Serotonergic activity contributes to analgesic overuse in chronic tension-type headache

Medication overuse headache and awareness

BACKGROUND

Medication overuse headache (MOH) is the worsening of an underlying headache due to the overuse of its acute treatment. Unintentionally, healthcare professionals may contribute to this condition. Health professionals play an important role in preventing this increasingly frequent and difficult-to-treat condition.

OBJECTIVE

To investigate MOH awareness among physicians with headache through a survey conducted among medical doctors on our university campus.

METHODS

This was an observational cross-sectional study about MOH awareness. The total number of medical doctors working in the Dokuz Eylül University Health Campus was provided by the administrative unit. A total of 18 questions were prepared and administered on a voluntary basis to obtain information about MOH awareness.

RESULTS

A total of 312 medical doctors were surveyed, including 198 (63.5%) from internal medical sciences, 81 (26%) from surgical medical sciences, and 33 (10.5%) from basic medical sciences. Half of the physicians in our sample were unaware of MOH. Our results showed that awareness of MOH, was quite low even among medical doctors.

CONCLUSIONS

MOH causes both labor and financial losses to countries and impairs the quality of life of patients. Preventing excessive use of medications by raising awareness among doctors is an important step to prevent the development of MOH.

Optimising migraine treatment: from drug-drug interactions to personalized medicine

Migraine is the most disabling and expensive chronic disorders, the etiology of which is still not fully known. The neuronal systems, (glutammatergic, dopaminergic, serotoninergic and GABA-ergic) whose functionality is partly attributable to genetically determined factors, has been suggested to play an important role. The treatment of acute attacks and the prophylactic management of chronic forms include the use of different category of drugs, and it is demonstrated that not each subject has the same clinical answer to them. The reason of this is to be searched in different functional capacity and quantity of phase I enzymes (such as different isoforms of CYP P450), phase II enzymes (such as UDP-glucuronosyltransferases), receptors (such as OPRM1 for opioids) and transporters (such as ABCB1) involved in the metabolic destiny of each drug, all of these dictated by DNA and RNA variations. The general picture is further exacerbated by the need for polytherapies, often also to treat comorbidities, which may interfere with the pharmacological action of anti-migraine drugs. Personalized medicine has the objective of setting the optimal therapies in the light of the functional biochemical asset and of the comorbidities of the individual patient, in order to obtain the best clinical response. Novel therapeutic perspectives in migraine includes biotechnological drugs directed against molecules (such as CGRP and its receptor) that cause vasodilatation at the peripheral level of the meningeal blood vessels and reflex stimulation of the parasympathetic system. Drug-drug interactions and the possible competitive metabolic destiny should be studied by the application of pharmacogenomics in large scale. Drug-drug interactions and their possible competitive metabolic destiny should be studied by the application of pharmacogenomics in large scale.

Associations between serotonin transporter gene polymorphisms and heat pain perception in adults with chronic pain

BACKGROUND

The triallelic serotonin transporter gene linked polymorphic region (5-HTTLPR) has been associated with alterations in thermal pain perception. The primary aim of this study was to investigate the associations between heat pain (HP) perception and the triallelic 5-HTTLPR in a large cohort of adults with chronic pain.

METHODS

The cohort included 277 adults with chronic pain who met inclusion criteria, and were consecutively admitted to an outpatient pain rehabilitation program from March 2009 through March 2010. Individuals were genotyped for the triallelic 5-HTTLPR (including rs25531) and categorized as high, intermediate, or low expressors of the serotonin transporter. Standardized measures of HP perception were obtained using a validated quantitative sensory test method of levels.

RESULTS

The distribution of the high, intermediate, and low expressing genotypes was 61 (22%), 149 (54%) and 67 (24%), respectively. The Hardy-Weinberg P-value was 0.204 which indicated no departure from equilibrium. A significant effect of genotype was observed for values of HP threshold (P = 0.029). Individual group comparisons showed that values of HP threshold were significantly greater in the intermediate compared to the high expressing group (P = 0.009) but not the low expressing group (P > 0.1). In a multiple variable linear regression model, the intermediate group (P = 0.034) and male sex (P = 0.021) were associated with significantly greater values of HP 0.5, but no significant genotype-by-sex interaction effect was observed.

