Identify changes of brain regional homogeneity in early and later adult onset patients with first-episode depression using resting-state fMRI

Data integration with Fusion Searchlight: Classifying brain states from resting-state fMRI

Resting-state fMRI captures spontaneous neural activity characterized by complex spatiotemporal dynamics. Various metrics, such as local and global brain connectivity and low-frequency amplitude fluctuations, quantify distinct aspects of these dynamics. However, these measures are typically analyzed independently, overlooking their interrelations and potentially limiting analytical sensitivity. Here, we introduce the Fusion Searchlight (FuSL) framework, which integrates complementary information from multiple resting-state fMRI metrics. We demonstrate that combining these metrics enhances the accuracy of pharmacological treatment prediction from rs-fMRI data, enabling the identification of additional brain regions affected by sedation with alprazolam. Furthermore, we leverage explainable AI to delineate the differential contributions of each metric, which additionally improves spatial specificity of the searchlight analysis. Moreover, this framework can be adapted to combine information across imaging modalities or experimental conditions, providing a versatile and interpretable tool for data fusion in neuroimaging.

Age-related abnormalities in brain functional and molecular neuroimaging signatures in first-episode depression

Abnormalities in resting-state brain activity have been demonstrated in depression patients with different ages, yet the age-related changes in dynamics of brain activity in depression are still limited. Here, we investigated the impacts of age on dynamics of brain activity and the molecular architecture. Resting-state functional magnetic resonance images were obtained from 138 first-episode depression patients and 120 healthy volunteers. All the participants were classified into two age cohorts, including adolescents and adults. Two-way analysis of variance was performed to examine the effect of age on dynamic amplitude of low-frequency fluctuations (ALFF) in depression. Then, cross-modal correlation analyses between dynamic ALFF and neurotransmitter maps were established. Significant diagnosis-by-age interaction of dynamic ALFF was located in medial frontal gyrus, supplementary motor area, postcentral gyrus, paracentral lobule and rolandic operculum. Dynamic ALFF alterations in the diagnosis-by-age interaction effect were associated with serotonergic, dopaminergic, noradrenergic, and GABAergic systems. These findings highlight the interaction between depression and age in brain functional and molecular neuroimaging signatures, which may be useful for future treatment strategies of different ages of depression.

Integrative intrinsic brain activity and molecular analyses of the interaction between first-episode depression and age

BACKGROUND

Numerous studies have underscored the presence of abnormal intrinsic neural activity (INA) in individuals with depression. However, recognizing that the age stage may influence the pathophysiology of depression, our study sought to delve into the interplay of depression and age on INA and molecular architecture.

METHODS

One hundred and thirty-eight first-episode depression patients and 120 healthy controls (HC) were recruited and underwent resting-state functional magnetic resonance imaging. The participants were stratified into four groups based on age. Utilizing amplitude of low-frequency fluctuation (ALFF) analyses, we employed an ANCOVA to compare INA patterns in four groups. Additionally, we conducted correlation analyses between ALFF and neurotransmitter maps to elucidate molecular underpinnings of INA abnormalities.

RESULTS

In comparison to adolescents with early-onset depression and adult HC, adult-onset depression exhibited increased ALFF in the right paracentral lobule. Conversely, early-onset depression, when contrasted with adolescent HC, displayed reduced ALFF in the right paracentral lobule. The interactive brain regions affected by ALFF alterations were associated with serotonergic, GABAergic, and opioid neurotransmitter systems.

LIMITATIONS

The present study was limited to its cross-sectional design.

CONCLUSIONS

This study illuminates an antagonistic effect of depression and age on brain activity in paracentral lobule and provides molecular underpinnings of the corresponding INA abnormalities related to key neurotransmitter systems. These insights may prove valuable in the development of neuromarkers for clinical intervention and treatment of depression.

