Disability is the major determinant of the severity of depressive symptoms in primary headaches but not in low back pain.

Pain syndromes are often associated with depression. In a prospective study we analysed if determinants of depression differ among patients with different primary headaches and between headaches and non-headache pain. During a 2-year period between 1 February 2002 and 31 January 2004, 635 subjects (migraine n = 231; tension-type headache n = 176; cluster headache n = 11; patients with low back pain n = 103; and healthy subjects n = 114) seen by two neurologists filled in a questionnaire on pain characteristics, the MIDAS questionnaire and the Beck Depression Inventory. A multivariate general regression model was used to identify independent predictors of the severity of depressive symptoms. Pain was most frequent in chronic tension-type headache and most intense in the cluster subgroup (P < 0.001, Kruskal-Wallis ANOVA). In univariate tests gender, age, pain frequency, pain intensity and disability were all significantly associated with the severity of depressive symptoms. In the multivariate model disability was the most important independent determinant of the severity of depressive symptoms in the pooled headache group as well as in the migraine and tension-type headache subgroups. In contrast to patients with headache, pain frequency and pain intensity were the significant independent predictors of the severity of depressive symptoms in patients with low back pain. In a multivariate model, after controlling for other factors, determinants of the severity of depressive symptoms were different in headache and non-headache pain subjects, suggesting a different mechanism for developing depression in primary headaches and in other pain syndromes.