CONCLUSIONS

In this study that involved adults with chronic pain, the intermediate triallelic 5-HTTLPR expressing group, but not the low expressing group, was associated with greater HP thresholds compared to the high expressing group.

Predictive index for the onset of medication overuse headache in migraine patients

Migraine patients are particularly prone to develop medication overuse headache (MOH). However, the risk factors for the transformation of migraine to MOH are still not clear. We investigated gene polymorphisms, personality traits, and characteristics of headache and lifestyle in 47 migraine patients (aged 36.4 ± 10.3) and 22 MOH patients (aged 39.6 ± 9.9) who progressed from migraine and made a scoring system for a predictive index (PI) of the onset of MOH in patients with migraine. By multivariate logistic stepwise regression analysis, type of migraine, regular and sufficient dietary intake, and methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) and dopamine D2 receptor (DRD2) C939T (rs6275) polymorphisms were selected as significant factors that contribute independently to the development from migraine to MOH (P < 0.05). The regression coefficients (β) of these four selected factors were approximated and scored. The PI score in MOH patients (7.32 ± 1.60) was significantly higher than that in migraine patients (4.62 ± 1.83, P < 0.001). The proposed scoring system should in the future be the object of larger studies to confirm its validity.

Medication-overuse headache and opioid-induced hyperalgesia: A review of mechanisms, a neuroimmune hypothesis and a novel approach to treatment

Introduction

Patients with chronic headache who consume large amounts of analgesics are often encountered in clinical practice. Excessive intake of analgesics is now considered to be a cause, rather than simply a consequence, of frequent headaches, and as such the diagnosis “medication-overuse headache” (MOH) has been formulated. Despite the prevalence and clinical impact of MOH, the pathophysiology behind this disorder remains unclear and specific mechanism-based treatment options are lacking.

Discussion

Although most acute headache treatments have been alleged to cause MOH, here we conclude from the literature that opioids are a particularly problematic drug class consistently associated with worsening headache. MOH may not be a single entity, as each class of drug implicated may cause MOH via a different mechanism. Recent evidence indicates that chronic opioid administration may exacerbate pain in the long term by activating toll-like receptor-4 on glial cells, resulting in a pro-inflammatory state that manifests clinically as increased pain. Thus, from the available evidence it seems opioid-overuse headache is a phenomenon similar to opioid-induced hyperalgesia, which derives from a cumulative interaction between central sensitisation, due to repeated activation of nociceptive pathways by recurrent headaches, and pain facilitation due to glial activation.

Conclusion

Treatment strategies directed at inhibiting glial activation may be of benefit alongside medication withdrawal in the management of MOH.

Pharmacogenetics of pain and analgesia

Pain severity ratings and the analgesic dosing requirements of patients with apparently similar pain conditions may differ considerably between individuals. Contributing factors include those of genetic and environmental origin with epigenetic mechanisms that enable dynamic gene-environment interaction, more recently implicated in pain modulation. Insight into genetic factors underpinning inter-patient variability in pain sensitivity has come from rodent heritability studies as well as familial aggregation and twin studies in humans. Indeed, more than 350 candidate pain genes have been identified as potentially contributing to heritable differences in pain sensitivity. A large number of genetic association studies conducted in patients with a variety of clinical pain types or in humans exposed to experimentally induced pain stimuli in the laboratory setting, have examined the impact of single-nucleotide polymorphisms in various target genes on pain sensitivity and/or analgesic dosing requirements. However, the findings of such studies have generally failed to replicate or have been only partially replicated by independent investigators. Deficiencies in study conduct including use of small sample size, inappropriate statistical methods and inadequate attention to the possibility that between-study differences in environmental factors may alter pain phenotypes through epigenetic mechanisms, have been identified as being significant.

