Changes of Structural and Functional Attention Control Networks in Subclinical Hypothyroidism

Exploring the interaction effects of subclinical hypothyroidism and major depressive disorder on brain networks

BACKGROUND

Major depressive disorder (MDD) often presents alongside physical illnesses, such as a high incidence of subclinical hypothyroidism (SHypo) in patients, highlighting the common occurrence of these comorbidities. Recent research has indicated that the presence of comorbid SHypo in individuals diagnosed with MDD may result in notable alterations in both brain structure and function. This study aimed was to investigate the neurological mechanisms underlying this co-occurrence using a data-driven approach to analyze brain activity patterns.

METHODS

Twenty-nine patients diagnosed with MDD without any comorbid conditions (nSHypo-MDD) were included in the study, along with 29 MDD patients who also had SHypo (SHypo-MDD), 26 patients with SHypo only, and 29 healthy individuals as controls (HCs). Each participant received resting-state functional magnetic resonance imaging scans and underwent neuropsychological evaluations.

RESULTS

We found significantly altered functional connectivity (FC) within the resting-state networks (RSNs) of the ventral and dorsal sensorimotor network (VSMN and DSMN) and occipital pole visual network (PVN) (p < 0.05, FDR corrected). A vital interaction effect between SHypo and MDD was detected in the PVN, showing that SHypo-MDD patients had higher FC values in the left cuneus than nSHypo-MDD patients. Serum-free triiodothyronine (FT3) levels in SHypo-MDD patients demonstrated an inverse relationship with FC values of the right supplementary motor area (SMA.R) (r = - 0.563, p = 0.003). Furthermore, the FC values in the left cuneus are positively associated with the Digit Symbol Substitution Test (DSST) scores (r = 0.507, p = 0.008).

CONCLUSIONS

Our study reveals significant FC changes in SHypo-MDD patients, particularly in the PVN, VSMN, and DSMN, suggesting compensatory mechanisms that mitigate cognitive deficits and highlighting the need for integrated management of SHypo and MDD to improve cognitive outcomes.

Brain compensatory activation during Stroop task in patients with mild cognitive impairment: a functional near-infrared spectroscopy study

Purpose

This study investigated the disparities in brain activation patterns during the Stroop task among individuals with mild cognitive impairment (MCI) and those without any cognitive impairments (healthy controls, HCs) using functional near-infrared spectroscopy (fNIRS).

Methods

We analyzed the cortical activation patterns of 73 patients with MCI and 63 HC individuals as they completed the Stroop task, employing fNIRS. The regions of interest (ROIs) included the dorsal prefrontal cortex (dPFC), ventrolateral prefrontal cortex (VLPFC), and parietal lobe (PL). The Stroop task is divided into early stage (0-15 s) and late stage (15-30 s). We also measured participants' behavior during the Stroop task, analyzed variations in cortical activation intensity at different experiment stages, and performed correlation analysis between Montreal Cognitive Assessment (MoCA) scores, Stroop performance, and oxygenation levels.

Results

Our analysis revealed that individuals with MCI and HC demonstrated elevated cortical activation in the dPFC, VLPFC, and PL areas while performing the Stroop task (q < 0.05, FDR-corrected). The MCI group displayed longer response latencies compared to the HC group while demonstrating comparable accuracy performance across both congruent and incongruent Stroop trials. The MCI group showed compensatory activation in the VLPFC, and PL regions compared to the HC group during the late stage of the Stroop task (q < 0.05, FDR-corrected). Correlational analysis revealed a negative association between MoCA scores and oxygenation levels in the dPFC, VLPFC, and PL regions during the late stage of the Stroop task (p < 0.05). However, no correlation was found with behavioral performance.

Conclusion

Mild cognitive impairment patients demonstrated effective compensation for their cognitive impairments at a partial behavioral level by engaging compensatory activation in the prefrontal, and parietal regions while performing the Stroop task.

Associations Between Thyroid Hormones Levels and Gray Matter Volume of Frontal Lobe Involved into Violence in Male Schizophrenia Patients

Background

Thyroid dysfunction and frontal lobe gray matter volume (GMV) alterations are associated with violence in schizophrenia (SCZ); however, little is known about the relationship between thyroid dysfunction and frontal lobe GMV. This study aimed to evaluate whether thyroid hormone levels were associated with frontal lobe GMV in male patients with schizophrenia and violence.

Methods

Fifty-five male patients with SCZ underwent triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) tests and structural magnetic resonance imaging (sMRI) scans. The sMRI data were processed using the FreeSurfer version 5.0. Multiple linear stepwise regression analysis was used to investigate the relationship between frontal lobe GMV and thyroid hormone levels in all patients.

