Potentials and Pitfalls in Analytical Headache Epidemiological Studies—Lessons to be Learned from the Head-HUNT Study

Exploring the Hereditary Nature of Migraine

Migraine is a common neurological disorder which affects 15-20% of the population; it has a high socioeconomic impact through treatment and loss of productivity. Current forms of diagnosis are primarily clinical and can be difficult owing to comorbidity and symptom overlap with other neurological disorders. As such, there is a need for better diagnostic tools in the form of genetic testing. Migraine is a complex disorder, encompassing various subtypes, and has a large genetic component. Genetic studies conducted on rare monogenic subtypes, including familial hemiplegic migraine, have led to insights into its pathogenesis via identification of causal mutations in three genes (CACNA1A, ATP1A2 and SCN1A) that are involved in transport of ions at synapses and glutamatergic transmission. Study of familial migraine with aura pedigrees has also revealed other causal genes for monogenic forms of migraine. With respect to the more common polygenic form of migraine, large genome-wide association studies have increased our understanding of the genes, pathways and mechanisms involved in susceptibility, which are largely involved in neuronal and vascular functions. Given the preponderance of female migraineurs (3:1), there is evidence to suggest that hormonal or X-linked components can also contribute to migraine, and the role of genetic variants in mitochondrial DNA in migraine has been another avenue of exploration. Epigenetic studies of migraine have shown links between hormonal variation and alterations in DNA methylation and gene expression. While there is an abundance of preliminary studies identifying many potentially causative migraine genes and pathways, more comprehensive genomic and functional analysis to better understand mechanisms may aid in better diagnostic and treatment outcomes.

Migraine, obesity and body fat distribution - a population-based study

BACKGROUND

Obesity has been linked to an increased prevalence of migraine, and to increased migraine attack frequency, but several questions are left unanswered by previous studies. We examined the relationship between obesity and headache in a large, population-based study where we could take into account body fat distribution, migraine subtypes and tension-type headache.

METHODS

The third population-based Nord-Trøndelag Health Study (HUNT3) included validated headache questionnaires and objective anthropometric measurements. Using a cross-sectional design, our sample consisted of 18,191 women and 14,985 men, aged 19 to 96 years. Of these 4290 (12.9%) had migraine, 4447 (13.4%) had frequent tension-type headache (TTH), and 24,439 were headache-free controls. A total of 5049 individuals with unclassified headache were excluded from the analyses. Using logistic regression, we modeled the association between obesity and headache prevalence, adjusting for relevant confounders.

RESULTS

Both total body obesity (TBO) and abdominal obesity (AO) were associated with a higher prevalence of migraine when compared to headache-free controls (OR 1.45 95% CI 1.32-1.59 and OR 1.29 95% CI 1.18-1.41, respectively), in particular for individuals < 50 years of age (OR 1.74 95% CI 1.54-1.98 and OR 1.89 95% CI 1.69-2.11). Similar results were seen for migraine with and without aura. Similar Overall, a weaker associations were as observed between obesity and TTH. There was a dose-response relationship between obesity categories and increased headache frequency in subjects with migraine. TBO was associated with migraine prevalence and attack frequency independent of AO.

CONCLUSION

Both TBO and AO were associated with migraine prevalence and attack frequency. This association was largely limited to individuals < 50 years of age. TBO, rather than AO, may be a better measure of obesity in relation to migraine.

Genetics of migraine aura: an update

Migraine is a common brain disorder with a large genetic component. Of the two main migraine types, migraine with aura and migraine without aura, the genetic underpinning in the former is least understood. Given the evidence from epidemiological studies in cohorts and families that the genetic contribution is highest in migraine with aura, this seems paradoxical. Various genetic approaches have been applied to identify genetic factors that confer risk for migraine. Initially, so-called candidate gene associations studies (CGAS) have been performed that test DNA variants in genes prioritized based on presumed a priori knowledge of migraine pathophysiology. More recently, genome-wide association studies (GWAS) tested variants in any gene in an hypothesis-free manner. Whereas GWAS in migraine without aura, or the more general diagnosis migraine have already identified dozens of gene variants, the specific hunt for gene variants in migraine with aura has been disappointing. The only GWAS specifically investigating migraine with aura yielded only one single associated single nucleotide polymorphism (SNP), near MTDH and PGCP, with genome-wide significance. However, interrogation of all genotyped SNPs, so beyond this one significant hit, was more successful and led to the notion that migraine with aura and migraine without aura are genetically more alike than different. Until now, most relevant genetic discoveries related to migraine with aura came from investigating monogenetic syndromes with migraine aura as a prominent phenotype (i.e. FHM, CADASIL and FASPS). This review will highlight the genetic findings relevant to migraine with aura.

