I don't think the article or the parent comment make any claim that ADHD is not a real disorder. What the study is saying is that children who are relatively y

I don't think the article or the parent comment make any claim that ADHD is not a real disorder. What the study is saying is that children who are relatively young compared to their peers are diagnosed with ADHD at a higher rate because their teachers report them acting in ways "consistent with ADHD" more often than their peers. The physicians use these reports as part of their evidence when making a diagnosis. The explanation is that these children are probably just less mature due to relative age. Their ADHD diagnosis rate is higher than the other group of children, who are essentially the exact same age, but relatively old compared to their classmates.