Less restrictive diagnostic criteria have contributed to a steep rise in diagnoses for the behavioral brain condition -particularly among children - the researchers said, and in the use of stimulant drugs to manage it.
The broader definition also "devalues the diagnosis in those with serious problems", said Rae Thomas, a senior researcher at Australia's Bond University who led an analysis of the problem and has published it in the British Medical Journal.
"The broadening of the diagnostic criteria is likely to increase what is already a significant concern about overdiagnosis," he said. "It risks resulting in a diagnosis of ADHD being regarded with skepticism, to the harm of those with severe problems who unquestionably need sensitive, skilled specialist help and support."
People with the ADHD are excessively restless, impulsive and easily distracted, and children with the condition often have trouble in school. It is most often diagnosed in children, mainly boys, but it is also known to persist into adulthood.
There is no cure, but the symptoms can be kept in check by a combination of behavioral therapy and medications such as Ritalin or a newer drug called Vyvanse.
Image: Hyper boy, via Shutterstock