The cause of attention deficit hyperactivity disorder (ADHD) has long puzzled doctors and scientists. The most commonly held theory is that a chemical imbalance in the brain is behind the disorder's symptoms -- inattention, lack of focus, impulsive behavior and often hyperactivity. But now a new and promising study indicates that children with ADHD have a functional abnormality in a neurological pathway, and this may be at least part of the disorder's genesis. Manzar Ashtari, PhD, an associate professor of radiology and psychiatry at North Shore Long Island Jewish Health System in New Hyde Park, New York, was the lead researcher. I spoke with her about the study, which included 18 children with ADHD and a control group of 15 non-ADHD children, all ages seven to 11. Through scans, the research team discovered that the ADHD children had subtle differences in a brain circuit that leads from the brain stem to the frontal area. This is the circuit that regulates behaviors having to do with attention, impulsive behavior, inhibition and motor activity -- all, of course, associated with ADHD. Furthermore, Dr. Ashtari says that this might be the same circuit that transports certain brain chemicals from one part of the brain to another. If so, this finding could be the missing link between neurological chemical imbalances and anatomical irregularities as the cause of ADHD.
Based on past research findings regarding the effects of stimulant medication and the possibility that children grow out of ADHD due to physiological development, Dr. Ashtari is putting together a carefully controlled study with funding from the National Institute of Mental Health. It will follow medicated ADHD, non-medicated ADHD and normal children for a year-and-a-half to see what impact the drugs have on brain normalization as opposed to what evolves from a normal physiological change. Stay tuned.