Proteomic analysis of urine in medication-overuse headache patients: possible relation with renal damages

Medication-overuse headache (MOH) is a chronic disorder associated with overuse of analgesic drugs, triptans, non-steroidal anti-inflammatory drugs (NSAIDs) or other acute headache compounds. Various epidemiologic investigations proved that different drug types could cause nephrotoxicity, particularly in chronic patients. The aim of the present work was to analyze, by a proteomic approach, the urinary protein profiles of MOH patients focusing on daily use of NSAIDs, mixtures and triptans that could reasonably be related to potential renal damage. We selected 43 MOH patients overusing triptans (n = 18), NSAIDs (n = 11), and mixtures (n = 14), for 2–30 years with a mean daily analgesic intake of 1.5 ± 0.9 doses, and a control group composed of 16 healthy volunteers. Urine proteins were analyzed by mono-dimensional gel electrophoresis and identified by mass spectrometry analysis. Comparing the proteomic profiles of patients and controls, we found a significantly different protein expression, especially in the NSAIDs group, in which seven proteins resulted over-secreted from kidney (OR = 49, 95% CI 2.53–948.67 vs. controls; OR = 11.6, 95% CI 0.92–147.57 vs. triptans and mixtures groups). Six of these proteins (uromodulin, α-1-microglobulin, zinc-α-2-glycoprotein, cystatin C, Ig-kappa-chain, and inter-α-trypsin heavy chain H4) were strongly correlated with various forms of kidney disorders. Otherwise, in mixtures and in triptans abusers, only three proteins were potentially associated to pathological conditions (OR = 4.2, 95% CI 0.33–53.12, vs. controls). In conclusion, this preliminary proteomic study allowed us to define the urinary protein pattern of MOH patients that is related to the abused drug. According with the obtained results, we believe that the risk of nephrotoxicity should be considered particularly in MOH patients who abuse of NSAIDs.

Polymorphism of the Glutamate Transporter Protein EAAT2 and Migraine Transformation into Chronic Daily Headache

Background and Purpose

The progression of migraine into chronic daily headache involves multiple risk factors, but the main contributor is not known. Glutamate is the major excitatory neurotransmitter in central sensitization, which is an important process in the pathogenesis of migraine transformation. The glutamate transporter protein excitatory amino acid transporter 2 (EAAT2) is the primary modulator of glutamatergic neurotransmission, and genetic polymorphisms of its gene, EEAT2, have been identified. The aim of this study was to determine the effect of EAAT2 polymorphisms on migraine transformation into chronic daily headache.

Methods

We included 74 migraine patients with episodic attack (M-E) and 59 migraine patients with chronic daily headache (M-CDH). After amplifying EAAT2 by polymerase chain reaction, we assessed its genotype frequencies based on restriction fragment length polymorphisms. We reclassified all migraine patients into two groups according to their EAAT2 genotype, either with the A allele (n=62) or without it (n=71), and compared the clinical variables between the two groups.

Results

The genotype frequencies of EAAT2 polymorphisms did not differ between the M-E and M-CDH groups. Comparison between EEAT2 genotypes revealed that the frequency of analgesic usage was significantly higher among migraine patients with the A allele (12.9±1.6 days/month) than in those without the A allele (8.1±1.2 days/month; p=0.019). The other clinical variables of migraine did not differ between the two groups.

Conclusions

The results suggest that EEAT2 polymorphism contributes to the tendency toward frequent analgesic usage in migraine patients. This implies a potential genetic influence on the progression of migraine into chronic daily headache through the development of medication-overuse headache.

Pain, analgesia and genetics

OBJECTIVES

In the clinical setting, there is marked intersubject variability in the intensity of pain reported by patients with apparently similar pain states, as well as widely differing analgesic dosing requirements between individuals to produce satisfactory pain relief with tolerable side-effects. Genetic and environmental factors as well as their interaction are implicated, and these are discussed in this review.

KEY FINDINGS

Pioneering work undertaken in mice more than a decade ago, showed a strong genetic contribution to levels of nociception/hypersensitivity as well as levels of antinociception produced by commonly available analgesic agents. To date more than 300 candidate 'pain' genes have been identified as potentially contributing to heritable differences in pain sensitivity and analgesic responsiveness in animals and humans, with this information available in a publicly accessible database http://www.jbldesign.com/jmogil/enter.html. Since then, many genetic association studies have been conducted in humans to investigate the possibility that single nucleotide polymorphisms (SNPs) in an individual gene may explain drug inefficacy or excessive toxicity experienced by a small subset of the whole population who have the rare allele for a particular SNP.

SUMMARY

Despite the fact that SNPs in more than 20 genes that affect pain sensitivity or contribute to interindividual variability in responses to analgesic medications have been identified in the human genome, much of the data is conflicting. Apart from deficiencies in the design and conduct of human genetic association studies, recent research from other fields has implicated epigenetic mechanisms that facilitate dynamic gene-environment communication, as a possible explanation.

