Altered Effective Connectivity of Bilateral Hippocampus in Type 2 Diabetes Mellitus

Taiyuan Liu; Yan Bai; Lun Ma; Xiaoyue Ma; Wei Wei; Junran Zhang; Neil Roberts; Meiyun Wang

doi:10.3389/fnins.2020.00657

Altered Effective Connectivity of Bilateral Hippocampus in Type 2 Diabetes Mellitus

Front Neurosci. 2020 Jun 23:14:657. doi: 10.3389/fnins.2020.00657. eCollection 2020.

Authors

Taiyuan Liu¹, Yan Bai¹, Lun Ma¹, Xiaoyue Ma¹, Wei Wei¹, Junran Zhang², Neil Roberts³, Meiyun Wang¹

Affiliations

¹ Henan Key Laboratory of Neurological Imaging, Department of Medical Imaging, Zhengzhou University People's Hospital & Henan Provincial People's Hospital, Zhengzhou, China.
² Huaxi MR Research Center, Department of Radiology, West China Hospital of Sichuan University, Chengdu, China.
³ The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.

Abstract

Patients with type 2 diabetes mellitus (T2DM) experience cognitive deficits but the underlying pathophysiologic mechanisms are not known. We therefore applied Granger causality analysis of resting-state functional magnetic resonance imaging to study the effective connectivity (EC) of the hippocampus in patients with T2DM. Eighty six patients with T2DM and 84 matched healthy controls (HC) were recruited. The directional EC between anatomically defined seeds in left hippocampus (LHIP) and right hippocampus (RHIP) and other brain regions was compared between T2DM and HC and Pearson correlation analysis was performed to determine whether alterations in EC were related to clinical characteristics of diabetes. Compared with HC, patients with T2DM had altered EC between LHIP and RHIP and the default mode network (DMN), occipital cortex and cerebellum. In addition, for LHIP only duration of diabetes positively correlated with decreased inflow from right postcentral gyrus and right parietal lobe, glycosylated hemoglobin (HbA1c) negatively correlated with decreased inflow from right thalamus (r = -0.255, p = 0.018) and Montreal Cognitive Assessment (MoCA) negatively correlated with decreased inflow from left inferior parietal lobe (r = -0.206, p = 0.05). The altered EC between hippocampus and DMN is interpreted to be related to cognitive deficits in patients with T2DM particularly affecting memory and learning.

Keywords: Effective Connectivity (EC); Granger causality analysis (GCA); Hippocampus; resting-state functional magnetic resonance imaging (rs-fMRI); type 2 diabetes mellitus (T2DM).