Large study links abdominal obesity to increased risk of migraines

A massive new longitudinal study conducted in South Korea indicates that obesity is a risk factor for the development of migraines in young adults. The research suggests that abdominal obesity, measured by waist circumference, is a stronger predictor of this neurological condition than general body mass index. The findings were published in the medical journal Neurology.

Migraine is a debilitating headache disorder that imposes a heavy burden on individuals and society. While genetics play a major role in who develops migraines, environmental and lifestyle factors are also significant contributors. Medical professionals have long recognized that managing comorbidities is a key part of treatment.

Obesity is a known risk factor for many diseases and has been linked to the worsening of existing migraine conditions. This process is often called chronification. However, the question of whether obesity actually causes the onset of migraines in people who did not previously have them has been less clear.

Previous research on this topic often relied on cross-sectional data. Such studies look at a population at a single point in time. This makes it difficult to determine whether obesity leads to migraines or if the condition leads to lifestyle changes that cause obesity.

The authors of the new study sought to establish a clearer causal link. They designed a prospective cohort study to observe changes over time. Their primary goal was to investigate the association between obesity and the risk of developing migraines. They also aimed to see if the risk increased in proportion to the severity of obesity.

To achieve this, the researchers utilized the extensive database of the Korean National Health Insurance Service. This service covers approximately 99 percent of the South Korean population. The team focused their analysis on young adults aged 20 to 39. These individuals underwent general health examinations between the years 2009 and 2012.

The scale of the study was exceptionally large. The initial dataset included over six million people. The researchers applied strict exclusion criteria to ensure the validity of their results. They removed anyone who had a recorded history of migraine prior to the study. They also excluded individuals with missing data regarding body measurements or lifestyle factors.

To avoid counting cases that might have been present but undiagnosed at the start, they excluded anyone diagnosed with migraine within the first year of the study. This resulted in a final sample size of 6,106,560 participants. The average age of the participants was roughly 30 years old. About 39 percent of the sample was female.

Participants were followed from their initial health exam until the end of 2018. The researchers tracked medical claims to identify new cases of migraine. They specifically looked for the International Classification of Diseases code G43. The average follow-up duration was seven years.

During the health examinations, medical staff collected precise body measurements. They measured height, weight, and waist circumference while participants wore light clothing. Body mass index was calculated by dividing weight in kilograms by the square of height in meters.

The researchers categorized body mass index into five groups. These ranged from underweight to stage 2 obesity. Waist circumference was divided into six levels, with increments of 5 centimeters. This allowed the team to assess abdominal obesity specifically.

The study included detailed information on lifestyle and demographic factors. Participants completed questionnaires about their smoking status and alcohol consumption. They also reported their physical activity levels and income. Blood tests provided data on cholesterol, glucose levels, and other metabolic indicators.

The results showed a clear association between body composition and migraine risk. In the initial analysis, the risk of developing migraine increased as body mass index increased. Individuals with stage 2 obesity had a higher likelihood of diagnosis compared to those with a normal weight.

This relationship was even more pronounced when looking at waist circumference. The researchers observed a dose-dependent relationship. This means that as waist size increased, the risk of migraine rose in a step-by-step fashion. This trend held true even after the researchers adjusted their statistical models for various confounding factors.

The team ran multiple statistical models to isolate the specific effects of different types of obesity. When they adjusted for waist circumference, the link between general body mass index and migraine became less direct. However, the link between waist circumference and migraine remained robust even when body mass index was taken into account.

This suggests that abdominal obesity acts as a stronger independent risk factor than total body obesity. The researchers found that individuals with the largest waist measurements had a significantly higher hazard ratio for migraine. Conversely, those with the smallest waist measurements showed a decreased risk.

The study also shed light on the relationship between being underweight and migraine risk. Initial unadjusted data seemed to suggest underweight individuals had a higher risk. However, this association disappeared in the fully adjusted models. This indicates that being underweight itself may not be a direct cause of migraine.

The analysis revealed complex interactions regarding muscle mass. When waist circumference was controlled for, extremely low body mass index was linked to higher migraine risk. The authors suggest this might be related to low muscle mass. Skeletal muscle plays a role in regulating inflammation in the body.

Inflammation is a key suspect in the biological mechanism linking obesity and migraine. Fat tissue, particularly visceral fat located deep in the abdomen, is metabolically active. It secretes various substances, including proinflammatory cytokines.

Visceral fat produces more of these inflammatory markers than subcutaneous fat. This biological difference might explain why waist circumference was a better predictor of migraine than general weight. The inflammatory state caused by excess abdominal fat could potentially lower the threshold for migraine attacks.

The researchers also conducted subgroup analyses to see if the results varied by demographic. They found that the association between abdominal obesity and migraine was modified by age. The link was stronger in adults under the age of 30 compared to those in their thirties.

Lifestyle factors also played a modifying role. The association was stronger in non-smokers than in smokers. It was also more intense in heavy drinkers. Alcohol consumption has known vasodilatory effects, which can trigger headaches.

The combination of alcohol use and obesity appeared to compound the risk. The researchers proposed that the physiological effects of alcohol might interact with the inflammatory state of obesity. This could make individuals more susceptible to the onset of the disorder.

There are some limitations to consider. The reliance on health insurance claims means that only treated cases of migraine were counted. Many people suffer from migraines without seeking professional medical help. This could lead to an underestimation of the true incidence rate.

The study was also limited to the Korean population. Body composition and fat distribution can vary among different ethnic groups. The specific cut-off points used for waist circumference and body mass index might not apply universally. The gender ratio in the study was also imbalanced due to the nature of the screening program.

The observational nature of the study means it cannot definitively prove causation. While it establishes a strong temporal association, other unmeasured variables could be at play. The researchers attempted to control for many factors, but residual confounding is always possible in epidemiological research.

Future research is needed to validate these findings in other populations. Studies with more detailed clinical information could provide further insight. Investigating the specific biological pathways, such as the role of specific adipokines, would also be beneficial.

Despite these limitations, the study provides evidence that maintaining a healthy weight may be important for migraine prevention. It highlights that body shape and fat distribution matter just as much as the number on the scale. The findings suggest that clinicians should consider abdominal obesity when assessing migraine risk in young adults.

The study, “Association Between Obesity and the Risk of Migraine: A Nationwide Cohort Study in South Korea,” was authored by Soo-Im Jang, Namoh Kim, Kyungdo Han, and Mi Ji Lee.