This section is dedicated to the essential data on developmental language disorder (DLD). You will find the main statistics and highlights to better understand the extent of this neurodevelopmental disorder, which affects a large number of people, both in Quebec and elsewhere in the world. Putting these numbers into perspective provides a better understanding of the importance of recognizing DLD, providing access to specialized services, and providing long-term support for those affected and their families.
DLD is a complex disorder that affects more than 7% of the population and whose exact cause is often unknown.
The manifestations of developmental language disorder (DLD) are diverse and can have significant consequences on several aspects of daily life, including behaviour, concentration, academic learning and social interactions.
Check out the data presented to better understand the real impact of DLD and the importance of acting quickly. Awareness, early detection and appropriate support play a key role in supporting those affected and promoting their full development.
More than 7% of the population
Developmental language disorder (DLD), previously referred to as dysphasia or primary language disorder, affects approximately 7 to 8% of the population. This means that it is more common than one might think (Source: Norbury et al., 2016).
72% still have difficulties at 12 years old
Among children affected by DLD, 72% continue to have significant language difficulties at the age of 12. This demonstrates the long-lasting nature of the disorder and the importance of long-term support. (Source: Ordre des orthophonistes et des audiologistes du Québec (OOAQ), 2014).
1 in 2 children identified before the age of 5
Although early detection is essential, only one in two children with DLD is identified before the age of 5. This delay in identification can limit timely access to necessary services. (Source: American Academy of Pediatrics – AAP).
In the classroom, 1 in 14 students lives with DLD.
(Source: OOAQ, 2014).
81% have an unrecognized language disorder
According to a meta-analysis, 81% of children aged 5 to 12 who consult for emotional or behavioural difficulties also have a significant undiagnosed language disorder. This raises concerns about the adequacy of the services received. (Source: Hollo, Wehby, & Oliver, 2014).
3 to 4 boys for each girl
Developmental language disorder (DLD) is diagnosed more frequently in boys, with a ratio varying from 3 to 4 boys for every girl. This difference could be related to biological factors or biases in screening. (Source: American Speech-Language-Hearing Association – ASHA).
3 times more likely to have difficulties at school
Children with a developmental language disorder (DLD) are three times more likely to experience learning difficulties compared to those without them. This underlines the importance of a rapid and appropriate response. (Source: American Speech-Language-Hearing Association – ASHA).
66% to 91% of children with behavioral disorders have DLD
While not all children living with DLD have behavioral disorders, the vast majority (66% to 91%) of children with behavioral disorders would have difficulties or a language disorder (Source: Hollo et al., 2019). A certain proportion are thought to be undiagnosed (Source: Hollo et al., 2014).
43% of girls with DLD are victims of abuse
Girls living with a language disorder are significantly more vulnerable to sexual abuse: 43% of them are victims before the age of 18, compared to 16% of girls without language difficulties. This figure underlines the importance of vigilance and prevention.
Long-term risks: Follow-up of individuals with DLD in childhood shows, at 36 years of age, an increased risk of schizotypal traits (64% vs. 18%), schizophrenia (38% vs. 11%), and personality disorders (49% vs. 22%) (Source: Mouridsen and Hauschild, 2008; 2009).
50% of incarcerated people have language disorders
Nearly half of people in prison have significant difficulties related to oral and written language. This worrying link between language disorders and criminalization highlights the importance of appropriate screening and support from childhood.
(Source: Morken, F., Jones, L. O. and Andersen Helland, W. (2021), Disorders of Language and Literacy in the Prison Population: A Scoping Review, Education Sciences, 11(2)).
Billions of dollars in TDL costs
Developmental language disorder (DLD) has significant social and economic costs. Between health services, education supports, and long-term productivity losses, TDL expenditures are in the billions of dollars annually in many countries.
(Source: American Journal of Speech-Language Pathology).