Background: As a risk factor for Alzheimer's disease (AD), type 2 diabetes mellitus (T2DM)
itself causes cognitive impairment and has higher prevalence of mild cognitive impairment (MCI). Objective:
The aim of this study was to explore the cognition especially the episodic memory difference,
the DMN functional connectivity and DMN-related white matter integrity in patients with both T2DM
and amnestic MCI (T2DM-MCI) as compared to patients with T2DM only.
Methods: Focusing especially on T2DM population, we investigated the default mode network (DMN)
through resting-state functional magnetic resonance imaging among 22 elderly T2DM-MCI patients and
24 elderly T2DM patients. Including primarily the bilateral cingulum, hippocampus and uncinate fasciculus,
these DMN white matter fibers were also closely associated with episodic memory and the integrity
of them was also investigated using diffusion tensor imaging in 19 elderly T2DM-MCI patients
and 23 elderly T2DM patients.
Results: Compared with the patients with T2DM, the T2DM-MCI patients performed worse in several
areas of cognition besides episodic memory, and showed stronger DMN functional connectivity in the
left precuneus and weaker functional connectivity in the left calcarine, as well as decreased integrity of
the left cingulate bundle and bilateral uncinate fasciculus. Furthermore, a correlation analysis indicated
that higher left calcarine connectivity was associated with better episodic memory performance among
the overall group.
Conclusion: Our results demonstrated that T2DM patients with comorbid amnestic MCI had abnormal
functional connectivity patterns and decreased white matter integrity, which could potentially serve as
AD or AD risk biomarkers for early detection of those elderly individuals with T2DM.