Neurotransmitters and ADHD have been shown to be related because the majority of children diagnosed with Attention Deficit Hyperactivity Disorder present with clinical symptoms of neurotransmitter imbalance and dysfunction. Certain common neurotransmitters and ADHD are linked in that anomalies within the neurotransmitter’s mechanisms of production, transport, and reuptake are hypothesized to be present and are sometimes readily apparent in brain imaging of ADHD patients. The neurotransmitters dopamine, norepinephrine, and serotonin are the most well-researched and most commonly targeted in ADHD treatment. Low dopamine, for example, is thought to be the cause of many of the primary symptoms of the disorder and is treated with stimulant-type drugs that help the body to produce, transport, and metabolize the neurotransmitter more efficiently. Norepinephrine and serotonin are newer additions in the hypothesized etiology of ADHD; drugs that target these neurotransmitters are used in treatment as well.
In addition, neurotransmitters and ADHD are related in that certain neurotransmitter gene mutations may account for the subsets seen within an ADHD diagnosis. Research suggests that patients with a predominantly inattentive form of the disorder have anomalies on the norepinephrine transporter gene, whereas those who have more hyperactive symptoms have abnormalities on the dopamine transport gene. Vanderbilt University Research Center reports that abnormalities may be present in the brain’s choline transport system as well, which plays a significant part in neuronal communication, having action comparable to both dopamine and norepinephrine. This research shows that newer, more targeted ADHD medications may be on the horizon. Genetic testing may become an invaluable tool in determining which medication approach to take first; an advantage that is especially appreciated when young children are being prescribed powerful psychoactive drugs.
The relationship between neurotransmitters and ADHD was further examined by researchers at Duke University. Researchers concluded that Ritalin, a drug often used as first line defense in ADHD treatment, acts profoundly on serotonin receptor sites in addition to dopamine receptor sites. Further testing proved that treatment with certain serotogenic agents, like selective serotonin reuptake inhibitors (SSRIS), can help to reduce hyperactivity in some patients. In addition, low serotonin levels are associated with aggressiveness and agitation, both symptoms in some cases of ADHD. Serotonin is mediated by 15 separate receptors within the brain, however, making targeted serotogenic treatment a challenge.
Other neurotransmitters and ADHD are showing signs that they may be correlated. Phenylethlamine (PEA), identified as a neurotransmitter in 2001, increases activity and alertness in the brain. For this reason, researchers look to PEA as being implicated in some cases of ADHD. In addition, dopamine and PEA are closely related in chemical structure, lending more credibility to the hypothesis.