Hyperactivity-Biochemistry Link Probed

Hyperactive boys with low levels of chemicals that transmit nerve impulses performed poorly in reading, spelling and math, suggesting a link between biochemistry and achievement, according to scientists.

Twenty-eight boys, whose disorder was characterized by short attention span, excitability, impulsive behavior and restlessness, were found to have lower levels of two biochemicals than a control group of 23 normal boys.

All 51 boys tested in a three-year UCLA study, the first to link biochemistry to achievement in the three Rs, confirmed earlier research showing that hyperactive boys have lower levels of norepinephine and dopamine byproducts.

But the latest study found that not only do hyperactive boys fail to retain information as well as non-hyperactive children, but those with the lowest levels of homovanilic acid, a dopamine byproduct, had the lowest achievement scores of all.

“There may very well be a relationship between dopamine metabolism and learning abilities,” said Dr. Walid Shekim, a psychiatry professor at the UCLA School of Medicine.

Shekim, who reported results of his study in the Journal of Child Neurology, hopes the findings may lead to development of a medical test for learning disabilities.

“This is probably also true of hyperactive girls,” Shekim said of the relationship between achievement and low levels of certain biochemicals. “We now have to extend these studies to children who have learning disabilities and who are not hyperactive and who do not have attention-deficit disorders.”

Shekim said all the boys in the study, who ranged between 7 and 12 years old, were given a wide range of achievement and intelligence tests and also were regularly tested for levels of neurotransmitter breakdown products.

Neurotransmitters are the biochemical substances that transmit nerve impulses from one nerve cell to another.