Background Nonational data on lifetime prevalence andrisk factors for DSM^IV psychiatric disorders are available in Mexico. Aims To presentdata on lifetime prevalence andprojectedlifetimerisk, age atonset and demographic correlates of DSM^IV psychiatric disorders assessed in the Mexican National Comorbidity

Declaration of interest None. Fundingdetailed in Acknowledgements. The Mexican National Comorbidity Survey (Medina-Mora et al, 2005; Borges et al, 2006) is the first nationally representative epidemiological survey of psychiatric disorders in Mexico, and forms part of the World Mental Health Surveys Initiative of the World Health Organization (WHO) (Demyttenaere et al, 2004; Kessler et al, 2004). Previously, DSM– III (Medina-Mora et al, 1993; Caraveo et al, 1996) and DSM–III–R (Caraveo et al, 1998) diagnoses among restricted groups were the only available data for the prevalence of psychiatric disorders in Mexico. In a previous study of the 12-month prevalence, severity and demographic correlates of 16 DSM–IV psychiatric disorders and service utilisation in Mexico (Medina-Mora et al, 2005), we showed that although psychiatric disorders are common, with a 12-month prevalence of 12.1%, very severe mental disorders are less common (prevalence of 3.7%); moreover, there was extreme under-utilisation of mental health services, with only 24% of those more severely affected using any services at all. The most common disorders were specific phobia (4.0%), major depressive disorder (3.7%) and alcohol abuse or dependence (2.2%). Income was associated with severity of illness, with people of low and low–average incomes more likely to report a 12-month disorder. Females were more likely to report a mood and anxiety disorder but less likely to report a substance use disorder. In this paper, we report the lifetime prevalence and the projected lifetime risk of DSM–IV psychiatric disorders in the Mexican population. We expand prior analyses of age at onset of major depression in Mexico (Benjet et al, 2004) to other psychiatric disorders which are now more common among youths in Mexico, and investigate whether new cohorts are at an increased risk, especially for substance use disorders (Villatoro et al, 2005). METHOD