Epidemiology

GAD has an estimated lifetime prevalence of 9% and a 1-year prevalence of 2.9% in the US.[1] In Europe, estimates for 1-month prevalence are approximately 0.2% to 1.5%, with a lifetime prevalence of around 1% to 7%. Around 4.0% to 7.9% of primary care patients and 22.0% of people presenting with anxiety are diagnosed with GAD.[4][5]

GAD is more common in high-income countries than in lower-income countries, where the reported prevalence can be under 1%.[4] Differences in estimates of disease prevalence in the US and internationally are likely to be due to several factors, including methodological differences and cultural differences in attitudes towards mental health disorders, in addition to actual differences between populations.[6][7]​​​​ There is a robust and growing body of evidence to suggest that the COVID-19 pandemic was associated with a rapid increase in prevalence of anxiety disorders globally.[8][9]​​​​ One study has estimated that the pandemic has resulted in an additional 76.2 million cases of anxiety disorders globally (an increase of 25.6%).[8] The longer-term impact of this is currently unclear.

GAD usually starts in adulthood and persists over time. Onset is reported to be later, and clinical course more persistent, in lower-income countries. GAD is the commonest anxiety disorder in old age, with prevalence ranging from 1.3% to 4.7%.[10]

About two-thirds of patients diagnosed with GAD are female, and more women (55% to 60%) than men are diagnosed in clinical settings.[1][7][11]

There is a higher prevalence of GAD during pregnancy and shortly after birth. Prevalence estimates during pregnancy and the postnatal period range from around 2.2% to 10%.[12][13]​​​​

Studies in several countries have shown that GAD commonly occurs along with, and often precedes, other mental health disorders.[4][5][6][7][14][15]​​​ The lifetime prevalence of depression is approximately 43% in people with GAD.[16]​ Comorbidity among anxiety disorders is substantial; 48% to 68% of adults with one anxiety disorder fulfil the criteria for another concurrent anxiety disorder.[17]

Prevalence of anxiety disorders also appears to be higher in people with chronic physical health conditions, including cardiovascular disease, cancer, respiratory disease, diabetes, and polycystic ovary syndrome.[10] GAD is associated with significant disability, affecting people's work and ability to carry out daily activities. 

Treatment is sought by approximately half of people affected by GAD.[4] A large US epidemiological study found that almost half of people with GAD retained the diagnosis after 2 years.[14] 

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