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

Medication-overuse headache: a widely recognized entity amidst ongoing debate

Medication overuse in primary headache disorders is a worldwide phenomenon and has a role in the chronification of headache disorders. The burden of disease on individuals and societies is significant due to high costs and comorbidities. In the Third Edition of the International Classification of Headache Disorders, medication-overuse headache is recognized as a separate secondary entity next to mostly primary headache disorders, although many clinicians see the disease as a sole complication of primary headache disorders. In this review, we explore the historical background of medication-overuse headache, its epidemiology, phenomenology, pathophysiology and treatment options. The review explores relevant unanswered questions and summarizes the current debates in medication-overuse headache.

Factors associated to chronic migraine with medication overuse: A cross-sectional study

BACKGROUND AND AIM

Factors implicated in the evolution of episodic migraine into chronic migraine are largely elusive. Medication overuse is considered to be one of the main determinants, but other possible clinical and psychological factors can play a role. The aim of this study is to identify factors that are associated with chronic migraine with medication overuse.

METHOD

We enrolled consecutive migraine patients, subdividing them in two groups: Subjects with a long history of episodic migraine and subjects with chronic migraine and medication overuse. We then compared their clinical and psychological variables in a cross-sectional study.

RESULTS

Three hundred and eighteen patients were enrolled, of which 156 were episodic migraine and 162 were chronic migraine and medication overuse patients. The mean age was 42.1 ± 10.3, 80.8% were female. The duration of migraine was 24.6 years in episodic migraine and 24.0 years in chronic migraine and medication overuse ( p = 0.57). After the multivariate analysis, the factors associated to chronic migraine and medication overuse were: Marital status (married vs. unmarried, OR 3.65, 95% CI 1.63-8.19, p = 0.002; separated/divorced/widowed vs. unmarried, OR 4.19, 95% CI 1.13-15.47, p = 0.031), physical activity (OR 0.42, 95% CI 0.19-0.91, p = 0.029), age at onset of migraine (OR 0.94, 95% CI 0.89-0.98, p = 0.016), use of at least one migraine preventive medication (OR 2.36, 95% CI 1.18-4.71, p = 0.014), history of depression (OR 2.91, 95% CI 1.25-6.73, p = 0.012), insomnia associated with the use of hypnotics (OR 5.59, 95% CI 1.65-18.93, p = 0.006), traumatic head injuries (OR 3.54, 95% CI 1.57-7.99, p = 0.002), snoring (OR 2.24, 95% CI 1.05-4.79, p = 0.036), previous and/or actual use of combined oral contraceptives (OR 3.38, 95% CI 1.10-10.3, p = 0.031) and higher scores in the Childhood Trauma questionnaire (OR 1.48, 95% CI 1.09-2.02, p = 0.012).

CONCLUSION

We considered several aspects that may be involved in the development of chronic migraine and medication overuse. A multivariate analysis identified 10 factors belonging to five different areas, to suggest that chronic migraine and medication overuse onset is likely influenced by a complex mixture of factors. This information is useful when planning strategies to prevent and manage chronic migraine and medication overuse.

A systematic review and critical appraisal of gene polymorphism association studies in medication-overuse headache

Purpose of review

Medication-overuse headache is a secondary chronic headache disorder, evolving from an episodic primary headache type, caused by the frequent and excessive use of headache symptomatic drugs. While gene polymorphisms have been deeply investigated as susceptibility factors for migraine, little attention has been paid to medication-overuse headache genetics. In the present study we conducted a systematic review to identify, appraise and summarize the current findings of gene polymorphism association studies in medication-overuse headache.

Methods

A comprehensive literature search was conducted on PubMed and Web of Knowledge databases of primary studies that met the diagnostic criteria for medication-overuse headache according to the temporally-relevant Classification of Headache Disorder of the International Headache Society.

Results

A total of 17 candidate gene association studies focusing on medication-overuse headache were finally included in the qualitative review. Among these, 12 studies investigated the role of common gene polymorphisms as risk factors for medication-overuse headache susceptibility, six studies focused on the relationship with clinical features of medication-overuse headache patients, and four studies evaluated their role as determinants of clinical outcomes in medication-overuse headache patients.

Conclusion

Results of single studies show a potential role of polymorphic variants of the dopaminergic gene system or of other genes related to drug-dependence pathways as susceptibility factors for disease or as determinants of monthly drug consumption, respectively. In this systematic review, we summarize the findings of gene polymorphism association studies in medication-overuse headache and discuss the methodological issues that need to be addressed in the design of future studies.

Risk of medication overuse headache across classes of treatments for acute migraine

BACKGROUND

The most commonly prescribed medications used to treat migraine acutely are single analgesics, ergots, opioids, and triptans. Due to varying mechanisms of action across drug classes, there is reason to believe that some classes may be less likely than others to elicit Medication Overuse Headache (MOH) than others. We therefore aimed to determine whether certain classes of acute migraine drugs are more likely to elicit MOH than others.