Role of 2 common variants of 5HT2A gene in medication overuse headache

OBJECTIVE

The aim of the present study was to evaluate a possible involvement of 2 polymorphisms of the serotonin 5HT2A receptor gene (A-1438G and C516T) as risk factors for medication overuse headache (MOH) and whether the presence of these polymorphic variants might determine differences within MOH patients in monthly drug consumption.

BACKGROUND

Despite a growing scientific interest in the mechanisms underlying the pathophysiology of MOH, few studies have focused on the role of genetics in the development of the disease, as well as on the genetic determinants of the inter-individual variability in the number of drug doses taken per month.

METHODS

Our study was performed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism on genomic DNA extracted from peripheral blood of 227 MOH patients and 312 control subjects. Genotype-specific risks were estimated as odds ratios with associated 95% confidence intervals by unconditional logistic regression and adjusted for age and gender. A stepwise multiple linear regression analysis was employed to identify significant predictors of the number of drug doses taken per month.

RESULTS

No significant association was found between 5HT2A A and 1438G and C516T gene polymorphisms and MOH risk. In contrast, a higher consumption of monthly drug doses was observed among 516T 5HT2A carriers (median 50, range 13-120) compared to 516CC patients (median 30, range 12-128) (Mann-Whitney U-test, P = .018). In the stepwise multiple regression analysis, C516T 5HT2A polymorphism (P = .018) and class of overused drug (P = .047) emerged as significant, independent predictors of the monthly drug consumption in MOH patients.

CONCLUSIONS

Although our results do not support a major role of the A-1438G and C516T polymorphic variants of the 5HT2A gene in the susceptibility of MOH, our findings support an influence of the C516T polymorphism on the number of symptomatic drug doses taken and, possibly, on the drug-seeking behavior in these patients.

Lack of association between five serotonin metabolism-related genes and medication overuse headache

Serotonin is involved in several central nervous system functions including pain threshold, mood regulation and drug reward. Overuse of acute medications is commonly identified as a causative factor for medication overuse headache (MOH). Apparently, MOH shares with other kinds of drug addiction some common neurobiological pathways. The objective of this study is to assess the role of serotonin metabolism genes in the genetic liability to MOH. We performed a genetic association study using polymorphisms of five serotonin metabolism-related genes: serotonin transporter (5HTT), serotonin receptor 1A (5-HT1A), serotonin receptor 1B (5-HT1B), serotonin receptor 2A (5-HT2A) and serotonin receptor 6 (5HT6) genes. We compared 138 patients with MOH with a control sample of 117 individuals without headache and without drug overuse, and with 101 patients with migraine without aura but without drug overuse (MO). The genotypic and allelic distributions of all polymorphisms investigated did not differ among the three groups. In conclusion, our study does not provide evidence that the 5HTT, 5-HT1A, 5HT1B, 5HT2A and 5HT6 gene polymorphisms play a role in the genetic predisposition to MOH.

Headache attributed to a substance or its withdrawal

Medication overuse, and subsequent medication overuse headache (MOH), is a growing and still underestimated problem worldwide. A significant number of recent epidemiological studies suggest that up to 4% of the general population in Europe, North America, and Asia overuse analgesics and other drugs for the treatment of pain conditions such as migraine. These studies also provide convincing evidence that about 1% of the general population suffers from MOH. The condition can be caused by almost all antiheadache drugs, including analgesics, ergots, triptans, and combined preparations. The clinical symptoms of MOH are heterogeneous and may vary from just an increase in headache attack frequency to a constant holocranial pain over years. The International Headache Society (IHS) defined MOH in its first classification in 1988 but modified the diagnostic criteria in its second classification in 2004 to facilitate diagnosis and the conduct of clinical trials. The underlying pathophysiology of MOH is not well understood. The only therapy is withdrawal from the overused substances. The only strategy to reduce the prevalence of MOH is to prevent the development of MOH in the first place by clear restriction of monthly doses of antiheadache drugs and constant education of both patients and physicians prescribing or recommending antiheadache drugs.

