Headache attributed to a substance use disorder (eg, dependence), headache attributed to substance withdrawal, headache attributed to acute intoxication and headache attributed to medication overuse are all coded as types or subtypes of 8. Headache attributed to a substance or its withdrawal.
Primary or secondary headache or both?
Headaches are common, and so are psychiatric disorders. Therefore, frequent comorbidity by chance alone is expected. Nevertheless, a causal relationship may exist between a new or significantly worsening headache and psychiatric disorder. The general rules for attribution to another disorder apply to 12. Headache attributed to psychiatric disorder with some adaptation.
- When a new headache occurs for the first time in close temporal relation to a psychiatric disorder, and causation is confirmed, the headache is 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.
- When a pre-existing headache with the characteristics of a primary headache disorder 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, and causation is confirmed, both the initial headache diagnosis and a diagnosis of 12. Headache attributed to psychiatric disorder (or one of its types) should be given, provided that there is good evidence that that disorder can cause headache.
- When in either case 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.
Evidence supporting psychiatric causes of headache remains scarce. Therefore, 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 sufficiently low 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 as a single episode or recurrent, and 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 and adjustment disorders). In such cases, when there is no evidence of a causal relationship, both a headache diagnosis and a separate psychiatric diagnosis should be made.
Epidemiological data nonetheless show that headache and psychiatric disorders are comorbid more frequently than would be expected by chance. Common underlying factors may cause or predispose to both types of disorder; alternatively, or also, confounding factors may lead to comorbidity being overestimated (for example, patients who have one diagnosis are more likely to be diagnosed with other conditions simply because they receive more medical scrutiny). Genuine causal associations also are possible, with the headache causing the psychiatric disorder, the psychiatric disorder causing the headache, or a reciprocal (bidirectional) influence between the headache and the psychiatric disorder.
In this context, 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 may be attributed to these disorders, uncertainties persist because of relative lack of evidence of causation. Criteria for headaches attributed to these and all but two other psychiatric disorders therefore remain in the Appendix. Further clarification of the mechanisms underlying these causal associations is necessary for sturdy conclusions.
Evidence suggests that a comorbid psychiatric disorder tends to worsen the course of 1. Migraine and of 2. Tension-type headache, increasing the frequency and severity of the headache and/or making it less responsive to treatment. Therefore, identification and treatment of any comorbid psychiatric condition is important for the proper management of these headaches. In children and adolescents, primary headache disorders (1. Migraine, 2.2 Frequent episodic tension-type headache and, especially, 2.3 Chronic tension-type headache) are often comorbid with psychiatric disorder. Sleep disorders, post-traumatic stress disorder (PTSD), 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 or not a headache should be attributed to a psychiatric disorder, it is necessary first to determine whether or not there is a concomitant psychiatric disorder. It is recommended to enquire in all headache patients about symptoms of commonly comorbid psychiatric disorders, such as depressive and anxiety disorders. When a psychiatric disorder is suspected to be a possible cause of the headache disorder, evaluation by an experienced psychiatrist or psychologist is recommended.