To me as a historian, ADHD looks a lot like feeblemindedness.
From the genotopia.scienceblog.com
When is sterilization socially and morally justified to prevent the transmission of feeblemindedness or other handicaps to offspring?
From the time.com
Synthesizing years of observations and testing of slow children, he suggested-counter to all common sense-that feeblemindedness was due to a single Mendelian recessive gene.
From the genotopia.scienceblog.com
More examples
Severe mental deficiency
The term feeble-minded is documented in use as early the 19th century through to the early 20th century as a loose description of a variety of mental deficiencies, including what would now be considered mental retardation in its various types and grades, and learning disabilities such as dyslexia.