METHODS

A comprehensive systematic literature was conducted to identify studies of varying designs that reported on MOH within the considered treatment classes. Only studies that reported MOH according to the International Classification of Headache Disorders (ICHD) were considered. Since no causal comparative design studies were identified; data from prevalence studies and surveys were retrieved. Prevalence-based relative risks between treatment classes were calculated by integrating both medication overuse and medication use from published studies. For each pair wise comparison, pooled relative risks were calculated as the inverse variance weighted average.

RESULTS

A total of 29 studies informed the relative risk between treatment classes, all of which reported country-specific data. Five studies reported country-specific medication use data. For triptans versus analgesics the study relative risks generally favored triptans. The pooled relative risk was 0.65 (i.e., relative risk reduction of 35 %). For ergots versus analgesics, a similar trend was observed in favor of ergots with a relative risk of 0.41. For triptans versus ergots, the direction of effect was mixed, and the pooled relative risk was 1.07. Both triptans and ergots appeared favorable when compared to opioids, with pooled relative risks of 0.35 and 0.76, respectively. However, the evidence was limited for these comparisons. Analgesics and opioids also appeared to yield similar risk of MOH (pooled relative risk 1.09).

CONCLUSION

Our study suggests that in patients receiving acute migraine treatment, analgesics and opioids are associated with a higher risk of developing MOH compared with other treatments. These findings provide incentive for better monitoring of use of analgesics and opioids for treating acute migraine, and suggest possible clinical preference for use of so-called "migraine-specific" treatments, that is, triptans and ergots.

Neural Plasticity in Common Forms of Chronic Headaches

Headaches are universal experiences and among the most common disorders. While headache may be physiological in the acute setting, it can become a pathological and persistent condition. The mechanisms underlying the transition from episodic to chronic pain have been the subject of intense study. Using physiological and imaging methods, researchers have identified a number of different forms of neural plasticity associated with migraine and other headaches, including peripheral and central sensitization, and alterations in the endogenous mechanisms of pain modulation. While these changes have been proposed to contribute to headache and pain chronification, some findings are likely the results of repetitive noxious stimulation, such as atrophy of brain areas involved in pain perception and modulation. In this review, we provide a narrative overview of recent advances on the neuroimaging, electrophysiological and genetic aspects of neural plasticity associated with the most common forms of chronic headaches, including migraine, cluster headache, tension-type headache, and medication overuse headache.

Risk factors of chronic daily headache or chronic migraine

Chronic daily headache (CDH) is a common neurological condition that affects 1-4 % of the general population. Most individuals with CDH originally suffered from episodic headaches, but over time, this developed into CDH. Although the pathophysiology of CDH is not fully understood, recent clinical and epidemiological studies suggest some risk factors that are associated with an increased risk of transformation from episodic headaches. If risk factors can be identified, they could provide a base for aggressive preventive intervention and thus decrease the transformation from episodic headaches to eventual CDH. In this article, we review and summarize the current data on risk factors for CDH.

Lack of association between oxidative stress-related gene polymorphisms and chronic migraine in an Italian population

Migraine patients present increased risks of vascular diseases such as high blood pressure, insulin resistance, metabolic syndrome, stroke and coronary heart disease. Oxidative stress (OS) is increasingly being studied in relation to the pathophysiology of migraine, stimulated by the described association with the most frequent migraine comorbidities. Because many of the gene-encoded players of the OS balance are characterized by functional polymorphisms, it is supposed that the individual genomic profile could affect susceptibility to OS and to related pathophysiological conditions. This study aimed to characterize a panel of 10 polymorphisms in 8 OS-related genes in a chronic migraine (CM) population and healthy controls, to recognize a genetic risk in the process of migraine chronification. The sample consisted of 45 healthy women and 96 women diagnosed with CM. No deviations from the Hardy-Weinberg equilibrium were detected, or in the overall population, or in the CM group or in the control group.

Combined effect of common gene variants on response to drug withdrawal therapy in medication overuse headache

PURPOSE

No information is currently available on genetic determinants of short-term response to drug withdrawal in medication overuse headache (MOH). In the present study, we aimed to evaluate the role of 14 polymorphisms in 8 candidate genes potentially relevant for drug addiction (OPRM1, DRD2, DBH, COMT, BDNF, SLC6A4, 5HT2A, and SLC1A2) as predictors for detoxification outcome of MOH patients at 2 months of follow-up.

METHODS

Genotyping was conducted by PCR, PCR-RFLP analysis, or real-time PCR allelic discrimination assay on genomic DNA extracted from peripheral blood. The association between gene variants and risk of unsuccessful detoxification was evaluated by univariate and multivariate logistic regression analyses.

RESULTS

One hundred and eight MOH patients with effective drug withdrawal therapy and 65 MOH patients with unsuccessful detoxification were available for the analysis. In the multivariable logistic regression analysis, triptan overuse (odds ratio (OR) 0.271, 95% confidence interval (CI) 0.083-0.890, P = 0.031) and TT genotype carriage of DRD2 NcoI (OR 0.115, 95% CI 0.014-0.982, P = 0.048) emerged as independent predictors for unsuccessful detoxification. In addition, carriers of at least four of the six top-ranked gene variants (P < 0.10) were found at higher odds for unsuccessful detoxification than patients with ≤3 high-risk genotypes (OR 3.40, 95% CI 1.65-7.01, P = 0.001).

