Nero-Chemical Inbalance

There is increasing evidence that variants in the gene for the dopamine transporter are related to the development of ADHD (Roman et al., 2004, American Journal of Pharmacogenomics 4:83-92). This evidence is consonant with the theory of inefficacy of dopamine in people with ADD/ADHD; according to other recent studies, people with ADHD usually have relatively high dopamine transporter levels, which clears dopamine from between neurons before the full effect is gained from dopamine. Stimulant medications used to treat ADHD are all capable of either inhibiting the action of dopamine transporter (as methylphenidate does) or promoting the release of dopamine itself (as the amphetamine-class medications do). Therefore, it is theorized that stimulant medication allows the brain to enhance the effect of dopamine by blocking dopamine transporters or increasing the release of dopamine. Currently this is the most widely accepted model of ADD/ADHD etiology in the scientific and medical community.