I thought this might be of interest to folks interested in the physiological aspects of ADHD. Assume the same is likely true for ADD folks, like me, as well.
Title: Current Research on Attention-Deficit Hyperactivity Disorder
Fact: Attention-deficit hyperactivity disorder (ADHD) is a behavioral condition characterized by symptoms of hyperactivity, impulsiveness, and inattention. An objective, biologically based set of criteria for diagnosis of ADHD does not currently exist; however, scientists have recently made progress in identifying several biological components of the condition:
Genetic predisposition: Children with ADHD usually have at least one afflicted family member, and children of fathers with ADHD have a 33 percent greater chance of being diagnosed with the disorder. In addition, among identical twins diagnosed with ADHD, there is a 92 percent chance that both will have the disorder (Faraone, et al. 2000).
Dopamine abnormality: Dopamine- a "feel good" chemical messenger in the brain-helps, among other things, to maintain attention span. A recent study suggests that ADHD patients have a defect in the dopamine transporter gene, which codes for a cell surface protein that removes dopamine from synapses (Barr, et al. 2001). This abnormality leads to increased activity of the transporter protein, resulting in lower then optimal levels of dopamine in the brain (Krause, et al. 2000). When ADHD patients are given medications to inhibit the dopamine transporter, dopamine levels increase and positive behavioral responses and memory improvements are often seen. This suggests that dopamine may play a prominent role in the biological cause of ADHS (Mehta, et al. 2000).
Brain glucose: The rate at which glucose is utilized in the brains of ADHD patients has been shown to be slower in two critical areas that control attentiveness-the frontal lobe and the putamen subregion of the basal ganglia. These two brain regions have also been shown to be smaller in ADHD patients (Hale, et al. 2000).
Treatment: Scientists, using positron emission topography (PET) scans, have determined that the drug Ritalin raises dopamine levels in a region within the basal ganglia called the striatum-a brain area involved in controlling the ability to focus on task accomplishment. The research further suggests that Ritalin raises dopamine levels by blocking the activity of dopamine transporter proteins (Volkow, et al. 2001).
Reference: The Learning Brain, New Briefs and Brain Bytes. Vol. 3, No. 4 (April, 2001)
Excerpted from The LearningBrain News: Visit: www.learningbrain.com