A number of behaviors that are frequently found associated with people who have ADHD, seem to be coping strategies. Thus these behaviors help to reduce stress associated with ADHD even though they may appear to be symptoms of the disorder and a part of the problem.
One behavior is procrastination. Deadline pressure seems to help someone with ADHD to complete a task. It appears that the brain of someone with ADHD. has to use energy that is usually reserved for emergencies or novel learning activities to concentrate and focus. Their brain is reluctant to do this and it seems that deadline pressure convinces their brain to use this energy to focus at least for a limited period of time. That may be why people with ADHD are more successful using procrastination to complete tasks than other people are.
Another behavior is irritability. Irritability occurs around people and may be held in check and not revealed to others. The irritability is not part of mood problems and seems to serve to remove someone with ADHD from the presence of others. This reduces stress as interacting with people requires a lot of concentration and attention.
An additional behavior is a tendency to interrupt others. This "impulsive behavior" is necessary to pass on some information that the person with ADHD will very likely not be able to remember if they wait until it is their turn during the conversation.
Additionally, people with ADHD have to use a different part of their brain to concentratea and the energy used to concentrate is depleted rapidly. Thus later in the day, when the child with ADHD is with their family or the adult with ADHD is with their significant other or spouse and/or children, the person with ADHD will have very little concentration left and will likely be quite irritable if they have to interact with others or they will isolate themselves from others.
Obviously, the above coping strategies frequently leads to stress in relationships, unhappiness and feelings of being a failure.
These coping strategies are not necessary [but may persist] after medication treatment has begun along with cognitive and behavioral strategies. Thus treatment can relieve a lot of stress that the person with ADHD experiences before treatment.