Headache, one of the most frequent reasons for consultation at neurology clinics, causes disability and impairment of quality of life. More than 50% of adults in European countries indicated that they had suffered from headaches within the past year [
Obesity is often comorbid with a number of chronic headache syndromes. Individuals with episodic headache and obesity are five times more likely to develop chronic daily headache (CDH) than normal-weight individuals [
In this study, we analyzed primary headache and its subtypes in order to (1) analyze the association of body mass index (BMI) with headache (episodic and chronic); (2) separately compare patients with episodic and chronic migraine/tension-type headache (TTH)/other headache types; and (3) analyze the BMI of migraine and TTH patients after adjusting for confounding factors.
The present study involved analysis of data from a previous study [
The intensity of the most frequent headache in the last 3 months was assessed by using an 11-point pain scale (0, no pain; 1–3, mild pain; 4–6, moderate pain; and 7–10, severe pain). Body height and weight and waist circumference were measured with the subjects wearing light clothing and no shoes.
BMI was calculated by using the following formula: BMI (kg/m2) = weight (kg) / height (m2). The patients were grouped into five categories on the basis of BMI in accordance with the World Health Organization (WHO) guidelines: underweight (<18.5 kg/m2); normal weight (18.5 to <25 kg/m2); overweight (25 to <30 kg/m2); obese (30 to 34.9 kg/m2); and morbidly obese (≥35 kg/m2). Because of the small number of morbidly obese patients, they were grouped with obese patients in a single group.
On the basis of the ICHD-II guidelines, primary headache was classified into three subtypes: migraine, TTH, and other headaches. We categorized other primary headache types, such as neuralgia, needle-like headache, and trigeminal autonomic cephalalgias, as other headaches because the sample size for each of these headaches was too small to analyze.
In accordance with the duration of headache and mean headache days per month over the last 3 months, the patients were assigned to the episodic (EM, episodic TTH [ETTH], or other episodic headache) or chronic (CM, chronic TTH [CTTH], or other chronic headache) headache groups. Patients who experienced headaches for at least 15 days per month for at least 3 months, thus fulfilling the ICHD-II criteria, were diagnosed with chronic headache (CM/CTTH/other chronic headache) [
Medication overuse was diagnosed in accordance with the following criteria: headaches for 15 days or more per month, developed as a consequence of regular overuse of acute or symptomatic headache medications (on 10 or more days or 15 or more days per month, depending on the medication) for more than 3 months.
The study protocol was reviewed and approved by the ethics committee of the First Affiliated Hospital of Chongqing Medical University. The patients were informed of the purpose of the study, and they provided consent before participating in this study.
Statistical analyses were performed by using SPSS version 23.0. Data were summarized by using frequency counts and descriptive statistics. Measurement variables were expressed as mean ± standard error of the mean. Intergroup comparisons were performed by one-way analysis of variance, t test, or multiple logistic regression analysis, as appropriate. A value of p < 0.05 was considered statistically significant.
During the study period, 10,315 patients visited the neurology outpatient department of our hospital, of whom 1327 patients (12.9%) had cited headache as their chief complaint. Among the 1327 patients, exact information on body height and weight was available for only 1311 patients. Of the 1311 patients, 396 were diagnosed with chronic headache (CM, 177; CTTH, 186; and other chronic headaches, 33) and 915 with episodic headache (EM, 369; ETTH, 319; and other episodic headaches, 227).
In the episodic and chronic headache groups, the proportion of women was greater than that of men, and there was no significant intergroup difference in this regard (68.5% vs. 73.4%; p = 0.075; Table
Demographic and clinical characteristics of the episodic and chronic headache groups.
