This is an interesting question and the answer can depend on which expert you consult. To some people there is no difference between ADHD (Attention Deficit Hyperactive Disorder) and ADD (Attention Deficit Disorder) or, the differences are so subtle that only a trained professional will understand them.
Some suggest it’s as if a team of experts studied human behaviour and believed that their patients are hyperactive in certain aspects of life and called this behavior ADHD while in another country another group of experts carried out similar research and labelled their patients as having ADD.
One of the reasons for the possible confusion is that ADD was the name given to the hyperactive behavior found in some children but later studies referred to the disorder as ADHD. So to some, ADD is simply a synonym of ADHD.
Aspects which are common to both ADD and ADHD are that the subject has difficulty maintaining attention and is easily distracted and will interrupt others without knowing they are doing that. It’s often found that they talk too much. Then the subject often appears to be listening but in fact is not and is thus unable to complete the allotted tasks. One common trait is that external things –people, actions outside a room, music, films, etc will grab the attention of the subject. Then there is the inability to complete a task either because they misplace materials or forget the steps needed to complete the task.
Finally it is not unusual for hyperactive people to get their organizational skills not to function properly. Even a simple task will not be completed and often the subject will switch from one task to another midstream. This swapping of horses can take place even if the tasks are quite simple in operation and degree of difficulty is low. To compound this aspect of their behavior, the subject will often become impatient.
It’s possible to distinguish between variation of ADHD with one type being labeled Inattentive ADHD and the other Hyperactive ADHD. For a person to be diagnosed with Inattentive ADHD it means that the hyperactive aspects of their ADHD disorder are not as prominent as someone with Hyperactive ADHD. It’s a small but measurable distinction.
One doubly frustrating aspect of ADD and ADHD for parents of children diagnosed with the condition is the mistaken claim that it is not a disorder at all. Some falsely claim it is simply children being exuberant or super busy and, to make a bad claim even worse, that the cause of the behavior is bad parenting.
Both claims are clearly wrong as all branches of the medical profession regard ADHD and ADD as distinguishable disorders and, while not being able to positively identify the cause or causes, certainly place no credence on claims that the parents are to blame.
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