The brain behind the words, understanding developmental language disorder and sensory processing
Language development and sensory processing skills are closely related. According
to an article on Brain Behavior, children who have problems with language development tend to experience challenges
with motor and auditory processes. This offers an opportunity to explore how language
development plays a larger role in sensory health, and a topic that the team at Sensory Research Institute at UNT Health Fort Worth is particularly interested in researching, as it continues
to grow as a research center on campus.
For Uyen Nguyen, a rising third-year medical student at the Texas College of Osteopathic Medicine at UNT Health, the connection between language processing disorders and sensory health is an area of interest. We asked Nguyen to share more about this connection.
What is developmental language disorder, and why do experts say many people still don’t know about it?
Developmental Language Disorder is a communication disorder in which difficulties with learning, understanding and using language persist beyond early childhood. Despite being one of the most prevalent neurodevelopmental disorders, awareness remains surprisingly low. DLD affects approximately 7.5% of children, yet it often goes unrecognized because it lacks cultural familiarity and may present without obvious behavioral signs. Because its signs can appear subtle in everyday conversation, many children remain undiagnosed until school places greater demands on language skills through reading, writing, classroom instruction and peer interaction.
What does DLD suggest about how the brain processes and organizes language, especially sounds and meaning?
DLD suggests that language development is deeply tied to how efficiently the brain receives and interprets sound. Most children acquire grammar and vocabulary simply by being exposed to language around them. However, children with DLD are less efficient at picking up speech patterns on their own because the brain pathways involved in interpreting what they hear are wired differently.
Current neuroimaging evidence suggests that children with DLD show atypical patterns of brain structure and function in regions involved in language processing. Such differences in brain volume, lateralization, and neural connectivity likely contribute to language difficulties. Structural brain studies of children aged approximately 10–16 years have reported reduced cortical surface area and overall brain volume relative to typically developing peers. Given that cortical surface area is closely associated with cortical folding, these findings may reflect less optimized organization of language and potentially reduced processing efficiency.
In addition to these neurobiological differences, children with DLD also struggle with verbal working memory, the ability to hold spoken information in mind and work with it in real time. A 2025 review in Frontiers in Psychologyfound consistent impairments in tasks such as repeating numbers, words or sentences. Accordingly, verbal working memory integrates sensory processing and higher-order thinking. Deficits of this skill are considered one of the key features of DLD.
How might early signs like late talking reflect differences in how a child’s brain hears or interprets speech sounds?
Late talking and frequent use of gestures instead of words may reflect differences in how the brain processes speech sounds. In typical development, infants rapidly attune to the sound patterns of their native language and begin parsing continuous speech into meaningful units like words. When this process develops less efficiently, a child may hear speech normally but struggle to interpret and organize it. As a result, both language comprehension and spoken language may develop more slowly.
Research, featured in the Journal of Speech, Language, and Hearing Research, followed children who were late talkers found that more than half were later diagnosed with a learning disability, indicating that late talking is an early red flag. The use of gestures and body language may be compensatory strategies that suggest the child’s intent to communicate when spoken language is not keeping pace. Together, these findings suggest that the neural systems involved in how a child’s brain hears or interprets speech sounds may be developing along a different trajectory.
An NIH article says DLD and dyslexia often occur together—what might that tell us about shared brain systems for spoken and written language?
The co-occurrence of DLD and dyslexia suggests that spoken and written language are not supported by entirely separate neural systems. As the NIH explains, “dyslexia and DLD often go hand in hand because both involve language,” with DLD primarily affecting oral language and dyslexia affecting written language. Consistent with this overlap, children with DLD are approximately six times more likely to develop reading and spelling difficulties, indicating a shared vulnerability in underlying phonological processing.
Early difficulties in spoken language may reflect struggles in connecting sounds to letters on a page, which can make it harder when a child learns to read later. Neuroimaging findings further support this overlap, showing atypical activation in left-hemisphere language networks implicated in phonological processing in both conditions. Overall, this suggests that speaking and reading depend on shared language systems in the brain, and disruption within these systems may increase vulnerability to both DLD and dyslexia.
Why might some children with mild DLD seem typical in conversation but struggle later
in school—what does that suggest about increasing brain demands?
Casual conversation relies on context, tone of voice, shared knowledge and back-and-forth
interaction. School, on the other hand, removes many of those conversational supports
and places more emphasis on written narratives, technical vocabulary, complex syntax,
and figurative language. In line with this, a systematic review of 44 studies found that students with DLD perform below their peers with typical
development across all areas of academic achievement.
This pattern fits with what is known about verbal working memory. As school tasks become more complex, language processing and executive functions rely more on overlapping brain systems rather than operating separately. As a result, children with DLD may find school increasingly challenging over time, especially as rising language demands place greater pressure on these shared cognitive systems.
Researchers are developing screening tools—what kinds of brain or sensory processing differences would those tests ideally detect early?
Researchers like Dr. Adlof, an associate professor of communication sciences and disorders at the University of South Carolina, are developing oral language screening tests by tracking typical language development from kindergarten through third grade to establish clear benchmarks. Ideally, such tools would capture the “upstream” processing capacities that predict language and literacy outcomes before academic failure accumulates. The most sensitive early indicators to assess would be phonological awareness, verbal working memory, rapid automatized naming, and sentence comprehension. Studies screening children aged 4 to 6 years have found that children with DLD show inadequacy in reading, writing, mathematics, and science relative to typical peers. This highlights the importance of early identification and intervention before cumulative learning gaps develop.
Different teaching strategies are being tested—how might these approaches tap into different brain learning systems, like pattern recognition versus explicit rule learning?
Dr. James W. Montgomery, a professor of hearing, speech, and language sciences at Ohio University and a former practicing speech-language pathologist, has spent decades studying how children with DLD learn grammar and build language processing systems. His research, featured in the American Journal of Speech-Language Pathology, compares explicit rule learning with exposure-based learning, drawing on two well-established memory systems. Explicit rule learning draws on declarative memory, which is typically intact in children with DLD. Exposure-based learning, by contrast, relies on procedural memory, a system that underlies automatic, implicit skill acquisition. For children with DLD, this system appears to be less efficient. Research using serial reaction time tasks with Spanish-speaking preschool children found that children with DLD showed significantly longer reaction times and reduced accuracy across sequential learning trials compared to typically developing peers. This provides behavioral evidence of procedural learning differences in DLD from an early age. Since DLD may specifically impair this procedural system, explicit rule-based teaching may serve as a more reliable pathway by leveraging a relatively intact declarative memory system to support language acquisition. For the Sensory Research Institute, the intersection of sensory processing and how children learn language represents a rich area for continued research.
For more information on sensory research, please visit the Sensory Research Institute’s website.