Researchers have been unable to pinpoint one cause of attention-deficit/hyperactivity disorder in children. there are several factors that can contribute to the existence of the disorder. not only might each of these factors have a direct impact on the disorder but they may interact with and affect each other in countless different ways. this is a good example of the of people that makes humans difficult to study.

Complexity

Explanation: Attention deficit hyperactivity disorder(ADHD) is a type of mental disorder .As this activity is related with the brain , the person having this disorder can behave in showing excessive activity, , not paying attention etc.

These are brain related acts which are not bound with the particular reason and symptoms as every person have different thoughts,response etc toward a certain situation . It could impact any person of any age due to several reason and can also affect others with such behavior .Thus ADHD is a case of complexity which is difficult to be analyzed and studied by human being.

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