Drug policy and treatment bias due to the dopamine-deficit theory of child attention-deficit hyperactivity disorder.

Abnormal dopamine (DA) transporter functioning has long been suspected to be involved in attention-deficit hyperactivity disorder (ADHD). My extensive search on theories concerning ADHD included: CENTRAL, MEDLINE, EMBASE, CINAHL, ERIC, PsycINFO, Complementary and Alternative Medicine-specific databases, Informit, JST, plus grey literature and trial registries from inception to May 2010. A new understanding of ADHD pathophysiology is required. DA-deficit theory of ADHD is insufficient to cover critical aspects of ADHD pathology and medication. The dominance of this theory discourages the human and financial investments needed to explore alternative theories and has caused an evident bias in health and drug policies. A combined theory of altered DA and serotonin (5HT), deficit DA, and weakened prefrontal cortex (PFC) circuits may serve as a good alternate to DA-theory alone. This combined theory may influence the future of drug polices, pharmaceutical investments, treatment options, and drug developments.