Seasonal Variation in Migraine

Investigating the relationship between sleep and migraine in a global sample: a Bayesian cross-sectional approach

BACKGROUND

There is a bidirectional link between sleep and migraine, however causality is difficult to determine. This study aimed to investigate this relationship using data collected from a smartphone application.

METHODS

Self-reported data from 11,166 global users (aged 18-81 years, mean: 41.21, standard deviation: 11.49) were collected from the Migraine Buddy application (Healint Pte. Ltd.). Measures included: start and end times of sleep and migraine attacks, and pain intensity. Bayesian regression models were used to predict occurrence of a migraine attack the next day based on users' deviations from average sleep, number of sleep interruptions, and hours slept the night before in those reporting ≥ 8 and < 25 migraine attacks on average per month. Conversely, we modelled whether attack occurrence and pain intensity predicted hours slept that night.

RESULTS

There were 724 users (129 males, 412 females, 183 unknown, mean age = 41.88 years, SD = 11.63), with a mean monthly attack frequency of 9.94. More sleep interruptions (95% Highest Density Interval (95%HDI [0.11 - 0.21]) and deviation from a user's mean sleep (95%HDI [0.04 - 0.08]) were significant predictors of a next day attack. Total hours slept was not a significant predictor (95%HDI [-0.04 - 0.04]). Pain intensity, but not attack occurrence was a positive predictor of hours slept.

CONCLUSIONS

Sleep fragmentation and deviation from typical sleep are the main drivers of the relationship between sleep and migraine. Having a migraine attack does not predict sleep duration, yet the pain associated with it does. This study highlights sleep as crucial in migraine management.

Molecular and Cellular Neurobiology of Circadian and Circannual Rhythms in Migraine: A Narrative Review

Migraine-a primary headache-has circadian and circannual rhythms in the onset of attacks. The circadian and circannual rhythms involve the hypothalamus, which is strongly associated with pain processing in migraines. Moreover, the role of melatonin in circadian rhythms has been implied in the pathophysiology of migraines. However, the prophylactic effect of melatonin in migraines is controversial. Calcitonin gene-related peptide (CGRP) has recently attracted attention in the pathophysiology and treatment of migraines. Pituitary adenylate cyclase-activating peptide (PACAP)-a neuropeptide identical to CGRP-is a potential therapeutic target after CGRP. PACAP is involved in the regulation of circadian entrainment to light. This review provides an overview of circadian and circannual rhythms in the hypothalamus and describes the relationship between migraines and the molecular and cellular neurobiology of circadian and circannual rhythms. Furthermore, the potential clinical applications of PACAP are presented.

Prophylactic Treatment for Patients with Migraine Using Blue Cut for Night Glass

Objectives Migraine is a disease that leads to social loss due to a decrease in productivity since it is a primary headache with a high prevalence and readily occurs in working-age persons. As described in the diagnostic criteria of the International Classification of Headache Disorders, 3rd edition (beta version), migraine causes hypersensitivity, especially photosensitivity, during attacks, suggesting that light is an inducer of headaches. We developed Blue Cut for Night (BCN) glass, which reduces light stimulation to intrinsically photosensitive continental ganglion cells (ipRGCs), photoreceptors that can lead to exacerbation of migraine attacks. Methods Ten patients with migraine participated in the study. Each participant was made to wear BCN glasses only at night for four weeks. The number of headache days and Headache Impact Test-6 values before and after using the BCN glasses were compared. Results When the 10 patients with migraine wore the BCN glass at night only for 4 weeks, the number of headache days within that time tended to decrease (7.0±4.37 days) compared to before wearing the glasses (8.7±5.03 days). No participants had any side effects. Conclusion BCN glass, which reduces light stimulation to ipRGCs, was suggested to be a tool for reducing migraine attacks.

Investigating the effects of weather on headache occurrence using a smartphone application and artificial intelligence: A retrospective observational cross-sectional study

OBJECTIVE

To investigate the relationship between weather and headache occurrence using big data from an electronic headache diary smartphone application with recent statistical and deep learning (DL)-based methods.

BACKGROUND

The relationship between weather and headache occurrence remains unknown.

METHODS

From a database of 1 million users, data from 4375 users with 336,951 hourly headache events and weather data from December 2020 to November 2021 were analyzed. We developed statistical and DL-based models to predict the number of hourly headache occurrences mainly from weather factors. Temporal validation was performed using data from December 2019 to November 2020. Apart from the user dataset used in this model development, the physician-diagnosed headache prevalence was gathered.