Results

Patients with SCZ and violence exhibited lower GMV of the left frontal pole and higher TSH levels than those without violence. After controlling for potential covariates, the frontal pole GMV was negatively associated with TSH levels in all participants.

Conclusion

These findings expand our understanding of the influence of TSH on frontal pole GMV in patients with schizophrenia and violence.

Alterations in dynamic regional homogeneity within default mode network in patients with thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a significant autoimmune eye disease known for causing exophthalmos and substantial optic nerve damage. Prior investigations have solely focused on static functional MRI (fMRI) scans of the brain in TAO patients, neglecting the assessment of temporal variations in local brain activity. This study aimed to characterize alterations in dynamic regional homogeneity (dReHo) in TAO patients and differentiate between TAO patients and healthy controls using support vector machine (SVM) classification. Thirty-two patients with TAO and 32 healthy controls underwent resting-state fMRI scans. We calculated dReHo using sliding-window methods to evaluate changes in regional brain activity and compared these findings between the two groups. Subsequently, we employed SVM, a machine learning algorithm, to investigate the potential use of dReHo maps as diagnostic markers for TAO. Compared to healthy controls, individuals with active TAO demonstrated significantly higher dReHo values in the right angular gyrus, left precuneus, right inferior parietal as well as the left superior parietal gyrus. The SVM model demonstrated an accuracy ranging from 65.62 to 68.75% in distinguishing between TAO patients and healthy controls based on dReHo variability in these identified brain regions, with an area under the curve of 0.70 to 0.76. TAO patients showed increased dReHo in default mode network-related brain regions. The accuracy of classifying TAO patients and healthy controls based on dReHo was notably high. These results offer new insights for investigating the pathogenesis and clinical diagnostic classification of individuals with TAO.

Structural and Functional Alterations of Hippocampal Subfields in Patients With Adult-Onset Primary Hypothyroidism

CONTEXT

Hypothyroidism is often associated with cognitive and emotional dysregulation; however, the underlying neuropathological mechanisms remain elusive.

OBJECTIVE

The study aimed to characterize abnormal alterations in hippocampal subfield volumes and functional connectivity (FC) in patients with subclinical hypothyroidism (SCH) and overt hypothyroidism (OH).

METHODS

This cross-sectional observational study comprised 47 and 40 patients with newly diagnosed adult-onset primary SCH and OH, respectively, and 53 well-matched healthy controls (HCs). The demographics, clinical variables, and neuropsychological scale scores were collected. Next, the hippocampal subfield volumes and seed-based FC were compared between the groups. Finally, correlation analyses were performed.

RESULTS

SCH and OH exhibited significant alterations in cognitive and emotional scale scores. Specifically, the volumes of the right granule cell molecular layer of the dentate gyrus (GC-ML-DG) head, cornu ammonis (CA) 4, and CA3 head were reduced in the SCH and OH groups. Moreover, the volumes of the right molecular layer head, CA1 body, left GC-ML-DG head, and CA4 head were lower in SCH. In addition, the hippocampal subfield volumes decreased more significantly in SCH than OH. The seed-based FC decreased in SCH but increased in OH compared with HCs. Correlation analyses revealed thyroid hormone was negatively correlated with FC values in hypothyroidism.

CONCLUSION

Patients with SCH and OH might be at risk of cognitive decline, anxiety, or depression, and exhibited alterations in volume and FC in specific hippocampal subfields. Furthermore, the reduction in volume was more pronounced in SCH. This study provides novel insights into the neuropathological mechanisms of brain impairment in hypothyroidism.

Gray matter reduction is associated with cognitive dysfunction in depressed patients comorbid with subclinical hypothyroidism

Introduction

To explore the association between regional gray matter volume (GMV) and cognitive impairments and ascertain whether the regional brain alterations related to cognitive impairments occur in major depressive disorder (MDD) patients with comorbid subclinical hypothyroidism (SHypo).

Methods

We enrolled 32 MDD patients, 32 MDD patients with comorbid SHypo, and 32 normal controls and subjected them to thyroid function tests, neurocognitive tests, and magnetic resonance imaging (MRI). Using voxel-based morphometry (VBM) analysis, we examined the pattern of gray matter (GM) in these participants. We also used ANOVA to detect group differences and partial correlation to explore the potential association between GMV alterations and cognitive tests in comorbid patients.

Results

The comorbid patients exhibited significantly smaller GMV in the right middle frontal gyrus (MFG) than the non-comorbid group. Furthermore, the partial correlation analysis showed that GMV of the right MFG was associated with poor executive function (EF) performance in comorbid patients.

Conclusion

These findings provide valuable insight into the relationship between the alteration of GMV and cognitive dysfunction of MDD patients with comorbid SHypo.