Tension-type headache with medication overuse: pathophysiology and clinical implications

Tension-type headache (TTH) is the most prevalent primary headache disorder. An important factor in the long-term prognosis of TTH is the overuse of acute medications used to treat headache. There are many reasons why patients with TTH overuse acute medications, including biobehavioral influences, dependency, and a lack of patient education. Chronic daily headache occurs in 4.1% of the general population, and chronic tension-type headache and medication overuse headache (MOH) occur in approximately 2.2% and 1.5%, respectively. A proper diagnosis is essential for the treatment of these patients. Treatment should include pathological considerations concerning TTH and MOH, which include peripheral and central mechanisms. Because TTH with MOH carries the worst prognosis, more clinical studies focusing on the complex interaction and treatments of TTH and MOH are needed.

Genetic variation in the serotonin transporter gene (5-HTTLPR, rs25531) influences the analgesic response to the short acting opioid Remifentanil in humans

Background

There is evidence from animal studies that serotonin (5-HT) can influence the antinociceptive effects of opioids at the spinal cord level. Therefore, there could be an influence of genetic polymorphisms in the serotonin system on individual variability in response to opioid treatment of pain. The serotonin transporter (5-HTT) is a key regulator of serotonin metabolism and availability and its gene harbors several known polymorphisms that are known to affect 5-HTT expression (e.g. 5-HTTLPR, rs25531). The aim of this study was to investigate if the triallelic 5-HTTLPR influences pain sensitivity or the analgesic effect of opioids in humans. 43 healthy volunteers (12 men, 31 women, mean age 26 years) underwent heat pain stimulations before and after intravenous injection of Remifentanil; a rapid and potent opioid drug acting on μ-type receptors. Subjects rated their perceived pain on a visual analogue scale (VAS). All participants were genotyped for the 5-HTTLPR and the rs25531 polymorphism. We recruited by advertising, with no history of drug abuse, chronic pain or psychiatric disorders.

Results

At baseline, there was no difference in pain ratings for the different triallelic 5-HTTLPR genotype groups. However, the opiod drug had a differential analgesic effect depending on the triallelic 5-HTTLPR genotype. Remifentanil had a significantly better analgesic effect in individuals with a genotype coding for low 5-HTT expression (S_A/S_A and S_A/L_G) as compared to those with high expression(L_A/L_A), p < 0.02. The analgesic effect for the three different genotype groups was linear to degree of 5-HTT expression.

Conclusion

This is the first report showing an influence of the triallelic 5-HTTLPR on pain sensitivity or the analgesic effect of opioids in humans. Previously the 5-HTTLPR s-allele has been associated with higher risk of developing chronic pain conditions but in this study we show that the genotype coding for low 5-HTT expression is associated with a better analgesic effect of an opioid. The s-allele has been associated with downregulation of 5-HT1 receptors and we suggest that individuals with a desensitization of 5-HT1 receptors have an increased analgesic response to opioids during acute pain stimuli, but may still be at increased risk of developing chronic pain conditions.

Medication overuse headache

The term medication overuse headache (MOH) was recently introduced by the International Headache Society to describe daily or nearly daily (chronic) headache that occurs after the regular intake (overuse) of any kind of antiheadache or antimigraine drug. Chronic headache is a growing problem throughout the world. It affects up to 3% to 4% of the general population, and 30% to 50% of such headaches are attributed to overuse of antiheadache drugs. This article reviews the literature on the epidemiology, risk factors, and pathophysiology of MOH. It also summarizes current strategies for treating and preventing headache chronicity.

5-HTTLPR genotype and anxiety-related personality traits: a meta-analysis and new data

We investigated the strength of evidence for association of the 5-HTTLPR polymorphism and the personality trait of Harm Avoidance. We used new primary data from a large sample of adults drawn from the Finnish population. We also applied meta-analytic techniques to synthesize existing published data. The large number of studies of the 5-HTTLPR polymorphism allowed us to apply a formal test of publication bias, as well as formally investigate the impact of potential moderating factors such as measurement instrument. Univariate ANOVA of primary data (n = 3,872), with 5-HTTLPR genotype as a between-groups factor, indicated no evidence of association with Harm Avoidance (P = 0.99). Meta-analysis indicated no evidence of significant association of 5-HTTLPR with Harm Avoidance (d = 0.02, P = 0.37), or EPQ Neuroticism (d = 0.01, P = 0.71), although there was evidence of association with NEO Neuroticism (d = 0.18, P < 0.001). Our analyses indicate that the 5-HTTLPR variant is not associated with Harm Avoidance. Together with our previous analyses of a large sample of participants with extreme Neuroticism scores (defined by the EPQ), we have data that excludes a meaningful genetic effect of the 5-HTTLPR on two measures of anxiety-related personality traits. There remains the possibility that the variant influences the NEO personality questionnaire measure of Neuroticism. However, a large, well-powered primary study is required to test this hypothesis directly and adequately.