RESULTS

Of the 40,617 respondents, 15,127/40,617 (37.2%) users experienced physician-diagnosed migraine, and 2458/40,617 (6.1%) users had physician-diagnosed non-migraine headaches. The mean (standard deviation) age of the 4375 filtered users was 34 (11.2) years, and 89.2% were female (3902/4375). Lower barometric pressure (p < 0.001, gain = 3.9), higher humidity (p < 0.001, gain = 7.1), more rainfall (p < 0.001, gain = 3.1), a significant decrease in barometric pressure 6 h before (p < 0.001, gain = 11.7), higher barometric pressure at 6:00 a.m. on the day (p < 0.001, gain = 4.6), lower barometric pressure on the next day (p < 0.001, gain = 6.7), and raw time-series barometric type I (remaining low around headache attack, p < 0.001, gain = 10.1) and type II (decreasing around headache attack, p < 0.001, gain = 10.1) changes over 6 days, were significantly associated with headache occurrences in both the statistical and DL-based models. For temporal validation, the root mean squared error (RMSE) was 13.4, and the determination coefficient (R² ) was 52.9% for the statistical model. The RMSE was 10.2, and the R² was 53.7% for the DL-based model.

CONCLUSIONS

Using big data, we found that low barometric pressure, barometric pressure changes, higher humidity, and rainfall were associated with an increased number of headache occurrences.

The chronobiology of migraine: a systematic review

BACKGROUND

The paroxysmal nature of migraine is a hallmark of the disease. Some patients report increased attack frequency at certain seasons or towards the end of the week, while others experience diurnal variations of migraine attack onset. This systematic review investigates the chronobiology of migraine and its relation to the periodicity of attacks in existing literature to further understand the oscillating nature of migraine.

MAIN BODY

PubMed and Embase were systematically searched and screened for eligible articles with outcome measures relating to a circadian, weekly or seasonal distribution of migraine attacks. We found that the majority of studies reported morning hours (6 am-12 pm) as the peak time of onset for migraine attacks. More studies reported Saturday as weekly peak day of attack. There was no clear seasonal variation of migraine due to methodological differences (primarily related to location), however four out of five studies conducted in Norway reported the same yearly peak time indicating a possible seasonal periodicity phenomenon of migraine.

CONCLUSIONS

The findings of the current review suggest a possible role of chronobiologic rhythms to the periodicity of migraine attacks. Future studies are, however, still needed to provide more knowledge of the oscillating nature of migraine.

Hypothalamic functional MRI activity in the initiation phase of spontaneous and glyceryl trinitrate-induced migraine attacks

The hypothalamus has been suggested to be important in the initiation cascade of migraine attacks based on clinical and biochemical observations. Previous imaging studies could not disentangle the changes due to the attack and those due to the trigger compound. With a novel approach, we assessed hypothalamic neuronal activity in early premonitory phases of glyceryl‐trinitrate (GTN)‐induced and spontaneous migraine attacks. We measured the hypothalamic blood oxygen level‐dependent (BOLD) response to oral glucose ingestion with 3T‐functional magnetic resonance imaging (MRI) in 27 women, 16 with migraine without aura and 11 controls group matched for age and body mass index (BMI), on 1 day without prior GTN administration and on a second day after GTN administration (to coincide with the premonitory phase of an induced attack). Interestingly, subgroups of patients with and without GTN‐triggered attacks could be compared. Additionally, five migraineurs were investigated in a spontaneous premonitory phase. Linear mixed models were used to study between‐ and within‐group effects. Without prior GTN infusion, the BOLD response to glucose was similar in migraine participants and controls (P = .41). After prior GTN infusion, recovery occurred steeper and faster in migraineurs (versus Day 1; P < .0001) and in those who developed an attack versus those who did not (P < .0001). Prior GTN infusion did not alter the glucose‐induced response in controls (versus baseline; P = .71). Just before spontaneous attacks, the BOLD‐response recovery was also faster (P < .0001). In this study, we found new and direct evidence of altered hypothalamic neuronal function in the immediate preclinical phase of both GTN‐provoked and spontaneous migraine attacks.

Effectiveness of preventive onabotulinumtoxin A injections for migraine headaches is dependent on the circadian time of administration

We have previously shown that quarterly preventive onabotulinumtoxin A (BTA) injections administered to diurnally active patients for chronic migraines (CM) associate with increased discomfort when performed in the morning. The purpose of this study was to further examine if the effectiveness of preventive BTA injections depends on the procedure's circadian timing. A total of 90 diurnally active patients with a medical history of CM and undergoing BTA injection therapy were enrolled in the study. One hundred and fifty-five units of BTA were administered according to the standardized PREEMPT protocol, either during the course of morning (AM) or afternoon (PM) clinic hours. Patients were asked to keep headache diaries, which were reviewed at the time of their follow-up BTA injections 3 months later. The number of headache days experienced during the first, second, and third month following BTA injection, and the number of headache days during the last 7 days prior to follow-up was collected, as was the self-rating of the effectiveness of BTA treatment. Fifty-five (61%) patients were injected during the AM clinic and 35 (39%) during the PM clinic. There was no difference in gender, race, and age variables between the AM and PM patients. The average total number of headache days during 3 months following injection was significantly higher for the AM-treated compared to the PM-treated patients (22.37 ± 18.85 vs. 10.54 ± 7.5, p =.0007). AM patients also reported a higher number of headache days during each of the 3 months following BTA injection. In contrast, PM patients reported higher effectiveness of preventive BTA treatment. The average number of headache days during the week prior to the follow up, as well as the presence of headache on the day of the follow-up was not significantly different between the AM and PM groups. Scheduling diurnally active CM patients with stable circadian sleep/wake routine for afternoon BTA injections appear to improve the effectiveness of BTA therapy as well as patients' satisfaction with the treatment.

