Recent developments in the study of the condition have helped increase the
life expectancy of people with Downs massively - it was about 20 thirty years ago, and well over 40 now. The "low
IQ" is largely the product of neurological auditory problems, particularly with short-term auditory memory; it's difficult to follow speech if you can't remember the beginning of the word when the speaker gets to the end of it, hence more a legitimate case of the phrase "learning difficulties": delayed
speech development tends to knock on all the way through education, of course, as a result of which most people with Downs are denied any chance of academic achievement, largely by virtue of being hived off into
ghettos for easy containment. However, approaches using
sign language from an early age alongside speech therapy have proven very successful, and in more
enlightened societies (and
Great Britain, too) Downs children are increasingly being educated within mainstream systems.
Subtext: you reckon my kid's unintelligent? No way. He's a destructive monster with whom it is impossible to reason, much like most other two nine year olds, but with impressive reserves of practical problem solving ability, as you would realise if you ever tried to keep him indoors when he wants to go outdoors for an unsupervised wander.