When researchers looked at the serotonin transporter gene and the serotonin receptor 2A gene, they found that the IBS, migraine and
tension headache groups had at least one gene that differed from the genes of the healthy
participants.
To be eligible for the trial,
participants needed to be between 18 and 65 years of age, and diagnosed as suffering from chronic
headache (
tension - type
headache or migraine, for at least 12 months), and Major Depressive Disorder.