I didn’t say it was? Some quick research indicates that the origins of the disease came out of observations of younger children, in which hyperactivity was a clear indicator. As time went on it was realized that other observable symptoms existed in older populations. A link between the symptoms was realized and it was determined they were in fact symptoms of the same disorder. Hence: ADHD. It turns out when doctors came up with the name it was based on the realities of the disorder and not as a slight to the people diagnosed with it.