“Epilepsy and migraine ‘could have a shared genetic link’”, reports BBC News.
This headline is based on a study of people with epilepsy who also had two or more close relatives with epilepsy.
Researchers were interested in whether having this type of family history increased the risk of participants experiencing migraines. If this was the case, it would suggest that epilepsy and migraines may have ‘shared genetic effects’.
The study found that participants with two or more first-degree relatives (parents, siblings or children) with epilepsy were more likely to suffer from migraine with aura (where the headache is preceded by warning signs such as visual problems), than participants with fewer additional affected relatives.
Overall, this study does not clarify whether there is a definite genetic link between epilepsy and migraine, it can only indicate an association in some groups of people.
The study was carried out by researchers from Colombia University in New York. It was funded by the US National Institute of Neurological Disorders and Stroke.
The study was published in the peer-reviewed journal, Epilepsia.
This story was well-reported by the BBC, although it did not comment on the methods of this study or their limitations.
This was a cohort study that aimed to determine whether there was a link between whether a person had a confirmed diagnosis of either generalised epilepsy (where a person loses consciousness during a seizure) or focal epilepsy (where a person does not lose consciousness during a seizure), and:
By seeing if individuals who have a greater number of family members affected by epilepsy (suggesting they may have genetic susceptibility) are more likely to suffer from migraines, the researchers aimed to strengthen the evidence for a genetic link between epilepsy and migraine.
Previous research into a possible link has produced inconclusive results – some studies found evidence of a link, others report finding no evidence.
The researchers recruited 730 participants aged 12 years or older with either focal or generalised epilepsy from 501 families containing two or more individuals with epilepsy of unknown cause. This meant that at least two siblings or a parent-child pair had to have epilepsy.
Participants were asked about their history of migraine using a standardised interview, and participants were classified as having had:
The researchers then asked participants about additional relatives affected with epilepsy or a seizure disorder. For each family, the researchers calculated the total number of relatives affected beyond the enrolled participants (referred to as ‘additional’ affected relatives) and the number of first-degree relatives of participants who were affected.
The researchers looked to see if a history of seizures in additional relatives increased the likelihood of migraine. The researchers controlled for age, sex, participant type (for example, whether the participant was the first enrolled person, a sibling or a parent), and epilepsy type (focal epilepsy or generalised epilepsy).
The prevalence of migraine in all participants was 25.2%. Women were more likely to have had a migraine than men: 31.5% of women had had a migraine, compared to 14.5% of men (odds ratio 2.4, 95% confidence interval 1.62 to 3.52).
The prevalence of migraine with aura increased when individuals had two or more additional first degree relatives with seizure disorder not enrolled in the study:
This meant that the odds of having a history of migraine with aura were 2.5 times higher if an individual had at least two additional relatives with a seizure disorder.
However, if more distant relatives were included, the association between number of affected relatives and migraine disappeared.
The prevalence of the other type of migraine, migraine without aura, did not vary with the number of additional first-degree relatives with seizure disorder.
The researchers concluded that the “prevalence of a history of migraine with aura (but not migraine without aura) was significantly increased in enrolled participants with two or more additional affected first-degree relatives.” They go on to say that, “these findings support the hypothesis of a shared genetic susceptibility to epilepsy and migraine with aura.”
This paper suggests there is a link between the number of close relatives with a seizure disorder and the likelihood that an individual with epilepsy will also suffer from migraines with aura.
However, it seems that the researchers were only interested in what they term ‘additional’ family members, and did not take into account the fact that to be eligible for this study at least two siblings or a parent and child both had to suffer from epilepsy.
There seems to be the possibility that if, for example, four members of a family were enrolled in the study but the family had no further affected members, all members of this family would be classified as having no additional family members with seizure disorders.
It is unclear what would have been the effect on the results if only one member of each family had been studied and all other members of the family had been considered as relatives with seizure disorder.
The authors also identify limitations to their study:
Overall, this study does not clarify whether there is a definite genetic link between epilepsy and migraine.
Though it does suggest an association, in some familes at least, which would seem to make the case for futher research.
Learning more about the genetics of both epilepsy and migraines could eventually lead to a theraputic breakthrough.