Headache: a marker of depression Patients who presented with a chief complaint of headache in the outpatient family practice setting were found to have a high prevalence of depression (63%) by the Zung Self-Rating Depression Scale (SDS) index. A statistically significant relationship was found between the frequency of headaches (P = .03) with level of depression. In fact, 74% of patients with headaches recurring almost every day had a clinically significant depression diagnosed as defined by the Zung SDS score. The Zung SDS score also correlated with the length of time that the problem of headache existed (P less than .05). Item analysis of the individual 20-item depression score revealed that four questions accounted for 93% of the variance. This analysis suggests that shorter, more abbreviated screening questions could be developed and refined in the future for use by the busy clinician. Headache is an important marker for depression in the primary care setting. It can be inferred from this study that the clinician may need to focus more on treating the entity of depression than on treating just the symptom of headache. 