (5-HT1A) and -1B (5-HT1B) receptors, inhibitory auto-receptors in the raphe region and projection areas, respectively, are likely to determine serotonin release. Thereby, they are involved in the regulation of extracellular serotonin concentrations and the extent of serotonergic effects in respective projection areas. Complex receptor interactions can be assessed in vivo with positron emission tomography (PET) and single-nucleotide-polymorphisms, which are thought to alter protein expression levels. Due to the complexity of the serotonergic system, gene × gene interactions are likely to regulate transporter and receptor expression and therefore subsequently serotonergic transmission. In this context, we measured 51 healthy subjects (mean age 45.5 ± 12.9, 38 female) with PET using [carbonyl-(11)C]WAY-100635 to determine 5-HT1A receptor binding potential (5-HT1A BPND). Genotyping for rs6296 (HTR1B) and 5-HTTLPR (SERT gene promoter polymorphism) was performed using DNA isolated from whole blood. Voxel-wise whole-brain ANOVA revealed a positive interaction effect of genotype groups (5-HTTLPR: LL, LS+SS and HTR1B: rs6296: CC, GC+GG) on 5-HT1A BPND with peak t-values in the bilateral parahippocampal gyrus. More specifically, highest 5-HT1A BPND was identified for individuals homozygous for both the L-allele of 5-HTTLPR and the C-allele of rs6296. This finding suggests that the interaction between two major serotonergic structures involved in serotonin release, specifically the SERT and 5-HT1B receptor, results in a modification of the inhibitory serotonergic tone mediated via 5-HT1A receptors.

Pain and depression: a neurobiological perspective of their relationship

Remarkable progresses have been achieved regarding the understanding of the neurobiological bases of pain and depression. The principal role of neurotransmitters, neuromodulators, and neurohormones has been proposed in the development of pain and depression. With the progression of molecular biology, an intricate interaction among biological factors accountable to the development and management of pain and depression has been also shown in a numerous preclinical and clinical researches. This mini-review will briefly describe the current issues and future research direction for better understanding of the relationship between pain and depression.

Genetic variations underlying self-reported physical functioning: a review

PURPOSE

Genetic associations with self-reported physical functioning (SPF) are less well-studied than genetic associations with performance-measured physical functioning (PPF). We review the literature on the associations of genetic variations on SPF. We provide an overview of SPF assessment, genetic contributions to SPF including heritability, effects of genetic variations and mutations, and effects of interventions on the gene-SPF relationship. We also aim to provide directions for future research.

METHODS

A computerized literature search using PubMed, Web of Science, and PsychInfo was conducted to select relevant literature published up to November 2013. Inclusion criteria were the use of an SPF questionnaire, original articles in English on human subjects, published in peer-reviewed journals and reporting significant associations between SPF and the genome.

RESULTS

Nineteen articles were included. SPF was commonly assessed with the Short Form-36 questionnaire involving mainly convenience samples of either older persons or chronically ill. Heritability estimates were 10-30 %. Candidate genes associated with SPF could be ascribed to biological pathways associated with neurodegeneration, physiological systems regulation, or cell regulation. The APOE gene associated with neurodegeneration was most studied (n = 3). Three papers included both SPF and PPF assessments. No genome-wide association study on SPF has been conducted.

CONCLUSIONS

Associations between SPF and the genome have been investigated in selected populations in a limited number of publications. Future research should consider increasing sample variation and incorporate both SPF and PPF assessments. Also, longitudinal studies should be conducted in order to elicit stronger conclusions regarding the genetic associations with SPF.

Serotonin-prefrontal cortical circuitry in anxiety and depression phenotypes: pivotal role of pre- and post-synaptic 5-HT1A receptor expression

Decreased serotonergic activity has been implicated in anxiety and major depression, and antidepressants directly or indirectly increase the long-term activity of the serotonin system. A key component of serotonin circuitry is the 5-HT1A autoreceptor, which functions as the major somatodendritic autoreceptor to negatively regulate the "gain" of the serotonin system. In addition, 5-HT1A heteroreceptors are abundantly expressed post-synaptically in the prefrontal cortex (PFC), amygdala, and hippocampus to mediate serotonin actions on fear, anxiety, stress, and cognition. Importantly, in the PFC 5-HT1A heteroreceptors are expressed on at least two antagonist neuronal populations: excitatory pyramidal neurons and inhibitory interneurons. Rodent models implicate the 5-HT1A receptor in anxiety- and depression-like phenotypes with distinct roles for pre- and post-synaptic 5-HT1A receptors. In this review, we present a model of serotonin-PFC circuitry that integrates evidence from mouse genetic models of anxiety and depression involving knockout, suppression, over-expression, or mutation of genes of the serotonin system including 5-HT1A receptors. The model postulates that behavioral phenotype shifts as serotonin activity increases from none (depressed/aggressive not anxious) to low (anxious/depressed) to high (anxious, not depressed). We identify a set of conserved transcription factors including Deaf1, Freud-1/CC2D1A, Freud-2/CC2D1B and glucocorticoid receptors that may confer deleterious regional changes in 5-HT1A receptors in depression, and how future treatments could target these mechanisms. Further studies to specifically test the roles and regulation of pyramidal vs. interneuronal populations of 5-HT receptors are needed better understand the role of serotonin in anxiety and depression and to devise more effective targeted therapeutic approaches.