Glymphatic system metrics derived from DTI-ALPS are associated with cognitive impairment, brain atrophy, and plasma tauopathy biomarkers of type 2 diabetes patients: Analysis in dual-cohort

BackgroundGlymphatic dysfunction is implicated in neurodegenerative disorders and may contribute to the elevated risk of mild cognitive impairment (MCI) in type 2 diabetes mellitus (T2DM) patients. The diffusion tensor imaging along the perivascular space (DTI-ALPS) index has been proposed as a non-invasive imaging surrogate that may reflect aspects of glymphatic system activity.ObjectiveWe investigated the relationship between ALPS index, cognition, brain structure, and plasma Alzheimer's disease biomarkers in T2DM patients.MethodsTwo independent cohorts were analyzed: Cohort 1 included 60 age, sex, and education matched participants (20 T2DM with MCI, 20 T2DM with normal cognition, and 20 healthy controls); Cohort 2 comprised 35 elderly T2DM patients assessed for plasma AD biomarkers. All participants underwent MRI for ALPS index calculation and structural imaging. Cognition was evaluated using the Mini-Mental State Examination and Montreal Cognitive Assessment.ResultsThe ALPS index was significantly lower in T2DM patients with MCI compared to cognitively normal T2DM patients and healthy controls, and showed discriminative ability for MCI. Lower ALPS index correlated with poorer cognitive scores and was associated with brain atrophy. Mediation analysis indicated that the volume of the right opercular inferior frontal gyrus mediated the relationship between ALPS index and cognition scores. Furthermore, the ALPS index negatively correlated with plasma pTau217 adjusted by age and sex in T2DM patients.ConclusionsA lower ALPS index is associated with cognitive impairment, brain atrophy, and plasma tauopathy, which may serve as a promising non-invasive imaging biomarker for early identification of neurodegeneration risk in T2DM patients.