12. Headache attributed to psychiatric disorder

Primary or secondary headache or both?
Headaches are common, and so are psychiatric disorders. Therefore, frequent coexistence by chance alone is expected.

When a headache occurs for the first time in close temporal relation to a psychiatric disorder, however, a causal relationship may be present. If causation is confirmed, the headache must be coded as a secondary headache attributed to that disorder. This remains true when the new headache has the characteristics of any of the primary headache disorders classified in Part One of ICHD-3 (beta). When a pre-existing headache with the characteristics of a primary headache disorder becomes chronic, or is made significantly worse (usually meaning a two-fold or greater increase in frequency and/or severity), in close temporal relation to a psychiatric disorder, both the initial headache diagnosis and a diagnosis of 12. Headache attributed to psychiatric disorder (or one of its subtypes) should be given, provided that there is good evidence that that disorder can cause headache. When a causal relationship cannot be confirmed, the pre-existing primary headache and the psychiatric disorder are diagnosed separately.

Chronic headache attributed to and persisting after resolution of a psychiatric disorder has not yet been described.

Introduction
Evidence supporting psychiatric causes of headache remains scarce. Thus, the diagnostic categories in this section of the classification are limited to those few cases in which a headache occurs in the context and as a direct consequence of a psychiatric condition known to be symptomatically manifested by headache.

Diagnostic criteria must be restrictive enough not to include false positive cases, but must set the threshold low enough to admit the majority of affected patients. In the vast majority of cases of 12. Headache attributed to psychiatric disorder, the diagnosis is based on personal evaluation of case histories and physical examinations rather than objective diagnostic biomarkers.

Headache disorders may, of course, occur in association with psychiatric disorders without any causal connection. Headache disorders occur coincidentally with a number of psychiatric disorders, including depressive disorders (major depressive disorders, single episode or recurrent; persistent depressive disorder), anxiety disorders (separation anxiety disorder, panic disorder, social anxiety disorder and generalized anxiety disorder) and trauma- and stress-related disorders (reactive attachment disorder, acute stress disorder, post-traumatic stress disorder, adjustment disorders). In such cases, when there is no evidence of a causal relationship, both a primary headache diagnosis and a separate psychiatric diagnosis should be made.

Epidemiological data nonetheless show that headache and psychiatric disorders occur together at frequencies higher than would be expected by chance. Confounding factors may in part explain these apparent comorbidities. For example, patients who have one diagnosis are more likely to be diagnosed with other conditions simply because they receive more medical scrutiny. Genuine comorbidities also are possible, such as between migraine and depression, indicating the likelihood of an underlying association. Putative casual associations include the headache causing the psychiatric condition, the psychiatric condition causing the headache, reciprocal influence between the headache and the psychiatric condition and a common underlying factor causing both.

Although it is suggested that headache occurring exclusively in association with some common psychiatric disorders such as depressive disorders, anxiety disorders and trauma/stress-related disorders might be considered as attributed to these disorders, because of uncertainties concerning the causal relationships and relative lack of evidence in this context, criteria for headaches attributed to these psychiatric disorders have been included only in the Appendix. Further clarification of the mechanisms underlying these causal associations is necessary for sturdy conclusions.

Evidence suggests that the presence of a comorbid psychiatric disorder tends to worsen the course of 1. Migraine and/or 2. Tension-type headache by increasing the frequency and severity of the headache and/or making it less responsive to treatment. Thus, identification and treatment of any comorbid psychiatric condition is important for the proper management of these headaches. In children and adolescents, primary headache disorders (migraine, episodic tension-type headache and especially chronic tension-type headache) are often comorbid with psychiatric disorder. Sleep disorders, post-traumatic stress disorder, social anxiety disorder (school phobia) attention-deficit/hyperactivity disorder (ADHD), conduct disorder, learning disorder, enuresis, encopresis and tic disorder should be carefully looked for and treated when found, considering their negative burden in disability and prognosis of paediatric headache.

To ascertain whether a headache should be attributed to a psychiatric disorder, it is necessary to determine whether or not there is a concomitant psychiatric disorder. It is recommended to inquire about commonly comorbid psychiatric symptoms such as depressive and anxiety disorders in all headache patients. When a psychiatric disorder is suspected to be a possible cause of the headache condition, then an evaluation by an experienced psychiatrist or psychologist is recommended.