High sensitivity C-reactive protein and risk of migraine in a 11-year follow-up with data from the Nord-Trøndelag health surveys 2006-2008 and 2017-2019

Background

Several previous studies have reported a cross-sectional association between elevated high sensitivity C-reactive protein (hs-CRP) and migraine. The aim of this population-based follow-up study was to investigate the influence of hs-CRP at baseline on the risk of developing migraine 11 years later.

Methods

Data from the Nord-Trøndelag Health Study performed in 2006–2008 (baseline) and 2017–2019 were used. A total of 19,574 participants without migraine at baseline were divided into three groups based on hs-CRP levels (< 3 mg/L, 3–9.99 mg/L and 10.00–20 mg/L). Poisson regression was used to evaluate the associations between hs-CRP levels and risk ratios (RRs) of migraine, and precision of the estimates was assessed by 95% confidence interval (CIs).

Results

In the multi-adjusted model, increased risk of migraine (RR 1.46, 95% CI 1.05–2.04) was found in the highest hs-CRP levels group compared to the lowest group. In the group with the highest hs-CRP levels, a nearly three times higher risk of chronic migraine (RR 2.81, 95% CI 1.12–7.06) was found, whereas no evident relationship was found between high hs-CRP level and risk of developing episodic migraine.

Conclusions

The main finding in this 11-year follow-up was that hs-CRP levels between 10.00–20.00 mg/L at baseline was associated with increased risk of chronic migraine.

Time trends of major headache diagnoses and predictive factors. Data from three Nord-Trøndelag health surveys

AIMS

The primary aim of this study was to investigate time trends of major headache diagnoses using cross-sectional data from two population-based health surveys. In addition, we aimed to perform a longitudinal assessment of baseline characteristics and subsequent risk for having headache at 22-years' follow-up among those participating in three health surveys.

METHODS

Data from the Nord-Trøndelag Health Study (HUNT) performed in 1995-1997 (HUNT2), 2006-2008 (HUNT3) and 2017-2019 (HUNT4) were used. The 1-year prevalence time trends of major headache diagnoses were estimated among 41,460 participants in HUNT4 and among 39,697 participants in HUNT3, two surveys with identical headache questions. 16,118 persons participated in all three surveys, and among these, a Poisson regression was used to evaluate health-related baseline information in HUNT2 and the risk ratios (RRs) with 95% confidence interval (CIs) of consistently reporting headache during follow-up.

RESULTS

Compared with the 1-year prevalence in HUNT3, a higher proportion of participants in HUNT4 had tension-type headache (20.7% vs. 15.9%, p < 0.001), whereas a lower 1-year prevalence was found for migraine (11.1% vs. 12.0%, p < 0.001) and medication overuse headache (MOH) (0.3% vs. 1.0%, p < 0.001). Participants in the age group 20-39 years at baseline nearly three times increased risk (RR = 2.8, 95% CI 2.5-3.1) of reporting headache in HUNT2, HUNT3 and HUNT4 than persons aged 50 years or more. Female sex, occurrence of chronic musculoskeletal complaints and high score of depression or anxiety at baseline doubled the risk of having headache in all three surveys.

CONCLUSIONS

The 1-year prevalence of migraine and MOH was lower in HUNT4 than in HUNT3. Young age, female sex, and occurrence of musculoskeletal complaints and high score of anxiety and/or depression were all associated with substantially increased risk of reporting headache in all three surveys.

Does insomnia modify the association between C-reactive protein and migraine? The Tromsø Study 2015-2016

BACKGROUND

The relationship between high sensitivity C-reactive protein and migraine is unclear. The aim of this cross-sectional population-based study was to investigate the association between high sensitivity C-reactive protein and types of headache, and to evaluate the impact of insomnia on this association.

