||BACKGROUND: The comorbidity of headache and psychiatric symptoms is a well-recognized clinical phenomenon, but there are only limited data regarding the temporal relationship between headache and symptoms of anxiety and depression as well as behavioral problems in adolescents. This study investigates the relationship of anxiety and depressive symptoms and behavioral problems at baseline with recurrent headache at follow-up four years later. METHODS: Within the Nord-Tr[latin small letter o with stroke]ndelag Health Study (HUNT), including repeated population-based studies conducted in Norway, 2399 adolescents in junior high schools aged 12-16 years (77% of the invited) participated in Young-HUNT1 (1995-1997) and again at follow-up four years later, in Young-HUNT2 (2000-2001). The same comprehensive questionnaire that included assessment of symptoms of anxiety and depression and behavioral problems, i.e. conduct and attention difficulties was completed in both studies. In addition 1665 of the participants were interviewed about their headache complaints in Young-HUNT2. RESULTS: In adjusted multivariate analyses we found that higher scores of anxiety and depressive symptoms at baseline were associated with recurrent headache at follow-up four years later (OR: 1.6, 95%CI: 1.2-2.1, p = 0.001), evident for migraine (OR: 1.8, 95%CI: 1.2-2.7, p = 0.008) and non-classifiable headache (OR: 1.7, 95%CI: 1.0-2.8, p = 0.034), but not statistically significant for tension-type headache (OR: 1.4, 95%CI: 1.0-1.9, p = 0.053). Higher scores of anxiety and depressive symptoms at baseline were significantly associated with more frequent headache at follow-up (monthly vs. no recurrent headache OR: 1.8, 95%CI: 1.3-2.5, p = 0.001, weekly or daily vs. no recurrent headache OR: 1.9, 95%CI: 1.2-2.9, p = 0.005). Among adolescents without recurrent headache at baseline, higher scores for symptoms of anxiety and depression were associated with new onset migraine four years later (OR: 2.6, 95%CI: 1.1-4.8, p = 0.036). Higher scores of attention problems at baseline were associated with non-classifiable headache at follow-up (OR: 2.0, 95%CI: 1.3-3.4, p = 0.017). CONCLUSIONS: Results from the present study showed that symptoms of anxiety and depression in early adolescence were associated with recurrent headache four years later. Recognizing anxiety and depressive symptoms should be considered part of the clinical assessment in young headache patients, as early identification of these associated factors may lead to improved headache management.