Definition of anxiety

Anxiety is considered to be a universal adaptive response to a threat; this response can, however, become maladaptive. The distinction between abnormal and normal anxiety occurs when the anxiety is out of proportion to the level of threat or when there are symptoms that are unacceptable regardless of the level of threat, including recurrent panic attacks, severe physical symptoms and abnormal beliefs such as fear of sudden death. Abnormal anxiety is present when it causes ‘unacceptable and disruptive problems in its own right’ (House & Stark, 2002).

Epidemiology and classification

Anxiety disorders are usually the most common mental health condition in community settings (Kessler et al, 2005) and are responsible for more than 50% of the diagnosable mental health conditions in international prevalence surveys (Bijl et al, 2003). The same is also true in primary care settings, where as many as 20% of patients have an anxiety condition based on the categories of DSM–IV (American Psychiatric Association, 2000).

In primary care, anxiety disorders overall are more common in women (26%) than in men (12%) and more common in young people than in older people (25–44 years versus 65 or older). In young women, the prevalence is as high as 35%, compared with only 8% in older women. A similar decline with age occurs in men but with lower prevalence rates (MaGPIe Research Group, 2005). Recent research has shown that about half of adults with anxiety disorders have had psychiatric problems in childhood, emphasising the scope for early diagnosis (Gregory et al, 2007).

Burden of anxiety disorders

Among the various subcategories of anxiety disorders, as many as half are single phobias such as fear of spiders, fear of flying and so on, which do not interfere with functioning on a daily basis. However, generalised anxiety disorder (GAD), panic disorder, post-traumatic stress disorder (PTSD), obsessive–compulsive disorder (OCD), social phobia and agoraphobia are more pervasive and disabling conditions, which between them are as common as depression (Table 10.1).

Follow-up studies suggest that GAD, panic disorder and social phobia have a chronic clinical course, low rates of recovery and high probabilities of recurrence (Bruce et al, 2005). The presence of comorbid psychiatric disorders significantly lowers the likelihood of recovery from anxiety disorders.