METHODS

A total of 20,486 (63%) out of 32,591 invited, aged ≥40 years or older, participated in the seventh wave of the Tromsø study conducted in 2015-2016 and had valid information on headache, insomnia and high sensitivity C-reactive protein. The influence of insomnia on the association between questionnaire-based diagnoses of headache and elevated high sensitivity C-reactive protein defined as >3.0 mg/L was assessed using multiple logistic regression, estimating prevalence odds ratio with 95% confidence intervals.

RESULTS

A total of 6290 participants (30.7%) suffered from headache during the last year. Among these, 1736 (8.5%) fulfilled the criteria of migraine, 991 (4.8%) had migraine with aura, 746 (3.6%) migraine without aura (3.8%), and 4554 (22.2%) had non-migrainous headache. In the final multi-adjusted analysis, elevated high sensitivity C-reactive protein was associated with headache (odds ratio 1.10, 95% confidence interval 1.01-1.20), migraine (odds ratio 1.17, 95% confidence interval 1.01-1.35), and migraine with aura (odds ratio 1.23, 95% confidence interval 1.01-1.53). No association was found between elevated high sensitivity C-reactive protein and migraine without aura or non-migrainous headache. The association between high sensitivity C-reactive protein and migraine was strongly dependent on insomnia status. Among individuals with insomnia, elevated high sensitivity C-reactive protein was associated with migraine (odds ratio 1.49, 95% confidence interval 1.02-2.17), and migraine with aura (odds ratio 1.59, 95% confidence interval 1.03-2.45), whereas no such relationship was found among those without insomnia.

CONCLUSIONS

In this cross-sectional study, participants with migraine, in particular migraine with aura, were more likely to have elevated high sensitivity C-reactive protein, evident only among those with insomnia.

Pituitary Hormones and Orofacial Pain

Clinical and basic research on regulation of pituitary hormones, extra-pituitary release of these hormones, distribution of their receptors and cell signaling pathways recruited upon receptor binding suggests that pituitary hormones can regulate mechanisms of nociceptive transmission in multiple orofacial pain conditions. Moreover, many pituitary hormones either regulate glands that produce gonadal hormones (GnH) or are regulated by GnH. This implies that pituitary hormones may be involved in sex-dependent mechanisms of orofacial pain and could help explain why certain orofacial pain conditions are more prevalent in women than men. Overall, regulation of nociception by pituitary hormones is a relatively new and emerging area of pain research. The aims of this review article are to: (1) present an overview of clinical conditions leading to orofacial pain that are associated with alterations of serum pituitary hormone levels; (2) discuss proposed mechanisms of how pituitary hormones could regulate nociceptive transmission; and (3) outline how pituitary hormones could regulate nociception in a sex-specific fashion. Pituitary hormones are routinely used for hormonal replacement therapy, while both receptor antagonists and agonists are used to manage certain pathological conditions related to hormonal imbalance. Administration of these hormones may also have a place in the treatment of pain, including orofacial pain. Hence, understanding the involvement of pituitary hormones in orofacial pain, especially sex-dependent aspects of such pain, is essential to both optimize current therapies as well as provide novel and sex-specific pharmacology for a diversity of associated conditions.

Remission of chronic headache: An 11-year follow-up study. Data from the Nord-Trøndelag Health Surveys 1995-1997 and 2006-2008

OBJECTIVES

To estimate remission rates of chronic headache and predictors of remission.

METHODS

In this longitudinal population-based cohort study, we used validated headache questionnaire data from the second (1995-1997, baseline; n = 51,856 aged ≥ 20 years, response rate: 55%) and third wave (2006-2008, follow-up, response rate: 42%) of the Nord-Trøndelag Health Study. Chronic headache was defined as ≥15 headache days/month during the last year. Chronic headache remission was defined as headache less than 15 days/month at follow-up. Potential predictors of remission were evaluated using logistic regression.

