A current update on ADHD pharmacogenomics.

Pharmacological treatment for attention deficit hyperactivity disorder, although highly effective, presents a marked variability in clinical response, optimal dosage needed and tolerability. Clinical and neurobiological investigations have juxtaposed findings on both response to medication and etiologic factors, generating the hypothesis that genetic factors may underlie differences in treatment outcome. Over the last decade, research has focused on the catecholaminergic system to investigate a potential role of genotype on pharmacological effect. Despite an increasing number of associations reported (for methylphenidate, nine in 2005, 24 in 2008 and 52 reported in the current article), the identification of clinically relevant genetic predictors of treatment response remains a challenge. At present, additional studies are required to allow for a shift from a trial-and-error approach to a more rational pharmacologic regimen that takes into account the likelihood of treatment effectiveness at the individual level.