Attention Deficit Hyperactivity Disorder (ADHD) was a disorder characterised by compulsively unfocused behaviour. (PROSE: The Least Important Man [+]Steven Moffat, Professor Bernice Summerfield and the Dead Men Diaries (Bernice Summerfield short stories, 2000).)
Gavin Oliver Scott was a "habitually dreamy" child. Professor Milligan postulated he had attention deficit disorder but this was disputed by Kent-Green. (PROSE: The Least Important Man [+]Steven Moffat, Professor Bernice Summerfield and the Dead Men Diaries (Bernice Summerfield short stories, 2000).)
Panda said the Hither were an entire culture suffering from ADHD. (PROSE: Lieut. Gullivar Jones: His Bad Weekend [+]Daniel Tessier, Iris Wildthyme of Mars (Iris Wildthyme, 2014).)
Reliable remedies were available for ADHD by 2036. (PROSE: Artificial Intelligence [+]Andy Campbell, Short Trips: 2040 (Short Trips short stories, 2004).)
Donna Noble didn't give the Tenth Doctor coffee because he was "last person [she would] give caffeine". She told Silvi to search ADHD and joked that the Doctor's picture would come up. (AUDIO: Technophobia [+]Matt Fitton, The Tenth Doctor Adventures (Big Finish Productions, 2016).)
Clara Oswald told the Twelfth Doctor he had "Attention Deficit something or other". (TV: The Doctor's Meditation [+]Steven Moffat, Prequels (BBC America, 2015).)