OBJECTIVES: To estimate the prevalence and workplace consequences of adult attention-deficit/hyperactivity disorder (ADHD). METHODS: An ADHD screen was administered to 18-44-year-old respondents in 10 national surveys in the WHO World Mental Health (WMH) Survey Initiative (n = 7075 in paid or self-employment; response rate 45.9-87.7% across countries). Blinded clinical reappraisal interviews were administered in the USA to calibrate the screen. Days out of role were measured using the WHO Disability Assessment Schedule (WHO-DAS). Questions were also asked about ADHD treatment. RESULTS: An average of 3.5% of workers in the 10 countries were estimated to meet DSM-IV criteria for adult ADHD (inter-quartile range: 1.3-4.9%). ADHD was more common among males than females and less common among professionals than other workers. ADHD was associated with a statistically significant 22.1 annual days of excess lost role performance compared to otherwise similar respondents without ADHD. No difference in the magnitude of this effect was found by occupation, education, age, gender or partner status. This effect was most pronounced in Colombia, Italy, Lebanon and the USA. Although only a small minority of workers with ADHD ever received treatment for this condition, higher proportions were treated for comorbid mental/substance disorders. CONCLUSIONS: ADHD is a relatively common condition among working people in the countries studied and is associated with high work impairment in these countries. This impairment, in conjunction with the low treatment rate and the availability of cost-effective therapies, suggests that ADHD would be a good candidate for targeted workplace screening and treatment programs.

These activities were supported by the United States National Institute of Mental Health (R01MH070884), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the US Public Health Service (R13- MH066849, R01-MH069864, and R01 DA016558), the Fogarty International Center (FIRCA R01-TW006481). The ESEMeD project is funded by the European Commission (Contracts QLG5-1999-01042; SANCO 2004123), the Piedmont Region (Italy), Fondo de Investigación Sanitaria, Instituto de Salud Carlos III, Spain (FIS 00/0028), Ministerio de Ciencia y Tecnología, Spain (SAF 2000-158-CE), Departament de Salut, Generalitat de Catalunya, Spain, Instituto de Salud Carlos III (CIBER CB06/02/0046, RETICS RD06/0011 REM-TAP). The Mexican National Comorbidity Survey (MNCS) is supported by The National Institute of Psychiatry Ramon de la Fuente (INPRFMDIES 4280) and by the National Council on Science and Technology (CONACyT-G30544- H). The US National Comorbidity Survey Replication (NCS-R) is supported by the National Institute of Mental Health (NIMH; U01-MH60220) with supplemental support from the Robert Wood Johnson Foundation (RWJF; Grant 044708)