RESULTS

At baseline, 1266 (2.4%) participants reported chronic headache. Of these, 605 (48%) answered headache questions at follow-up. Remission was observed in 452 (74.7%), the proportion being almost identical in men and women (74.4% vs. 74.9, p = 0.92). In analyses adjusting for age, gender and education level, remission at follow-up was more than two times more likely among individuals without medication overuse headache (OR = 2.4, 95% CI 1.7-3.6) and without chronic musculoskeletal complaints (OR = 2.9, 95% CI 1.5-5.0) at baseline.

CONCLUSIONS

In this longitudinal population-based cohort study, three-quarters of chronic headache participants remitted from chronic headache. Remission was associated with no medication overuse headache and no chronic musculoskeletal complaints at baseline.

Lifestyle factors and risk of migraine and tension-type headache. Follow-up data from the Nord-Trøndelag Health Surveys 1995-1997 and 2006-2008

AIMS

The aim of this population-based historical cohort study was to investigate the influence of lifestyle factors on the risk of developing migraine or tension-type headache (TTH).

METHODS

Data from the Nord-Trøndelag Health Study performed in 1995-1997 and 2006-2008 was used. A total of 15,276 participants without headache at baseline were included. A Poisson regression was used to evaluate the associations between lifestyle factors and risk ratios (RRs) of migraine and TTH 11 years later. Precision of the estimates was assessed by 95% confidence interval (CIs).

RESULTS

Increased risk of migraine (RR 1.30, 95% CI 1.11-1.52) was found in smokers (past or current) compared to those who had never smoked. Hard physical exercise 1-2 hours per week reduced the risk of migraine (OR 0.71, 95% CI 0.54-0.94) compared to inactivity, and the risk of migraine was also lower among those who consumed alcohol (RR 0.73, 95% CI 0.57-0.94) compared to abstainers. No association was found between smoking, physical activity, alcohol use and risk of TTH.

CONCLUSIONS

The main finding was that current and previous smoking was associated with increased risk of migraine, but not of TTH.

Medication overuse headache: An entrenched idea in need of scrutiny

It is a widely accepted idea that medications taken to relieve acute headache pain can paradoxically worsen headache if used too often. This type of secondary headache is referred to as medication overuse headache (MOH); previously used terms include rebound headache and drug-induced headache. In the absence of consensus about the duration of use, amount, and type of medication needed to cause MOH, the default position is conservative. A common recommendation is to limit treatment to no more than 10 or 15 days per month (depending on medication type) to prevent headache frequency progression. Medication withdrawal is often recommended as a first step in treatment of patients with very frequent headaches. Existing evidence, however, does not provide a strong basis for such causal claims about the relationship between medication use and frequent headache. Observational studies linking treatment patterns with headache frequency are by their nature confounded by indication. Medication withdrawal studies have mostly been uncontrolled and often have high dropout rates. Evaluation of this evidence suggests that only a minority of patients required to limit the use of symptomatic medication may benefit from treatment limitation. Similarly, only a minority of patients deemed to be overusing medications may benefit from withdrawal. These findings raise serious questions about the value of withholding or withdrawing symptom-relieving medications from people with frequent headaches solely to prevent or treat MOH. The benefits of doing so are smaller, and the harms larger, than currently recognized. The concept of MOH should be viewed with more skepticism. Until the evidence is better, we should avoid dogmatism about the use of symptomatic medication. Frequent use of symptom-relieving headache medications should be viewed more neutrally, as an indicator of poorly controlled headaches, and not invariably a cause.

Inverse relationship between type 1 diabetes mellitus and migraine. Data from the Nord-Trøndelag Health Surveys 1995-1997 and 2006-2008

