Metacognition, cortical thickness, and tauopathy in aging

We investigated two aspects of metacognition and their relationship with cortical thickness and Alzheimers Disease (AD) biomarkers, amyloid and tau, in cognitively healthy older adults (N=151). The two metacognition measures were self-appraisal rating of task performance and the difference between self-appraisal rating and actual task performance (appraisal discrepancy). All participants underwent neuropsychological testing and 1.5T structural MRI. A subset (N=66) received amyloid-PET with [11C] PiB and tau-PET with [18F] Flortaucipir. We found that worse performers had lower self-appraisal ratings, but still overestimated their performance, consistent with the Dunning-Kruger effect. Self-appraisal rating and appraisal discrepancy revealed distinct relationships with cortical thickness and AD pathology. Greater appraisal discrepancy, indicating overestimation, was related to thinning of inferior-lateral temporal, fusiform, and rostral anterior cingulate cortices. Lower self-appraisal was associated with higher entorhinal and inferior temporal tau. These results suggest that overestimation could implicate structural atrophy beyond AD pathology, while lower self-appraisal could indicate early behavioral alteration due to AD pathology, supporting the notion of subjective cognitive decline prior to objective deficits.