Background: Traumatic events are common globally; however, comprehensive population-based cross-national data on the epidemiology of posttraumatic stress disorder (PTSD), the paradigmatic trauma-related mental disorder, are lacking.Methods: Data were analyzed from 26 population surveys in the World Health Organization World Mental Health Surveys. A total of 71 083 respondents ages 18+ participated. The Composite International Diagnostic Interview assessed exposure to traumatic events as well as 30-day, 12-month, and lifetime PTSD. Respondents were also assessed for treatment in the 12 months preceding the survey. Age of onset distributions were examined by country income level. Associations of PTSD were examined with country income, world region, and respondent demographics.Results: The cross-national lifetime prevalence of PTSD was 3.9% in the total sample and 5.6% among the trauma exposed. Half of respondents with PTSD reported persistent symptoms. Treatment seeking in high-income countries (53.5%) was roughly double that in low-lower middle income (22.8%) and upper-middle income (28.7%) countries. Social disadvantage, including younger age, female sex, being unmarried, being less educated, having lower household income, and being unemployed, was associated with increased risk of lifetime PTSD among the trauma exposed.Conclusions: PTSD is prevalent cross-nationally, with half of all global cases being persistent. Only half of those with severe PTSD report receiving any treatment and only a minority receive specialty mental health care. Striking disparities in PTSD treatment exist by country income level. Increasing access to effective treatment, especially in low- and middle-income countries, remains critical for reducing the population burden of PTSD.

Comorbidity, defined as the presence of 1 or more disorders in relation to an index disorder,¹ has been the focus of a substantial body of research during the 5 decades since the term was introduced.² In the mental health field, it is widely acknowledged that individuals treated for incident mental disorders are at increased risk of subsequently developing other mental disorders.³ Based on a survey of mental health among adolescents 13 to 17 years of age, Kessler et al⁴ reported that 27.9% of respondents met criteria for 2 or more disorders. Several community surveys have reported that, among respondents with at least 1 mental disorder, 45% to 54% have 1 or more additional lifetime diagnoses.^3,5,6

Much evidence has accrued from record linkage and clinical studies attesting to the higher incidence of chronic physical conditions and associated earlier mortality among individuals with severe mental illness,^1-3 as well as among those with common mental disorders.^4-7 However, the findings of these studies are limited to those who receive treatment,¹ so it is less clear whether mental disorders in the community (untreated and treated) might be linked with subsequent risk of chronic physical conditions. It also remains unclear as to how generalized these associations might be across a range of physical health outcomes. This information has important implications for mental health care and the primary prevention of chronic physical disease.

There is evidence that social anxiety disorder (SAD) is a prevalent and disabling disorder. However, most of the available data on the epidemiology of this condition originate from high income countries in the West. The World Mental Health (WMH) Survey Initiative provides an opportunity to investigate the prevalence, course, impairment, socio-demographic correlates, comorbidity, and treatment of this condition across a range of high, middle, and low income countries in different geographic regions of the world, and to address the question of whether differences in SAD merely reflect differences in threshold for diagnosis. Data from 28 community surveys in the WMH Survey Initiative, with 142,405 respondents, were analyzed. We assessed the 30-day, 12-month, and lifetime prevalence of SAD, age of onset, and severity of role impairment associated with SAD, across countries. In addition, we investigated socio-demographic correlates of SAD, comorbidity of SAD with other mental disorders, and treatment of SAD in the combined sample. Cross-tabulations were used to calculate prevalence, impairment, comorbidity, and treatment. Survival analysis was used to estimate age of onset, and logistic regression and survival analyses were used to examine socio-demographic correlates. SAD 30-day, 12-month, and lifetime prevalence estimates are 1.3, 2.4, and 4.0% across all countries. SAD prevalence rates are lowest in low/lower-middle income countries and in the African and Eastern Mediterranean regions, and highest in high income countries and in the Americas and the Western Pacific regions. Age of onset is early across the globe, and persistence is highest in upper-middle income countries, Africa, and the Eastern Mediterranean. There are some differences in domains of severe role impairment by country income level and geographic region, but there are no significant differences across different income level and geographic region in the proportion of respondents with any severe role impairment. Also, across countries SAD is associated with specific socio-demographic features (younger age, female gender, unmarried status, lower education, and lower income) and with similar patterns of comorbidity. Treatment rates for those with any impairment are lowest in low/lower-middle income countries and highest in high income countries. While differences in SAD prevalence across countries are apparent, we found a number of consistent patterns across the globe, including early age of onset, persistence, impairment in multiple domains, as well as characteristic socio-demographic correlates and associated psychiatric comorbidities. In addition, while there are some differences in the patterns of impairment associated with SAD across the globe, key similarities suggest that the threshold for diagnosis is similar regardless of country income levels or geographic location. Taken together, these cross-national data emphasize the international clinical and public health significance of SAD.

In recent years, interest in the epidemiologic landscape of hallucinations and delusions has grown.^1,2 These psychotic experiences (PEs) are reported by a sizeable minority of the general population. A recent meta-analysis based on 61 studies² reported that the median lifetime prevalence of PE was 7.2%. Because this prevalence is substantially higher than the lifetime morbid risk for psychotic disorders, such as schizophrenia (median morbid risk, 0.7%),³ the field of psychiatric epidemiology has been forced to rethink how PEs fit into the epidemiologic landscape of psychotic disorders. The terms used to describe these experiences have also evolved over time. Although psychoticlike experiences has been used, we will use the general term psychotic experiences to encompass hallucinatory experiences (HEs) and delusional experiences (DEs).²

Understanding of generalized anxiety disorder (GAD) has lagged behind understanding of other anxiety disorders.^1,2 Since its introduction in DSM-III,³ the GAD diagnosis has undergone frequent substantial revision, challenging efforts to accumulate a knowledge base for the disorder. Originally, GAD was considered a “wastebasket diagnosis” presumed to be associated with fairly modest impairment.^4,5 Although GAD has evolved into a well-defined condition characterized by excessive, uncontrollable worry, the assumption that GAD is associated with relatively minimal impairment has persisted in some circles, with the term “worried well” sometimes used to describe affected individuals.^1,6 This assumption may partially account for lower clinical and research attention to GAD than to other emotional disorders.^7,8