Cluster Headache Genomewide Association Study and Meta-Analysis Identifies Eight Loci and Implicates Smoking as Causal Risk Factor

OBJECTIVE

The objective of this study was to aggregate data for the first genomewide association study meta-analysis of cluster headache, to identify genetic risk variants, and gain biological insights.

METHODS

A total of 4,777 cases (3,348 men and 1,429 women) with clinically diagnosed cluster headache were recruited from 10 European and 1 East Asian cohorts. We first performed an inverse-variance genomewide association meta-analysis of 4,043 cases and 21,729 controls of European ancestry. In a secondary trans-ancestry meta-analysis, we included 734 cases and 9,846 controls of East Asian ancestry. Candidate causal genes were prioritized by 5 complementary methods: expression quantitative trait loci, transcriptome-wide association, fine-mapping of causal gene sets, genetically driven DNA methylation, and effects on protein structure. Gene set and tissue enrichment analyses, genetic correlation, genetic risk score analysis, and Mendelian randomization were part of the downstream analyses.

RESULTS

The estimated single nucleotide polymorphism (SNP)-based heritability of cluster headache was 14.5%. We identified 9 independent signals in 7 genomewide significant loci in the primary meta-analysis, and one additional locus in the trans-ethnic meta-analysis. Five of the loci were previously known. The 20 genes prioritized as potentially causal for cluster headache showed enrichment to artery and brain tissue. Cluster headache was genetically correlated with cigarette smoking, risk-taking behavior, attention deficit hyperactivity disorder (ADHD), depression, and musculoskeletal pain. Mendelian randomization analysis indicated a causal effect of cigarette smoking intensity on cluster headache. Three of the identified loci were shared with migraine.

INTERPRETATION

This first genomewide association study meta-analysis gives clues to the biological basis of cluster headache and indicates that smoking is a causal risk factor. ANN NEUROL 2023;94:713-726.

Relationship between alcohol and primary headaches: a systematic review and meta-analysis

BACKGROUND

Headache is one of the most common neurological symptoms. Many previous studies have indicated a relationship between primary headaches and alcohol. Drinking has been associated with increased risk of tension-type headache (TTH) and migraine. However, recently published studies have not confirmed this relationship. The existing literature is inconclusive; however, migraine patients avoid alcohol. Therefore, the primary objective was to provide a reliable assessment of alcohol intake in people with primary headaches; the secondary objective was to identify any potential relationship between alcohol consumption and headache risk.

METHODS

This study was based on PubMed, Embase and Web of Science database searches performed on 11 July 2023. This systematic review was registered in PROSPERO (CRD42023412926). Risk of bias for the included studies was assessed using the Joanna Briggs Institute critical appraisal tools. Meta-analyses were performed using Statistica software. The Risk Ratio (RR) was adopted as the measure of the final effect. Analyses were based on a dichotomous division of the respondents into "non-drinkers" and "drinkers" for headache patients and matched non-headache groups.

RESULTS

From a total of 1892 articles, 22 were included in the meta-analysis. The majority demonstrated a moderate or high risk of bias. The first part of the meta-analysis was performed on data obtained from 19 migraine studies with 126 173 participants. The risk of migraine in alcohol drinkers is approximately 1.5 times lower than in the group of non-drinkers (RR = 0.71; 95% CI: 0.57-0.89). The second part involved 9 TTH studies with 28 715 participants. No relationship was found between TTH diagnosis and alcohol consumption (RR = 1.09; 95% CI: 0.93-1.27). Two of the included cluster-headache articles had inconclusive results.

CONCLUSIONS

Alcohol consumption and migraine are inversely correlated. The exact mechanism behind this observation may indicate that migraine leads to alcohol-avoidance, rather than alcohol having any protective role against migraine. There was no relationship between TTH and drinking. However, further studies related to primary headaches and alcohol consumption with low risk of bias are required. Additionally, patients and physicians should consider the latest medical data, in order to avoid the myths about alcohol consumption and primary headaches.

Epidemiology of diagnosed cluster headache in Norway

Background:

Cluster headache (CH) is one of the most painful conditions in humans and there is limited epidemiological data on this debilitating condition.

Objectives:

To describe the epidemiology of CH in Norway

Methods:

We conducted a nationwide study to investigate the prevalence, incidence, and comorbidity of CH in Norway between January 1 2008 and December 31 2016. Treatment and outcome data from the Norwegian patient registry and the Norwegian prescription database were linked on an individual basis.

