Headache disorders constitute a major global disease burden, and migraine - with a one-year prevalence of 15 % - is the sixth most disabling condition. Though a common disease, the pathogenesis is still unclear. Thus, the treatments have different mechanisms of action and preventive treatments are only effective in approximately 50% of chronic migraine patients. Recent evidence from mice models and a study of prolactine-associated headaches have indicated that dopamine agonists such as cabergoline might be used as a treatment of migraine.

The aim of this study is to test the hypothesis that the dopamine agonist cabergoline can be used as a treatment of chronic migraine. A randomized controlled trial of 24 patients with chronic migraine will be conducted, comparing cabergoline to placebo as an add-on medication to the patients' migraine treatment over a 12 weeks period. The primary outcome is change in migraine frequency, but also headache-related hospital contacts, and quality of life as well as prolactin levels and biomarkers of the pituitary-gonadal-axis. The results of the study will help understand the pathogenesis of migraine and might also introduce a more effective and affordable preventive migraine treatment.

Inclusion Criteria:

• Migraine and more than 6 days with headache every months

Exclusion Criteria:

• Cardiac valve disease
• Hypertension
• Psychiatric disease
• Treated with dopamine receptor agonists, dopamin receptor antagonists, macrolides and itraconazole
• pregnant or breastfeeding