Aims The aim of this cross-sectional population-based study was to investigate the associations between migraine and type 1 and type 2 diabetes mellitus (DM). Methods We used data from the second (1995-1997) and third survey (2006-2008) in the Nord-Trøndelag Health Study. Analyses were made for the 26,121 participants (30-97 years of age, median 58.3 years) with known headache and DM status in both surveys, and for the 39,584 participants in the third survey (20-97 years, median 54.1 years). The diagnosis of migraine was given to those who fulfilled the questionnaire-based migraine diagnosis in the second and/or third survey. Associations were assessed using multiple logistic regression, estimating prevalence odds ratio (OR) with 95% confidence intervals (CIs). Results In the multivariate analysis of the 26,121 participants in both surveys, adjusting for age, gender, years of education, and smoking, classical type 1 DM (n = 81) was associated with a lower prevalence of any headache (OR = 0.55, 95% CI 0.34-0.88),and migraine (OR = 0.47, 95% CI 0.26-0.96) compared to those without DM (n = 24,779). Correspondingly, the merged group of classical type 1 DM and latent autoimmune diabetes of adults (LADA) (n = 153) were less likely to have migraine (OR = 0.53, 95% CI 0.31-0.91). Similarly, an inverse relationship between type 1 DM and migraine was found in analyses of 39,584 participants in the third survey. No clear association was found between headache and type 2 DM. Conclusions In this cross-sectional population-based study of mainly middle-aged participants, type 1 DM was inversely associated with headache, in particular migraine.

Migraine and endothelial function: The HUNT3 Study

Background

Reduced endothelial function is associated with elevated risk of cardiovascular disease, but evidence on the association between migraine and endothelial function is conflicting. The aim of this population-based study was to examine the relationship between flow-mediated dilatation (FMD) and migraine with aura, migraine without aura and tension-type headache.

Methods

In the third Nord-Trøndelag Healthy Study (HUNT3) FMD was measured by ultrasound during reactive hyperaemia of the brachial artery in a sample of 4739 healthy adult participants, 3929 of whom answered headache questions. The cross-sectional association between different headache diagnoses and FMD was evaluated by logistic regression, using a categorical approach.

Results

Mean FMD did not differ between the headache groups and headache-free controls. In multi-adjusted analyses, no consistent association was found between FMD quintiles and headache groups.

Conclusions

There was no relationship between FMD and migraine or other headache diagnoses in this large cross-sectional study of otherwise healthy respondents including freedom from pulmonary and cardiovascular diseases.

Paranasal sinus opacification in headache sufferers: A population-based imaging study (the HUNT study-MRI)

Background

The association between headache and paranasal sinus disease is still unclear. Because of symptom overlap, the two conditions are not easily studied on the basis of symptoms alone. The aim of the present study was to investigate whether paranasal sinus opacification on magnetic resonance imaging (MRI) was associated with migraine, tension-type headache (TTH) or unclassified headache.

Methods

This was a cross-sectional study of 844 randomly selected participants (442 women, age range 50–65 years, mean age 57.7 years). Based on 14 headache questions, participants were allocated to four mutually exclusive groups: migraine, TTH, unclassified headache or headache free. On MRI, opacifications as mucosal thickening, polyps/retention cysts and fluid in the five paired sinuses were measured and recorded if ≥1 mm. For each participant, opacification thickness was summed for each sinus and, in addition, a total sum of all sinuses was calculated. Opacification in each sinus was compared between headache-free participants and the headache groups using non-parametric tests, and the total sum was compared by logistical regression.

Results

No significant association was found between paranasal sinus opacification and headache in general, nor when headache was differentiated into migraine, TTH and unclassified headache. This was also true in separate analyses of mucosal thickening and fluid and of opacification from each paranasal sinus.

Conclusion

Migraine, TTH and unclassified headache were found not to be associated with an increased degree of paranasal sinus opacification at MRI.

Headache and peak oxygen uptake: The HUNT3 study

Background

Evidence on the association between headache and physical fitness is conflicting. The aim of this population-based study was to examine the relationship between peak oxygen uptake (VO2peak) and headache, including migraine and tension-type headache (TTH).

Methods

In the third Nord-Trøndelag Health study (HUNT3), VO2peak was measured by ergospirometry in a sample of 4631 healthy adult participants. Of these, 3899 (54% women) also answered headache questions. The cross-sectional association between headache and VO2peak was evaluated by logistic regression using a categorical approach based on quintiles. Scores in the upper quintile were used as reference.