Variable | Episodic headache (n = 915) | Chronic headache (n = 396) | p value |
---|---|---|---|
Sex | |||
Female (n, %) | 632 (68.5%) | 287 (73.4%) | 0.075 |
Female to male ratio | 2.18 | 2.76 | |
Age (years, mean ± SD) | 43.41 ± 13.05 | 46.92 ± 12.51 | <0.001 |
Marriage (n, %) | 0.301 | ||
Married | 798 (86.7%) | 353 (90.3%) | |
Unmarried | 98 (10.7%) | 30 (7.7%) | |
Divorced | 6 (0.7%) | 3 (0.8%) | |
Widowed | 18 (2%) | 5 (1.3%) | |
Education level (n, %) | <0.001 | ||
Primary school or less | 501 (55.4%) | 269 (70.1%) | |
High school or technical school | 197 (21.8%) | 67 (17.4%) | |
University | 207 (22.9%) | 48 (12.5%) | |
Elevated blood pressure (n, %) | 203 (22.6%) | 96 (25.4%) | 0.287 |
Smoking (n, %) | 141 (16.9%) | 67 (18.9%) | 0.414 |
Alcohol consumption (n, %) | 43 (5.3%) | 25 (7.1%) | 0.207 |
Medication overuse | 8 (0.9%) | 133 (34%) | <0.001 |
Family headache history (n, %) | 333 (38%) | 151 (40.5%) | 0.412 |
Duration of headache history (years, mean ± SD) | 6.85 ± 9.41 | 11.23 ± 11.31 | <0.001 |
Pain intensity (mean ± SD) | 4.41 ± 2.22 | 4.14 ± 2.30 | 0.048 |
Average headache days/month (days, mean ± SD) | 3.08 ± 5.02 | 22.73 ± 9.14 | <0.001 |
BMI (mean ± SD) | 22.57 ± 3.07 | 22.76 ± 3.02 | 0.311 |
BMI classification | 0.163 | ||
Underweight | 68 (7.4%) | 28 (7.2%) | |
Normal weight | 669 (72.7%) | 266 (68%) | |
Overweight | 169 (18.4%) | 86 (22%) | |
Obese |
14 (1.5%) | 11 (2.8%) | |
Waist/height ratio | 0.45 ± 0.12 | 0.45 ± 0.12 | 0.951 |
Note:
In order to have a better understanding of the relationship between headache and BMI, we further analyzed the three subtypes of primary headache separately (Tables
Comparison of BMI and other variables in the migraine group: EM vs. CM.
Variable | EM (n = 369) | CM (n =177) | p value |
---|---|---|---|
Female (n, %) | 289 (77.5%) | 143 (82.7%) | 0.176 |
Age (years, mean ± SD) | 40.71 ± 20.34 | 46.9 ± 16.89 | <0.001 |
Marriage (n, %) | 0.001 | ||
Married | 304 (82.4%) | 164 (92.7%) | |
|
65 (17.6%) | 13 (7.3%) | |
Education level (n, %) | <0.001 | ||
Primary school or less | 192 (52.7%) | 127 (75.6%) | |
High school or technical school | 81 (22.3%) | 28 (16.7%) | |
University | 91 (25%) | 13 (7.7%) | |
Elevated blood pressure (n, %) | 68 (18.9%) | 50 (29.8%) | 0.005 |
Smoking (n, %) | 40 (11.4%) | 25 (15.3%) | 0.211 |
Alcohol consumption (n, %) | 17 (4.9%) | 15 (9.2%) | 0.06 |
Pain intensity (mean ± SD) | 4.5 ± 2.40 | 4.4 ± 2.62 | 0.714 |
Medication overuse | 2 (2.1%) | 94 (97.9%) | <0.001 |
Average headache days/month (days, mean ± SD) | 3.94 ± 5.18 | 21.79 ± 8.95 | <0.001 |
Family headache history (n, %) | 183 (68.8%) | 83 (31.2%) | 0.385 |
Duration of headache history (years, mean ± SD) | 10.83 ± 10.60 | 14.74± 11.98 | <0.001 |
BMI (mean ± SD) | 21.90 ± 2.88 | 23.34 ± 2.34 | <0.001 |
Waist/height ratio | 0.45 ± 0.08 | 0.45 ± 0.11 | 0.682 |
Notes: #Single patients included unmarried, divorced, and widowed individuals. SD: standard deviation; EM: episodic migraine; CM: chronic migraine.
