Frontal Vulnerability vs. Temporal Resilience within the core Language Network: Neuro-compensatory mechanisms underline differential language aging trajectories
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Age-related decline underlies cognitive functions such as sensorimotor control, executive functioning, memory, and language production (LP), whereas language comprehension (LC) tends to remain intact or improve across healthy adult lifespan. This preservation likely stems from structural and functional integrity within core language network (cLAN) regions. To investigate this hypothesis, we analyzed the relationships among brain’s resting-state functional connectivity (FC), structural connectivity (SC), and language behaviour (LC and LP) using a cross-sectional cohort of healthy adults (N = 652; M/F = 322/330; aged 18–88) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) dataset. Six cognitive tasks assessing LC and LP were employed, with neuroimaging measures focused on region-specific connections within the cLAN. Using generalized additive mixed models (GAMMs), complex brain-behaviour interactions were identified. Behavioral analyses revealed established age-related dichotomy, LC abilities in vocabulary and proverb comprehension improved and in syntactic and semantic comprehension remained stable, whereas LP tasks, e.g., verbal fluency, picture priming, and tip of tongue exhibited significant decline across the lifespan. SC exhibited decline in both intra-and inter-hemispheric fronto-temporal and frontal lobe connections, contrasted by preserved or enhanced temporal lobe connectivity, supporting a pattern of frontal vulnerability concomitant with temporal resilience. Age-related FC patterns demonstrated overall preservation, reflecting compensatory mechanisms to sustain functional integrity despite structural degradation. GAMM analyses revealed complex relationships between brain connectivity and language performance across age. Thus, integrating knowledge of brain structure, function, and language abilities, we identified the brain network mechanisms associated with dichotomous language behavior along lifespan.
Significance
Understanding age-related changes in language abilities is vital for early detection of cognitive decline and intervention development. This study reveals heterogeneous language aging trajectories: language production often declines, while comprehension remains stable or improves. Notably, comprehension tasks with high executive and working memory demands also show resilience, suggesting compensatory mechanisms beyond crystallized knowledge. Using multimodal neuroimaging in a large adult lifespan cohort, we link behavioral patterns to distinct network dynamics within the core language system. We uncover relative vulnerability in frontal brain regions, with pronounced structural decline in fronto-temporal pathways, contrasted by resilience in temporal connectivity, which is preserved or strengthened. These findings highlight regionally specific vulnerabilities and compensatory functional adaptations, refining current models and providing a framework to guide research promoting healthy cognitive aging.
