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Karla K. McGregor, Ph.D.
Boys Town National Research Hospital
Hope Sparks Lancaster, Ph.D.
Boys Town National Research Hospital

Developmental Language Disorder, or DLD, is a spectrum disorder. Spectrum disorders are conditions that affect several related skills, not just one. Any two individuals who have a spectrum disorder may differ in the severity of the problem and combination of skills involved.

This simple definition holds a lot of implications for understanding DLD. Considering a different sort of spectrum — the color spectrum — can help us think through these implications. The color spectrum ranges from red to violet. We can reliably identify green on the spectrum, yet there are no distinct boundaries between the color categories. When we diagnose a particular neurodevelopmental disability, like DLD, we are in a sense distinguishing it from other disabilities just as we distinguish green from the other colors on the color spectrum. Our judgement is guided by what we know to be DLD, but we must acknowledge that, “at the edges,” these judgements can be tricky.

What shade of green?

Because DLD is a spectrum disorder, any two people with DLD may have different language problems. Consider two of the children, Elvis and Porter, profiled in a paper we wrote on vocabulary intervention. Both children had problems with grammar, but that is where the similarities ended.

  • Elvis had been exposed to drugs before birth. His speech was hard to understand, but he was happy to talk with peers and adults in the classroom.
  • Porter was healthy at birth. His speech was clear, but vocabulary learning was a challenge. His language difficulties affected his communication with peers. He avoided talking to other children and he tended to cry when communication failed.

Despite having different strengths and weaknesses, both boys had DLD. To use the color analogy, we might say that Elvis was “spring green” and Porter was “evergreen,” but both were “green.” We could identify DLD in both children.

Does light green count?

Because DLD is a spectrum disorder, it can sometimes be difficult to diagnose. There will be borderline cases where the child’s problems are mild, and we are not sure if a clinical diagnosis is warranted. The key in these cases is to determine whether the problems are interfering with the child’s success at school, at home, or with other children. If so, a diagnosis can lead to the supports this child needs to overcome those functional limitations. Even a “light green” case could require help.

Is it green or yellow; Is it green or blue?

There are also cases where the RIGHT diagnosis can be challenging. Language problems accompany many neurodevelopmental disabilities so deciding whether the collection of strengths and weaknesses is better considered DLD or some other condition—like Intellectual Disability or Autism—will be tricky sometimes. In color terms, we are asking, is this green or is it yellow; is it green or blue? The key is to consider the child’s abilities beyond language. For example, if the child also has significant nonverbal problems, intellectual disability may be the more accurate diagnosis. If the child also has repetitive behaviors, autism would be more accurate. Even with these other biomedical conditions, we might recognize a child’s particular difficulty with language by diagnosing a ‘Language Disorder associated with {the biomedical condition}’.

Is it green AND blue?

Another consequence of the spectral nature of DLD is that a child might have so many “green” characteristics but also so many “blue” characteristics that two diagnoses are required to get the child the help that they need. Neurodevelopmental disabilities frequently co-occur. For example, a child can be diagnosed with DLD and dyslexia, DLD and Developmental Coordination Disorder, or DLD and ADHD.

Is the green changing to blue?

Finally, we must remember that DLD is a developmental condition. That means that symptoms, and even diagnoses, may change as the child grows and as our expectations change. Imagine a child who is four years old. At that age, communication—learning a basic vocabulary and sentence structure, learning how to take turns in a conversation—is a primary demand. The child who is struggling to meet that demand might be accurately diagnosed as having DLD. When that same child is in the fifth grade, academic success is a primary demand. If the child can now succeed at conversation but is struggling to read, they might accurately be diagnosed as having a Specific Learning Disability. This does not mean that the earlier diagnosis was wrong. DLD is a lifelong condition, but the nature of the problem changes over time. How people struggle with new, more complicated language tasks as they grow up will be different for different individuals. As well, when investigators follow young children with DLD into adulthood, they often find that the children acquire or ‘grow into’ new diagnoses along the way.

Getting a diagnosis for your child is a stressful and often confusing journey. Understanding DLD as a spectrum may help you to make sense of the diagnostic process, to anticipate its complexity, and seek the best supports for your child.

  1. Lancaster, H. S., & Camarata, S. (2019). Reconceptualizing developmental language disorder as a spectrum disorder: Issues and evidence. International journal of language & communication disorders, 54(1), 79-94.
  2. McGregor, K. K., Van Horne, A. O., Curran, M., Cook, S. W., & Cole, R. (2021). The challenge of rich vocabulary instruction for children with developmental language disorder. Language, speech, and hearing services in schools, 52(2), 467-484.