Mechanisms of migraine as a chronic evolutive condition

Understanding the mechanisms of migraine remains challenging as migraine is not a static disorder, and even in its episodic form migraine remains an "evolutive" chronic condition. Considerable progress has been made in elucidating the pathophysiological mechanisms of migraine, associated genetic factors that may influence susceptibility to the disease, and functional and anatomical changes during the progression of a migraine attack or the transformation of episodic to chronic migraine. Migraine is a life span neurological disorder that follows an evolutive age-dependent change in its prevalence and even clinical presentations. As a disorder, migraine involves recurrent intense head pain and associated unpleasant symptoms. Migraine attacks evolve over different phases with specific neural mechanisms and symptoms being involved during each phase. In some patients, migraine can be transformed into a chronic form with daily or almost daily headaches. The mechanisms behind this evolutive process remain unknown, but genetic and epigenetic factors, inflammatory processes and central sensitization may play an important role.

Circadian Variation of Migraine Attack Onset: A Review of Clinical Studies

Several studies suggested that migraine attack onset shows a circadian variation; however, there has not been an overview and synthesis of these findings. A PubMed search with keywords "migraine" AND "circadian" resulted in ten studies directly investigating this topic. Results of these studies mostly show that migraine attacks follow a monophasic 24-hour cyclic pattern with an early morning or late night peak while other studies reported an afternoon peak and also a biphasic 24-hour cycle of attacks. The identified studies showed methodological variation including sample size, inclusion of medication use, comorbidities, and night or shift workers which could have contributed to the contradictory results. Several theories emerged explaining the diurnal distribution of migraine attacks suggesting roles for different phenomena including a morning rise in cortisol levels, a possible hypothalamic dysfunction, a circadian variation of migraine triggers, sleep stages, and a potentially different setting of the circadian pacemaker among migraineurs. At the moment, most studies show an early morning or late night peak of migraine attack onset, but a significant amount of studies reveals contradictory results. Further studies should investigate the arising hypotheses to improve our understanding of the complex mechanism behind the circadian variation of migraine attacks that can shed light on new targets for migraine therapy.

Monthly variation in pediatric visits for headache to US emergency departments

Headache is a common pediatric symptom often associated with stress and fatigue which may be more common during the school year. The purpose of this study is to determine if visits for headache are more common during the months of the school year. This study is a secondary analysis of the National Hospital Ambulatory Medical Care Survey (NHAMCS) database from 2001 to 2010. Patient visits in those aged 18 years or younger not associated with injury were examined. Only visits with an International Classification of Diseases, ninth revision (ICD-9) code consistent with headache were included. Data were analyzed using cumulative binomial probabilities. This statistic was used to establish the chance of seeing up to the observed number of visits for headache in a given month assuming that all months have an equal number of visits. A total of 660 unweighted visits representing 3.2 million patient encounters met the inclusion and exclusion criteria. Visits for headache were more common during the months of January, September, and October and less common in March, April, July, and November. Subgroup analysis was performed for children aged 13-18 years. In this subgroup, headaches were more common in January, September, and October. They were less common in July and December. Headache is more common during the first 2 months back to school in the fall as well as after the winter break in January. While we are not able to establish causality, we propose that children with headache require additional attention during the school year, particularly in the months following summer and winter breaks.

Examination of fluctuations in atmospheric pressure related to migraine

Background

Japan has four seasons and many chances of low atmospheric pressure or approaches of typhoon, therefore it has been empirically known that the fluctuation of weather induces migraine in people. Generally, its mechanism has been interpreted as follows: physical loading, attributed by atmospheric pressure to human bodies, compresses or dilates human blood vessels, which leads to abnormality in blood flow and induces migraine. We report our examination of the stage in which migraine tends to be induced focusing on the variation of atmospheric pressure.

Findings

Subjects were 34 patients with migraine, who were treated in our hospital. The patients included 31 females and three males, whose mean age was 32 ± 6.7. 22 patients had migraine with aura and 12 patients had migraine without aura. All of patients with migraine maintained a headache diary to record atmospheric pressures when they developed a migraine. The standard atmospheric pressure was defined as 1013 hPa, and with this value as the criterion, we investigated slight fluctuations in the atmospheric pressure when they developed a migraine. It was found that the atmospheric pressure when the patients developed a migraine was within 1003–1007 hPa in the approach of low atmospheric pressure and that the patients developed a migraine when the atmospheric pressure decreased by 6–10 hPa, slightly less than the standard atmospheric pressure.

Conclusion

Small decreases of 6–10 hPa relative to the standard atmospheric pressure of 1013 hPa induced migraine attacks most frequently in patients with migraine.