Comparison of BMI and other variables in the TTH group: ETTH vs. CTTH.
Variable | ETTH |
CTTH |
p value |
---|---|---|---|
Female (n, %) | 197(61.8%) | 123 (66.1%) | 0.325 |
Age (years, mean ± SD) | 45.49 ± 12.52 | 46.84 ± 13.76 | 0.272 |
Marriage (n, %) | 0.357 | ||
Married | 291 (91.2%)) | 165 (88.7%) | |
|
28 (8.8%) | 21 (11.3%) | |
Education level (n, %) | 0.533 | ||
Primary school or less | 189 (60%) | 119 (64.3%) | |
High school or technical school | 65 (20.6%) | 37 (20%) | |
University | 61 (19.4%) | 29 (15.7%) | |
Elevated blood pressure (n, %) | 86 (27.2%) | 39 (21.5%) | 0.161 |
Smoking (n, %) | 63 (21.7%) | 36 (21.8%) | 0.981 |
Alcohol consumption (n, %) | 16 (5.7%) | 8 (4.9%) | 0.73 |
pain intensity (mean ± SD) | 3.97 ± 1.88 | 3.87 ± 2.03 | 0.584 |
Medication overuse (n, %) | 4 (1.3%) | 37 (19.9%) | <0.001 |
Average headache days per month (days, mean ± SD) | 1.67 ± 9.03 | 11.81 ± 28.69 | <0.001 |
Family headache history (n, %) | 96 (31.4%) | 62 (34.1%) | 0.3 |
Duration of headache history (years, mean ± SD) | 4.60 ± 7.07 | 9.05 ± 10.27 | <0.001 |
BMI (mean ± SD) | 22.94 ± 2.95 | 22.21 ± 3.24 | 0.012 |
Waist/height ratio | 0.44 ± 0.13 | 0.44 ± 0.13 | 0.975 |
Notes.
Among the migraineurs, the proportion of women was greater than that of men, with no significant difference in this regard between the CM and EM groups (77.5% vs. 82.7%; p = 0.176). Compared with the EM patients, the CM patients had a lower education level (p < 0.001), and a greater proportion of them were married (p = 0.001). The BMI of the CM group was significantly higher (21.90 ± 2.88 vs. 23.34 ± 2.34; p < 0.001) than that of the EM group.
The episodic and chronic TTH patients showed similar trends as the migraineurs in terms of age, sex, education level, and pain intensity (Table
There was no statistically significant difference between the other episodic and chronic headache groups except in pain intensity. There was no significant difference in BMI or distribution of the four BMI subgroups between these two groups (p > 0.05; data not shown).
We performed multiple comparisons of BMI among the migraine, TTH, and other headache groups. The migraineurs had lower BMI than TTH and other headache patients; however, the difference was statistically significant only between the migraine and other headache groups (p = 0.018). The difference in BMI between the migraineurs and TTH patients (p = 0.05), or the TTH and other headache patients, (p > 0.05) was not significant (Figure
Results of multiple comparisons of BMI among the migraine/TTH/other headache groups. Note.
Finally, we compared the proportions of patients with abnormal and normal BMI in the three primary headache groups (Table
Distribution of patients with abnormal and normal BMI in the three headache groups: migraine, TTH, and other headache groups.
Migraine
Variable | EM (n = 369) | CM (n =177) | p value |
---|---|---|---|
Compared with normal BMI | |||
Underweight | 35 (10.8%) | 9 (7.5%) | 0.198 |
Overweight | 41 (12.4%) | 52 (31.9%) | <0.001 |
Obese | 4 (1.4%) | 5 (4.3%) | 0.078 |
TTH
Variable | ETTH (n = 319) | CTTH (n = 186) | p value |
---|---|---|---|
Compared with normal BMI | |||
Underweight | 20 (8.1%) | 16 (10.2%) | 0.296 |
Overweight | 81 (26.4%) | 30 (17.5%) | 0.018 |
Obese | 4 (1.7%) | 5 (3.4%) | 0.24 |
EM: episodic headache; CM: chronic headache; ETTH: episodic tension-type headache; CTTH: chronic tension-type headache.