Local brain abnormalities in emotional disorders: Evidence from resting state fMRI studies

Emotional disorders inflict an enormous burden on society. Research on brain abnormalities implicated in emotional disorders has witnessed great progress over the past decades. Using cross-sectional and longitudinal designs, resting state functional magnetic resonance imaging (rs-fMRI) and its analytic approaches have been applied to characterize the local properties of patients with emotional disorders. Additionally, brain activity alterations of emotional disorders have shown frequency-specific. Despite the gains in understanding the roles of brain abnormalities in emotional disorders, the limitation of the small sample size needs to be highlighted. Lastly, we proposed that evidence from the positive psychology research stream presents it as a viable discipline, whose suggestions could be developed in future emotional disorders research. Such interdisciplinary research may produce novel treatments and intervention options. This article is categorized under: Psychology > Brain Function and Dysfunction.

Gender differences in major depressive disorder at different ages: a REST-meta-MDD project-based study

BACKGROUND

Major depressive disorder (MDD) is a highly heterogeneous disease, with differences in clinical manifestations among depression patients based on onset ages and genders. The neural mechanisms underlying these differences remain unclear. In this study, we utilized resting state functional imaging data from a large sample database and adopted the ReHo method to investigate gender differences in local brain function in MDD patients across different onset age groups.

METHODS

The study included 364 MDD patients and 695 healthy participants who were part of the REST-meta-MDD project. Regional homogeneity (ReHo) assessed gender disparities in MDD and healthy individuals within groups delineated by gender and onset age (young group: 18-29 years; middle-aged group: 30-45 years).

RESULTS

Among the young MDD groups, there were significant gender differences in the right superior frontal gyrus, right inferior frontal gyrus, left superior temporal gyrus, and right superior parietal lobule, with male MDD patients having higher ReHo values compared to females. When compared to healthy males, male MDD patients exhibited elevated ReHo values in the right superior parietal lobule. In the middle-aged groups, a marked ReHo difference was observed in the bilateral cerebellum posterior lobe, with female MDD patients showing higher ReHo values.

CONCLUSIONS

The functional mechanisms of MDD differ between genders and show distinct variations across different onset age groups. These findings underscore the importance of developing personalized interventions that address the unique needs of MDD patients, tailored to their gender and age, and necessitate the development of antidepressant medications targeted at each gender-age subgroup.

Taste dysfunction as a predictor of depression in schizophrenia: A systematic review and meta-analysis

OBJECTIVE

This study aims to investigate the relationship between taste dysfunction and depression among patients with schizophrenia, to achieve early detection of depression in clinical practice.

METHODS

Following PRISMA guidance, a comprehensive literature search was conducted globally, covering papers published from 1961 to June 2023. A total of 17 manuscripts were selected through meta-analysis and sensitivity analysis after examining available materials from seven databases to determine the correlation between depression and taste dysfunction.

RESULTS

The comparison of the 17 selected manuscripts revealed that individuals with gustatory dysfunction may be more likely to experience depressive symptoms (SMD, 0.51, 95% CI, 0.08 to 0.93, p = 0.02). Depression is associated with taste dysfunction in certain aspects, as indicated by the pleasantness ratings of sucrose solutions (SMD, -0.53, 95% confidence interval [CI] -1.11 to 0.05, p = 0.08), gustatory identification ability (SMD, 0.96, 95% CI, 0.03 to 1.89, p = 0.04), and the perception threshold of sweet taste (MD, 0.80, 95% CI, 0.79 to 0.81, p < 0.00001).

CONCLUSIONS

Due to variations in the methods, designs, and selection criteria employed in the included studies, it is necessary to establish a feasible framework. Future research using detailed and targeted approaches can provide clearer and more unified conclusions on the relationship between taste dysfunction and depression. Moreover, further high-quality research is needed to obtain clearer conclusions and explore the potential of taste dysfunction as an effective tool for early screening of depression.

TRIAL REGISTRATION

This review has been registered in the PROSPERO on April 2022 with the identifier CRD42023400172.