Seasonal effects on gene expression

Many health conditions, ranging from psychiatric disorders to cardiovascular disease, display notable seasonal variation in severity and onset. In order to understand the molecular processes underlying this phenomenon, we have examined seasonal variation in the transcriptome of 606 healthy individuals. We show that 74 transcripts associated with a 12-month seasonal cycle were enriched for processes involved in DNA repair and binding. An additional 94 transcripts demonstrated significant seasonal variability that was largely influenced by blood cell count levels. These transcripts were enriched for immune function, protein production, and specific cellular markers for lymphocytes. Accordingly, cell counts for erythrocytes, platelets, neutrophils, monocytes, and CD19 cells demonstrated significant association with a 12-month seasonal cycle. These results demonstrate that seasonal variation is an important environmental regulator of gene expression and blood cell composition. Notable changes in leukocyte counts and genes involved in immune function indicate that immune cell physiology varies throughout the year in healthy individuals.

Weather and headache onset: a large-scale study of headache medicine purchases

It is widely recognized that weather changes can trigger headache onset. Most people who develop headaches choose to self-medicate rather than visit a hospital or clinic. We investigated the association between weather and headache onset using large-sample sales of the headache medicine, loxoprofen. We collected daily sales figures of loxoprofen and over-the-counter drugs over a 1-year period from a drugstore chain in western Shizuoka prefecture, Japan. To adjust for changes in daily sales of loxoprofen due to social environmental factors, we calculated a proportion of loxoprofen daily sales to over-the-counter drug daily sales. At the same time, we obtained weather data for the study region from the website of the Japan Meteorological Agency. We performed linear regression analysis to ascertain the association between weather conditions and the loxoprofen daily sales proportion. We also conducted a separate questionnaire survey at the same drugstores to determine the reason why people purchased loxoprofen. Over the study period, we surveyed the sale of hundreds of thousands of loxoprofen tablets. Most people purchased loxoprofen because they had a headache. We found that the sales proportion of loxoprofen increased when average barometric pressure decreased, and that precipitation, average humidity, and minimum humidity increased on loxoprofen purchase days compared to the previous day of purchases. This study, performed using a large dataset that was easy-to-collect and representative of the general population, revealed that sales of loxoprofen, which can represent the onset and aggravation of headache, significantly increased with worsening weather conditions.

Seasonal variation of presentation for headache in a pediatric emergency department

OBJECTIVES

Headache is a common pediatric complaint. Our experience indicated that there was a seasonal variation in children seeking emergency department (ED) care for headache. We hypothesized that visits to the ED would be more common during the school year compared with that during the summer months.

METHODS

Electronic medical record data were reviewed from January 1, 2008 through June 30, 2010. All patients age 4 years and older with a chief complaint of headache were examined. Patients with ventriculoperitoneal shunts, intracranial mass, trauma, or stroke were excluded. The following data were accumulated: date of visit, birth date, sex, race, and diagnosis. Visits were grouped by month of occurrence and school year (September through May) and non-school year (June through August). Cumulative binomial probabilities were used to determine the likelihood of experiencing the observed number of occurrences or fewer in each period.

RESULTS

A total of 2731 visits met the inclusion and exclusion criteria. Girls were older, more likely to be white, and more likely to be diagnosed with migraine. There is a clear nadir in May and June and a peak in September, October, and November that is statistically significant (P< 0.001) across age groups, sex, race, and headache type. These findings persisted when comparing the groups based on school year versus non-school year.

CONCLUSIONS

Visits to the ED for headache were less common in May and June and more common during the fall. This remained true across headache type, age, sex, and racial groups.

Seasonal changes in gene expression represent cell-type composition in whole blood

Seasonal patterns in behavior and biological parameters are widespread. Here, we examined seasonal changes in whole blood gene expression profiles of 233 healthy subjects. Using weighted gene co-expression network analysis, we identified three co-expression modules showing circannual patterns. Enrichment analysis suggested that this signal stems primarily from red blood cells and blood platelets. Indeed, a large clinical database with 51 142 observations of blood cell counts over 3 years confirmed a corresponding seasonal pattern of counts of red blood cells, reticulocytes and platelets. We found no direct evidence that these changes are linked to genes known to be key players in regulating immune function or circadian rhythm. It is likely, however, that these seasonal changes in cell counts and gene expression profiles in whole blood represent biological and clinical relevant phenomena. Moreover, our findings highlight possible confounding factors relevant to the study of gene expression profiles in subjects collected at geographical locations with disparaging seasonality patterns.

Insomnia and periodicity of headache in an arctic cluster headache population

OBJECTIVE

To assess the prevalence of chronic insomnia and the periodicity of headache attacks in an Arctic cluster headache population.

BACKGROUND

Cluster headache is a sleep-related disorder, and attacks have both circadian and circannual rhythmicity.

METHODS

Through a retrospective hospital chart review, we identified all subjects diagnosed with episodic cluster headache (ICD-10 G 44.0) at the Neurological Departments in Northern Norway (located north of 66°33'N) between January 1, 2000 and December 31, 2010. Patients with a confirmed diagnosis (ICHD-2) received a comprehensive questionnaire covering demographic data, clinical characteristics, sleep, and periodicity of attacks.

