Changes of Structural and Functional Attention Control Networks in Subclinical Hypothyroidism

Jingjing Yin,Ruiwei Guo,Dongxue Luo,Wencan Xu,Shouxing Duan,Shuhua Ma,Yanmin Zheng,Lei Xie,Zhirong Lin,Jinzhuang Huang

doi:10.3389/fnbeh.2021.725908

Abstract

Objective: This study aimed to explore the structural changes in patients with subclinical hypothyroidism (SCH) using voxel-based morphometry (VBM) and to investigate the altered attentional control networks using functional MRI (fMRI) during the performance of a modified Stroop task with Chinese characters.Methods: High-resolution three-dimensional (3D) T1-weighted images and an fMRI scan were taken from 18 patients with SCH and 18 matched control subjects. The Montreal Cognitive Assessment Chinese-revised (MoCA-CR) and the Stroop task were used to evaluate the cognitive and attention control of the participants.Results: Compared to controls, the VBM results showed decreased gray matter volumes (GMVs) in bilateral prefrontal cortices (PFCs, including middle, medial, and inferior frontal gyri), cingulate gyrus, precuneus, left middle temporal gyrus, and insula in patients with SCH. The fMRI results showed a distributed network of brain regions in both groups, consisting of PFCs (including superior and middle and inferior frontal cortices), anterior cingulate cortex (ACC), posterior cingulate cortex, and precuneus, as well as the insula and caudate nucleus. Compared to controls, the SCH group had lower activation of the above brain areas, especially during the color-naming task. In addition, the normalized GMV (nGMV) was negatively correlated with thyroid-stimulating hormone (TSH) level (r = −0.722, p < 0.001).Conclusion: Results indicate that patients with SCH exhibit reduced GMVs, altered BOLD signals, and activation in regions associated with attention control, which further suggest that patients with SCH may have attentional control deficiency, and the weakened PFC–ACC–precuneus brain network might be one of the neural mechanisms. Negative correlations between nGMV and TSH suggest that TSH elevation may induce abnormalities in the cortex.

Highlights

Thyroid dysfunction is a common endocrine disease that is manifested in four types, namely, hyperthyroidism, hypothyroidism, subclinical hyperthyroidism, and subclinical hypothyroidism (SCH)
In a general linear model for repeated measures performed on the Stroop task, performance accuracy, and reaction time were significantly different in both groups [F(1, 34) = 52.48, F(1,34) = 132.32, p < 0.001]
For the VBM-based analysis across the whole brain, we found that normalized GMV (nGMV) of patients with SCH were significantly less than that of the control group (p < 0.05, Table 3)

Summary

Introduction

Thyroid dysfunction is a common endocrine disease that is manifested in four types, namely, hyperthyroidism, hypothyroidism, subclinical hyperthyroidism, and subclinical hypothyroidism (SCH). Mainly using neuropsychological tests, that hypothyroidism or SCH is related to cognitive impairments, such as attention, memory, psychomotor, and executive functions (Resta et al, 2012; Pasqualetti et al, 2015; Yuan et al, 2020). A series of task-based functional MRI (fMRI) studies reveal task-induced deactivation in the default mode network or reversible alterations of the brain during working memory tasks (Zhu et al, 2006; He et al, 2011). Kumar et al showed that the alterations of intrinsic resting-state functional connectivity in the somatomotor and right frontalparietal attention networks may be one of the reasons for mild impairment of motor, working memory, attention, and executive cognitive functions in patients with SCH (Kumar et al, 2018)

Methods

Results

Conclusion