Over 10% children in the US are living with attention deficit hyperactivity disorder (ADHD), according to a new study. It also suggested that cases of the disorder have surged among girls and minority groups in the US in last few years.

Experts believe surge in confirmed ADHD cases among girls, older kids and Hispanics could be because of better screening among some previously under diagnosed groups. More than 5.5 million kids aged five to 17 years have the neurodevelopmental psychiatric disorder, as per the study which analyzed ADHD cases confirmed by parents from 2003 to 2011.

The study also suggested that disorder diagnosis cases jumped about 43% overall. The diagnosis rate was 8.4% in 2003, while it was 12% in 2011. During the study period, diagnosis among girls in the US jumped more than 50%, from 4.7% in 2003 to more than 7% in 2011. In the same time, prevalence among boys remained higher than girls, the study explained.

Co-author of the study Sean Cleary from George Washington University said it was surprising to notice spike in diagnoses among girls because the disorder is usually detected in boys. “One possibility to explain the increasing trend among females is a greater recognition of ADHD symptoms observed (e.g. withdrawn, internalizing) that is traditionally overlooked because they are not typically considered a sign of this condition”, explained Cleary.

For the study, Cleary and co-author Kevin Collins examined data on over 190,000 US children from surveys in 2003, 2007 and 2011.