RESULTS

A total of 196 subjects were registered, and 178 received the questionnaire. The response rate was 88/178 (49%). Fifty-eight men (aged 49.2 ± 13.6) and 12 women (aged 49.7 ± 15.5) were included. Forty percent of the responders suffered from chronic insomnia (Diagnostic and Statistical Manual of Mental Disorders 4th edition). Forty-nine percent of the responders and 42% of the non-responders were shift workers, which is much higher than compared with the general population (24%). Insomnia was significantly associated with shift work and experiencing longer-lasting cluster bouts. One third attributed their insomnia to the cluster headache. Thirty-seven percent reported a seasonal predilection of the cluster periods, and 58% a diurnal periodicity of attacks. Eighty percent often or always had headache attacks during sleep, the most frequent time interval being at 12:00-4:00 am. Shift workers were significantly more likely to see lack of sleep as a cluster attack trigger than daytime workers.

CONCLUSIONS

Chronic insomnia and shift work seem to be common among Arctic cluster headache patients. The small number of subjects included in this study implies that conclusions should be drawn with caution, but the findings support the idea of cluster headache as a circadian rhythm disorder.

Migraine and triggers: post hoc ergo propter hoc?

The influence of environmental factors on the clinical manifestation of migraine has been a matter of extensive debate over the past decades. Migraineurs commonly report foods, alcohol, meteorologic or atmospheric changes, exposure to light, sounds, or odors, as factors that trigger or aggravate their migraine attacks. In the same way, physicians frequently follow this belief in their recommendations in how migraineurs may reduce their attack frequency, especially with regard to the consumption of certain food components. Interestingly, despite being such a common belief, most of the clinical studies have shown conflicting results. The aim of the review is to critically analyze clinical and pathophysiological facts that support or refute a correlation between certain environmental stimuli and the occurrence of migraine attacks. Given the substantial discrepancy between patients' reports and objective clinical data, the methodological difficulties of investigating the link between environmental factors and migraine are highlighted.

Headache yesterday in China: a new approach to estimating the burden of headache, applied in a general-population survey in China

BACKGROUND

In order to minimize recall bias in burden estimation, questions about headache yesterday were included in a population-based survey initiated by LIFTING THE BURDEN : The Global Campaign against Headache.

METHODS

Throughout China, nonrelated respondents aged 18-65 years were randomly sampled from the general population by a door-to-door survey. A validated structured questionnaire included inquiry into occurrence and burden of headache on the preceding day ("headache yesterday").

RESULTS

The participation rate was 94.1%. Of 5041 participants, 286 (5.7%) (male 3.6%, female 7.9%) reported headache yesterday. Age-weighted prevalence of headache yesterday was 4.8% (male 3.0%, female 6.6%). Headache yesterday lasted all day in 36.8%, <1 hour in 14.3% and for a mean of 3.7 ± 3.3 hours in 48.9%. Headache yesterday was moderate to severe in 79.9%; disability such that they could do less than half of what they had expected was reported by 19.9% and such that they could do nothing by a further 7.5% (total 27.4%). Almost three-quarters (71.5%) with headache yesterday took medication to treat it.

CONCLUSIONS

Of the adult Chinese population, 1.8% have headache at any one time that is of moderate to severe intensity in 1.4%, and 1.3% lose the equivalent of a whole day to headache-attributed disability every day. In China this means 12.3 million people.

[Migraine and hypothalamus]

Migraine is a complex brain disease. The "generator" of the migrainous attacks remains a subject of debate, but the hypothalamus, with its multiple connections with the other parts of the central nervous system and its controls on the pituitary gland and the autonomic nervous system, is a very serious candidate. Many of the premonitory symptoms of migraine attacks find their origin in the hypothalamus. The hormonal changes which occur during feminine genital life and which impact on the life of the migrainous women have their origin in the hypothalamus. The hypothalamus exerts control over the balance between the parasympathetic and orthosympathetic systems. Orexine, hormones originating in the hypothalamic, are involved in sleep regulation, thermoregulation and neuroendocrine and nociceptive functions. They could play a crucial role in the origin of the migrainous attack and might explain the influence of sleep, eating habits and excessive weight in the occurrence of attacks. Hypothalamic cerebral activation via H2 15OPET activity, suspected by clinical and experimental arguments as a possible trigger for migraine, has been demonstrated during spontaneous attacks. However, no conclusion can be made however as to whether this activation is the cause or the consequence of the migrainous pain.

