Published on: October 27, 2018
by Women’s Brain Health Initiative:
For the 10% to 15% of the population who experience migraines, the intense pain can be incapacitating. It is a complex neurological disorder that can affect one or both sides of the brain, and involves varied symptoms including headache, nausea, blurred vision, dizziness, sensitivity to light and sound, and/or aversion to particular smells.
Approximately one-third of those with migraines experience “migraine with aura,” which is a migraine that occurs with a wide range of neurological symptoms that can include visual disturbances, sensory changes, and speech or language difficulties. Migraines are a major contributor to ill health and disability, affecting an estimated 959 million people worldwide.
Everyone’s experience of migraine is unique, with differing times of onset, symptoms, and impact. Shari Orenstein from Toronto began having migraines later in life, commencing around the same time she entered menopause. In the beginning, she would experience one to four migraines each month, but now, 12 years later, she might have up to 25 migraines a month. “I can’t even remember the last time I had a day when I’ve been completely OK,” Shari said. “Even when I take medication – and I’ve tried them all – any relief I enjoy is temporary and the rebound effect afterwards comes quickly and can be just as bad as the original migraine, or worse. Like so many migraineurs, when I do have a good day I live in constant fear that the next migraine is right around the corner.”
Shari is sharing her story because she wants people to learn that migraines are not just bad headaches. In fact, in some instances, a headache is not even one of the symptoms of a migraine attack. For Shari, the impact on all aspects of her life has been devastating. “Most days I have to sequester myself away in a dark room. I am afraid to make plans as most often I am forced to cancel. I cancelled my own birthday dinner for the last two years, I’ve missed so many family celebrations, and even had to leave my son’s birthday dinner early,” she explained. “I feel that I’ve let everyone down and as a result, I feel depressed, overwhelmed, and terribly isolated.”
WOMEN ARE MORE LIKELY TO EXPERIENCE MIGRAINES THAN MEN DUE TO HORMONAL INFLUENCES.
It is estimated that approximately 20% of the female population is affected, with the percentage being the highest during the reproductive years (up to 37%).
Migraine With Aura Linked to Stroke
A systematic review conducted by Markus Schürks and colleagues, published in the medical journal BMJ in 2009, assessed the findings of nine studies examining the association between migraine and ischemic stroke. The researchers found that migraine with aura was associated with a two-fold increase in the risk of ischemic stroke compared to individuals without migraine, and that the risk was higher among women (compared to men).
A study conducted by Leah MacClellan and colleagues, published in the American Heart Association’s journal Stroke in 2007, examined the migraine-stroke association specifically in women. The researchers reported that women who suffered from migraines with aura had a 1.5-fold increase in the risk of ischemic stroke compared to women with no migraines. Behavioural risk factors such as smoking dramatically increased the risk of ischemic stroke. Women with migraines with aura who were current cigarette smokers and current users of oral contraceptives had seven-fold greater odds of stroke than women suffering from migraines with aura who did not smoke or use oral contraceptives.
More recently, a meta-analysis of eight studies concluded that INDIVIDUALS WITH MIGRAINES ALSO HAVE AN INCREASED RISK OF HEMORRHAGIC STROKE COMPARED TO THOSE WITHOUT MIGRAINES (although the risk was lower than what has been reported for ischemic stroke). The researchers also examined women’s risk in particular and found that women who experience migraines have a higher risk of suffering from a hemorrhagic stroke compared with control subjects. The researchers noted, however, that the women-specific findings should be interpreted with caution because only two of the studies contained data relevant to that analysis, and that data did not allow a direct comparison of risk between women and men. This research was conducted by Simona Sacco and colleagues, and reported in Stroke in 2013.
The Impact of Migraine on Brain Structure Remains Unclear
A small number of studies have found that migraine with aura, particularly in women, is linked with an increased risk of changes to brain structure – more white matter hyperintensities and silent infarcts, in particular. But a recent study, published in BRAIN in 2016, had results that were inconsistent with those earlier findings.
Using the Danish Twin Registry, the researchers identified 172 women between the ages of 30 and 60 years old who experienced migraines with aura, as well as a control group of 139 unrelated women with no history of migraines. Additionally, 34 co-twins who, unlike their participating twin sisters, did not experience migraines with aura, also participated in the study. The women all had magnetic resonance imaging (MRI) brain scans conducted at a single centre, looking for the presence of infarcts and white matter intensities.
“In our study, we found that migraine with aura is not associated with an increased risk of silent brain infarcts or white matter hyperintensities,” explained Dr. Messoud Ashina, a Professor of Neurology at the University of Copenhagen and one of the study’s authors.
Association Between Migraine and Cognitive Decline Also Unclear
Since both stroke and structural brain lesions are linked with an increased risk of cognitive decline, it is not surprising that researchers have hypothesized that perhaps migraine may be associated with increased risk of cognitive impairment or dementia.
MANY STUDIES HAVE EXAMINED THE RELATIONSHIP BETWEEN MIGRAINE AND COGNITIVE FUNCTION, AND THE RESULTS HAVE BEEN MIXED.
Some studies found no differences in cognitive function between individuals with or without migraines, and others found cognitive performance was worse among those suffering from migraines. However, the findings seem to be affected by study design. Some studies looked at cognitive function at a single point in time (cross-sectional) whereas others (prospective) compared cognitive function at different points in time, i.e. measured cognitive decline, which is a more meaningful measure. Prospective studies have not found greater rates of cognitive decline in individuals with migraines compared to those without.
A study conducted by Dr. Pamela Rist and colleagues, published in BMJ in 2012, looked specifically at migraines and cognitive decline in women. “Our research revealed that women with migraines did not experience different rates of cognitive decline, compared to women with no history of migraines. This was true for women experiencing migraines with or without aura,” said Dr. Rist, Assistant Professor of Medicine at Harvard Medical School and Brigham and Women’s Hospital in Boston. “We concluded, based on our own study results and findings of previous studies, that patients with migraines should be reassured that migraines may not have long-term consequences on cognitive function.”
Why Women and Men are Affected Differently
Sex hormones may play a role in the differences between women and men when it comes to migraines. For most women with migraines, attacks are more likely to occur during the two days before, and first three days of, menstruation. Jelena Pavlovi and colleagues researched the connection between hormones and migraines in women. Their research, reported in Neurology in 2016, revealed that women affected by migraines have distinct patterns of estrogen decline leading up to their periods compared to women without migraines. Men do not experience large hormonal fluctuations each month like women do, which may help explain why men are less likely to experience migraines and when they do, why the effects are different than they are for women.
The Newest Migraine Drugs
There are many drugs to prevent and treat migraines, yet symptoms continue to disable many people. The search continues for new drug therapies, and a new one was approved by the United States Food and Drug Administration (FDA) in May 2018. Aimovig™ is the first and only FDA-approved treatment to prevent migraines in adults by blocking the calcitonin gene-related peptide (CGRP) receptor. It is a monoclonal antibody self-administered once each month via an autoinjector. Research to date has shown that patients who took Aimovig™ experienced 1 to 2.5 fewer migraine days each month. And in the fall of 2018, Eli Lilly is hoping for FDA approval on its own once-monthly self-administered CGRP antibody Emgality™.
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