Migraine and air pollution: A systematic review

Comorbidities as risk factors for migraine onset: A systematic review and three-level meta-analysis

INTRODUCTION

Migraine is a debilitating neurological disease with a multifaceted pathophysiology. Pre-existing comorbidities may influence the risk of developing migraine. This review and meta-analysis aim to present a comprehensive overview of the known comorbidities predisposing individuals to new migraine onset, thereby improving our understanding of the respective diseases' interactions.

METHODS

A systematic search of PubMed and EMBASE identified studies on pre-existing comorbidities as risk factors for new migraine onset. We performed three-level meta-analyses employing restricted maximum likelihood estimation to calculate pooled risk ratios (pRR). Subgroup and sensitivity analyses were conducted to assess the robustness of the data. Risk of bias (RoB) was assessed with the Quality in Prognostic Studies Tool. This review was pre-registered on Prospero (CRD42024501140).

RESULTS

From a total of 17,330 records, we identified 38 studies, encompassing 124 effect sizes from 58 exposures. Most studies (n = 28, 74%) had a low RoB. Heterogeneity was high (>90%), primarily due to within-study differences (>50%), and was not significantly impacted by moderator tests or the exclusion of outliers. We found significantly increased risks for migraine onset associated with prior atopic conditions [pRR = 1.53 (1.15, 2.03)], psychiatric or psychological disorders [pRR = 2.63 (1.79, 3.85)], sleep disorders [pRR = 1.89 (1.26, 2.85)], and cardiovascular conditions [pRR = 1.72 (1.07, 2.76)].

CONCLUSIONS

Pre-existing atopic, psychiatric, sleep, and cardiovascular conditions are significantly associated with new migraine onset, likely due to shared genetic predisposition and mediating factors like stress and inflammation. Future research should focus on these associations to advance targeted prevention and treatment strategies.

Assessment of Relationship Between Dietary Factors, Socioeconomic Factors, Behavioral Factors, Physical Measurement, and Risk of Migraine: A Univariable and Multivariable Mendelian Randomization Study

OBJECTIVE

Although numerous studies have identified associations between socioeconomic, behavioral, dietary, and physical factors and migraine, the causal nature of these relationships has yet to be adequately established.

MATERIALS AND METHODS

We utilized 2-sample Mendelian randomization (MR) to elucidate the causal associations of 28 distinct traits for socioeconomic factors, behavioral factors, dietary factors, and physical measurement with migraine. In the univariable MR analysis, the inverse-variance weighted method served as the primary analytic approach. Robustness checks included the Cochran Q test, Egger intercept test, and leave-one-out analysis. A multivariable MR analysis framework was utilized to assess the direct causal impacts of these traits on migraine risk.

RESULTS

The univariable MR analysis analysis revealed that genetic predispositions to higher coffee intake (Odds Ratio (OR) = 0.547; 95% CI = 0.359-0.834; P = 0.005), greater oily fish intake (OR = 0.556; 95% CI = 0.394-0.785; P = 0.001), and higher educational attainment (OR = 0.916; 95% CI = 0.884-0.949; P < 0.001) were associated with reduced migraine risk. In contrast, predispositions to higher poultry intake (OR = 4.690; 95% CI = 1.377-15.977; P = 0.013) and longer mobile phone use (OR = 1.526; 95% CI = 1.080-2.157; P = 0.017) correlated with increased risk. These associations remained consistent in the multivariable MR analysis after adjusting for stroke and particulate matter air pollution.

CONCLUSIONS

Our study robustly supports the significant causal roles of specific socioeconomic, behavioral, and dietary factors with physical measurement in the development of migraine. Notably, coffee intake, oily fish intake, and educational attainment appear protective, whereas poultry intake and extensive mobile phone use elevate risk. These insights pave the way for developing targeted preventive strategies for migraine.

Associations between environmental perchlorate, nitrate, and thiocyanate exposure and severe headache or migraine: a cross-sectional, population-based analysis

Background

Environmental contaminants may play a significant role in the development of migraine. Perchlorate, nitrate, and thiocyanate were selected for this study due to their known impact on thyroid function, which is closely linked to neurological processes. Disruptions in thyroid function have been associated with various neurological disorders, including migraines. However, there is currently no evidence linking exposure to these specific chemicals to migraine. The study aims to evaluate the association between urinary concentrations of perchlorate, nitrate, and thiocyanate with the prevalence of severe headache or migraine in U.S. adults.

Methods

A cross-sectional study was conducted using data from the National Health and Nutrition Examination Survey (NHANES) 2001-2004. Utilizing electrospray tandem mass spectrometry in conjunction with ion chromatography, urinary concentrations of perchlorate, nitrate, and thiocyanate urine were measured. Multiple logistic regression models were employed to evaluate the linear correlation between perchlorate, nitrate, and thiocyanate exposure and severe headache or migraine. The non-linear relationship is described analytically using a fitted smoothing curve and a two-piecewise regression model. Subgroup analyses were used to further clarify the stability of this relationship across different populations.

