Generalised Anxiety Disorder Health Article

Clinical Features

The requirements for the diagnosis of generalised anxiety disorder have changed with time. The symptoms have always included generalised and persistent excessive anxiety ^10,11 and a combination of various psychological and somatic complaints. These psychological and somatic complaints are given prominence in the WHO's International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) criteria, where at least one symptom of autonomic arousal (palpitations, sweating, trembling, or dry mouth) is essential for the diagnosis, together with up to three other symptoms (table 1 ). Three of the symptoms of restlessness, being easily fatigued, difficulty in concentrating, irritability, sleep disturbance, and muscle tension, are necessary for a DSM-IV diagnosis (table 1). The additional symptom of worry over minor matters is included in the DSM-IV criteria but is not in ICD-10. This new criterion allows the diagnosis to be made irrespective of any overlap in anxious symptoms, and seems to separate generalised anxiety from other disorders that involve anxious symptoms. ^12,13 These disorders include hypochondriasis (health anxiety), ¹⁴ panic disorder, ¹⁵ medically unexplained symptoms (somatisation disorder), ¹⁶ obsessive-compulsive disorder, ¹⁷ social anxiety disorder, ¹⁸ and eating disorders. ¹⁹ Anxiety is also a common complication of substance misuse disorders, including alcohol misuse, ²⁰ and so these too have to be excluded. Because none of the individual symptoms are specific to generalised anxiety disorder, it is therefore necessary to exclude the other anxiety conditions before making the diagnosis. Exclusion of these other disorders is not always easy, especially if the patient has more than one disorder. Two diagnoses can only be made when the specific features of the other disorders can be discriminated reliably.

When the predecessor to DSM-IV, DSM-III, was introduced in 1980 the duration of symptoms necessary for a diagnosis of generalised anxiety disorder was 1 month and there was a diagnostic hierarchy that excluded the diagnosis if a depressive, phobic, or panic disorder was present. ²¹ This hierarchy was soon recognised to be inappropriate as the concurrent presence of other disorders was the norm rather than the exception ²² so the criteria for diagnosis were changed. However, if the symptoms of generalised anxiety disorder occurred only in the course of a mood disorder, the hierarchy still applied. Subsequent enquiry has suggested that the hierarchical relation is not fully representative for all patients, because patients with anxiety and depressive symptoms have greater morbidity than those with a mood disorder alone. ²³ The duration of symptoms necessary for a diagnosis of generalised anxiety disorder was raised from 1 to 6 months in later editions of DSM and ICD, ¹¹ in recognition of its status as a chronic illness, although there is little difference between patients who have a duration of symptoms of 1–6 months and those who qualify for diagnosis when their symptoms cross the 6-month threshold. ²⁴

Assessment

Anxiety is a relatively easy symptom to detect in both primary and secondary care settings; the diagnostic difficulty lies in its interpretation. The scope for the use of screening or other instruments to aid the diagnosis or to assess the severity of generalised anxiety disorder is therefore restricted. A simple symptom-based algorithm to aid diagnosis of anxiety disorders has been proposed . ²⁵ One of the most widely used scales is the Hospital Anxiety and Depression Scale, which includes anxiety and depression subscales, is both sensitive and specific in identifying pathological anxiety, ^26,27 and asks questions about symptoms that can distinguish people who have anxiety symptoms associated with other medical conditions. The best-known instrument used in research is the Hamilton Rating Scale for Anxiety ²⁸ but this instrument might include too many physical symptoms, is not simple to use, and alternatives are becoming widely employed; some of these are more specific to generalised anxiety disorder than the Hamilton scale. ^29,30 All these instruments are useful in recording the severity of anxiety quantitatively but are not diagnostic assessments. The formal diagnosis has to be made by clinical or structured interview. ^30,31