Results

Participants age 20–50 years had significant trends of increasing prevalence of any headache ( p < 0.001), migraine ( p < 0.001), TTH ( p = 0.002) and unclassified headache ( p = 0.027) with lower VO2peak. The highest prevalence odds ratios (ORs) were found in those with VO2peak in the lower quintile: For any headache the OR was 2.3 (95% confidence interval (1.6–3.3), for TTH 1.8 (1.2–2.8), for unclassified headache 1.9 (1.1–3.8), and for migraine 3.7 (2.1–6.6). Similar results were also found among those who reported physical activity levels in accordance with current recommendations of the American College of Sports Medicine but nevertheless had low VO2peak. Being in the lowest VO2peak quintile was also strongly associated with migraine aggravated by physical activity (OR 4.1, 2.1–8.1). No significant association was found between VO2peak and headache for those 50 years or older.

Conclusions

In this large cross-sectional study, an inverse relationship was found between VO2peak and headache for adults younger than 50 years of age.

Headache as a risk factor for dementia: A prospective population-based study

Background

Headache has not been established as a risk factor for dementia. The aim of this study was to determine whether any headache was associated with subsequent development of vascular dementia (VaD), Alzheimer’s disease (AD) or other types of dementia.

Methods

This prospective population-based cohort study used baseline data from the Nord-Trøndelag Health Study (HUNT 2) performed during 1995–1997 and, from the same Norwegian county, a register of cases diagnosed with dementia during 1997–2010. Participants aged ≥20 years who responded to headache questions in HUNT 2 were categorized (headache free; with any headache; with migraine; with nonmigrainous headache). Hazard ratios (HRs) for later inclusion in the dementia register were estimated using Cox regression analysis.

Results

Of 51,383 participants providing headache data in HUNT 2, 378 appeared in the dementia register during the follow-up period. Compared to those who were headache free, participants with any headache had increased risk of VaD ( n = 63) (multivariate-adjusted HR = 2.3, 95% CI 1.4–3.8, p = 0.002) and of mixed dementia (VaD and AD ( n = 52)) (adjusted HR = 2.0, 95% CI 1.1–3.5, p = 0.018). There was no association between any headache and later development of AD ( n = 180).

Conclusion

In this prospective population-based cohort study, any headache was a risk factor for development of VaD.

Risk factors for medication-overuse headache: an 11-year follow-up study. The Nord-Trøndelag Health Studies

Medication-overuse headache (MOH) is relatively common, but its incidence has not been calculated and there are no prospective population-based studies that have evaluated risk factors for developing MOH. The aim of this study was to estimate incidences of and identify risk factors for developing chronic daily headache (CDH) and MOH. This longitudinal population-based cohort study used data from the Nord-Trøndelag Health Surveys performed in 1995-1997 and 2006-2008. Among the 51,383 participants at baseline, 41,766 were eligible approximately 11 years later. There were 26,197 participants (responder rate 63%), among whom 25,596 did not report CDH at baseline in 1995-1997. Of these, 201 (0.8%) had MOH and 246 (1.0%) had CDH without medication overuse (CDHwoO) 11 years later. The incidence of MOH was 0.72 per 1000 person-years (95% confidence interval 0.62-0.81). In the multivariate analyses, a 5-fold risk for developing MOH was found among individuals who at baseline reported regular use of tranquilizers [odds ratio 5.2 (3.0-9.0)] or who had a combination of chronic musculoskeletal complaints, gastrointestinal complaints, and Hospital Anxiety and Depression Scale score ≥ 11 [odds ratio 4.7 (2.4-9.0)]. Smoking and physical inactivity more than doubled the risk of MOH. In contrast, these factors did not increase the risk of CDHwoO. In this large population-based 11-year follow-up study, several risk factors for MOH did not increase the risk for CDHwoO, suggesting these are pathogenetically distinct. If the noted associations are causal, more focus on comorbid condition, physical activity, and use of tobacco and tranquilizers may limit the development of MOH.

Validation of the web-based LUMINA questionnaire for recruiting large cohorts of migraineurs

Objective: To assess validity of a self-administered web-based migraine-questionnaire in diagnosing migraine aura for the use of epidemiological and genetic studies.

Methods: Self-reported migraineurs enrolled via the LUMINA website and completed a web-based questionnaire on headache and aura symptoms, after fulfilling screening criteria. Diagnoses were calculated using an algorithm based on the International Classification of Headache Disorders (ICHD-2), and semi-structured telephone-interviews were performed for final diagnoses. Logistic regression generated a prediction rule for aura. Algorithm-based diagnoses and predicted diagnoses were subsequently compared to the interview-derived diagnoses.

