Disrupted Brain Networks Underlying High-fidelity Memory Retrieval in Subjective Cognitive Decline: A Task-based FMRI Study

Introduction: Subjective cognitive decline (SCD) is linked to memory complaints and disruptions in certain brain regions identified by molecular imaging and resting-state functional magnetic resonance imaging studies. However, it remains unclear how these regions interact to contribute to both subjective and potential objective memory issues in SCD.

Methods: To address this gap, task-based imaging studies are essential. The Mnemonic Similarity Task assessed high-fidelity retrieval meanwhile MRI data measured group differences in activation and functional connectivity (FC) (calculated by generalized psychophysiological Interaction) between SCD individuals and normal controls.

Results: Worse high-fidelity retrieval in SCD was associated with hypoactivation in the hippocampus, hyperactivation in the control network (CN), and reduced FC between the hippocampus and CN. The angular gyrus (AG) partially drives this disconnection.

Discussion: This study confirms objective cognitive deficits in SCD and highlights the AG's failure to integrate, addressing a gap in the literature that has primarily focused on the hippocampus and CN.

Highlights: Objective high-fidelity retrieval deficits detected in older adults with SCD. Dysfunctional neural activations within retrieval networks impair memory accuracy. Reduced task-based FC drives high-fidelity retrieval deficits. The SCD-related disruption of integrative function partly explains such deficits. Future studies may benefit from inspections on obstruction in cognitive process.