If you are one of the 10% of the population who regularly suffer from migraines, it would be fair to consider yourself unlucky. Characterised by severe throbbing in the head and accompanied by strong feelings of nausea, dizziness and increased sensitivity to light; little is known about the cause of migraines. One suggestion is that they are produced by drops in serotonin levels. This results in the release of neuropeptides, small proteins found in the brain, which have been proposed as the cause of the intense pain.
Perhaps sufferers have been previously consoled by the belief that their condition is correlated to their intelligence. I am sorry to break it to you, but this is simply not the case. More intelligent people are simply either more likely or more able to go to the doctors to report their migraine. This has produced what looks like a significant correlation between intelligence and migraine risk in the absence of any causing factors. It raises an important case against sampling bias; a phenomenon whereby a selection process does not lead to a sample representative of the population as a whole.
One factor which is significantly related to migraine risk is a person’s sex; women are around twice as likely to regularly suffer from migraines in comparison to men. This follows a general pattern where females are more susceptible to pain related disorders compared to men. Determining the reasons why this is the case may hold the key in finding the cause of migraines. A 2012 study may have taken us a step closer to this goal. Through the magnetic (MRI) imaging of 44 brains it was determined that the posterior insula (see Fig. 1) area of the brain was significantly thicker in females that were prone to migraines compared to their male counterpart. It is known that this area of the brain is involved in emotional processing and is activated in response to painful stimuli. Furthermore, the researchers asked both male and female subjects to rank their headache intensity and “unpleasantness” on a scale from 1-10. Whilst there were no significant differences in the headache intensity experienced by both sexes, unpleasantness was scored significantly lower by males. It can be concluded that differences in the brain morphology of the two sexes may cause females brains to be more negatively affected by the onset of a migraine. Interestingly the findings from this study justifies further research into the development of sex-specific drugs.
Figure 1: The female thicker posterior insula (PIC) observed may explain the higher incidence of migraines found in women. The phenomenon has been dubbed “The Sex Phenotype”.
Many studies have drawn correlations between mental disorders such as depression and bipolar disease and the occurrence of a migraine. For example, a study conducted in 2004 found that the prevalence of anxiety was significantly greater in migraine sufferers compared to healthy individuals (9.1% compared to 2.5%). In 2009 a link between eating disorders and migraines was made. Characterised by the upregulation of dopamine and downregulation of noradrenalin; eating disorders affect 725,000 people in the UK alone. These chemical changes, as well as the disruption of tyrosine (see Fig 2.) production are also key features of a migraine onset. This newly discovered linkage between migraine occurrence and mental illness adds to the increasing wealth of evidence suggesting that improving our mental health can have positive long term physical health benefits. As of 2015 mental health funding represented a measly 11% of the UK’s NHS budget, and yet its increased funding could save long term expenditure in this field.
Figure 2: Tyrosine is one of the 22 amino acids found in all organisms. Disruptions to its metabolism is a common factor associated with the onset of migraines and mental disorders.
In conclusion, it’s sad that the illness which has the most patient entries throughout the neurology sector has no true cure in sight, a fact which isn’t particularly surprising given so little is known about its cause. Despite genetic disposition being considered an important factor; an increasing body of evidence has suggested that increasing our general wellbeing and mental health may reduce migraine risk. Perhaps these are promising avenues to explore in the future.