Your IQ should remain fairly consistent throughout your life, unless you suffer brain trauma of some sort. My son’s has certainly stayed pretty much the same the two times he has been tested. And he has a “high average” IQ, and ADHD. Average IQ is 100, and the majority of people will be close to that, including those with ADHD.
In response to the subject of ADHD being a developmental disorder – I think it certainly qualifies. My son is below his IQ level when looking at mental maths, written language, ability to express ideas fluently, and reading ability. The best example to explain what I mean is that of reading. Despite having very good reading comprehension, as well as reading ability, he cannot put the two together to read, understand, and follow the story when reading a novel. His ADHD does not allow him to focus on both reading the words AND comprehending the story. His reading comprehension (when read to) is at a 15 1/2 year old level, but his reading ability (including understanding) is at a 12 year old level. He is 14. So he has not developed in a way that his IQ would predict, and he has not developed in the same manner as his “average” peers. There are obvious holes in his academic development, social development, and ways of thinking, that can be attributed to his ADHD. He met all his early developmental milestones, but milestones become more difficult to assess as a child ages, so where do you draw the line at saying whether a disorder is one which affects development or not?!REPORT ABUSE