Stress is the uncomfortable feeling in your gut when your nervous system senses conflict. We all feel stress at times, and much of this post applies to all human beings, not just people with ADHD. The negative feeling of stress motivates people to act to end the conflict swiftly. When that motivation is acted upon without pause for thought, bigger problems are usually created.
Barkley has talked about the issues of emotional regulation in ADHD. What I missed the first couple times I watched the video was the role the anterior cingulate plays in resolving CONFLICT. Many times in the past when I have been insulted, I have reacted with a verbal counter-attack. Like all other children, I was taught to be polite in the presence of adults, even if they behaved offensively. When a child is five years old and an adult tells them the painting they just finished is ugly, few are surprised when the child responds "Well you are ugly!" By twenty-five, that child is expected to behave like other adults. When someone insults me, like many people, I instantly feel angry. Anger motivates people to fight, and besides Barkley's physical example, the attack can be verbal. Everyone has experienced times when they failed to suppress a verbal attack. For people with ADHD it is much more difficult to suppress those motivations. And as Barkley showed, this capability is limited by the physical characteristics of the brain. Since it is invisible, people don't consider it when they set expectations like they do for visible capabilities. We don't expect the small, weak child to carry the same weight of groceries as the stocky and strong child. However, since nobody could see the size of my anterior cingulate, I was expected to control my temper the same as everyone else.
I read a family court case in Virginia that happened a few years ago. A father lost his temper while arguing over custody of his daughter. The judge ordered him to sit and be quiet. He turned around to leave. The judge ordered the bailiff to restrain the man. The man swore at the bailiff and yelled, "I need to take a walk!" In a matter of seconds, the judge summarily found the man guilty of criminal contempt and sentenced him to 10 days in jail. What typically happens afterwards is the man is required to attend an anger management group after his release. The group therapist will think that they can teach him to manage his temper, and if he doesn't respond he will be dismissed as being defiant and angry. A few sociologist know ADHD is 4-8 times more prevalent in criminals and are able to recognize it. However they are not licensed to make a diagnosis or prescribe medication, and in many jurisdictions they cannot make referrals to a psychiatrist. Since social workers want to help people, they are going to look for ways they can help. Since they can't help people with ADHD (or other psychiatric disorder for that matter), they aren't going to look for ADHD.
When I am able to suppress my urge to attack, the anger subsides and I'm left with a churning feeling in my gut. I'm feeling conflicted since I know I shouldn't react despite the urge I'm feeling. The capability to self-regulate is very important in this context. Most people can easily use the anterior cingulate in their thinking brain to tell their emotional brain, "Shut up and stop making me feel like I'm going to puke up my lunch!" When that doesn't work, it's a good idea to get up, go for a walk, and calm down. However in situations where you are expected or required to stay like the man in court, the stress remains, making it even easier to blow up at the next irritating situation.