Results:

Among 3,892,260 individuals ≥18 years old of age, we identified a total of 1891 patients with CH. The prevalence of CH was 48.6 per 100,000, and the male-to-female ratio was 1.47. The estimated incidence of CH was 3.0 per 100,000/year. Among patients with CH, increased age and sex adjusted odds ratios ([OR], all with p-values <0.0001, were observed for medication-induced headache (OR 50.7, 95% CI 36.7–69.9), migraine (OR 25.2, 95% CI 22.5–28.3), chronic posttraumatic headache (OR 22.2, 95% CI 12.8–38.45), history of cranial trauma (OR 1.9, 95% CI 1.5–2.4), somatoform disorders (OR 4.2, 95% CI 3.0–5.8), suicide attempt (OR 3.9, 95% CI 2.6–5.8), personality disorder (OR 3.6, 95% CI 2.6–4.9), bipolar disorder (OR 3.6, 95% CI 2.8–4.8), peptic ulcer (OR 2.8, 95% CI 2.3–3.3), depression (OR 2.8, 95% CI 2.4–3.1), substance abuse (OR 2.6, 95% CI 2.0–3.3), and cerebrovascular disease (OR 2.4, 95% CI 1.8–3.1). Use of opioid analgesics during the study period was more common among patients with CH compared to others (81% vs. 22%, sex and age adjusted OR 23.4, 95% CI 20.8–26.2, p < 0.0001).

Cluster Headache and Associated Risk Factors: A Systemic Review and Meta-Analysis

Cluster headache (CH) has always been associated with several risk factors, including hereditary, environmental, and lifestyle habits. This study focuses on important risk factors, including family history, smoking, alcohol consumption, male predominance, and head trauma associated with CH. The present study aimed at investigating the available literature on cluster headaches and evaluating their associated risk factors. A systematic data search was designed, and scientific data were collected from renowned databases, including PubMed, Cochrane, Embase, Cumulative Index of Nursing and Allied Health Literature (CINAHL), and Google Scholar. Thirty-two studies were selected to execute a systemic review, and 26 studies, consisting of 6,065 CH patients, qualified for a meta-analysis. Statistical analyses were conducted by using MedCalc, version 16.8.4; (MedCalc Software, Ostend, Belgium; http://www.medcalc.org) and Rapidminer statistical software, version 9.6.0 (www.rapidminer.com). We conclude the evidence of family history, smoking, alcohol consumption, male predominance, and head trauma are associated with cluster headaches. However, sex discrimination in familial cases needs to be revisited because of the female predominance reported by familial history and CH association studies.

The neurobiology of cluster headache

Cluster headache is a primary headache form occurring in paroxysmal excruciatingly severe unilateral head pain attacks usually grouped in periods lasting 1-2months, the cluster periods. A genetic component is suggested by the familial occurrence of the disease but a genetic linkage is yet to be identified. Contemporary activation of trigeminal and cranial parasympathetic systems-the so-called trigemino-parasympathetic reflex-during the headache attacks seem to cause the pain and accompanying oculo-facial autonomic phenomena respectively. At peripheral level, the increased calcitonin gene related peptide (CGRP) plasma levels suggests trigeminal system activation during cluster headache attacks. The temporal pattern of the disease both in terms of circadian rhythmicity and seasonal recurrence has suggested involvement of the hypothalamic biological clock in the pathophysiology of cluster headache. The posterior hypothalamus was investigate as the cluster generator leading to activation of the trigemino-parasympathetic reflex, but the accumulated experience after 20 years of hypothalamic electrical stimulation to treat the condition indicate that this brain region rather acts as pain modulator. Efficacy of monoclonal antibodies to treat episodic cluster headache points to a key role of CGRP in the pathophysiology of the condition.

New insights in post-traumatic headache with cluster headache phenotype: a cohort study

OBJECTIVES

To define the characteristics of post-traumatic headache with cluster headache phenotype (PTH-CH) and to compare these characteristics with primary CH.

METHODS

A retrospective study was conducted of patients seen between 2007 and 2017 in a headache centre and diagnosed with PTH-CH that developed within 7 days of head trauma. A control cohort included 553 patients with primary CH without any history of trauma who attended the headache clinic during the same period. Data including demographics, attack characteristics and response to treatments were recorded.