Tension-type headache: current research and clinical management

Tension-type headache (TTH) is the most common form of headache, and chronic tension-type headache (CTTH) is one of the most neglected and difficult types of headache to treat. The pathogenesis of TTH is multifactorial and varies between forms and individuals. Peripheral mechanisms (myofascial nociception) and central mechanisms (sensitisation and inadequate endogenous pain control) are intermingled: the former predominate in infrequent and frequent TTH, whereas the latter predominate in CTTH. Acute therapy is effective for episodes of TTH, whereas preventive treatment--which is indicated for frequent and chronic TTH--is, on average, not effective. For most patients with CTTH, the combination of drug therapies and non-drug therapies (such as relaxation and stress management techniques or physical therapies) is recommended. There is clearly an urgent need to improve the management of patients who are disabled by headache. This Review summarises the present knowledge on TTH and discusses some of its more problematic features.

Muscle pain in the head: overlap between temporomandibular disorders and tension-type headaches

PURPOSE OF REVIEW

A variety of painful problems can affect the muscles in the head and face. Both temporomandibular disorders and tension-type headaches are believed to have a significant contribution from the skeletal muscles and have several clinical features in common. It still unclear, however, to what extent these two prevalent disorders are separate entities or have similar pathophysiological background.

RECENT FINDINGS

There is now reasonably good evidence that myofascial temporomandibular disorder patients are more likely to have a tension-type headache problem and vice versa, but the overlap is not complete. Studies have documented similarities regarding sensitization of the nociceptive pathways, dysfunction of the endogenous pain modulatory systems as well as contributing genetic factors, but there are also a number of distinct differences between temporomandibular disorders and tension-type headaches that need to be considered.

SUMMARY

Using the current classification systems, myofascial temporomandibular disorder pain and tension-type headache disorders do overlap and appear to share many of the same pathophysiological mechanisms, but it would be premature to consider them as identical entities since the importance of, for example, the affected muscles and associated function and genetic background needs to be established. Orofacial pain and headache specialists should collaborate to further develop diagnostic procedures and management strategies of temporomandibular disorders and tension-type headaches.

Serotonin transporter protein polymorphism and harm avoidance personality in migraine without aura

OBJECTIVE

To investigate polymorphisms in the serotonin transporter protein gene and harm avoidance personality dimension in patients with migraine without aura (MWOA).

BACKGROUND

The serotonin transporter protein is a key modulator of serotonergic synaptic neurotransmission. Two polymorphic regions of the gene for serotonin transporter protein have been found, and are associated with variations in the functional activity of serotonin caused by differing transcriptional efficiency. The harm avoidance (HA) personality trait may also be heritable and associated with altered serotonergic neurotransmitter activity.

DESIGN

We amplified the polymorphism in the promoter of serotonin transporter protein (5-HTTLPR) and the variable number of tandem repeats polymorphism within intron 2 (VNTR) using the polymerase chain reaction and performed genotype polymorphism analyses in 97 patients with MWOA and 100 healthy controls. We investigated serotonin-related personality traits by evaluating the HA personality dimension using a tridimensional questionnaire.

RESULTS

The genotype frequencies and allele distributions of 5-HTTLPR did not differ between patients with MWOA and controls. The VNTR genotype STin2.12/STin2.12 was significantly more common in patients with MWOA (90%) than in controls (77%; P= .017). Patients with MWOA also had HA scores (21.9 +/- 6.4) significantly higher than those of controls (16.3 +/- 6.1; P < .001).

CONCLUSIONS

Serotonergic activity might be involved in the development of MWOA and VNTR of serotonin transporter gene might be one of the genetically contributing factors.