Dyslexia really is more common in boys than girls, new research says, contradicting studies suggesting that boys are simply more likely to be diagnosed with the problem because they tend to act up in class when they get frustrated.
The findings suggest boys are at least twice as likely to have dyslexia, a learning disability that involves trouble with reading, said the authors, led by Dr. Michael Rutter of King’s College in London. They said the findings should prompt research into why this is so.
Rutter and colleagues based their findings on data from four large studies involving more than 10,000 children who had been given standard reading tests in New Zealand and Britain.
Dyslexia was found in 18 percent to about 22 percent of the boys, compared with 8 percent to 13 percent of the girls. Children took reading tests at various times in each study, between ages 7 and 15.
Rutter and colleagues said the results are strong because the studies did not rely on children who were already known to be having learning difficulties — a weakness that plagued some previous research.
Rutter’s report appears in Wednesday’s Journal of the American Medical Association.
Debate likely to continue
It is unlikely to settle a debate among learning specialists over the gender issue.
Sheldon Horowitz, director of professional services at the National Center for Learning Disabilities, said boys are not necessarily more likely to have reading problems. Instead, he suggested girls’ reading problems may be more likely to go unnoticed by teachers.
“Boys who are sitting in class and not getting it are going to be acting out with greater frequency than girls because that’s not 'girl' behavior,” Horowitz said.
Girls are more likely to sit quietly and may have verbal skills that make it appear as though they are understanding when they are not, he said.
Of the nearly 3 million U.S. youngsters with learning disabilities, Horowitz said about 80 percent have dyslexia. Children with the disorder have normal intelligence but reading problems that can include difficulties identifying words and letter sounds.
Some data have suggested that male and female brains process reading differently, and girls are believed to become proficient in language skills earlier.
Horowitz said there is strong evidence suggesting there are no significant gender differences when it comes to dyslexia.
Some of the strongest evidence favoring that theory came from Dr. Sally Shaywitz’s study of more than 400 Connecticut schoolchildren, published in 1990. The Yale University researcher found that boys were much more likely than girls to be placed in special reading classes, but that there were no substantial differences between the numbers of boys and girls with reading difficulties.
Horowitz said research is needed to determine if there are any sex-linked genes that would explain Rutter’s theory.