Sleep-related migraine occurrence increases with aging

A preferential occurrence of attacks at night-time or during early morning is documented in migraine without aura, suggesting a relationship between migraine and sleep and an impairment of circadian rhythms. The objective of this study was to verify the occurrence of sleep-related migraine in a large sample of migraineurs divided in different age groups and to evaluate the possible role of physiological variables (i.e., aging, gender) and comorbidities (i.e., psychiatric diseases). 734 patients (519 women and 215 males), aged 21-70 years, fulfilling IHS criteria (2004) for migraine without aura, were enrolled. The population was divided into five groups according to decades of life and it was evaluated the percentage of sleep-related migraine (at least 75% migraine attacks occurring during night sleep and/or upon awakening) in the different age groups. Headache clinical diary, Pittsburgh Sleep Quality Index and Beck Depression Inventory were also used. The preferential emergence of attacks during night sleep and/or upon awakening progressively increased with aging, without gender predilection; the percentage of patients with sleep-related migraine was: 16% between 20 and 30 years, 27% between 31 and 40 years, 38% between 41 and 50 years, 45% between 51 and 60 years, and 58% between 61 and 70 years, respectively. Poor sleep quality and depression did not account for night-time and/or awakening migraine collocation. These data suggest the main role of aging in order to favor nocturnal/early morning emergence of migraine without aura and support the hypothesis of an involvement of impaired chronobiological mechanisms and sleep regulation.

Sun-induced migraine attacks in an Arctic population

Aims: The main purpose of the study was to evaluate the impact of weather, and especially sun exposure, on migraine.

Methods: Data from a previous prospective 12-month diary study was compared with meteorological data. We retrospectively evaluated 1250 migraine attacks recorded by a group of 40 women with a mean age of 37.1 years who fulfilled the IHS criteria for migraine with and without aura.

Results: The patients reported more sun-induced migraine attacks on sunny days, but the total distribution of migraine attacks was constant throughout the year. Also, no seasonal variation of migraine, nor any relationships between weather parameters and onset of migraine attacks, were found. An analysis of a subgroup of patients with ‘sun-induced’ migraine showed a significant increase in frequency of migraine attacks in the summer compared to the winter ( p = 0.04).

Conclusion: This study confirms that sunlight might be a trigger for migraine, but a risk for increased impact of light on the total ailment of migraine headache should be searched for in a subgroup of sensitive migraineurs.

Influence of barometric pressure in patients with migraine headache

OBJECTIVE

Barometric pressure has been reported as a triggering and exacerbating factor in migraine headaches, although there are few reports concerning the association of weather change and migraine headache. The relationship between barometric pressure changes and migraine headaches was prospectively examined.

METHODS

A total of 28 migraine patients who lived within 10 km of the Utsunomiya Local Meteorological Observatory kept a headache diary throughout the year. Daily and monthly mean barometric pressure data of the Utsunomiya Local Meteorological Observatory were obtained via the homepage of the Meteorological Office.

RESULTS

The correlation between headache frequency obtained by the headache diaries for 1 year and changes in the barometric pressure during the period of 2 days before and 2 days after the headache onset were evaluated. The frequency of migraine increased when the difference in barometric pressure from the day the headache occurred to the day after was lower by more than 5 hPa, and decreased when the difference in barometric pressure from the day the headache occurred to 2 days later was higher by more than 5 hPa. Of 28 patients, weather change was associated with migraine headache development in 18 (64%) patients, 14 of which reported low barometric pressure to be a cause of headache. There was no association between the monthly mean barometric pressure and headache frequency throughout the year.

CONCLUSION

Barometric pressure change can be one of the exacerbating factors of migraine headaches.

Frequency and seasonal variation of ophthalmology-related internet searches

OBJECTIVE

To use internet search activity to reveal the intensity of public interest and seasonal variation in ophthalmology-related diseases, symptoms, and treatments.

DESIGN

Time-series analysis of internet search data.

METHODS

Google trend data for ophthalmology terms for the United States, the United Kingdom, Canada, and Australia from 2004 through 2008 were studied. Mean population-weighted temperature and fraction of schools in session were estimated from databases, and relative potential sunlight intensity was calculated. Multivariable linear regression was used to predict search term frequency based on environmental variables.

RESULTS

Relative to diabetes searches (100%), common US eye-related searches were: "glasses" (44%), "Lasik" (16%), "contact lenses" (12.4%), "pink eye" (9.5%), "glaucoma" (5.9%), "cataract" (4.1%), "dry eyes" (2.1%), "eye twitching" (1.9%), and "eye pain" (1.9%). Seasonal nature was high for "conjunctivitis" (r(2) = 0.37), "pink eye" (r(2) = 0.32), "eye floaters" (r2 = 0.26), and "stye" (r(2) = 0.19), moderate for "glaucoma" (r(2) = 0.09) and "eye twitching" (r(2) = 0.06), and low for "uveitis" (r(2) = 0.02) and "macular degeneration" (r(2) < 0.01). Heat was associated with "stye" and cold was associated with "pink eye," "conjunctivitis," and "glaucoma" (all p < 0.002). Sunlight intensity was associated with "dry eyes" and "eye floaters" (p < 0.01). School sessions were associated positively with "eye twitching" (p >= 0.001) and negatively with "eyeglasses." "Eye allergy," "itchy eyes," and "watery eyes" were highly seasonal (r(2) = 0.75-0.38) and associated with "pollen" searches.

CONCLUSIONS

Internet ophthalmology searches relate (in decreasing order) to refractive correction, eye diseases, and eye symptoms. Search study reveals the seasonality and environmental associations of interest in health terms.

