A Different Kind of Sign Language

Researchers find certain children's hand movements may be associated with ADHD

(RxWiki News) Researchers have discovered markers for measuring the ability of children with Attention Deficit Hyperactivity Disorder to control impulsive movements.

The finding from researchers at the Kennedy Krieger Institute in Baltimore, MD, and the Cincinnati Children's Hospital Medical Center may lead to better understanding of the neurobiological processes involved in ADHD.

According to the study, children with ADHD performing a finger-tapping task showed more than twice the amount of so-called overflow movements (movements in the opposite hand) than typically developing children. This marks the first instance in which scientists have been able to quantify the degree to which ADHD affects motor control.

Dr. Stewart Mostofsky, the study's senior author and Director of the Laboratory for Neurocognitive and Imaging Research at the Kennedy Krieger Institute said there is a lack of understanding about the neurobiological basis of ADHD because of thus-far unavailable quantifiable evidence.

Researchers looked at 50 right-handed children between 8 and 12 years old, half of whom had been diagnosed with ADHD, and found that during a left-handed finger-tapping exercise in which the children tapped each finger to the thumb of the same hand, children with ADHD showed more than twice as much mirror overflow than typically developing children. (Mirror overflow refers to unintentional, unnecessary movements occurring in the same muscles on the opposite side of the body.)

Children with ADHD also showed a considerable decrease in SICI (short interval cortical inhibition -- measurements of muscle movements according to brain activity) with significantly less inhibition of motor activity compared to typically developing children.

Dr. Donald Gilbert, study author and Director of the Transcranial Magnetic Stimulation Laboratory at the Cincinnati Children's Hospital Medical Center said the study. ADHD is the most common behavioral diagnosis in U.S. children.

Review Date: 
February 16, 2011