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It seems that this study didn't consider the etiological factors
which other studies showed. Although it is believed that there is no
specific cause of ADHD known, some studies indicate that the
disorder is highly heritable and that genetics cause about 75% of ADHD
cases. Hyperactivity also seems to be primarily a genetic condition,
however other causes do have an effect, including difficulties with
pregnancy, birth, early childhood severe illness, and environmental
Considering the different groups in this study might obligate taking
these etiological factors into consideration, and rolling them out might give
more credence to the conclusion that medically
attended injury before the age of 2 may be a marker for subsequent diagnosis of
1. "Stimulant medication for the treatment of attention-deficit
hyperactivity disorder: evidence-b(i)ased practice? -- Bailly 29 (8): 284
-- Psychiatric Bulletin".
2. "CG72 Attention deficit hyperactivity disorder (ADHD): full guideline".
NHS (24 September 2008). Retrieved on 2008-10-08