Primary headache: What’s stress got to do with it?

Philosophers, scientists and physicians alike have commented on the relationship of stress and headache for centuries. Many have attributed the onset or exacerbation of headache to a variety of stress-related emotional and cognitive states including suppressed anger (Junkerius, 1743), mental anxiety (Airy, 1870), repression and conversion (Breuer and Freud) or resentment and dissatisfaction (Wolff) (1,2). The 1970s ushered in several decades of well-designed, rigorous, interesting studies into the relationship of stress and many medical conditions including primary headache disorders. Today stress is well established as playing a significant role in headache. Both retrospective and prospective studies support the relationship as well as stress induction procedures and recent imaging research. In the current issue of Cephalalgia, Schramm and colleagues offer an intriguing new study to add to this rich, long, and ever expanding body of research (3). Assessing the relationship of stress and headache is complex and multifaceted. The term ‘‘stress’’ itself has been defined and measured in many different ways, using a variety of study designs, over a range of time periods. Stress can be operationalized as the objective occurrence of challenging, unpleasant or threatening events (e.g. major life events or daily hassles), in subjective ratings measuring perception and appraisal, or on the level of biology, using physiologic measures such as autonomic reactivity and cortisol levels. The relationship of stress, headache disorders and headache/migraine attacks may take various forms (4). Among hypotheses that have been proposed and tested, stress has been conceptualized as an etiologic factor, contributing to the first onset of a primary headache disorder. It has been seen as an exacerbating factor, associated with increasing headache/migraine attack frequency, severity or duration in individuals with a pre-existing headache disorder. And stress (and relaxation after stress) has been viewed as a trigger increasing the probability of a headache/migraine attack. In the case of migraine, it has been proposed that the perception of events and situations as stressful may be a result of changes in brain structure and function that are the result of experiencing migraine (5,6). Recent research also suggests that the perception of stress may be a premonitory symptom of an attack (7). In the current study, Schramm and colleagues measured perceived stress and linked it to both the presence of primary headache subtypes and the frequency of days with headache. Using data from the German Headache Consortium longitudinal population-based study of citizens from three different German regions, researchers asked 5159 participants to rate their perceived stress over the preceding three months using a visual analog scale with scores ranging from 0 (lowest) to 100 (highest). They repeated assessments every three months for a period of two years. They gathered data necessary to classify respondents into one of five diagnostic categories based on International Classification of Headache Disorders, second edition criteria (8): migraine or probable migraine (14.0%), tension-type headache (TTH) or probable TTH (31.0%), migraine with coexisting TTH (10.6%), ‘‘unclassifiable headache’’ (23.6%) and no headache (20.8%).