After re-reading the help questions I think this belongs here as I am more interested in the biochemical motivations rather than any medical query or advice(but may also fit Chemistry SE).
So from what I know, Adderall consists mainly of 2 compounds, those being Dextroamphetamine and Levoamphetamine(enantiomers) broken up among 4 'salts' most of which are sulfates and saccharates.
Biochemically, Levoamphetamine affects the PNS primarily and Dex the CNS. Why is Adderall preffered over straight Dextroamphetamine for the treatment of ADHD wrt the biochemical pathways? I can't find any studies linking ADHD to any PNS mechanisms.