Developmental Language Disorder (DLD): A brief history of terminology

There has been a myriad of terminology used within the field of Speech and Language Therapy (SALT), and until recently, there was no agreed upon label for unexplained language difficulties (Bishop, 2014). Dorothy Bishop found that between 1994 and 2013, 132 different terms were used in the literature, with Specific Language Impairment (SLI) being the most common. By contrast, the term “dyslexia” was used in 93% of research papers to describe reading and writing disorders, rising even higher, to 99% later on (Bishop, 2014).

She points out that this lack of consensus creates confusion and contributes to poor public awareness, as well as impeding research and even access to clinical services. Having multiple possible search terms for a particular condition makes it difficult to synthesise research, whilst the different diagnostic criteria associated with a range of labels risk inadvertently excluding deserving individuals from services.

Of course, such inconsistency not only to causes confusion, but also probably reflects the existing confusion in the field. The words that we choose for certain concepts reveal how we think about those concepts. And this changing terminology mirrors our evolving understanding of the nature of these conditions, and what we consider to be the most salient aspects at a given moment.

Older terms such as “developmental dysphasia”, for example, likely reflected the thinking of the time, which drew parallels between aphasia, the acquired condition suffered by adult stroke survivors, and the developmental difficulties observed in young children. The term “language delay”, which has sometimes been applied to young children hints at the possibility of them “catching up”, but was recently rejected by a panel of experts as “confusing and illogical” (Bishop et al, 2017).

As mentioned earlier, the term “Specific Language Impairment”, or SLI, was until recently applied quite widely to language disorders which were deemed “specific” in nature, i.e. unrelated to another biomedical condition or to overall intelligence. In fact, getting an SLI diagnosis required a “discrepancy” between a child’s language abilities, and their non-verbal IQ scores. (See my post on “cognitive referencing” for more information: https://secondaryschoolslt.wordpress.com/2026/03/13/what-is-cognitive-referencing-and-should-speech-and-language-therapists-slts-use-it/)

Inherent in this label was an assumption that language difficulties occurring in isolation are somehow intrinsically different from those forming part of a more general pattern of delayed development. This is far from clear, and in any case, “pure language difficulties” appear to be the exception, rather the rule in clinical practice (Bishop et al, 2016/7). The term has now been rejected as “not reflecting clinical realities”, whilst the word “specific” was considered misleading. Such a narrow definition has also likely led to many being denied services that they sorely needed.

Given this confusing state of affairs, a panel of experts from a range of English-speaking countries met in 2016 and 2017 to resolve some of these disagreements and arrive at a consensus regarding terminology and diagnostic criteria. They agreed on three separate terms relating to language difficulties.

“Language disorder” was proposed as an umbrella term for language difficulties likely to persist into middle childhood and beyond, significantly impacting on everyday interactions and educational progress, and unlikely to resolve without specialist support (Bishop et al, 2017). A child who is a second language learner and is struggling to learn the local language due to lack of experience would not be considered language disordered, unless they were also struggling in their mother tongue. The word “disorder” was chosen over “impairment” to emphasise the serious nature of the condition.

The term “language disorder associated with X” applies to language disorders with a “differentiating condition”. According to the panel, this would be a biomedical condition with a genetic or neurological cause, where language difficulties occur as part of a more complex pattern of impairment, for example, traumatic brain injury, Down’s Syndrome, ASD or intellectual disability. They reasoned that different intervention pathways would be needed for such individuals in order to take into account the other features of their conditions (Bishop et al, 2017).

Finally, the term “Developmental Language Disorder” applies to language disorders with no known differentiating conditions, yet to be explained. The word  “developmental” was chosen to emphasise that these difficulties occur during the course of development, rather than being acquired. The panel also stressed that in contrast to previous SLI diagnoses, a large discrepancy between verbal and nonverbal scores would not be required. So, hypothetically, a child with low nonverbal scores who did not meet the threshold for Intellectual Disability could still qualify for a diagnosis of DLD.

As SLTs, this newfound agreement and clarity is welcome and long overdue. Still, Bishop (2014) cautions us not to “reify our labels”, since without fully understanding the biological basis for DLD, they are really just a collection of temporarily useful constructs. They may well change again in time, as our understanding of the nature and causes of these conditions evolves. Other researchers have advocated spending more time working on finding solutions, rather than focusing overly on labels. That’s something I’m happy to get behind.

For more information about what a language disorder is, please see my blog post: https://secondaryschoolslt.wordpress.com/2026/01/02/what-is-developmental-language-disorder-dld/

Notes

Afasic, NAPLIC, RCSLT and Speech and Language UK (2023) A vision for Developmental Language Disorder (DLD) for the UK. ​

Bishop, D.V.M. (2014). Ten questions about terminology for children with unexplained language problems. International Journal of Language & Communication Disorders, 49(4), pp. 381-415.

Bishop DVM, Snowling MJ, Thompson PA, Greenhalgh T, CATALISE consortium (2016)

CATALISE: A Multinational and Multidisciplinary Delphi Consensus Study. Identifying Language Impairments in Children. PLoS ONE 11(7): e0158753.

Bishop, D.V.M., Snowling, M.J., Thompson, P.A., Greenhalgh, T., and the CATALISE-2 consortium (2017). ​ Phase 2 of CATALISE: a multinational and multidisciplinary Delphi consensus study of problems with language development: Terminology. ​ Journal of Child Psychology and Psychiatry, 58(10), pp. ​ 1068–1080.