Children with ADHD (attention deficit hyperactivity disorder) have a higher chance of having WLD (written language disorder).
Although the risk is greater for both sexes with ADHD, girls with ADHD have a higher chance of having WLD together with reading difficulties than boys with ADHD, researchers from Mayo Clinic in Rochester, Minn., and Children's Hospital Boston reported in the journal Pediatrics.
Kouichi Yoshimasu, M.D. and team set out to determine what percentage of children - 5,718 of them, 2,762 girls and 2,956 boys - had WLD. Some of the children had ADHD, while others did not.
They were all born in Rochester between 1976 and 1982 and were still there when they were five years old. They gathered information from school, private tutorial and medical records. They calculated cumulative incidences of WLD, hazard ratios (HRs) and with or without RD.
Author Dr. Slavica Katusic explained that problems with reading and math will usually catch a teacher's attention, whereas writing difficulties are often overlooked.
The USA has one of the highest rates of ADHD in children in the world. The CDC (Centers for Disease Control and Prevention) estimates that up to 10% of 4 to 17 year old American kids have ADHD.
The investigators found that for boys and girls with ADHD, there was a considerably higher cumulative WLD rate by the time they were 19 years old, compared to children without ADHD. 64.5% of boys with ADHD and 16.5% of boys without ADHD had WLD by 19 years of age, compared to 57% and 9.4% among the girls.
Girls with ADHD were found to have a higher risk of having WLD combined with reading difficulties than boys with ADHD. The chances of having just WLD for both girls and boys with ADHD was similar.
The authors concluded:
"ADHD is strongly associated with an increased risk of WLD (with or without RD) for both boys and girls. Girls with ADHD are at higher risk of having WLD with RD compared with boys with ADHD, whereas boys and girls are at the same risk of having WLD without RD."
"Written-Language Disorder Among Children With and Without ADHD in a Population-Based Birth Cohort"
Kouichi Yoshimasu, MD, William J. Barbaresi, MD, Robert C. Colligan, PhD, Jill M. Killian, BS, Robert G. Voigt, MD, Amy L. Weaver, MS, Slavica K. Katusic, MD Pediatrics August 2011. doi: 10.1542/peds.2010-2581