This review looked at studies of adults with ADHD published over about the past ten years. The authors say the condition is often missed in many parts of the world, and they found few studies that examined how culture affects diagnosis. They point to several reasons adults go undiagnosed: doctors are unfamiliar with the disorder, the DSM-IV criteria were not designed or tested for adults, people are not accurate when recalling childhood symptoms, other conditions occur alongside ADHD, and health systems and cultures differ.
The review pulled figures from other studies. It estimates that between 2.3% and 4.5% of adults worldwide have ADHD, and that fewer than one in three are diagnosed in the United States. In one survey of 400 US primary care doctors, nearly half felt uncomfortable diagnosing adults (48%) and many said no clear criteria exist for adults (44%). Adults with ADHD were less likely to work full time (34% versus 59% of matched controls) and more likely to have an accident claim (38% versus 18%). Their medical costs were higher (about $5,651 versus $2,771). This is a narrative review funded by a drug company, and it cites studies rather than searching them systematically.
The authors suggest a positive rating-scale result should be followed by a full diagnostic assessment, including a clinical interview, to confirm ADHD.
Source: Asherson P, Akehurst R, Kooij J, et al.. Under Diagnosis of Adult ADHD. Journal of Attention Disorders (2012). doi:10.1177/1087054711435360