Multi-feature concatenation and multi-classifier stacking: An interpretable and generalizable machine learning method for MDD discrimination with rsfMRI

Major depressive disorder (MDD) is a serious and heterogeneous psychiatric disorder that needs accurate diagnosis. Resting-state functional MRI (rsfMRI), which captures multiple perspectives on brain structure, function, and connectivity, is increasingly applied in the diagnosis and pathological research of MDD. Different machine learning algorithms are then developed to exploit the rich information in rsfMRI and discriminate MDD patients from normal controls. Despite recent advances reported, the MDD discrimination accuracy has room for further improvement. The generalizability and interpretability of the discrimination method are not sufficiently addressed either. Here, we propose a machine learning method (MFMC) for MDD discrimination by concatenating multiple features and stacking multiple classifiers. MFMC is tested on the REST-meta-MDD data set that contains 2428 subjects collected from 25 different sites. MFMC yields 96.9% MDD discrimination accuracy, demonstrating a significant improvement over existing methods. In addition, the generalizability of MFMC is validated by the good performance when the training and testing subjects are from independent sites. The use of XGBoost as the meta classifier allows us to probe the decision process of MFMC. We identify 13 feature values related to 9 brain regions including the posterior cingulate gyrus, superior frontal gyrus orbital part, and angular gyrus, which contribute most to the classification and also demonstrate significant differences at the group level. The use of these 13 feature values alone can reach 87% of MFMC's full performance when taking all feature values. These features may serve as clinically useful diagnostic and prognostic biomarkers for MDD in the future.

How does feeling pain look like in depression: A review of functional neuroimaging studies

INTRODUCTION

Major Depression Disorder (MDD) and pain appear to be reciprocal risk factors and sharing common neuroanatomical pathways and biological substrates. However, the role of MDD on pain processing remains still unclear. Therefore, this review aims to focus on the effect of depression on pain anticipation, and perception, before and after treatment, through functional magnetic resonance imaging (fMRI).

METHODS

A bibliographic search was conducted on PubMed, Scopus and Web of Science, looking for fMRI studies exploring pain processing in MDD patients.

RESULTS

Amongst the 602 studies retrieved, 12 met the inclusion criteria. In terms of pain perception, studies evidenced that MDD patients generally presented increased activation in brain regions within the prefrontal cortex, insula and in the limbic system (such as amygdala, hippocampus) and occipital cortex. The studies investigating the effect of antidepressant treatment evidenced a reduced activation in areas such as insula, anterior cingulate, and prefrontal cortices. In terms of pain anticipation, contrasting results were evidenced in MDD patients, which presented both increased and decreased activity in the prefrontal cortex, the insula and the temporal lobe, alongside with increased activity in the anterior cingulate cortex, the frontal gyrus and occipital lobes.

LIMITATIONS

The small number of included studies, the heterogeneous approaches of the studies might limit the conclusions of this review.

CONCLUSIONS

Acute pain processing in MDD patients seems to involve numerous and different brain areas. However, more specific fMRI studies with a more homogeneous population and rigorous approach should be conducted to better highlight the effect of depression on pain processing.

Neural activity changes in first-episode, drug-naïve patients with major depressive disorder after transcutaneous auricular vagus nerve stimulation treatment: A resting-state fMRI study

Introduction

Major depressive disorder (MDD) is a disease with prominent individual, medical, and economic impacts. Drug therapy and other treatment methods (such as Electroconvulsive therapy) may induce treatment-resistance and have associated side effects including loss of memory, decrease of reaction time, and residual symptoms. Transcutaneous auricular vagus nerve stimulation (taVNS) is a novel and non-invasive treatment approach which stimulates brain structures with no side-effects. However, it remains little understood whether and how the neural activation is modulated by taVNS in MDD patients. Herein, we used the regional homogeneity (ReHo) to investigate the brain activity in first-episode, drug-naïve MDD patients after taVNS treatment.

