So. Migraines. We don't really know what they are, but
there's probably a component of neurovascular disorder. Our best guess about how
triptans work is by (tl;dr) causing constriction of blood vessels in the brain. Per my zolmitriptan Patient Information Leaflet:
Migraine symptoms may be caused by the widening of blood vessels in the head. Zolmitriptan is thought to reduce the widening of these blood vessels. This helps to take away the headache and other symptoms of a migraine attack.
Alright, fair enough, thinks I. But... caffeine? Why does caffeine help me so much? What's the mechanism of action here? Isn't caffeine a
vasodilator? (I stopped consuming caffeine after my first term at university when I finally twigged that "a soothing cup of tea" was absolutely consistently making everything Worse, and that if I timed it wrong so would "two squares of dark chocolate". But was I... making up the panic attacks?
Could I have been drinking proper tea all this time?)
It turns out (and please forgive my somewhat sketchy citations here) that caffeine causes vasodilation in smooth muscle (indirectly, e.g.
review of Echeverri et al. 2010), but vaso
constriction when it comes to blood supply to the brain (e.g.
Addicott et al. 2009).
Which I looked at and went !!! because -- while my grasp on the details of the biology here might charitably be described as shaky -- it looks to me as though This Explains Everything (about my personal experiences, sample size of 1, etc).
Like so: if we accept that one factor in migraines is vasodilation, and that the mechanism by which triptans work (when they do) is restricting of blood supply to the brain, then: caffeine (in the form of two mugs of weak tea), to which I am both highly sensitive
and unhabituated, is a plausible explanation for the part where my last migraine lasted less than 24 hours instead of
three days, and I was genuinely back to normal by the next day, instead of gritting my teeth through a miserable hangover.
In contrast, if I do
not have an Active Neurovascular Event In Progress, the effects of caffeine are:
- vasodilation in most of my body, resulting rapidly in readily observable flushing, increased surface temperature, and clamminess, as well as (presumably) increased oxygen and glucose delivery to my muscles; and
- cerebral vasoconstriction, resulting in reduced delivery of glucose and (circuitously) oxygen to my brain; and
- hyperventilation and increased heart rate, in an attempt to increase the oxygen available for my brain, which apparently results in a counterintuitive drop in oxygen availability to specifically the brain (the term for which appears to be "paradoxical effects of hyperventilation")
... which is to say, a panic attack.
In very slightly more detail: physiology and psychology are interacting and interdependent systems, and you can influence the one by manipulating the other. Thus the positive contributions of "slow exhales" and "gentle stretching" and "cold water" and "strong sensory input" in managing anxiety or panic or distress, and, similarly, the ability to induce psychological distress via physical arousal. If my body acts enough like it's having a panic attack, my mind will get in on the action.
So, in conclusion: I still shouldn't be drinking tea when I don't have a migraine, but
given I'm getting two migraines a month with
monotonous regularity, it's time for me to buy myself small quantities of all the fancy teas I've spent the past thirteen years missing. I am
very glad I took the nice NHS 111 doctor's advice to try caffeine, on the basis that it couldn't possibly render me any more miserable than I was already, and only a
little petulant about the inadvisability of drinking highly caffeinated and absolutely delicious alcohol -- normally off-limits because of the caffeine -- to "treat" a headache...
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