The aim of the thesis was to give new insight into the novel phenotype of people with complete freedom from headache using a cohort from the Danish Blood Donor Study.

We found a prevalence of complete freedom from headache of 4.1% and a female-male ratio of 1:2.2. We found no indication that complete freedom from headache was associated with a high socioeconomic status or a healthier lifestyle. 

We investigated if men with complete freedom from headache had a lower pain sensitivity compared with controls. The study showed that complete freedom from headache was not caused by a lower general pain sensitivity. 

We investigated if the nitric oxide – cGMP pathway could be protecting against headache by provoking with the organic nitrate isosorbide mononitrate. The study showed that men with complete freedom from headache can develop a headache when provoked and that the nitric oxide – cGMP pathway is not involved in complete freedom from headache. 

We performed a genome wide association study and uncovered a locus in the ADARB2 gene associated with complete freedom from headache. 

Combined, the studies included in this thesis identified a new phenotype of complete freedom from headache and adds a new perspective to our understanding of headache.

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Thomas Folkmann Hansen​