Heck, my sister was diagnosed (and I wish I had been diagnosed) in the 80's.
Plus, before it got the name ADD (and after, ADHD), it was studied by the names "Hyperactive child syndrome", "Hyperkinetic reaction of childhood", and a few others.
This has been recognized and studied for over a century.
People have been talking like this since at least the 90's and always claiming it's a new, recent, thing.