The increased risk was found even in children who were iron deficient but hadn't developed anemia. The difference in performance was most striking adolescent girls, who also had the highest prevalence of iron deficiency, said the study lead by Dr. Jill Halterman of the University of Rochester. It published in the June issue the journal Pediatrics. This study suggests that iron deficiency may contribute to this gender discrepancy. Iron deficiency, sometimes because of blood loss or low-iron diets, is the most common cause of anemia, a condition which the blood can't provide adequate oxygen supplies to body tissues.
Adolescent girl are especially prone to iron deficiency because of menstruation.
Previous research has linked iron-deficiency anemia with developmental test scores in young children, but there is less information on older children and on those who were iron deficient but not anemic. The study involved nationally representative data on 5,398 children ages 6 to 16 who participated in a survey from 1988 to 1994. Iron deficiency was found in 3 percent of the children over all, representing 1.2 million school-age children. It occurred in 8.7 percent of the girls ages 12 to 16, including 7 percent without anemia. Average math scores for iron-deficient children with or without anemia were about six points lower than those with normal iron levels.