Co-occurring DLD or Language Disorder Associated with...?

by Lisa Archibald

Scenario: An SLP/T assesses a child who has an existing condition and determines that the child has a language disorder. Is the SLP/T diagnosis ‘DLD co-occurring with the existing condition’ OR ‘Language Disorder associated with the existing condition’?

The CATALISE consensus (Bishop et al., 2016, 2017) made a distinction between two subtypes of Language Disorder: (1) Developmental Language Disorder (DLD), and (2) Language Disorder associated with {biomedical condition}. Importantly, however, this latter diagnosis is only given when the biomedical condition is a differentiating condition. In other cases, DLD is described as co-occurring with the existing (nondifferentiating) condition.

Let’s consider the case of a child who has an existing condition and is referred for a SLP/T assessment. The child’s existing condition has been diagnosed previously by a relevant professional or multidisciplinary team. The assessment is being completed in the context of this existing diagnosis, and the child is found to meet criteria for a language disorder (i.e., the child has a persistent language problem with a functional impact). Do you provide the diagnosis of DLD as co-occurring with the existing condition OR Language Disorder associated with the existing condition? Answer: it depends on the nature of the existing condition.

First of all, is the existing condition relevant to language development or performance? If it is a condition unrelated to language such as hip dysplasia or juvenile arthritis, then there is likely no impact on the SLP/T assessment. Refer to volume 1 of the #DLDToolbox for a general approach to reporting a diagnosis of DLD.

Next comes the most important question, is this existing condition a differentiating condition for language disorder? Differential diagnosis is the distinguishing of a particular condition (like DLD) from other conditions that present with similar clinical features (like Language Disorder associated with {biomedical condition}). This differentiation is made when the biomedical condition is a differentiating condition.

So what is a differentiating condition? A differentiating condition is a biomedical condition with a complex pattern of impairments that commonly includes language disorder. The language disorder might be a primary symptom of the disorder such as the persistent social communication traits described as part of the diagnostic criteria of Autism Spectrum Disorder in the American Psychiatric Association’s Diagnostic and Statistical Manual, 5th edition (DSM-5). The language disorder might be a common secondary symptom, which refers to complications associated with the primary symptoms of the disorder. Take, for example, Intellectual Disability or Sensorineural Hearing Loss. Language disorders are commonly associated with these biomedical conditions. If the child’s existing condition is considered to be a differentiating condition AND the SLP/T assessment determines the presence of a language disorder, the diagnosis of Language Disorder associated with {biomedical condition} would be provided.

In the CATALISE studies, it was considered important to distinguish Language Disorder associated with {biomedical condition} because of the potential for the language disorders arising from these conditions to be qualitatively different from DLD. There are a number of ways that the associated language disorder might differ: (1) there might a clear genetic aetiology (unlike DLD), or (2) the disorder might have a different prognosis related to the biomedical condition. (3) There might also be a need for a different approach to intervention. Now, you might say that right now, your intervention approach tends to be similar regardless of the language disorder subtype. Nevertheless, the potential is there. By adopting a more consistent approach to identifying these subtypes, we can direct more focused research to children with language disorders related to different biomedical conditions and develop a better understanding of (potentially) unique intervention approaches. (4) Finally, the language limitations associated with a differentiating condition might be qualitatively different from DLD.

I know! Immediately you want to know what ‘language limitations qualitatively different from DLD’ would look like! To be perfectly honest, that’s a tough question. It’s important, however, that we try to tackle this question. If the DLD phenotype is so broad that it encompasses all possible language limitations, then that’s a problem. We run the risk of the diagnosis being such a ‘catch all’ that it loses its impact. A starting place would be to know the hallmark / key features of DLD, which can be found at these links: (1), (2), and (3) (Visser-Bochane et al., 2016). Let's talk more about language limitations that would be qualitatively different from DLD. What about an absence of even subtle oral or written morphosyntatic or lexical difficulties, or disproportionately severe pragmatic limitations? Join me on social media to discuss this topic further. With evidence, this could become the topic of another volume of the toolbox   

So now, what if a child has an existing condition relevant to language performance, but it is not considered a differentiating condition? That is, the pattern of impairments commonly associated with the existing condition does not include language disorder. If the SLP/T assessment reveals a language disorder in this case, then a diagnosis of DLD should be provided. The DLD and the existing condition are considered co-occurring conditions. Conditions co-occurring with DLD are not the clear or obvious cause of the language disorder BUT, the presence of the condition can affect the pattern of the language impairment or the response to intervention. Co-occurring conditions include impairments in cognitive, sensori-motor, or behavioral domains such as attentional, motor, reading, spelling, speech, adaptive, behavioural, or emotional difficulties. I’m confident that many SLP/Ts will be able to think of instances when language performance has been impacted by weaknesses in these areas!

By this point, I know you’ll all be saying, just tell me the name of the disorder and whether it is differentiating or co-occurring! In the flowchart accompanying this blog, #DLDToolbox volume 4, I provide such lists. Please note that these lists are not exhaustive – they don’t include every possible condition you might come across. The lists provide a starting point for your consideration, and along with this blog and volume, assist you in categorizing any other conditions you encounter.

At the risk of this being the longest #DLDToolbox blog ever, I’ll just make one additional point: Sometimes a child is referred who does not have an already diagnosed condition, but the child’s team has concerns about a possible biomedical condition. Please refer to #DLDToolbox volume 2, which includes the case of when a child is in the process of being assessed for a biomedical condition. Finally, please do follow the #DLDToolbox on Instagram @dld_diagnostics for additional materials and descriptions supporting this volume, and other volumes. You can also follow me on twitter at @larchiba6.