Australian classrooms are likely to be impacted by developmental language disorders, according to Curtin University researchers Dr Sam Calder and Dr Lizz Hill.
It is estimated that two children in every mainstream classroom are likely affected by a neurodevelopmental condition called Developmental Language Disorder (DLD).
Previously known by other labels such as Specific Language Impairment, Language Learning Impairment, and Primary Language Impairment, DLD is diagnosed when a child demonstrates difficulties understanding and/or producing language compared to children their own age.
Diagnostic criteria for DLD are outlined in both the DSM-5 and the ICD-11, and include persistent difficulties in the acquisition of language; language abilities that are substantially and quantifiably below what is expected for the child’s age, which cause significant functional limitations; difficulties that are not attributed to another biomedical condition such as autism, sensorineural hearing loss, or intellectual disability, and; the onset of symptoms arising during the early developmental period.
DLD is typically diagnosed by a speech pathologist in concert with paediatricians, educational and developmental psychologists, and educators. Children are often identified for assessment of DLD once they begin formal schooling and their difficulties communicating their wants and needs and understanding classroom instructions become pronounced compared to their peers.
Previous research in English-speaking countries (both the US and UK) has estimated the prevalence of DLD at about 7% in early childhood (4-5 years). Although existing Australian research has looked at the number of children with reduced language skills, our study was the first to apply the latest diagnostic criteria for DLD to an Australian population-based study.
It was also the first – to our knowledge – to provide an estimate of DLD in middle childhood at 10 years of age. We found the prevalence rate of DLD was 6.4%, indicating the persistence of DLD from early to middle childhood. Previous research has also indicated that children, adolescents, and adults with DLD experience lower success on social, academic, well-being and vocational outcomes compared with those who have not experienced childhood language difficulties.
Collectively, these findings suggest children with DLD are at risk of lifelong challenges associated with their language disorder.
Early identification is critical in providing timely, targeted and effective support aimed at mitigating the functional challenges associated with the disorder. We tend to see more males being referred to these clinical services, and this is mirrored in the research.
However, our study indicates that there are no differences between the number of males and females who meet diagnostic criteria for DLD. This speaks to a referral bias for males, which is particularly alarming when we consider that females with DLD are three times more likely to experience negative outcomes such as sexual abuse compared to those without language difficulties.
It is important to understand what factors place a child at risk of language disorder in order to increase the likelihood of early identification and timely support. Consequently, we also examined potential perinatal and environmental risk factors that may predict a diagnosis of DLD at 10 years.
We found that having a mother who smoked while pregnant was the only significant risk factor of DLD at 10. While it was not possible to draw a causal link between exposure to environmental teratogens in utero and later neurodevelopmental disorder in our study, we believe this finding adds weight to public health messages for mothers to avoid smoking, especially while pregnant.
Additionally, there is research to suggest that the relationship between language disorder and smoking in pregnancy is reflective of a shared association with social and/or financial disadvantage. Consequently, it is critical that families experiencing socioeconomic disadvantage receive targeted and consistent financial and social support.
We know that the early developmental period is associated with enormous individual variability. This means that it is difficult for professionals to reliably identify a child with DLD before the age of four years. In fact, Australian research has indicated that late language emergence (aka late talkers) is not a reliable predictor of language disorder in later childhood. Despite this, there are some things that medical practitioners can look out for that may help identify a child with DLD.
We would recommend referring the family to a speech pathologist if a child has not met early communication and language milestones. The speech pathologist can assess for early language difficulties.
If a child has commenced formal schooling and is experiencing difficulties socialising, following instructions, and/or engaging in the classroom, a speech pathologist can help determine whether language difficulties are contributing to these problems. Involving a speech pathologist can increase the chances that a child will receive targeted and effective support as early as possible.
Oral language skills form the foundation for socioemotional development and academic success. If a child is facing challenges within and beyond the classroom, let’s go to the potential source: language.