The Neural Cost of Language Processing: Broader Network Recruitment in Adults with Developmental Language Disorder

Abstract Developmental Language Disorder (DLD) is a neurodevelopmental disorder characterized by persistent difficulties in language comprehension and production, despite otherwise typical cognitive abilities. Although DLD is most commonly studied in children, it often persists into adulthood, yet little is known about the neural substrates underlying language abilities in adults with DLD. To address this gap, we examined 50 adults with (n = 23) and without DLD (n = 27) using an fMRI language localizer paradigm. Participants passively listened to intelligible and acoustically degraded speech, to assess both lower-level auditory processing and higher-level language comprehension. We also administered standardized language assessments to relate behavioral performance to neural activation patterns. Results indicated that auditory processing in DLD is largely intact, as both groups showed comparable activation in bilateral auditory cortices during degraded speech. In contrast, during comprehension of intact speech, adults with DLD recruited additional domain-general regions, including bilateral midline, frontal, and parietal areas. This pattern suggests compensatory or effortful engagement of broader cognitive systems to support comprehension, even during a very simple task. Critically, participants whose activation patterns more closely resembled canonical left-lateralized language networks demonstrated stronger performance on standardized language measures, implying that diffuse network recruitment may come at a cognitive cost. Overall, these findings indicate that while adults with DLD can achieve functional language comprehension, they do so through altered neural pathways.