Materials and methods

Twenty-two first-episode, drug-naïve MDD patients were enrolled in the study. These patients received the first taVNS treatment at the baseline time, and underwent resting-state MRI scanning twice, before and after taVNS. All the patients then received taVNS treatments for 4 weeks. The severity of depression was assessed by the 17-item Hamilton Depression Rating Scale (HAMD) at the baseline time and after 4-week’s treatment. Pearson analysis was used to assess the correlation between alterations of ReHo and changes of the HAMD scores. Two patients were excluded due to excessive head movement, two patients lack clinical data in the fourth week, thus, imaging analysis was performed in 20 patients, while correlation analysis between clinical and imaging data was performed in only 18 patients.

Results

There were significant differences in the ReHo values in first-episode, drug-naïve MDD patients between pre- or post- taVNS. The primary finding is that the patients exhibited a significantly lower ReHo in the left/right median cingulate cortex, the left precentral gyrus, the left postcentral gyrus, the right calcarine cortex, the left supplementary motor area, the left paracentral lobule, and the right lingual gyrus. Pearson analysis revealed a positive correlation between changes of ReHo in the right median cingulate cortex/the left supplementary motor area and changes of HAMD scores after taVNS.

Conclusion

The decreased ReHo were found after taVNS. The sensorimotor, limbic and visual-related brain regions may play an important role in understanding the underlying neural mechanisms and be the target brain regions in the further therapy.

Altered spontaneous brain activity in major depressive disorder: An activation likelihood estimation meta-analysis

BACKGROUND

Wide application of resting-state functional magnetic resonance imaging (fMRI) in psychiatric research has revealed that major depressive disorder (MDD) manifest abnormal neural activities in several brain regions involving key resting state networks. However, inconsistent results have hampered our understanding of the exact neuropathology associated with MDD. Therefore, our aim was to conduct a meta-analysis to identify the consistent vulnerable brain regions of MDD in resting state, and to reveal the potential pathogenesis of MDD.

METHODS

A systematic review analysis was conducted on studies involving brain resting-state changes in MDD using low-frequency amplitude (ALFF), fractional low-frequency amplitude (fALFF) and regional homogeneity (ReHo) analysis. The meta-analysis was based on the activation likelihood estimation method, using the software of Ginger ALE 2.3.

RESULTS

25 studies (892 MDD and 799 healthy controls) were included. Based on the meta-analysis results of ReHo, we found robust reduction of resting-state spontaneous brain activity in MDD, including the left cuneus and right middle occipital gyrus (cluster size = 216, 256 mm³, uncorrected P < 0.0001), while no increased spontaneous activation in any of the brain regions. We also found reduced ALFF in the left middle occipital gyrus (cluster size = 224 mm³, uncorrected P < 0.0001), and no increased spontaneous brain activation in any regions.

CONCLUSION

Our meta-analysis study using the activation likelihood estimation method demonstrated that MDD showed significant abnormalities in spontaneous neural activity, compared with healthy controls, mainly in areas associated with visual processing, such as the cuneus and the middle occipital gyrus. Dysfunction of these brain regions may be one of the pathogenesis of MDD.

Impaired robust interhemispheric function integration of depressive brain from REST-meta-MDD database in China

BACKGROUND

Recently, functional homotopy (FH) architecture, defined as robust functional connectivity (FC) between homotopic regions, has been frequently reported to be altered in MDD patients (MDDs) but with divergent locations.

METHODS

In this study, we obtained resting-state functional magnetic resonance imaging (R-fMRI) data from 1004 MDDs (mean age, 33.88 years; age range, 18-60 years) and 898 matched healthy controls (HCs) from an aggregated dataset from 20 centers in China. We focused on interhemispheric function integration in MDDs and its correlation with clinical characteristics using voxel-mirrored homotopic connectivity (VMHC) devised to inquire about FH patterns.

