Glymphatic system dysfunction mediates amyloid deposition and cognitive impairment in Alzheimer's disease: a PET/MRI multimodality imaging study.

BACKGROUND: Abnormal glymphatic system may play a critical role in amyloid-β (Aβ) accumulation in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) patients. This study aims to use diffusion tensor image analysis along the perivascular space (DTI-ALPS) and perivascular space volume fraction (PVSVF) to investigate the aberrant glymphatic functions and the association between Aβ deposition and clinical symptoms in AD spectrum. RESULTS: The ALPS index was significantly lower in AD patients compared to MCI and normal controls (NC) groups. Additionally, the AD group showed a significantly higher PVSVF in hippocampus (HP) compared to NC group. No notable variations were observed in the ALPS index or PVSVF across various regions when comparing the MCI group to the NC group. Apolloprotein E (APOE) ε4 + group showed significantly higher PVSVF-HP and PVSVF in basal ganglia compared to APOE ε4 − group. All participants’ HP volume, lower cognitive scores, and higher 18F-AV45 PET SUVr were linked to a lower ALPS index. Enlarged perivascular space was linked to worse cognitive function. Mediation analysis further revealed that the detrimental effects of Aβ pathology and APOE genotype on cognitive decline were mediated by glymphatic dysfunction. CONCLUSIONS: Our findings demonstrate that glymphatic dysfunction is associated with cognitive decline, underscoring the critical roles of Aβ pathology and the APOE genotype in mediating this relationship. Further exploration of glymphatic function holds significantly promise for advancing research on AD pathogenesis.