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

Pain from Internal Organs and Headache: The Challenge of Comorbidity

Headache and visceral pain are common clinical painful conditions, which often co-exist in the same patients. Numbers relative to their co-occurrence suggest possible common pathophysiological mechanisms. The aim of the present narrative review is to describe the most frequent headache and visceral pain associations and to discuss the possible underlying mechanisms of the associations and their diagnostic and therapeutic implications based on the most recent evidence from the international literature. The conditions addressed are as follows: visceral pain from the cardiovascular, gastrointestinal, and urogenital areas and primary headache conditions such as migraine and tension-type headache. The most frequent comorbidities involve the following: cardiac ischemic pain and migraine (possible shared mechanism of endothelial dysfunction, oxidative stress, and genetic and hormonal factors), functional gastrointestinal disorders, particularly IBS and both migraine and tension-type headache, primary or secondary dysmenorrhea and migraine, and painful bladder syndrome and headache (possible shared mechanisms of peripheral and central sensitization processes). The data also show that the various visceral pain-headache associations are characterized by more than a simple sum of symptoms from each condition but often involve complex interactions with the frequent enhancement of symptoms from both, which is crucial for diagnostic and treatment purposes.

Biomarkers in Migraine

Background

Disability from migraine has a profound impact on the world's economy. Research has been ongoing to identify biomarkers to aid in diagnosis and treatment.

Objective

The aim of this study was to highlight the purported diagnostic and therapeutic migraine biomarkers and their role in precision medicine.

Methods

A comprehensive literature search was conducted using PubMed, Google Scholar, and clinicaltrials.gov using keywords: "migraine" OR "headache" combined with "biomarkers" OR "marker." Other keywords included "serum," "cerebral spinal fluid," "inflammatory," and "neuroimaging."

Results

After a review of 88 papers, we find the literature supports numerous biomarkers in the diagnosis of migraine. Therapeutic biomarkers, while not as extensively published, highlight calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide-38 (PACAP-38) as biomarkers with the most substantiated clinical relevance. Genetic markers mainly focusing on gene mutations with resultant biochemical alterations continue to be studied and show promise.

Conclusion

Although there are several proposed biomarkers for migraine, continued research is needed to substantiate their role in clinical practice.

Personality profile and depression in migraine: a meta-analysis

BACKGROUND

Despite the clinical importance of psychological factors in migraine, the relationship between personality traits, depression, and migraine has been poorly investigated.

OBJECTIVE

To delineate the personality profile distinctive for migraineurs and to explore the relationship between personality traits and depression in migraineurs compared to non-migraineurs.

METHODS

A systematic literature search was performed up to March 2019 using PsycInfo (PROQUEST), PubMed and Scopus. Sixteen primary studies met inclusion and exclusion criteria and were included in the meta-analysis.

RESULTS

The meta-analysis on the personality defined according to Psychobiological model revealed high Harm Avoidance (Hedges'g = 0.31; 95% confidence interval [CI] = 0.01-0.60), Persistence (Hedges'g = 0.37; 95% CI = 0.01to - 0.72) and low self-directedness (Hedges'g = - 0.33; 95% CI = -0.57 to - 0.09) in migraineurs. The meta-analysis on the personality defined according to Three Factor Model revealed high neuroticism (Hedges'g = 0.47; 95% CI = 0.32-0.63) and low extraversion (Hedges'g = - 0.08; 95% CI = - 0.14 to - 0.03) in migraineurs. Meta-regression analysis revealed that neuroticism moderated the relationship between depression and migraine.

CONCLUSION

The findings evidenced that migraine is characterized by specific personality traits. Among them, neuroticism influenced the severity of depression in migraineurs, and, therefore, an early evaluation of the personality traits could allow identifying patients susceptible to develop migraine-associated psychopathological symptoms.