RESULTS

As compared with HCs, MDDs showed decreased VMHC in visual, motor, somatosensory, limbic, angular gyrus, and cerebellum, particularly in posterior cingulate gyrus/precuneus (PCC/PCu) (false discovery rate [FDR] q < 0.002, z = -7.07). Further analysis observed that the reduction in SMG and insula was more prominent with age, of which SMG reflected such age-related change in males instead of females. Besides, the reduction in MTG was found to be a male-special abnormal pattern in MDDs. VMHC alterations were markedly related to episode type and illness severity. The higher Hamilton Depression Rating Scale score, the more apparent VMHC reduction in the primary visual cortex. First-episode MDDs revealed stronger VMHC reduction in PCu relative to recurrent MDDs.

CONCLUSIONS

We confirmed a significant VMHC reduction in MDDs in broad areas, especially in PCC/PCu. This reduction was affected by gender, age, episode type, and illness severity. These findings suggest that the depressive brain tends to disconnect information exchange across hemispheres.

A Comparative Study of Regional Homogeneity of Resting-State fMRI Between the Early-Onset and Late-Onset Recurrent Depression in Adults

Background

Neurobiological mechanisms underlying the recurrence of major depressive disorder (MDD) at different ages are unclear, and this study used the regional homogeneity (ReHo) index to compare whether there are differences between early onset recurrent depression (EORD) and late onset recurrent depression (LORD).

Methods

Eighteen EORD patients, 18 LORD patients, 18 young healthy controls (HCs), and 18 older HCs were included in the rs-fMRI scans. ReHo observational metrics were used for image analysis and further correlation of differential brain regions with clinical symptoms was analyzed.

Results

ANOVA analysis revealed significant differences between the four groups in ReHo values in the prefrontal, parietal, temporal lobes, and insula. Compared with EORD, the LORD had higher ReHo in the right fusiform gyrus/right middle temporal gyrus, left middle temporal gyrus/left angular gyrus, and right middle temporal gyrus/right angular gyrus, and lower ReHo in the right inferior frontal gyrus/right insula and left superior temporal gyrus/left insula. Compared with young HCs, the EORD had higher ReHo in the right inferior frontal gyrus/right insula, left superior temporal gyrus/left insula, and left rolandic operculum gyrus/left superior temporal gyrus, and lower ReHo in the left inferior parietal lobule, right inferior parietal lobule, and left middle temporal gyrus/left angular gyrus. Compared with old HCs, the LORD had higher ReHo in the right fusiform gyrus/right middle temporal gyrus, right middle temporal gyrus/right angular gyrus, and left rolandic operculum gyrus/left superior temporal gyrus, and lower ReHo in the right inferior frontal gyrus/right insula. ReHo in the right inferior frontal gyrus/right insula of patients with LORD was negatively correlated with the severity of 17-item Hamilton Rating Scale for Depression (HAMD-17) scores (r = −0.5778, p = 0.0120).

Conclusion

Adult EORD and LORD patients of different ages have abnormal neuronal functional activity in some brain regions, with differences closely related to the default mode network (DMN) and the salience network (SN), and patients of each age group exhibit ReHo abnormalities relative to matched HCs.

Clinical Trial Registration

[http://www.chictr.org.cn/], [ChiCTR1800014277].

Altered Cingulum Functioning in Major Depressive Disorder Patient With Suicide Attempts: A Resting-State Functional Magnetic Resonance Imaging Study

Background

Major depressive disorder (MDD) with suicide attempts (SA) poses a significant public health issue. This study aims to identify neurobiological markers for MDD with SA on resting-state brain functional magnetic resonance imaging (rs-fMRI).

Methods

Fifty-one unmedicated adult MDD participants, 27 with SA on the Beck Scale for Suicidal Ideation and 24 without SA, underwent rs-fMRI scanning. A group of 30 healthy controls (HC) matched for age, gender, and education-level with MDD were chosen. A whole brain analysis of regional homogeneity (ReHo) was performed on subjects to identify regions where brain activity was associated with SA. Multiple comparison analysis was performed for ReHo. Pearson’s correlation analysis was performed between HAMD-SA scores and ReHo. The statistical significance level was set at p < 0.05.

