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Correct. They are two different strands of the same condition. Inattentive type is what is generally referred to as ADD without physical hyperactivity. ADHD has a physical component as well. The kids I knew in school growing up who were diagnosed with ADHD were those who, in addition to what was going on in their brain, couldn't control themselves physically either. They were the ones always wrestling with you, jumping on you etc. for no apparent reason.

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3 strands. ADHD Combined is also a subtype.

The current theory suggests that ADHD is caused by a mild disorder somewhere between when dopamine is released to communicate between the brain's neurons via synapses and when most of it is reuptaken back into the brain's dopamine bank and the rest is transported to other parts of the body. Some of this dopamine is converted in norepinephrine (adrenaline).

Explained in the simplest way, ADHD is caused either when not enough dopamine is let out, too much dopamine is reuptaken back into the storage and transported to become norepinephrine, and/or norepinephrine is reuptaken too fast.

This is why, theoretically, different ADHD medications are only effective on different types of ADHD patients.

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