ADHD stands for Attention-Deficit Hyperactivity Disorder. It is a life-long disorder (though children and teens tend to be most strongly affected, growing out of some of the hyperactivity as they get older). ADHD is characterized by inattention, hyperactivity, forgetfulness, disorganization, poor impulse control, and distractibility; a non-hyperactive variant exists and is more common among girls.
Having ADHD may make it easier to navigate HQ.
Many Suethors apparently have some form of ADHD unrecognized by medical science which leads them to post weird stories at 2am, then whinge about flamers because "I have ADHD" (which is, somehow, supposed to be an excuse) when they are told that their story is dreadful. Since part of learning to live with ADHD is learning to compensate for one's own impulsiveness and disorganization, a large part of which is learning to anticipate consequences, these Suethors' ADHD is no reason not to leave them constructive criticism, and also not a reason that they could not become good writers.
Several PPC Boarders also have ADHD. Many of them find that a dependable beta reader is one of the ADHD writer's most important assets, since they can catch the absent-minded mistakes that may be missed on the first couple (or first dozen) readings. Some believe that the ADHD brain is better at lateral thinking because of the random topic-to-topic switches that can lead the person way off track or just be utterly silly... but can also make it easier to think of new ideas. At least one boarder carries a PDA so that new ideas don't get lost in the general absent-minded chaos.