Causes
The exact cause of ADHD is yet to be discovered. However, lots of research has examined different possible explanations of ADHD.
Genetic and Neurological:
ADHD seems to be partly caused by your genetic makeup. ADHD is more common in relatives of people with ADHD than people without, and a twin is much more likely again to have ADHD if their twin brother/sister has it (1). However, it is important to understand that having someone in your family with ADHD does not mean you will definitely have ADHD. Having the genes for ADHD does not cause you to have the disorder; it just means that you may have it.
People with ADHD have been shown to have different levels of activity in certain areas of the brain, such as the areas at the front of the brain which are involved in planning and control of behaviour. Also, the areas of the brain that are involved in controlling movement show differences. This may be why children with ADHD seem to fidget and move uncontrollably.
Cognitive:
Researchers also come up with models of how the core symptoms of ADHD affect the other areas of someone’s life. For example, the model below shows how problems of inattention, hyperactivity, and impulsivity may cascade to affect their life.
An example of this model would be Sam, who has just got a new job. On Sam’s first project, he doesn’t meet his deadline due to procrastination and an inability to organise all the things he needs to get the job done. Sam then feels negative about himself and thinks ‘I can’t do this job, I should never have got it anyway’. This makes him feel depressed for not feeling competent enough, guilty for taking a job he thinks someone else may have been able to do, and angry that he wasn’t able to concentrate to get the job done. These emotions make it even harder for him to organise and plan his next job, and the cycle continues.
This model may not explain everybody’s experience of adult ADHD. However, it can be useful in identifying what changes you can make if you have adult ADHD and want to do something about it.
References:
(1) Biederman J, Faraone SV, Mick E, et al. (1995). High risk for attention deficit hyperactivity disorder among children of parents with childhood onset of the disorder: a pilot study. Am J Psychiatry. 152:431–435.