CONCLUSION

This exploratory study suggests that DRD2 NcoI may be a genetic determinant of detoxification outcome in MOH patients. Our findings also show that an approach based on the combination of multiple genetic markers could be clinically useful for identification of MOH patients at higher risk for unsuccessful detoxification.

Pharmacogenomics of episodic migraine: time has come for a step forward

Migraine is characterized by heterogeneous behavior in response to drugs. Many resources have been invested in attempting to unravel the genetic basis of migraine, while the role of genetics in responses to currently available drugs has received less attention. We performed a systematic literature search identifying original articles pertaining to pharmacogenomics of episodic migraine. Few primary studies on the pharmacogenomics of symptomatic and preventive medication in episodic migraine were found. The number of patients studied in the individual articles ranged from 40 up to 130. There was a strong heterogeneity among these studies. We believe that pharmacogenomics studies, if properly designed, could contribute towards optimizing the treatment and reducing the burden of migraine, in turn helping patients and optimizing resources. Our knowledge on the pharmacogenomics of migraine is growing too slowly, and concerted measures should be undertaken to speed up the process.

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.

Cortical response to somatosensory stimulation in medication overuse headache patients is influenced by angiotensin converting enzyme (ACE) I/D genetic polymorphism

BACKGROUND

Medication overuse headache (MOH) is a disabling health problem. Convincing evidence attributes a pathophysiologic role to central sensitization. By recording somatosensory evoked potentials (SSEPs) in patients with MOH, we observed increased sensitization and deficient habituation to repetitive sensory stimuli consistent with drug overuse. The renin-angiotensin system in the brain seems to play a relevant role in neural plasticity and dependence behavior. We therefore sought differences in SSEP sensitization and habituation in patients with MOH who underwent angiotensin converting enzyme (ACE) I/D polymorphism analysis.

METHODS

We recorded median-nerve SSEPs (two blocks of 100 sweeps) in 43 patients with MOH. We measured N20-P25 amplitudes, and assessed sensitization using the first block amplitudes, and habituation using amplitude changes between the two sequential blocks. According to their genotype, subjects were divided into three groups: "D/D", "D/I" and "I/I" carriers.

RESULTS

The habituation slope of the two SSEP block amplitudes was significantly increased in the D/D subgroup (n = 16) with respect to that of the I/I subgroup (n = 6), with the D/I subgroup (n = 21) falling in between. In D/D carriers, the habituation slope correlated positively with the duration of the overuse headache, and the first SSEP block amplitudes, a measure of sensitization, increased in strict relationship with the type of overused medication in the MOH patients overall and in the D/D subgroup; this was not so in the D/I and I/I subgroups.

CONCLUSION

In patients with MOH, the homozygote D/D ACE polymorphism influences habituation and sensitization to repeated sensory stimuli in strict relationship with medication overuse. We suggest that angiotensin peptides influence neuronal mechanisms of plasticity by interacting with central monoaminergic synaptic transmission.

Migraine headache: a review of the molecular genetics of a common disorder

This tutorial summarises the state-of-the-art on migraine genetics and looks at the possible future direction of this field of research. The view of migraine as a genetic disorder, initially based on epidemiological observations of transmission of the condition within families, was subsequently confirmed by the identification of monogenic forms of "syndromic" migraine, such as familial hemiplegic migraine. We are currently witnessing a change in the way genetic analysis is used in migraine research: rather than studying modalities of inheritance in non-monogenic forms of migraine and in the persistent modalities of migraine headache, researchers are now tending to focus on the search for genetic markers of dysfunction in biological systems. One example of the evolution of migraine genetic research is provided by the recent efforts to shed light on the pharmacogenomic mechanisms of drug response in migraineurs. In addition, novel molecular approaches about to be introduced are expected to further increase knowledge on this topic and improve patient management.

Polymorphisms of the serotonin transporter and receptor genes: susceptibility to substance abuse

Serotonin (5-hydroxytryptamine [5-HT]) is an important neurotransmitter implicated in regulating substance-use disorder (SUD) acquisition, maintenance, and recovery. During the past several years, an abundance of research has begun discovering and describing specific 5-HT genetic polymorphisms associated with SUDs. Genetic variations in the 5-HT system, such as SLC6A4, HTR1B, HTR2A, HTR2C, HTR3 (HTR3A, HTR3B, HTR3C, HTR3D, and HTR3E), likely play a role contributing to SUD patient heterogeneity. The 5-HT transporter-linked polymorphic region S allele, located in SLC6A4, has now been modestly associated with alcohol dependence in two large meta-analyses. Additional 5-HT genes may also play a role but have not been extensively investigated. A limited number of SUD treatment studies have included 5-HT gene variation as moderating treatment outcomes, but the results have been equivocal. Future research on 5-HT addiction genetics should adopt whole-genome sequencing technology, utilize large study samples, and collect data from multiple ethnic groups. Together, these methods will build on the work already conducted with the aim of utilizing 5-HT genetics in SUD treatment settings.