The New *G29A and G1222A of HCRTR1, 5-HTTLPR of SLC6A4 Polymorphisms and Hypocretin-1, Serotonin Concentrations in Migraine Patients

Migraine is one of the most common primary headache disorders that affects 11% of the adult population. The disease is divided into two main clinical subtypes: migraine with aura (MA) and migraine without aura (MO). Both serotonergic and hypocretinergic systems are involved in the migraine pathomechanism. Polymorphisms in the serotonin transporter gene (SLC6A4) and the hypocretin receptor 1 gene (HCRTR1) may be risk factors for migraine development due to their ability to affect serotonin and hypocretin-1 (HCRT-1) concentrations. The aim of the study was to analyze, for the first time in the Polish population, the 5-HT transporter linked polymorphic region (5-HTTLPR) in SLC6A4, G1222A (rs2271933) and the never before studied *G29A (rs41263963) polymorphisms in the HCRTR1 gene, as well as the 5-HT and hypocretin-1 plasma concentrations in migraine patients (MA, MO) and control subjects. The study included 123 patients that were diagnosed with migraine and 123 control subjects. Methods such as PCR, HRMA and sequencing were used for genotyping, while 5-HT was determined by HPLC/EC and hypocretin-1 by ELISA. No significant differences were observed in 5-HTTLPR frequencies. The A allele of HCRTR1 G1222A occurred more often in MO, while the GA genotype of HCRTR1 *G29A was more frequent among MA when compared to control group (p < 0.05). The mean age of migraine onset in individuals with HCRTR1 *G29A was 18 years old for patients with MA and 26 years old for MO patients. The localization and type of HCRTR1 polymorphisms (G1222A-missense variant in exon 7, *G29A-3'UTR variant) may predispose patients to the clinical subtype of migraine: MO or MA, respectively. In control subjects, the short allele of 5-HTTLPR tended to decrease the 5-HT concentration, while the A allele of HCRTR1 G1222A decreased both 5-HT and hypocretin-1 levels. Serotonin concentrations differed in terms of clinical features of migraine. The relation between genotypes of 5-HTTLPR, HCRTR1 G1222A, and 5-HT concentrations may bedisturbed in migraine. It seems that HCRTR1 *G29A is more strongly associated with regulating the 5-HT in patients with MA than MO, and therefore may contribute to the early age of onset for migraine.

Midbrain raphe hypoechogenicity in migraineurs: An indicator for the use of analgesics but not triptans

Introduction The involvement of the serotonergic system of the brainstem raphe in the pathogenesis of migraine is discussed. Here we studied brainstem alterations in migraineurs using transcranial sonography and examined their relation to clinical features and self-medication. Methods We investigated 51 migraineurs (11 men, 40 women, mean age 29.7 ± 11.9 years) and 32 healthy individuals without history of headache or depressive disorder (eight men, 24 women, mean age 34.4 ± 13.0 years). Transcranial sonography was performed in an investigator-blinded fashion. Midbrain raphe echogenicity was quantified using digitized analysis. Migraine characteristics and the use of analgesics were evaluated by applying validated questionnaires. Eight migraineurs underwent neurophysiologic evaluation of contingent stimulus-related cortical potentials. Results Echo-reduced midbrain raphe was detected in 27 (53%) migraineurs, but only six (19%) control subjects (odds ratio = 4.87, p = 0.002). Lower raphe echogenicity correlated with both higher amplitude of terminal contingent negative variation (Spearman test, r = 0.76, p = 0.028) and higher use of analgesic drugs ( r = -0.45, p = 0.011), but not with use of triptans or with migraine frequency or severity (all p > 0.2). Compared to migraineurs without aura, migraineurs with aura had enlarged third ventricles (t-test, p = 0.014), while the lateral ventricle widths did not differ ( p = 0.62). Conclusions Midbrain raphe alteration is frequent in migraineurs and relates to self-medication behavior. This alteration may reflect the dysfunction of serotonergic raphe nuclei.