RESULTS

Twenty-six patients with PTH-CH were identified. Multivariate analysis revealed significant associations between PTH-CH and family history of CH (OR 3.32, 95% CI 1.31 to 8.63), chronic form (OR 3.29, 95% CI 1.70 to 6.49), parietal (OR 14.82, 95% CI 6.32 to 37.39) or temporal (OR 2.04, 95% CI 1.10 to 3.84) location of pain, and presence of prominent cranial autonomic features during attacks (miosis OR 11.24, 95% CI 3.21 to 41.34; eyelid oedema OR 5.79, 95% CI 2.57 to 13.82; rhinorrhoea OR 2.65, 95% CI 1.26 to 5.86; facial sweating OR 2.53, 95% CI 1.33 to 4.93). Patients with PTH-CH were at a higher risk of being intractable to acute (OR 12.34, 95% CI 2.51 to 64.73) and preventive (OR 16.98, 95% CI 6.88 to 45.52) treatments and of suffering from associated chronic migraine (OR 10.35, 95% CI 3.96 to 28.82).

CONCLUSION

This largest series of PTH-CH defines it as a unique entity with specific evolutive profile. Patients with PTH-CH are more likely to suffer from the chronic variant, have marked autonomic features, be intractable to treatment and have associated chronic migraine compared with primary CH.

Cluster headache is associated with unhealthy lifestyle and lifestyle-related comorbid diseases: Results from the Danish Cluster Headache Survey

AIM

To compare the prevalence of unhealthy lifestyle factors and comorbid disorders in cluster headache patients with headache-free controls, in order to discuss pathophysiology and possible consequences.

METHODS

Cluster headache patients from the Danish cluster headache survey aged 18-65 years, diagnosed according to ICHD-II, were compared to sex- and age-matched headache-free controls. Participants completed questionnaires and structured interviews.

RESULTS

A total of 400 cluster headache patients and 200 controls participated. Patients had a more unhealthy lifestyle compared with controls in the form of current and current/former smoking (48.3% vs. 9.0%, p < 0.001 and 74.5% vs. 30.0%, p < 0.001, respectively), higher average alcohol intake per week (98.2 grams vs. 77.9 grams, p = 0.033) and BMI (26.1 vs. 24.2 kg/m², p < 0.001), whereas coffee and energy drink consumption was equally distributed. Further, lifestyle-related, psychiatric and pain-related diseases were much more prevalent in patients compared with controls, except for diabetes. Sub-group analyses revealed that current/former smokers had a worse clinical presentation than never smokers.

CONCLUSION

Unhealthy lifestyle factors and lifestyle-related diseases were more prevalent in cluster headache patients compared to controls. As lifestyle-related diseases might have serious consequences in the management of cluster headache, it is key to inform patients at an early time point about the possible risks of their lifestyle choices.

The comorbidity burden of patients with cluster headache: a population-based study

Background

Evidence is limited regarding the comorbidity burden of patients with cluster headache (CH). We aimed to characterize comorbid conditions in a cohort of CH patients diagnosed by headache experts, using electronic health record information from the Partners Research Patient Data Registry (RPDR).

Methods

We identified and reviewed the charts of unique patients diagnosed by headache specialists over an 11-year period, and a set of matched controls. Patients were categorized as having Definite, Unconfirmed or no CH. We calculated the prevalence of and tested for statistically significant differences of selected comorbid conditions in these populations.

Results

An RPDR query identified 170 patients with a free text or ICD diagnosis of cluster headache. 15 records belonging to Partners employees were excluded. 75 patients met diagnostic criteria for CH (Definite CH). 22 had headaches with some features of CH but the diagnosis was uncertain (Unconfirmed CH). In 58 the diagnosis was determined to be inaccurate due to data entry errors. Patients with Definite CH had an average age of 43.4 years; 80% were male. The average time from CH onset to diagnosis was 12.7 years (range 1–51). The average number of yearly emergency department and outpatient visits for the group of Definite CH patients was 4.5 and 25.4, respectively, compared with 1.1 and 6.9 in controls. Of the 55 examined conditions, four were statistically significantly less common in patients with definite CH compared with controls (diabetes, musculoskeletal/orthopaedic problems, “other gastrointestinal diagnoses” and skin conditions) and four were statistically significantly more common (smoking, depression, dental disorders and deviated septum).

Conclusions

In this large population-based study, we identified a surprisingly small number of patients who met strict diagnostic criteria for CH. In these patients, however, we identified a distinct pattern of selected comorbidities. The pattern is somewhat but not entirely consistent with that of the “classic” CH patient depicted in the medical literature. CH patients are frequently diagnosed with sinus or dental problems. Many experience substantial delay in receiving a diagnosis. These things may in part explain the high frequency of medical visits in this population. It is difficult to distinguish conditions that are genuinely comorbid with CH from those that reflect misdiagnoses or medical scrutiny of patients in frequent contact with the healthcare system.

