Metacognition and self-awareness : neural and cognitive mechanisms in brain ageing and Alzheimer's disease

Bellaali, Youssef
(2026)

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Ivanoiu, Adrian  
 ;
Hanseeuw, Bernard  
Abstract
Anosognosia is well characterized in the clinical stages of Alzheimer’s disease (AD), but remains comparatively under-described at the prodromal stage. This work examines how altered self-awareness may emerge along the continuum from normal ageing to AD. We first conducted a retrospective analysis of the Wisconsin Longitudinal Study to compare participants’ global memory self-ratings with spouse ratings. In individuals genetically at risk for AD, spouse assessments were the most robust predictors of subsequent cognitive decline, outperforming self-report. These results raised a mechanistic question: which neuroanatomical systems, affected early in AD, contribute to metacognitive deficits? We therefore designed an experimental study in healthy participants to perturb Default Mode Network (DMN) connectivity by inhibiting the posterior cingulate cortex (PCC), a core DMN hub that neuroimaging studies have consistently shown to be affected early in AD. Resting-state fMRI revealed DMN desynchronization following PCC inhibition with transcranial magnetic stimulation (TMS). The same protocol was then used to assess behavioral consequences for memory performance and self-evaluation measures; stimulation spared accuracy and standard metacognitive indices but modulated confidence response times in a stimulus-dependent manner. Overall, this thesis combines longitudinal observational evidence with a causal, network-level perturbation approach, highlighting the prognostic value of informant-based assessment and exploring how PCC/DMN mechanisms may relate to memory-related self-evaluation.
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Bellaali, Y. (2026). Metacognition and self-awareness : neural and cognitive mechanisms in brain ageing and Alzheimer’s disease. https://hdl.handle.net/2078.5/275668