Molecular factors in migraine

Migraine is a common neurological disorder that affects 11% of adults worldwide. This disease most likely has a neurovascular origin. Migraine with aura (MA) and more common form - migraine without aura (MO) - are the two main clinical subtypes of disease. The exact pathomechanism of migraine is still unknown, but it is thought that both genetic and environmental factors are involved in this pathological process. The first genetic studies of migraine were focused on the rare subtype of MA: familial hemiplegic migraine (FHM). The genes analysed in familial and sporadic migraine are: MTHFR, KCNK18, HCRTR1, SLC6A4, STX1A, GRIA1 and GRIA3. It is possible that migraine is a multifactorial disease with polygenic influence.Recent studies have shown that the pathomechanisms of migraine involves both factors responsible for immune response and oxidative stress such as: cytokines, tyrosine metabolism, homocysteine; and factors associated with pain transmission and emotions e.g.: serotonin, hypocretin-1, calcitonin gene-related peptide, glutamate. The correlations between genetic variants of the HCRTR1 gene, the polymorphism 5-HTTLPR and hypocretin-1, and serotonin were observed. It is known that serotonin inhibits the activity of hypocretin neurons and may affect the appearance of the aura during migraine attack.The understanding of the molecular mechanisms of migraine, including genotype-phenotype correlations, may contribute to finding markers important for the diagnosis and treatment of this disease.

Serotonin and Migraine: Biology and Clinical Implications

Migraine is the most frequent neurological disorder in the adult population worldwide, affecting up to 12% of the general population and more frequent in women (~25%). It has a high impact on our society due to its disabling nature and, therein, reduced quality of life and increased absenteeism from work. Headache is the primary clinical manifestation and it has been associated with ‘a hereditary or predisposed sensitivity of neurovascular reactions to certain stimuli or to cyclic changes in the central nervous system’ (1). Amongst the many neurotransmitters in the brain, the serotonergic (serotonin, 5-HT) system from the brainstem raphe nucleus has been most convincingly implicated in migraine pathophysiology. The documented changes in 5-HT metabolism and in the processing of central 5-HT-mediated responses during and in between migraine attacks have led to the suggestion that migraine is a consequence of a central neurochemical imbalance that involves a low serotonergic disposition. Although the exact cascade of events that link abnormal serotonergic neurotransmission to the manifestation of head pain and the accompanying symptoms has yet to be fully understood, recent evidence suggests that a low 5-HT state facilitates activation of the trigeminovascular nociceptive pathway, as induced by cortical spreading depression. In this short review, we present and discuss the original and most recent findings that support a role for altered serotonergic neurotransmission in the manifestation of migraine headache.

Concomitant functional gastrointestinal symptoms influence psychological status in Korean migraine patients

Background/Aims

Migraine is frequently accompanied by symptoms consistent with functional gastrointestinal disorders (FGIDs). This study evaluated the prevalence of functional gastrointestinal symptoms and assessed the symptoms' relationship with the concomitant functional symptoms of anxiety, depression, and headache-related disability.

Methods

This prospective study included 109 patients with migraine who were recruited from a headache clinic at a teaching hospital. The participants completed a self-administered survey that collected information on headache characteristics, functional gastrointestinal symptoms (using Rome III criteria to classify FGID), anxiety, depression, and headache-related disability.

Results

In total, 71% of patients met the Rome III criteria for at least one FGID. In patients with FGID, irritable bowel syndrome was the most common symptom (40.4%), followed by nausea and vomiting syndrome (24.8%) and functional dyspepsia (23.9%). Depression and anxiety scores were significantly higher in patients meeting the criteria for any FGID. The number of the symptoms consistent with FGID in individual patients correlated positively with depression and anxiety.

Conclusions

FGID symptoms defined by the Rome III criteria are highly prevalent in migraine. These symptoms correlate with psychological comorbidities, such as depression and anxiety.

AVPR1A and SLC6A4 polymorphisms in choral singers and non-musicians: a gene association study

