Both migraine and depression are significantly more common in women than men. Oestrogen plays a significant role in the production of, and the bodies ability to use serotonin.
Serotonin is thought to be a key player in both headache (including migraine) and depression due to the action of drugs that help boost serotonin in both conditions.
In migraine and other headache types, serotonin makes it harder for nerves from the upper cervical spine to "set off" the nerves in the trigeminal system which would give you head pain. In effect serotonin acts as a fire break, stopping the spread of the "fire" or activity in the brainstem.
Serotonin is also critical in other bodily functions and mood regulation - a depressed mood is thought to be related to abnormal serotonin levels - initially thought to be low, however this is hard to measure and there may be some suggestion for some people their serotonin might actually be high.
"Oestrogen makes both of these worse," he (Dr J Saper - Michigan Headache Institute) said describing the headaches and mood changes often triggered by the menstrual cycle. "Women are more prone to depression and more prone to migraines, and women who take oral contraceptives are often worse off."
The problem is that we can't measure serotonin in the brain of live humans so it is difficult to prove other than by association. Blood levels of serotonin can be measured and are low in people with depression, but it is not known if this is also true for the brain.
Roger O'Toole is the Director and Senior Clinician of the Melbourne Headache Clinic and has over 10 years experience as a physiotherapist.