Network efficiency of functional brain connectomes altered in type 2 diabetes patients with and without mild cognitive impairment.

AIM

To explore the topological organization alterations of functional connectomes in type 2 diabetes (T2DM) patients with and without mild cognitive impairment (MCI), and compare these with structural connectomes changes.

METHODS

Twenty-six T2DM patients with MCI (DM-MCI), 26 without cognitive impairment (DM-NC), and 28 healthy controls were included. Diffusion tensor imaging (DTI) and resting-state functional MRI images were acquired. Networks were constructed and graph-theory based network measurements were calculated. The global network parameters and nodal efficiencies were compared across the three groups using one-way ANOVA and a false-discovery rate correction was applied for multiple comparisons. Partial correlation analyses were performed to investigate relationships between network parameters, cognitive performance and clinical variables.

RESULTS

In the structural connectome, the DM-MCI group exhibited significantly decreased global efficiency (E) and local efficiency (E) compared to the DM-NC and control groups. In the functional connectome, the DM-MCI group exhibited increased E and clustering coefficient (Cp) compared to the controls. No significant differences were found in E, E, or Cp between the DM-NC and the control group, both in structural and functional connectomes. Nodal efficiencies decreased in some brain regions of structural and functional networks in the DM-MCI and DM-NC groups, but increased in five regions in functional network, some of which were involved in the default-mode network.

CONCLUSION

Unlike the consistently decreased global properties and nodal efficiencies in the structural connectome of T2DM patients, increases in E, Cp, and nodal efficiencies in the functional connectome may be viewed as a compensatory mechanism due to functional plasticity and reorganization. Altered nodal efficiency can hint at cognitive decrements at an early stage in T2DM patients.