An international team of researchers found that middle-aged women who had migraines with aura (perceptual disturbance that may precede or accompany the migraine such as a strange light or smell, or disturbed balance or speech) were more likely to develop brain lesions when they were older compared to counterparts who did not have such headaches.
However, independent experts say that while the findings raise important quesitons, they do not prove that migraines with aura actually cause brain damage and suggest more research is needed to establish the source and nature of the lesions, as well as evaluate their clinical symptoms and implications.
The study was the work of first author Dr Ann I. Scher, of the Uniformed Services University, Bethesda, Maryland, and colleagues from the US, Iceland and the Netherlands, and is published online in the 24 June issue of the Journal of the American Medical Association, JAMA.
About 1 in 10 adults has migraines, a common neurovascular disorder that tends to affect women more than men. Around one third of people who get migraines also have symptoms of aura just before the headache starts.
Until a few years ago it was thought that migraines just came and went with no long term consequences but recent studies suggest that the headaches may be linked to brain lesions that show up on magnetic resonance imaging (MRI) scans, particularly in an area of the brain known as the cerebellum, which sits in the hindbrain in the lower back of the head and is responsible for co-ordinating the senses and motor control.
So Scher and colleagues decided to investigate this more closely by looking at the links between having and not having symptoms of migraine in midlife and the presence of infarct-like brain lesions (scars of dead tissue) spotted by MRI scans in later life.
The study included over 4,500 men and women in Reykjavik, Iceland who were born between 1907 and 1935 and who were clinically assessed for migraine symptoms in 1967 (when their average age was 51 years, ranging from 33 to 65).
57 per cent of the participants were women.
The participants were followed for more than 26 years, until 2002 to 2006, during which period they underwent MRI brain scans.
Participants who reported having headaches once or more times a month in midlife were classed as having migraine with aura, migraine without aura, or non-migraine headaches.
The MRI scans showed that infarct-like lesions were present in 39.3 per cent of the men and 24.6 per cent of the women.
The analysis showed, after taking into account age, sex, and follow up time, compared with more than 3,200 participants not reporting headaches once or more times a month, those who had migraine with aura in midlife (361 participants) had an increased risk of late-life infarct-like lesions.
Compared with women not reporting headaches once or more times a month, women who had migraine with aura in midlife showed a higher rate of lesions in the cerebellum and no other parts of the brain (15 per cent and 23 per cent respectively). This was not the case for men where there was little difference (21 per cent versus 19 per cent).
Only the female participants showed a significant link between migraine with aura and increased risk of lesions in the cerebellum; those who had migraine without aura and nonmigraine headaches did not show and increased risk of lesions.
The results stayed the same when they controlled for cardiovascular risk factors and history of cardiovascular disease, which suggests that the biological mechanism that links the migraine aura with the brain lesions is not dependent on the usual risk factors that can cause such damage.
The authors concluded that:
“Migraine with aura in midlife was associated with late-life prevalence of cerebellar infarct-like lesions on MRI. This association was statistically significant only for women. This is consistent with the hypothesis that migraine with aura in midlife is associated with late-life vascular disease in the cerebellum and in women.”
They said longitudinal studies that follow the participants over a period of time and take repeated MRI scans should be done to assess how the lesions develop and look at how this might tie in with frequency of migraines with aura.
The authors said they did not assess whether the individuals who had the infarct-like lesions had any particular symptoms and thus were not able to evaluate their clinical significance, and that this should be done in future studies.
In an accompaying editorial Drs Tobias Kurth of the University Pierre et Marie Curie, Paris, and Christophe Tzourio of the University Pierre et Marie Curie and Harvard School of Public Health, Boston, said the clinical implications of this research “should be interpreted with caution”.
Since the source and nature of the lesions is unknown, and there is no information about their clinical symptoms or consequences, it is too early to say for sure that migraines can damage the brain.
“In this regard, brain scans among patients with migraine should not be initiated to detect silent brain lesions but to rule out rare secondary forms of migraine among those patients with atypical migraine forms or migraine courses,” they added.
But they did say the study raised some important questions and that:
“New studies examining the association of migraine with structural brain changes and brain function should improve understanding of the associations and perhaps further unveil migraine-specific mechanisms.”
“Migraine Headache in Middle Age and Late-Life Brain Infarcts.”
Ann I. Scher; Larus S. Gudmundsson; Sigurdur Sigurdsson; Anna Ghambaryan; Thor Aspelund; Guthny Eiriksdottir; Mark A. van Buchem; Vilmundur Gudnason; Lenore J. Launer.
Vol. 301 No. 24, June 24, 2009
Written by: Catharine Paddock, PhD