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(Dis)similarities in neuroanatomical correlates of semantic cognition between healthy young and older adults
Poster Session A, Friday, September 12, 11:00 am - 12:30 pm, Field House
Mara Alves1, Patrícia Figueiredo2, Ana Raposo3; 1Donders Institute for Brain, Cognition and Behaviour, Radboud University, The Netherlands, 2Research Center for Psychological Science, Faculdade de Psicologia, Universidade de Lisboa, Portugal, 3ISR-Lisboa/LARSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Portugal
Ageing is commonly seen as a process of neural decay. Yet, research has revealed that the brain remains flexible across the lifespan, with some cognitive abilities being preserved. One consistent finding is that people accumulate semantic information until later in life, potentially bolstering neural resources to maintain cognitive performance comparable to younger ages, despite age-related cortical atrophy. Notably, functional MRI studies have shown that, despite similar behaviour, older adults exhibit shifts in brain activation, showing over-activation in bilateral prefrontal regions – brain areas susceptible to cortical thinning, and showing more left-lateralized activation in younger adults. Such pattern has been interpreted as evidence of neural reorganization or compensation mechanisms that uphold cognitive function in older ages. However, how structural brain changes interact with semantic performance across age groups remains unclear. In this study, we used high-resolution structural MRI to investigate how cortical thickness relates to semantic performance in healthy young (n=15) and older adults (n=16). We conducted a whole-brain, regionally segmented analysis of cortical thickness without predefined regions of interest to allow for an unbiased investigation of age-related structural differences. We then assessed whether and how such differences associated with performance on the Camel and Cactus Test (CCT), used as an index of semantic cognition. Behavioural performance on the CCT was high and equivalent between young (M = 0.89, SD = 0.07) and older adults (M = 0.89, SD = 0.08), indicating preserved semantic abilities in later life. Structurally, older adults showed widespread cortical thinning relative to younger adults, particularly in bilateral frontal lobes and superior parietal lobules (SPL) – regions associated with multi-domain cognitive control. Importantly, cortical atrophy was also observed in regions linked to semantic processing, including the bilateral temporal poles (TP), bilateral posterior middle temporal gyrus (pMTG), and the left supramarginal gyrus (SMG). Moderation analyses revealed that better semantic performance was significantly associated with reduced cortical thickness in the left pMTG, left SMG, and right SPL (p ≤ .001) across both age groups. This counterintuitive pattern suggests that, in healthy ageing brains, cortical thinning may preserve neurodevelopmental optimized processes linked to increased neural efficiency and specificity. Interestingly, the relationship between cortical thickness and performance was reversed with age in a set of right-hemisphere regions. While young adults maintained negative associations in right inferior frontal gyrus (IFG), right middle frontal gyrus (MFG), and right pMTG, older adults showed positive association trends. These results align with neural compensation models, proposing that older adults increasingly engage right-hemisphere structures to uphold semantic processing, even with age-related thinning of those areas. Overall, these findings highlight the complexity of neurocognitive ageing, and suggest that successful semantic cognition in older adults may result from a dynamic balance between structural maintenance and compensatory neural upregulation in the ageing brain.
Topic Areas: Meaning: Lexical Semantics,