The jigsaw puzzle of developmental language disorders
Premature birth, sleep problems and smoking mothers are possible predictors
Premature birth, sleep problems and having a smoking mother have been found to be risk factors in causing developmental language disorders (DLD) in children. Six Utrecht researchers at different faculties studied this phenomenon. Elma Blom, a professor in child development, is excited by the findings: "These three factors are an interesting outcome. They give just a tad more concrete, detailed information about that mysterious phenomenon, developmental language disorder, that we still know so little about."
Corette Wierenga, an associate professor of neurophysiology, says: "With the research group 'The first 1001 days in a child’s life' we looked for a good, clear article about the risk factors for developmental language disorders. There wasn’t one yet, so this seemed a good topic to take an interdisciplinary approach to."
Rachida Ganga was appointed as a researcher to get the project going: "We started out with a sizeable list of risk factors influencing language development and whittled it down to twenty factors.’ Wierenga adds: ‘Some things are bad for the brain generally, so they’re also bad for language development."
Factors that may influence brain development, including language development, are a child’s sex, family composition and the mother drinking alcohol during pregnancy, among other factors (see the box below for a full list). These general risk factors are often about timing: the period during which the exposure takes place determines whether language development is affected. Wierenga: "Risks that occur in the final stages of pregnancy seem to be of special influence on language development. Language is such a complex cognitive function. All other aspects of brain development have to go well, only then are you able to acquire a language."
General risk factors with regard to brain development
- Belonging to the male sex
- Being a second or later child
- Not having been breastfed (for long)
- Having been exposed to alcohol or drugs
- Health problems on the part of the mother
- Infections
Premature birth
The researchers also found specific risk factors related to language problems. Firstly, premature babes appear to run a higher risk of having a developmental language disorder. Corette Wierenga, an associate professor of neurophysiology, says: "The brains of premature babies are not fully developed at birth. These children are exposed to all sorts of sounds and experiences earlier than full-term babies. Possibly, this interferes with that last bit of brain development, including language development."
Smoking
Smoking during pregnancy also increases children’s risk of developmental language disorders. Wierenga: ‘Nicotine has a specific receptor in the brain that interrupts the creation of connections in the brain that are important for language development.’
Sleep
In addition, researchers found a connection between sleep disorders and developmental language disorders. When small children have naps, this helps them acquire new words and grammatical rules. It is as yet uncertain whether children with a developmental language disorder actually have more sleep problems. It does seem to be the case, however, that quality of sleep is an important predictor of language development.
What is a developmental language disorder?
Interdisciplinary collaboration
The team found it highly valuable that this project spanned more than a single discipline. Ganga: "As a researcher, you’re often so caught up in your own field that you’re not too aware of what else is going on. A collaboration such as this one shows you that your subject area involves much more than you thought." Corette: "I found it very stimulating. I would write a piece and think: this is crystal-clear. Then I’d send it on to Elma and find out that all sorts of information were still missing. You learn to see that what you think are very logical steps aren’t so self-evident at all to someone from a different field." Elma believes this is also the only way to identify the risk factors for developmental language disorders clearly: "This issue is so wide-ranging and complex, it can only be approached through interdisciplinary cooperation. Otherwise, the approach is not complete enough. None of us could have written this on our own."