The Canary in the Mind
Migraine survives evolution as a psychological benefit.
Posted Oct 29, 2020
If evolution by natural selection can shape sophisticated mechanisms such as the eye, heart, and brain, why hasn’t it shaped ways to prevent nearsightedness, heart attacks, and Alzheimer’s disease?
—Nesse & Williams, Why We Get Sick: The New Science of Darwinian Medicine, 1995
Migraine and its related headache disorders have surprisingly survived the pruning of natural selection. The disability caused by migraine far exceeds the secondary benefits of other evolutionary disabilities, such as nearsightedness, which enhances the performance of fine handiwork by those who cannot see well enough to hunt. Nearsighted artisans could help their tribe thrive by fashioning a well-feathered arrow, fine arrowheads, and well-fitted moccasins. But migraine appears to have no such evolutionary value.
For migraine causes severe disability without obvious benefits. In 2012, The World Health Organization headache fact sheet reported, “Up to 4% of adults worldwide have a headache or migraine on 15 or more days each month.” According to Vinson, in Annals of Emergency Medicine (2002), “5.2 million emergency room visits each year are due to headache.” In Cephalgia (2013), Steiner and his colleagues reported that “Migraine is the 7th highest cause of disability worldwide. It is by far the most disabling neurological condition.” In 2007, also in Cephalgia, Shapiro and Goadsby cited “a comprehensive World Health Organization study,” showing “that severe, continuous migraine is as disabling as quadriplegia, dementia, and active psychosis.”
Perhaps our ancient forbearers had fewer, milder headaches, but they apparently possessed the genes for migraine, passing them on to us. Several causative genes have now been identified, including CACNATA, ATP1A2, SCN1A, and PRRT2. The more of these genes that one inherits, the worse the disorder. This knowledge has now led to the development of medications that do not simply treat generic “migraines,” but target disease-specific, gene-related pathways. But why are the genes still there?
When I was 19, a pre-medical student at UC Berkeley, I was frequently disabled by the migraine disorder I had suffered since I was 7, inherited from my father, who would get up in the middle of the night with a severe headache and nausea, especially after he returned from fighting in the Battle of the Bulge in WWII. As a young child, I heard him vomit so violently that he would eject down the drain, and then retrieve, his artificial tooth, featuring a gold hook prepared by a GI dentist on a military base in Frankfurt, Germany.
At that time, I was myself frequently awakened in the middle of the night with a throbbing right-sided headache, associated with mild nausea. The headache and the nausea would slowly worsen. I knew that the nausea would eventually drive me to the toilet to vomit, but because vomit disgusted me, I would postpone the toilet dash until the headache and the nausea overwhelmed me. Vomiting immediately resolved my suffering, to my relief and surprise.
In Berkeley in 1962, I continued to suffer the same migraines, still without knowing why headaches should be connected to vomiting. I didn’t even know that my headaches had a medical name. From my college courses, I was learning a lot about how one thing was connected to another. Lack of vitamin C caused scurvy. Viruses caused smallpox and polio. Since migraine was connected to vomiting, was it not likely connected to other things, too? What else could I do to avoid migraines?
I noticed that every time I skipped lunch to prepare for my chemistry lab, I was struck down. I had to lie down in a dark, quiet room, hoping to fall asleep, for that abolished my headache before I vomited. I was careful not to skip meals. I also noted that sleep deprivation, too, triggered a migraine. One night, I found myself with an unwritten essay due the next morning. I finished typing just in time to go down for breakfast in the dorm cafeteria. I had always hated coffee, but I made myself gobble down the stuff, tempered with milk, hoping that this would keep me sufficiently awake to submit my paper. Lo and behold, I stayed awake and did not get a migraine. I thought that coffee must be a migraine prophylactic.
Now how did caffeine get into this story? Every society we know seeks caffeine, sometimes by arduous methods. Why all this bother with a bean that doesn’t look very appetizing in the first place? As we all know, caffeine keeps us awake, gives us the energy to run, and this in turn helps us eat and sleep better, preparing us for another day in the race against starvation and annihilation.
What else might prevent migraine attacks? I noticed that if I did aerobic exercise at least three times a week, I suffered fewer migraines. So I invented a four-letter mnemonic, condensing what I had learned about preventing migraines: CASE. C was for caffeine. The young physician-to-be started drinking a cup of coffee every morning, actually learning to enjoy it, as long as he added milk, what the French call café au lait, a term I knew only because I was studying French. The chic French term was important because it led the un-chic undergraduate to learn the etymology of migraine. The word comes from the medieval-French mangling of the Greek hemicranium, mi for hemi (“half”) and grim for cranium (“head”). The two terms elided to make megrim, which was then Anglicized to migraine.
The A in my mnemonic stood for aerobics. I did at least 30 minutes of aerobics, either jogging or cycling, three times weekly, and this indeed did improve the frequency of my headaches.
The S was for sleep, regular, sufficient sleep, no all-nighters, no late-night cramming for tests. Sticking to a regular schedule of sufficient sleep led to better planning, better work habits, and fewer migraines.
E was for eating, regularly, without skipping meals.
Not wanting to be a headache case, I was governed by my mnemonic, CASE. As time passed, all four of the items in CASE were proven to be prophylactic activities, now validated for use in neurologic practice. For example, in 2011, Emma Valkey and colleagues showed in Cephalgia that regular aerobic exercise was as effective in preventing migraine as was the anticonvulsant topiramate or formal relaxation therapy. Since aerobic exercise has other health benefits, it seems prudent to encourage this approach to migraine prophylaxis before trying medications. In any case, prophylactic medications like topiramate work well for only two-thirds of migraineurs.
Regular but moderate caffeine consumption is well-established in the medical literature as a migraine prophylactic, but too much caffeine and consequent caffeine withdrawal is a known trigger for migraine, especially in those patients, such as nurses, who drink many cups of coffee during a long, stressful day and then suffer from a caffeine-withdrawal migraine on their day off. But such cases should not be cited to discourage moderate caffeine every morning.
Skipping meals and poor sleep are well-studied triggers of migraine. These produce stress, and stress triggers migraine. According to the American Migraine Foundation in 2019, stress is the number one trigger of migraine, affecting almost 70% of people with migraine. Caffeine, regular aerobic activity, regular sleep, and regular food minimize stress and thereby minimize migraine.
The efficacy of the CASE protocol gives us a hint about migraine’s potential evolutionary value. We can think of migraine as a kind of canary in the mind, a warning that one is living dangerously. One is not going to gather many berries, slay many deer, or even care for children if one is lying all day in a darkened cave vomiting, unable to tolerate light or noise, not even the pulling of one’s own child.
On the African savannah, our greatest anxiety was that we might starve, that in our weakened state we might become food for stronger animals. This motivated us to run for deer and berries, and the exercise lessened our stress, for we were optimizing our chances of finding food. The exercise also toned our self-protective skills. And it fatigued us, preparing us for a good night’s sleep in the arms of a mate. It is thus likely that evolution permitted migraine to persist in the gene pool to remind us to do what would improve our chances of passing on our genes. In this view, evolution has produced a system of protective reminders that only the human mind could create, understand and heed. It is not likely that apes suffer migraine.