Licit and illicit drug use in cluster headache

Cluster headache patients seem to use more licit and illicit substances than the general population. The epidemiologic data supporting this is growing. We included the licit drugs in this review because their use seems to be driven by the same addiction mechanisms leading to illicit drug abuse. Some drugs may be used in an attempt to treat cluster headache, especially cocaine and hallucinogens. Drug exposure may also play a role in CH pathophysiology, as suggested by interesting data on tobacco use and second-hand smoke exposure. A common factor may contribute both to CH and drug use predisposition. Genetic factors may be at play, and the dopaminergic and orexinergic pathways could be targeted for future studies.

Impact of continuing or quitting smoking on episodic cluster headache: a pilot survey

BACKGROUND

The majority of patients suffering from cluster headache (CH) are smokers and it has been suggested that smoking may trigger the development of CH. The aim of this pilot survey was to describe: 1. the differences between current, former, and never smokers CH patients; 2. if smoking changed during an active cluster period; 3. if CH changed after quitting.

METHODS

All outpatients with episodic CH according to the criteria of ICHD-II who were consecutively seen for the first time from October 2010 to April 2012 at a headache centre were interviewed by phone using a specifically prepared questionnaire. Statistical differences between continuous variables were analysed by the Student's t-test or the one-way analysis of variance (ANOVA), followed by Newman-Keuls post-hoc testing. Comparisons between percentages were made using the Chi-square test or Fisher's exact test. All data were expressed as the mean ± standard deviation (SD).

RESULTS

Among a total of 200 patients surveyed (172 males, 28 females; mean age ± SD: 48.41 ± 12 years) there were 60%, 21%, and 19% of current, former, and never smokers, respectively. Current smokers reported longer active periods (12.38 ± 10 weeks) and a higher maximum number of attacks per day (3.38 ± 1) compared to never smoker CH patients (5.68 ± 4 weeks, P <0.05 and 2.47 ± 1, P <0.05, respectively). During the active period most of the patients stated to decrease (45.7%) or not to change (45.7%) the number of cigarettes smoked. Among those who decreased smoking, most (83.8%) reported that they had less desire to smoke. After quitting, the majority of former smokers stated that their headache had not changed.

CONCLUSIONS

Patients with episodic CH who are also smokers appear to have a more severe form of the disorder. However, it is unlikely that between CH and smoking there is a causal relationship, as CH patients rarely improve quitting smoking.

Traumatic head injury in cluster headache: cause or effect?

Post-traumatic headache (PTH) is a common and well-recognized entity. Tension-type headache and migraine are the commonest phenotypes that can result from head trauma, while the onset of cluster headache (CH) in close temporal relation to a head trauma has only been described in rare cases. Nevertheless, CH patients seem to incur more frequent traumatic head injuries during their lifetimes when compared to migraine controls and the general population. The basis of this association remains unclear, since only a limited number of methodologically robust studies have examined it. However, three main hypotheses can be proposed to explain this association: head trauma is the direct cause of CH; head trauma is a risk factor for the future development of CH; and head trauma is a consequence of a CH trait. A better understanding of the association between head trauma and CH may provide important insights into both the pathophysiology of CH and the mechanisms by which traumatic head injury predisposes patients to developing headaches.

Aggressiveness in different presentations of cluster headache: Results from a controlled multicentric study

Background: The hypothalamus has been discussed as a pivotal structure for both cluster headache (CH) and aggressiveness, but little is known about the extent of self-reported aggressiveness in patients with CH.

Patients and methods: Twenty-six patients with chronic, 25 with active episodic and 22 with episodic CH outside the active period were examined interictally with a validated questionnaire quantifying factors of aggression and compared with 24 migraine patients and 31 headache-free volunteers.

Results: The ANOVA was significant for the subscale ‘self-aggression/depression’ ( F4, 123 = 5.771, p < 0.001) with significant differences between chronic and episodic CH and healthy volunteers. No significant changes were found for other subscales and the sum scale ( F4, 123 < 1.421, p > 0.230). Especially in the clinically most affected group of patients (chronic CH and active episodic CH), high levels of “self-aggression/depression” correlate with higher prevalence of depressive symptoms and higher impairment measured on an emotional and functional level.

Discussion: Self-aggressive and depressive cognitions with highest scores in chronic CH seem to be reactive as they correlate with depressive symptoms and impairment. They should be considered as an important therapeutic target since they impair the patient’s life significantly.