Men With Lower Cardiovascular Fitness at Higher Risk for Migraine, Swedish Study Says

Young men with a lower level of cardiovascular fitness had a higher risk of developing migraines, according to a recent national, population-based cohort study from Sweden.

Researchers examined the records of 1.8 million young men between 1968 to 2005 who had been drafted into the Swedish military (during those years, service was mandatory).

Men are an understudied population in migraine research; it is already known that women are 2 to 3 times more likely to suffer from migraines than men. Data on the relationship between cardiovascular fitness and the development of migraine are also lacking, but higher levels of physical fitness and higher levels of physical activity have been linked with the reduced risk of migraine. However, patients with migraine may be reluctant to engage in intense physical activity, particularly if it triggers their episodes.

The researchers stressed that cardiovascular fitness is not the same as physical activity, and physical activity that does not increase one’s fitness level may not provide protection against poor health.

Researchers examined prescriptions for migraine medication, using the Swedish Prescribed Drug Register, and linked them with the country’s military service conscription register, hospital registers, health insurance databases and death registers. The enlistment process encompassed a 2-day physical examination, including an evaluation of cardiovascular fitness, which enabled the creation of a baseline.

The Swedish Prescribed Drug Register began in 2005 and researchers obtained the first recorded dispensing of migraine-specific drugs for men between 20 and 60 years old. The medications sumatriptan, naratriptan, zolmitriptan, rizatriptan, almotriptan, eletriptan, frovatriptan, dihydroergotamine, and ergotamine were included.

A secondary analysis was performed for a migraine diagnosis for inpatient and outpatient visits recorded in a hospital setting. The final analysis used data from a total of 1,143,831 participants. Migraine-specific medication prescriptions were filled by 22,533 of the included men, or 2.0%, compared with those with a high cardiovascular fitness level at enlistment.

After adjusting for confounders, low and medium fitness increased the risk of migraine-specific medication, compared with those who had high cardiovascular fitness levels.

The risk ratio (RR) for those with low fitness levels were 1.29; 95% CI, 1.24-1.35, and for medium fitness levels, RR,1.15; 95% CI, 1.12-1.19. While the RR was higher for those with low levels, the number of cases was higher in the medium fitness group compared with the low fitness group (medium population attributable fraction: 8.0%, 95% CI, 4.0%-11.7%; low population attributable fraction: 3.6%, 95% CI 1.7%-5.3%).

A secondary point of the study was to see if the relationship between cardiovascular fitness and future risk of migraine is modified by baseline levels of body mass index (BMI) and blood pressure. That showed that lower fitness levels increased risk of migraine across all groups, except among underweight men or men with high diastolic blood pressure.

The authors said there might be an unknown, common predisposing factor for both lower cardiovascular fitness levels and migraine, and there could be a common pathology for both conditions; migraine could be a result of a systemic issue rather than a neurological one. Moreover, since the adolescent brain is still developing, the article speculated that it is possible that cardiovascular fitness during this timeframe has long-term positive effects on brain health that might reduce migraine susceptibility.

Researchers said it’s possible that the migraine incidence seen in the study is underestimated since men with undiagnosed migraine or those using over-the-counter medication were not captured in the data. It is also possible that some residual confounding factors, such as smoking and alcohol use, may remain in the estimates.

Reference

Nyberg J, Gustavsson S, Linde M, et al. Cardiovascular fitness and risk of migraine: a large prospective population-based study of Swedish young adult men. BMJ Open 2019;9:e029147. doi: 10.1136/bmjopen-2019-029147.