Results: In 1 year, we recruited 2397 migraineurs, of which 1067 were included in the validation. A seven-question subset provided higher sensitivity (86% vs. 45%), slightly lower specificity (75% vs. 95%), and similar positive predictive value (86% vs. 88%) in assessing aura when comparing with the ICHD-2-based algorithm.

Conclusions: This questionnaire is accurate and reliable in diagnosing migraine aura among self-reported migraineurs and enables detection of more aura cases with low false-positive rate.

Association between blood pressure measures and recurrent headache in adolescents: cross-sectional data from the HUNT-Youth study

The relationship between blood pressure and headache in youth has not been explored and the objective of the present study was to provide data on this association in an adolescent population. Cross-sectional data from a large population-based survey, the Young-HUNT study, on 5,847 adolescents were used to evaluate the association between blood pressure (systolic, diastolic, mean arterial and pulse pressure) and recurrent headache, including migraine and tension-type headache. Increasing pulse pressure was inversely related to recurrent headache prevalence, and both tension-type headache and migraine. For systolic blood pressure such an inverse relationship was present for recurrent headache and tension-type headache prevalence. For migraine, the results were not significant, although there was a tendency in the same direction (p = 0.05). High-pulse pressure has previously been found to be inversely related to the prevalence of migraine and tension-type headache in an adult population. This inverse relationship has now been demonstrated to be present among adolescents also, supporting the results from a previous study in adults, that blood pressure regulation may be linked to the pathophysiology of headache.

Time trends in the prevalence of headache disorders. The Nord-Trøndelag Health Studies (HUNT 2 and HUNT 3)

Earlier reports regarding secular trends of migraine are conflicting, and there is a lack of long-term follow-up studies of other headache syndromes among adults. The aim of the present study was to assess any changes in the prevalence of the major headache types in a large adult population. With an 11-year interval, all inhabitants aged ≥20 years ( n = 92,566 and 94,194) in the Norwegian county of Nord-Trøndelag were invited to participate in two cross-sectional surveys. Attendance rates were 56% and 42%. The age-adjusted 1-year prevalences, according to the diagnostic criteria of the International Headache Society, sex-ratios and attack frequencies were assessed. The migraine prevalence increased from 12.1% to 13.2% ( P < 0.001), but the sex ratio did not change. The prevalence of non-migrainous headache overall decreased (26.0% vs 24.2%; P < 0.001). The prevalences of ‘headache suffering’ (37.4%), chronic daily headache (2.5%) and medication overuse headache (1.0%) remained stable. Apart from a small increase of migraine, headache prevalences remained essentially stable among adults in a Norwegian county during an 11-year period.

The validity of questionnaire-based diagnoses: the third Nord-Trøndelag Health Study 2006-2008

The Nord-Trøndelag Health Study (HUNT 3) performed in 2006-2008 is a replication of the cross-sectional survey from 1995 to 1997 (HUNT 2). The aim of the present study was to assess the sensitivity and specificity of questionnaire-based headache diagnoses using a personal interview by a neurologist as a gold standard. For the questionnaire-based status as headache sufferer, a sensitivity of 88%, a specificity of 86%, and a kappa statistic of 0.70 were found. Chronic headache, chronic tension-type headache (TTH), and medication overuse headache (MOH) were diagnosed with a specificity of > or =99%, and a kappa statistic of > or =0.73. Lower figures were found for the diagnoses of migraine and TTH. For individuals with headache > or =1 day per month, a sensitivity of 58% (migraine) and 96% (TTH), a specificity of 91 and 69%, and a kappa statistic of 0.54 and 0.44 were found, respectively. The specificity for migraine with aura was 95%. In conclusion, the HUNT 3-questionnaire is a valid tool for identifying headache sufferers, and diagnosing patients with chronic headache, including chronic TTH and MOH. The more moderate sensitivity for migraine and TTH makes the questionnaire-based diagnoses of migraine and TTH suboptimal for determining the prevalence. However, the high specificity of the questionnaire-based diagnosis of migraine, in particular for migraine with aura, makes the questionnaire a valid tool for diagnosing patients with migraine for genetic studies.

