Twin study finds no link between migraines and cognitive dysfunction

Danish investigators of a study in middle-aged twins say their results showing similar cognitive functioning in migraineurs and nonmigraineurs should be reassuring to those with a history of migraine.Despite some studies suggesting a link between migraines and cognitive dysfunction, a large Danish study in middle-aged twins found no difference in cognitive test scores between migraineurs and nonmigraineurs.The study involved neurologist-conducted interviews of 1,393 twins, which established a diagnosis of migraine in 536 participants (migraine without aura n=347; migraine with aura n=157). To determine any link between migraine and cognitive functioning, all migraineurs and nonmigraineurs underwent a series of cognitive tests for fluency, forward and backward digit span, a modified 12-word learning test with immediate and delayed word recall, and a digit-symbol substitution test.The investigators conducted a range of analyses comparing the overall results of cognitive tests in migraineurs and nonmigraineurs. Sex-stratified cognitive scores were comparable between the groups, the authors report, although migraineurs' scores were marginally better than nonmigraineurs. Stratifying by age and the number of lifetime attacks found no significant difference in scores, and adjusting for potential confounders did not influence the results. The authors also compared mean cognitive scores of twin pairs discordant for migraine and found no significant differences between migraineurs and non-migraineurs. Stratifying by age, sex, and cumulative number of lifetime attacks produced similar results. The authors say that the within-pair results are "particularly interesting since these analyses control the large number of factors the twins share including childhood socioeconomic status." Discussing the study's findings in an editorial, Drs Elkind and Scher say that, although this is an important negative study, there are still questions to be answered. "...the absence of a general cognitive deficit in migraine patients, while reassuring, does not rule out the existence of deficits in specific psychological domains", they say. They suggest that studies need to explore whether particular migraine subtypes are associated with brain disease or cerebral injury. They say, "Future studies will need to account for categories of migraine, based on a better understanding of its pathophysiology, and investigate specific neuropsychological domains most likely to be affected by lesions of the posterior circulation." Reference...