Sleep and headache

There is a strong interaction between sleep and headache. Sleep and headache disorders overlap epidemiologically, and share elements of anatomy and physiology. Perhaps as a result, their treatment is often mutually interdependent. Despite this, headache and sleep disorders tend to be treated separately, by different subspecialties of neurology. The headache disorders and their relationship to sleep, the commonalities of headache and sleep pathophysiology, and headache disorders that are particularly susceptible to sleep modulation (and vice versa) are reviewed. Practical management advice for sleep-modulated headaches is provided.

Seasonal variation of migraine in an Arctic population

OBJECTIVES

To investigate seasonal variation of migraine headache in a population residing in an extreme Arctic locale.

BACKGROUND

Exposure to light may trigger migraine attacks and patients may also be hypersensitive to light between the attacks. In previous studies of migraine in Northern latitudes we have demonstrated that patients with migraine experience more attacks in the summer. In order to confirm this finding and gain more insight into a possible north-south effect of seasonal migraine variation, we performed a population-based study in Svalbard, which is one of the northernmost populated areas of the world.

METHOD

A postal questionnaire was mailed to all inhabitants aged 12 years or older living in Svalbard and the migraine diagnosis made by a structured telephone interview.

RESULTS

Of a total of 1569, 1029 (66%) returned the questionnaire. Of them, 184 (18%) experienced headache within the recent year prior to the study that could not be explained by alcohol, trauma, or viral infections. Eighty-eight individuals had migraine according to the revised criteria set by the International Headache Society. Nineteen (22%) reported seasonal variation of migraine. Ten (12%) experienced more migraine in the light season, while 9 (10%) got worse in the dark season. No differences in proportions of migraine with aura (MA) and migraine without aura (MO) could be detected. Also, the frequency of MA patients who used sunglasses to avoid migraine headache was nonstatistically increased compared with MO.

CONCLUSION

There was no indication of more seasonal variation of headache in a population of otherwise healthy people with migraine living in an extreme Arctic area with long periods of midnight sun and polar nights with complete darkness. The strength of conclusion, however, is significantly limited by a low response rate and small sample size.

Weather and air pollution as triggers of severe headaches

BACKGROUND

The roles of weather conditions and air pollution as triggers of headache have been inconsistent in previous, generally small studies.

METHODS

We performed a case-crossover study of 7,054 patients seen in a single emergency department between May 2000 and December 2007 with a primary discharge diagnosis of headache. We compared levels of temperature, barometric pressure, humidity, fine particulate matter, black carbon, and nitrogen and sulfur dioxides during the three 24-hour periods preceding presentation with corresponding levels on the remaining occurrences of that day of the week in a given month, using local meteorologic and pollutant monitors.

RESULTS

Higher mean ambient temperature in the 24 hours preceding hospital presentation positively and linearly increased the acute risk of headache (odds ratio [OR] for a 5 degrees C increment 1.075; 95% confidence interval [CI], 1.021-1.133; p = 0.006) [corrected]. Higher risk was observed for cases with and without a discharge diagnosis of migraine and for cases between October and March or between April and September. Lower barometric pressure also increased the risk of nonmigraine cases in the 48 to 72 hours before hospitalization (OR 0.939 per 5 mm Hg; 95% CI, 0.902-0.978; p = 0.002). Current levels of pollutants did not influence the risk of headache.

CONCLUSIONS

Higher ambient temperature and, to a lesser degree, lower barometric pressure led to a transient increase in risk of headache requiring emergency department evaluation. We did not find clear association of air pollutants with risk, but cannot exclude effects of air pollution of the magnitude previously observed for stroke and other cardiovascular events.

Lack of seasonal variation in menstrually-related migraine

The aim of the study was to study seasonal variation in migraine headache in a group of women with menstrually-related migraine (MRM) compared with non-menstrual migraine. Via newspaper advertisement, women with migraine living in North Norway were invited. The patients were included by questionnaire and telephone interview. We prospectively recorded migraine attacks from a 12-month headache diary performed by a group of 62 women with a mean age of 36.0 years (range 16-46 years), who fulfilled the criteria of migraine without aura. Of these, 29 had MRM and 33 non-menstrual migraine. Mean ratio between number of attacks in the light arctic season (May-June-July) divided with total number of migraine attacks during 12 months was 0.24 (9.4/38.4) in the group of MRM compared with 0.25 (5.6/22.1) in others (confidence interval -4.2, 6.3, P = 0.84). Nor were there more migraine attacks in the dark season in an arctic area (November-December-January) in any group. We found a higher migraine attack rate in those with MRM, but no indication of more or less frequency of attacks during the bright arctic season. These findings support the assumption that MRM and seasonal variation of migraine are due to different mechanisms.

Circannual periodicity of migraine?