Amateur choral singing is a common pastime and worthy of study, possibly conferring benefits to health and social behaviour. Participants might be expected to possess musical ability and share some behavioural characteristics. Polymorphisms in genes concerned with serotonergic neurotransmission are associated with both behaviour and musical aptitude. Those investigated previously include the variable number tandem repeats RS1, RS3 and AVR in the AVPR1A (arginine vasopressin receptor 1a) gene and STin2 in the SLC6A4 (solute carrier family 6 [neurotransmitter transporter, serotonin], member 4) gene, as well as the SLC6A4 promoter region polymorphism, 5-HTTLPR. We conducted a genetic association study on 523 participants to establish whether alleles at these polymorphisms occur more commonly in choral singers than in those not regularly participating in organised musical activity (non-musicians). We also analysed tagging single nucleotide polymorphisms (SNPs) for AVPR1A and SLC6A4 to determine whether other variants in these genes were associated with singer/non-musician status. At the STin2 polymorphism, overall association with singer/non-musician status was evident at P = 0.006. The 9-repeat (P = 0.04) and 12-repeat (P = 0.04) alleles were more common in singers and the 10-repeat allele less so (P = 0.009). Odds ratios were 0.73 (95% CI 0.57–0.94) for the 10-repeat allele and 2.47 (95% CI 0.88–6.94) for the rarer 9-repeat allele. No overall association was detected at P<0.05 between any other polymorphism and singer/non-musician status. Our null findings with respect to RS3, RS1 and AVR, polymorphisms associated with musical ability by other authors, suggest that choir membership may depend partly on factors other than musical ability. In a related musical project involving one participating choir, a new 40-part unaccompanied choral work, “Allele”, was composed and broadcast on national radio. In the piece, each singer's part incorporated their personal RS3 genotype.

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.

Association of 5-HTT gene polymorphisms with migraine: a systematic review and meta-analysis

BACKGROUND/AIMS

Serotonin is known to play an important role in the pathogenesis of migraine, but individual genetic association studies that examine the relationship between polymorphisms of serotonin transporter (5-HTT) gene and migraine have yielded inconsistent results. This study aimed to evaluate the association between 5-HTT gene variants (including 5-HTTLPR, VNTR and SNP) and migraine using systematic review with meta-analysis.

METHODS

Relevant studies were identified by searching English and Chinese databases extensively. Allele and genotype frequencies for each included study were extracted. The odds ratio (OR) was calculated using a random-effects or fixed-effects model. Q statistic was used to evaluate homogeneity, and Egger's test and Funnel plot were used to assess publication bias. For family-based association studies, a descriptive analysis was carried out.

RESULTS

A total of 15 studies were identified for meta-analysis. It was found that the 5-HTT VNTR Stin2.12 allele or 12/12 genotype had an increased risk for migraine in the general population (Stin2.12 allele: OR, 95% CI: 1.34, 1.09-1.64, p=0.006; 12/12 genotype: OR, 95% CI: 1.55, 1.17-2.05, p=0.002), but there was no significant association between migraine and 5-HTTLPR or SNP rs2020942.

CONCLUSIONS

Existing evidence indicates that the 5-HTT VNTR polymorphism (mainly the STin2.12 genotype) is associated with an increased risk of migraine in the general population. Future studies with larger sample sizes will be necessary to confirm the present results.

STin2 VNTR polymorphism in the serotonin transporter gene and migraine: pooled and meta-analyses

Data on the association between the SLC6A4 STin2 VNTR polymorphism and migraine are conflicting. To perform pooled and meta-analyses, we searched for studies published until September 2009 using electronic databases (MEDLINE, EMBASE, Science Citation Index) and reference lists of studies. Assessment for eligibility and extraction of data was performed by two independent investigators. We extracted allele and genotype frequencies for each study. We then calculated study-specific and pooled odds ratios (OR) and 95% confidence intervals (CI) assuming allele and genotype models. We also calculated pooled ORs and 95% CIs based on study-specific effect estimates for the allele model. We included five studies investigating the association between the STin2 VNTR polymorphism and migraine. Results from the allele model suggested a protective effect against migraine for the STin2.9 and STin2.10 alleles compared to the STin2.12 allele among populations of European descent, which however was not significant. Results from the genotype model indicated a significant ~25% reduced risk for migraine among carriers of the 10/12 genotype compared with carriers of the 12/12 genotype among all study populations (OR = 0.76, 95% CI 0.60–0.97) for any migraine, which was more pronounced among populations of European descent (OR = 0.68, 95% CI 0.53–0.87). Results for migraine with and without aura were of similar magnitude, but were not statistically significant. Our results suggest a protective effect of non-STin2.12 alleles compared to STin2.12 alleles, respectively, 10/12 and 10/10 genotypes compared to the 12/12 genotype against migraine among populations of European descent. Associations in non-European populations may differ.

