According to the Centers for Disease Control and Prevention, around 1 in 6 children in the US had a developmental disability, including intellectual disabilities, in 2006-2008. Now, new research suggests that gender and genes could play a part in delayed language development - with boys at greater risk than girls.
This is according to a study recently published in the International Journal of Language and Communication Disorders.
To reach their findings, the researchers, including Eivind Ystrøm of the Norwegian Institute of Public Health and senior author of the study, analyzed data from questionnaires completed by mothers who were a part of the Norwegian Mother and Child Cohort Study (MoBa).
The study included 10,587 children who were followed from week 17 of gestation up to 5 years of age.
At 3 and 5 years, the investigators divided the children into three groups.
The first group consisted of children with persistent delayed language development that was present at 3 and 5 years old.
The second group was made up of children with transient delayed language development that was present at 3 years old only, while the third group consisted of children with delayed language development that was first identified at 5 years of age.
Boys 'at greater biological risk' of language disorders than girls
The researchers found that the persistent and transient delayed language development groups were mainly made up of boys.
Explaining why this is, Ystrøm says that boys are at greater biological risk for development disorders while in the womb (in utero) than girls.
Ystrøm adds that in general, boys are later in language development than girls.
However, he points out that the majority of boys catch up with language development during the first year, meaning that many boys at risk of persistent and transient language disorders may be rid of them before school age.
The research team did not find any association with gender in the third group, which had language difficulties that arose between the ages of 3 and 5 years, suggesting another factor must be at play.
History of reading and writing difficulties in the family 'a risk factor'
The investigators say previous research has shown that genes play an important role in the language development of children, and that different genes are involved in various language disorders.
The researchers hypothesize that both a child's genes and the outside environment a child is exposed to can play a role in the late development of language disorders.
"We show for the first time that reading and writing difficulties in the family can be the main reason why a child has a speech delay that first begins between 3 to 5 years of age," says Ystrøm.
"Reading and writing difficulties in the family are the predominant risk factors for late-onset language difficulties. We see no language problems when the child is between 18 months and 3 years old. They are latent."
The researchers say that parents, health care workers and child carers should ensure they are aware of how a child is progressing in language development.
Ystrøm notes that in particular, they should look out for children who suddenly begin to experience language difficulties after the age of 3 years.
"Professionals and caregivers must be vigilant. It is difficult to detect language difficulties when language becomes more complex in older children.
They must be trained so that they are confident in how to spot language difficulties and how to encourage a child's language. We need more research into the needs of children with different trajectories."
Ystrøm stresses that any parent who has concerns about their child's language development should talk to their doctor as soon as possible, as well as ensure their child has regular check-ups regarding their language development between the ages of 3 and 5 years.
The researchers conclude that they hope to conduct further research looking at the association between gender and language development.
Medical News today recently reported on a study suggesting that preterm babies exposed to adult speech demonstrate better language skills later on.