Seasonal rhythm of migraine attacks may support a role of the suprachiasmatic nucleus of the hypothalamus in the pathophysiology of migraine. The objective of this study was to provide evidence for seasonal variation in migraine. Eighty-nine female migraineurs volunteered to record every migraine attack in detail for 12 consecutive months. Attacks associated with sleep complaints were defined as insomnia-related. By using Edwards' model for recognition and estimation of cyclic trends, time-series analysis was made. Fifty-eight patients, of which 26 had migraine without aura (MO) and 32 had migraine with aura (MA), completed the study. A total of 1840 attacks were recorded. The mean age +/- SD was 36.9 +/- 6.0. Patients with a lifetime history of MA showed marked seasonal fluctuation with more attacks in the light season compared to the dark. Time of peak was May 21. Peak/low ratio was 1.30 (95% CI: 1.08-1.55). When insomnia-related attacks (n = 312) were removed the seasonal variation became insignificant. There is a seasonal trend with more migraine attacks in the light season compared to the dark season in females with MA, but not MO, living in an arctic area. This is caused by the seasonal variation of insomnia-related attacks in patients with MA.

Weekend migraine

It is a general belief that migraine attacks are prone to occur on days off. Only a few studies, however, have addressed this issue. The objective of this study was to investigate the periodicity of migraine with respect to weekly (circaseptan) variations. Eighty-nine females of fertile age who had participated in a previous questionnaire-based study volunteered to record in detail every migraine attack for 12 consecutive months. Eighty-four patients completed recordings for a mean of 311 days (s.d. = 95.9, range 30-365). A total of 2314 attacks were recorded. Migraine occurrence was almost equally distributed during the week, except on Sundays, when there were significantly fewer attacks (t = -4.42, d.f. = 83, P < 0.001). A Mantel-Haenszel estimate of the relative risk of having an attack on a holiday vs. another day, not Sundays included, was 0.64 (95% CI 0.49-0.85). Our study suggests that days off protect against migraine.

Visual stimuli are common triggers of migraine and are associated with pattern glare

OBJECTIVE

To investigate the associations between interictal pattern glare, visual stress, and visual triggers of migraine.

BACKGROUND

There has been relatively little research on the visual stimuli that can trigger migraine episodes. This is surprising, since if practitioners can obviate such triggers, then some attacks may be prevented. The existing literature suggests that patients who are prone to visually triggered migraines report more illusions on viewing striped patterns ("pattern glare") and that colored filters may be an effective intervention for these people.

METHODS

Headache symptoms and headache triggers were investigated in migraine and control groups in 2 separate experiments. In one experiment, we also determined, for each participant, pattern glare, whether it was reduced by colored filters and, if so, what the optimum color of filter was. Color vision was also assessed with the D15 test.

RESULTS

People with migraine saw significantly more illusions on viewing each striped pattern and experienced greater pattern glare. They were also more likely to select a colored filter to aid visual comfort, particularly colors in the blue-to-green sector of the spectrum. Color vision was impaired subtly but significantly in migraine. Principal component analyses grouped common headache triggers into 5 broadly equal components: food, visual triggers, alcohol, stress and tiredness, and the environment. In a second analysis, the overall number of illusions seen in striped patterns was associated with visual triggers while pattern glare, use of colored filters, and interictal light sensitivity together formed a sixth component interpreted as visual stress.

CONCLUSIONS

It is suggested that clinicians should ask migraine patients whether visual stimuli trigger their migraine, about interictal visual symptoms, and use the pattern glare test to ensure that those who may benefit from optometric interventions are appropriately managed.

A chronopharmacological preventive treatment for sleep-related migraine headaches and chronic morning headaches: Nitric oxide supersensitivity can cause sleep-related headaches in a subset of patients

Frequent and recurrent migraine headaches can, over time, pose the additional risks of stroke, brain damage, heart failure and attention deficit. This is why prevention should always be a part of the treatment. Nitric oxide supersensitivity is the hypothesis upon which this model is based. Its role in causing migraine headaches and chronic morning headaches can be triggered by both normal and abnormal characteristics of the sleep cycle and more specifically by the release of nitric oxide that occurs towards the end of the sleep cycle. Stress and the age-related loss of sleep continuity, together with the corresponding increase in cortisol levels, potentiate delta rebound. Delta rebound results in deeper sleep intensity. It is associated with increased nitric oxide production. Increased delta rebound then causes an increase in the amount and duration of nitric oxide release at night. Migraineurs are susceptible to migraine headaches because they are supersensitive to nitric oxide. The diurnal pattern of the incidence of sleep-related headaches in a subset of the general population is caused by the effect of nitric oxide supersensitivity during the sleep cycle. The proposed treatment is for both sleep-related migraine headaches and chronic morning headaches. It consists of melatonin and moclobemide taken during the night, close the end of the sleep cycle so as to achieve the maximum concentrations. Both melatonin and moclobemide affect three important aspects of sleep-related headaches: nitric oxide supersensitivity, stress system dysfunction and sleep pathology. Both melatonin and moclobemide have demonstrated effectiveness in preventing migraine headaches. Additionally, both melatonin and moclobemide are compatible with most of the other therapeutic agents used to prevent migraine headaches and with at least 1 therapeutic agent that is used to treat migraine headaches.