Results

There were 1,446 participants in this population-based study, ranging in age from 20 to 85. After adjusting for potential confounding variables, the multiple logistic regression findings demonstrated that thiocyanate was significantly positively associated with the prevalence of migraine (odds ratio [OR] = 1.18; [1.06, 1.30]; p < 0.001). There was consistency in this connection across different subgroups (p for interaction >0.05). Furthermore, there was a non-linear correlation between urinary thiocyanate and migraine. Using a fitted smoothing curve and a two-piecewise regression model, it was found that the correlation between urinary thiocyanate and migraine was U-shaped (p for Log-likelihood ratio = 0.002). According to the findings of the multiple regression analysis, there was no significant correlation between urinary perchlorate and nitrate and migraine (both p > 0.05).

Conclusion

We should limit our exposure to thiocyanate by keeping it within a reasonable range, as indicated by the U-shaped correlation between urinary thiocyanate and migraine.

Carbon Monoxide as a Potential Therapeutic Agent: A Molecular Analysis of Its Safety Profiles

Carbon monoxide (CO) is endogenously produced in mammals, with blood concentrations in the high micromolar range in the hemoglobin-bound form. Further, CO has shown therapeutic effects in various animal models. Despite its reputation as a poisonous gas at high concentrations, we show that CO should have a wide enough safety margin for therapeutic applications. The analysis considers a large number of factors including levels of endogenous CO, its safety margin in comparison to commonly encountered biomolecules or drugs, anticipated enhanced safety profiles when delivered via a noninhalation mode, and the large amount of safety data from human clinical trials. It should be emphasized that having a wide enough safety margin for therapeutic use does not mean that it is benign or safe to the general public, even at low doses. We defer the latter to public health experts. Importantly, this Perspective is written for drug discovery professionals and not the general public.

A prospective exploration of the urban exposome in relation to headache in the Dutch population-based Occupational and environmental health cohort study (AMIGO)

OBJECTIVE

Headache is one of the most prevalent and disabling health conditions globally. We prospectively explored the urban exposome in relation to weekly occurrence of headache episodes using data from the Dutch population-based Occupational and Environmental Health Cohort Study (AMIGO).

MATERIAL AND METHODS

Participants (N = 7,339) completed baseline and follow-up questionnaires in 2011 and 2015, reporting headache frequency. Information on the urban exposome covered 80 exposures across 10 domains, such as air pollution, electromagnetic fields, and lifestyle and socio-demographic characteristics. We first identified all relevant exposures using the Boruta algorithm and then, for each exposure separately, we estimated the average treatment effect (ATE) and related standard error (SE) by training causal forests adjusted for age, depression diagnosis, painkiller use, general health indicator, sleep disturbance index and weekly occurrence of headache episodes at baseline.

RESULTS

Occurrence of weekly headache was 12.5 % at baseline and 11.1 % at follow-up. Boruta selected five air pollutants (NO2, NOX, PM10, silicon in PM10, iron in PM2.5) and one urban temperature measure (heat island effect) as factors contributing to the occurrence of weekly headache episodes at follow-up. The estimated causal effect of each exposure on weekly headache indicated positive associations. NO2 showed the largest effect (ATE = 0.007 per interquartile range (IQR) increase; SE = 0.004), followed by PM10 (ATE = 0.006 per IQR increase; SE = 0.004), heat island effect (ATE = 0.006 per one-degree Celsius increase; SE = 0.007), NOx (ATE = 0.004 per IQR increase; SE = 0.004), iron in PM2.5 (ATE = 0.003 per IQR increase; SE = 0.004), and silicon in PM10 (ATE = 0.003 per IQR increase; SE = 0.004).

CONCLUSION

Our results suggested that exposure to air pollution and heat island effects contributed to the reporting of weekly headache episodes in the study population.

Long-term exposure to air pollutants and new-onset migraine: A large prospective cohort study

BACKGROUNDS

Short-term exposure to air pollutants increases the risk of migraine, but the long-term impacts of exposure to multiple pollutants on migraine have not been established. The aim of this large prospective cohort study was to explore these links.

METHODS

A total of 458,664 participants who were free of migraine at baseline from the UK Biobank were studied. Cox proportional hazards models were used to estimate the risk of new-onset migraine from combined long-term exposure to four pollutants, quantified as an air pollution score using principal component analysis.

RESULTS

During a median (IQR) follow-up of 12.5 (11.8, 13.2) years, a total of 5417 new-onset migraine cases were documented. Long-term exposure to multiple air pollutants was associated with an increased risk of new-onset migraine, as indicated by an increased in the SDs of PM2.5 (hazard ratio (HR): 1.04, 95% CI: 1.01-1.06, P = 0.009), PM10 (HR: 1.07, 95% CI: 1.04-1.10, P < 0.001), NO2 (HR: 1.10, 95% CI: 1.07-1.13, P < 0.001) and NOx (HR: 1.04, 95% CI: 1.01-1.07, P = 0.005) in the main model. The air pollution score showed a doseresponse association with an increased risk of new-onset migraine. Similarly, compared with those of the lowest tertile, the HRs (95% CI) of new-onset migraine were 1.11 (95% CI: 1.04-1.19, P = 0.002) and 1.17 (95% CI: 1.09-1.26, P < 0.001) in tertiles 2 and 3, respectively, according to the main model (P trend < 0.001).

CONCLUSION

Long-term individual and joint exposure to multiple air pollutants is associated with an increased risk of new-onset migraine.