5-HTTLPR polymorphism in the serotonin transporter gene and migraine: a systematic review and meta-analysis

BACKGROUND AND METHODS

Data on the association between the SLC6A4 5-HTTLPR polymorphism and migraine are conflicting. We performed a systematic review and meta-analysis among studies published up to September 2009. For each study with genotype information, we calculated odds ratios (OR) and 95% confidence intervals (CI) assuming additive, dominant, and recessive genetic models. We then calculated pooled ORs and 95% CIs.

RESULTS

Among the ten studies identified there was no overall association between the polymorphism and any migraine for Europeans or Asians. However, European women carrying the S allele had an increased risk for any migraine (dominant model: pooled OR=2.02; 95% CI 1.24-3.28). Results among Europeans further suggested an increased risk for migraine with aura among carriers of the S/S genotype (recessive model: pooled OR=1.41; 95% CI 0.83-2.40).

CONCLUSIONS

While our results indicate no overall association between the SLC6A4 5-HTTLPR polymorphism and migraine among Europeans and Asians, gender and migraine aura status may have modifying roles among Europeans.

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.

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.

Polymorphisms of the serotonin transporter gene (5-HTTLPR, A/G SNP in 5-HTTLPR, and STin2 VNTR) and their relation to personality traits in healthy individuals from Russia

OBJECTIVE

Numerous studies have reported association of the serotonin transporter gene (5-HTT) polymorphisms and neuroticism and traits characterizing sociability and activity. This study aimed to define a single genotype effect of three polymorphic markers in the 5-HTT gene (5-HTTLPR, A/G SNP in 5-HTTLPR and STin2 VNTR) and to check possible association of the 5-HTT haplotypes and personality traits [assessed with Eysenck Personality Inventory (EPI) and Temperament and Character Inventory (TCI) questionnaires] in 301 healthy young individuals.

METHODS

To investigate single genotype and haplotype effects of all polymorphic markers, multivariate analysis of variance and haplotype trend regression analyses were conducted correspondingly.

RESULTS

Individuals with STin2.10 allele scored significantly lower on Neuroticism (EPI) (P=0.007) and Harm Avoidance (P=0.005) in the overall sample. The same pattern of association was reported in women: carriers of STin2.10 allele scored lower on Harm Avoidance (TCI) (P=0.008). Haplotype trend regression analyses revealed that carriers of S12 haplotype had lower sociability-related traits such as Extraversion (EPI) and Novelty Seeking (TCI), whereas Harm Avoidance (TCI) (anxiety-related trait) was higher. Opposite association was observed for S10 haplotype: Extraversion (EPI) score was higher, whereas Harm Avoidance (TCI) score was lower in carriers of this haplotype.

CONCLUSION

As single polymorphism effect of STin2 was observed in relation to anxiety-related traits, opposite S10 and S12 haplotype effects on Neuroticism and Harm Avoidance could be explained by the larger impact of STin2 polymorphism. Controversially, we consider that the variance in sociability-related traits is related to specific haplotypes of 5-HTT gene.

Family-based analysis of serotonin transporter gene polymorphisms in migraine with and without aura

Genetic epidemiological twin studies have demonstrated a significant heritability for migraine, with > 60% of liability to migraine either with or without aura coming from additive genetic factors. Because of the essential role of serotonin in the pathophysiology and treatment of migraine, genes of the serotonin system are candidates for involvement in migraine. Consequently, we examined two functional VNTR polymorphisms in the serotonin transporter gene, the 5-HTTLPR and the intron 2 VNTR, in a sample of 212 family trios each with a proband with childhood migraine, 153 with migraine without aura (MoA) and 59 with migraine with aura (MA). For the first time, we used transmission disequilibrium test analysis with the program TDTPHASE to examine the transmission of these two markers and their haplotypes to offspring affected by migraine. We found no significant transmission distortion of any marker, with the common L allele of the 5-HTTLPR transmitted 170 times and not transmitted 178 times, and the S allele 130 vs. 122 times. Likewise, the common 12 allele of the intron 2 VNTR was transmitted 201 times and not transmitted 188 times, and the 10 allele 107 vs. 120 times. The markers were not associated with MoA and MA and none of the haplotypes was associated with overall migraine, MoA or MA. The 5-HTTLPR and the intron 2 VNTRs do not play a major role in susceptibility to migraine.