A diagnosis of ADHD often comes as a surprise for adults. Some experts estimate that as many as 75 percent of adults with ADHD don’t know they have it. This might be because it was once considered a “childhood disorder” and it was thought that by the time you ended puberty, you outgrew it. It was also considered a “male disorder,” which means women were much less likely to be diagnosed with ADHD as a child. Today, more and more adults are being diagnosed with ADHD. Sometimes this happens when their child is diagnosed and they realize they share many of the same symptoms, such as lack of focus.