Among the TTH patients, the proportion of overweight patients in the CTTH group was lower than that in the ETTH group (ETTH vs. CTTH: 26.4% vs. 17.5%; p = 0.018). There was no statistically significant difference in this regard between episodic and chronic patients in the other headaches group (p > 0.05; data not shown).
Among the three primary headache types, only CM and ETTH were associated with BMI, especially in case of overweight patients. However, there were some other factors that might have influenced this association. We, therefore, evaluated the migraine and TTH groups by logistic regression analysis (Tables
Multiple logistic regression analysis of the CM group.
Variable | p value | OR | 95% CI for OR |
---|---|---|---|
Age | 0.46 | 1.02 | 0.98–1.05 |
Marriage | 0.90 | 0.92 | 0.22–3.74 |
Education level | 0.71 | 0.89 | 0.5–1.61 |
Elevated blood pressure | 0.76 | 0.86 | 0.31–2.37 |
Medication overuse | <0.001 | 0.01 | 0.001–0.035 |
Average headache days per month | <0.001 | 1.27 | 1.21–1.33 |
Duration of headache history | 0.54 | 0.99 | 0.95–1.03 |
BMI classification | 0.005 | ||
Compared with normal weight | |||
Underweight | 0.699 | 0.71 | 0.12–4.14 |
Overweight | 0.021 | 3.24 | 1.19–8.81 |
Obese | 0.004 | 28.63 | 2.96–276.6 |
CM: chronic migraine; OR: odds ratio; CI: confidence interval; BMI: body mass index.
Multiple logistic regression analysis of the TTH group.
Variable | p value | OR | 95% CI for OR |
---|---|---|---|
Medication overuse | <0.001 | 0.044 | 0.01–0.203 |
Average headache days per month | <0.001 | 1.233 | 1.19–1.28 |
Duration of headache history | 0.053 | 1.036 | 1.0–1.07 |
BMI classification | 0.361 | ||
Compared with normal weight) | |||
Underweight | 0.403 | 1.679 | 0.5–5.66 |
Overweight | 0.154 | 0.54 | 0.23–1.26 |
Obese | 0.736 | 1.46 | 0.16–13.45 |
TTH: tension-type headache; OR: odds ratio; CI: confidence interval; BMI: body mass index.
The results demonstrated that BMI was independently associated with CM (p = 0.005) but not with CTTH. Relative to normal weight, the odds ratios for overweight and obesity were 3.24 (95% CI, 1.19–8.81) and 28.63 (95%CI, 2.96–276.6) in CM patients. The relationship between BMI and headache was not influenced by medication overuse. The results of logistic regression analysis showed that the odds ratios for CM and CTTH were 0.01 (95% CI = 0.001–0.035) and 0.044 (95% CI = 0.01–0.203), respectively.
Both headache and obesity are highly prevalent disorders in the general population, and their relationship has been investigated in clinical studies in recent years. Headache is often accompanied by abnormal BMI, especially obesity. Low BMI (underweight) is associated with the least likelihood of headache, and the risk of headache increases significantly with increase in BMI [
The relationship between underweight and headache was uncertain. In our study, underweight had no association with primary headache. This is similar to the findings of another study which reported that migraine is not significantly associated with BMI < 18.5 kg/m2[
The main findings of our study were as follows: (1) Compared with episodic headache patients, chronic headache patients were less educated, older, and more likely to overuse analgesics and also had a longer duration of headache history. However, there was no significant difference in BMI or the distribution of the four BMI subgroups between the two groups. (2) CM and ETTH patients had a higher BMI than EM and CTTH patients; however, there was no statistically significant difference in this regard among patients with other episodic and chronic headaches. (3) After adjustment for age, sex, marriage, education level, and other clinical factors, overweight and obesity were associated with CM but not with CTTH.