Hypertension-associated hypalgesia: a clue to the comorbidity of headache and other pain disorders

BACKGROUND

Primary headaches and chronic musculoskeletal pain are prevalent disorders with incompletely known causes.

AIMS

To review the data from the HUNT studies on the comorbidity of these pain disorders, and their relation to blood pressure levels.

MATERIALS & METHODS

Cross-sectional and prospective data from more than 50,000 persons participating in the HUNT studies, a large Norwegian population-based health survey

RESULTS

Headache and chronic musculoskeletal complaints in all parts of the body were comorbid, and the prevalence of pain in all locations was inversely related to blood pressure levels.

DISCUSSION

A likely cause for this is hypertension-associated hypalgesia, described in both animal and human experimental models, involving interactions between cardiovascular and pain modulating centres at the brainstem level, and probably also peripheral baroreceptor mechanisms.

CONCLUSION

Better understanding of these mechanisms may be crucial for enabling better prevention and treatment of these very prevalent, costly and disabling disorders.

Associations between headache and stress, alcohol drinking, exercise, sleep, and comorbid health conditions in a Japanese population

We conducted a cross-sectional survey of 12,988 subjects aged 20–79 years (5,908 men and 7,090 women) receiving health checkups at a Tokyo clinic. They filled out a self-administered structured questionnaire, and 5.4% of the men and 15.4% of the women reported having headaches. Younger subjects were more prone to having headaches. The likelihood of having headaches increased with stress level and decreased ability to relieve stress in both genders. There was an inverse dose–response relationship between having headaches and alcohol consumption, and less walking/exercise and sleep problems increased the likelihood of headaches in both genders. Headache sufferers of both genders were more likely to report multiple additional poor health conditions. A multivariate stepwise logistic analysis showed that age, self-estimated degree of stress, reported number of additional poor health conditions, and less alcohol consumption were independently correlated with having headaches. In conclusion, although women were more susceptible to headache, Japanese men and women in Tokyo shared factors associated with headache, including age, stress, having other poor health conditions, alcohol consumption, sleep, and exercise.

High dietary caffeine consumption is associated with a modest increase in headache prevalence: results from the Head-HUNT Study

The aim of this study was to investigate the association between caffeine consumption and headache type and frequency in the general adult population. The results were based on cross-sectional data from 50,483 (55%) out of 92,566 invited inhabitants aged ≥20 years who participated in the Nord-Trøndelag Health Survey. In the multivariate analyses, adjusting for age, gender, smoking, and level of education as confounding factors, a weak but significant association (OR = 1.16, 95% CI 1.09–1.23) was found between high caffeine consumption and prevalence of infrequent headache. In contrast, headache >14 days/month was less likely among individuals with high caffeine consumption compared to those with low caffeine consumption. The results may indicate that high caffeine consumption changes chronic headache into infrequent headache due to the analgesic properties of caffeine. Alternatively, chronic headache sufferers tend to avoid intake of caffeine to not aggravate their headaches, whereas individuals with infrequent headache are less aware that high caffeine use can be a cause.

A face-to-face interview of participants in HUNT 3: the impact of the screening question on headache prevalence

The aim of this study was to evaluate the effect of the screening question phrasing on the 1-year prevalence figures of headache disorders, including migraine. Of a random sample of 563 invited participants in the Nord-Trøndelag Health Survey 2006-2008 in Norway, 297 (53%) met to a face-to-face interview. There were 74.1% that reported having had headache during the last year, whereas only 31.0% stated that they had suffered from headache in the same period. The 1-year prevalence of migraine was 17.2% and of tension-type headache (TTH) 51.9%. Migraine was ten times more likely (OR = 9.96, 95% CI 4.75-20.91) among those who stated that they were headache sufferers than among those who were not. Only headache sufferers had chronic TTH or medication-overuse headache. Thus "Have you suffered from headache?" can be a useful screening question in population-based questionnaire studies if the goal is to identify most migraineurs and almost all individuals with chronic headache.