Migraineurs usually have some gastrointestinal symptoms, such as nausea and vomiting. They also experience aggravation of migraine because of routine physical activity, and migraine attacks often influence their appetite. In adults with migraine, high BMI is associated with more frequent and severe migraine attacks [
However, a few studies have reported contradictory results, having found no significant relationship between migraine and abnormal BMI [
In our study, CM patients were more likely to be obese/overweight, while the proportion of overweight patients in the CTTH group was lower than that in the ETTH group. Recent findings based on data from 30,703 episodic headache cases revealed a similar trend: obesity was associated with an increased frequency of headaches and increased disability among patients with migraines but not among patients with severe tension-type headaches [
Some preventive drugs, such as topiramate, flunarizine, and amitriptyline, might be associated with weight gain or loss [
In our study, overweight, and not obese, was the most common classification among patients with abnormal BMI; we speculate that this is because of constitutional differences. Asians are less likely to be obese or morbidly obese than Europeans in accordance with the WHO criteria. The criteria of weight for adults proposed by the Chinese National Health and Family Planning Commission [
Some clinical studies have evaluated the association between weight loss and headache frequency. In a small prospective observational study by Bond et al.[
Few studies have evaluated the association between BMI and TTH. In our study, CM patients were more likely to have a higher BMI than EM patients, while ETTH patients were more likely to be overweight/obese than CTTH patients. A previous population study also found that obesity is associated with CM but not with CTTH [
The mechanisms responsible for the association of obesity with migraine and TTH are unclear. Some scholars believe that sympathetic dysfunction plays an important role in this association. Migraine is a disorder of sympathetic dysfunction [
Beta-blockers, which selectively bind to
Additionally, chronic inflammation, adipokines, sex hormones, and psychiatric factors might play a role in the development of chronic headache. Further studies are required to gain a more comprehensive understanding of the mechanism underlying the association between BMI and chronification of headache, which might aid headache prevention, treatment, and investigation.
Finally, our study has some limitations. First, this was a clinic-based study, and all participants were patients who visited our hospital for treatment. Second, this was a cross-sectional study with a limited study sample. Therefore, a follow-up study is needed to confirm our findings. Third, this study was conducted at a single center, which might be a potential source of bias. Therefore, the results might not be applicable to the general population. Further studies should be conducted among the general population in the future.
Migraine patients had lower BMI scores than those with other primary headaches. However, compared with EM and CTTH patients, those with CM and ETTH were more likely to be overweight and obese. Obesity/overweight plays an important role in the chronification of migraine. It is possible that sympathetic dysfunction and other mechanisms play an important role in the association between headache and obesity/overweight, and our findings support this theory. Further investigations are needed to better understand this mechanism.
Our findings demonstrating that overweight/obesity is independently associated with CM but not with CTTH are significant for clinicians. Further research is needed in the future to confirm these relationships.
Body mass index
Chronic migraine
Episodic migraine
Episodic tension-type headache
Tension-type headache
Chronic tension-type headache
International Classification of Headache Disorders
Chronic daily headache
Odds ratio.
The data used to support the findings of this study are available from the corresponding author upon request.
The study protocol was reviewed and approved by the Ethics Committee of the First Affiliated Hospital, Chongqing Medical University, China. Human rights and privacy were fully protected in this study.
The patients were informed of the purpose of the study, and they provided consent before participating in it.
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Qingqing Huang and Xiping Liang performed all the procedures, including designing of the study and collection of information of patients in 2011. Huiqing Yu and the other authors helped with statistical analysis. We thank Jiying Zhou for allowing us to use the previous study data. All authors read and approved the final manuscript and gave consent for its submission and publication.
The authors appreciate the members of the Neurological Clinic of the First Affiliated Hospital, Chongqing Medical University, China, for their assistance in screening for eligible participants. The authors heartily thank the participants. We deeply thank Dr. Jiying Zhou for her continuing support for this project. We also thank International Science Editing (