Results

We examined whether there were significant differences among the three groups in whole brain ReHo during resting state. Subjects with SA showed significant increase of ReHo in the right Cingulum Post in comparison with those without SA. Subjects with SA showed significant decrease of ReHo in the right Cingulate Gyrus/Precuneus in comparison with HC. The mean ReHo from the significant brain region was associated with HAMD-SA (item 3 of the HAMD) scores (r = 0.349, P = 0.012) but was not associated with HAMD-24 scores.

Conclusion

These results indicate that SA is associated with altered resting-state brain activity. The pattern of elevated activity in the cingulum functioning may be related to SA. Identifying cingulum activity associated with SA may help to elucidate its pathogenesis and etiology.

Dynamics of task-induced modulation of spontaneous brain activity and functional connectivity in the triple resting-state networks assessed using the visual oddball paradigm

The default mode network (DMN), the salience network (SN), and the central executive network (CEN) are considered as the core resting-state brain networks (RSN) due to their involvement in a wide range of cognitive tasks. Despite the large body of knowledge related to their regional spontaneous activity (RSA) and functional connectivity (FC) of these networks, less is known about the dynamics of the task-associated modulation on these parameters and the task-induced interaction between these three networks. We have investigated the effects of the visual-oddball paradigm on three fMRI measures (amplitude of low-frequency fluctuations for RSA, regional homogeneity for local FC, and degree centrality for global FC) in these three core RSN. A rest-task-rest paradigm was used and the RSNs were identified using independent component analysis (ICA) on the resting-state data. The observed patterns of change differed noticeably between the networks and were tightly associated with the task-related brain activity and the distinct involvement of the networks in the performance of the single subtasks. Furthermore, the inter-network analysis showed an increased synchronization of CEN with the DMN and the SN immediately after the task, but not between the DMN and SN. Higher pre-task inter-network synchronization between the DMN and the CEN was associated with shorter reaction times and thus better performance. Our results provide some additional insights into the dynamics within and between the triple RSN. Further investigations are required in order to understand better their functional importance and interplay.

Increased thalamo-cortical functional connectivity in patients with diabetic painful neuropathy: A resting-state functional MRI study

Functional changes in the brain of patients with painful diabetic neuropathy (PDN) have remained largely elusive. The aim of the present study was to explore changes in thalamo-cortical functional connectivity (FC) of patients with PDN using resting-state functional MRI. A total of 20 patients with type 2 diabetes mellitus (T2DM) with non-painful diabetic neuropathy (Group NDN), 19 patients with T2DM with PDN (Group-PDN) and 13 age-, sex- and education-matched healthy controls were recruited. The differences in thalamo-cortical FC among the three groups were compared. Patients in Group PDN had increased FC in the left thalamus, the right angular gyrus and the occipital gyrus as compared to those in Group NDN. Furthermore, patients in Group PDN had increased FC in the right thalamus and angular gyrus as compared to those in Group NDN. In conclusion, the present results suggested that the thalamo-cortical FC is increased in patients with T2DM and PDN. Furthermore, the increased FC in the thalamic-parietal-occipital connectivity may be a central pathophysiological mechanism for PDN. The study was retrospectively registered at ClinicalTrials.gov on 3 October 2018 (identifier no. NCT03700502).

Changes in Regional Homogeneity of Medication-Free Major Depressive Disorder Patients With Different Onset Ages

Background: Neurobiological mechanisms underlying the development of major depressive disorder (MDD) may differ depending on onset ages. Our aim was to determine whether regional homogeneity (ReHo) changes in early-onset depression (EOD) and late-onset depression (LOD) are different, which could also delineate EOD and LOD. Methods: Ninety-one MDD patients and 115 healthy controls (HCs) were recruited, and resting-state functional magnetic resonance imaging data were collected. The ReHo comparison was conducted using analysis of variance. Results: Compared with HCs, MDD patients showed decreased ReHo in the left precentral gyrus and the left middle cingulum area, and increased ReHo in the left middle orbital frontal gyrus and superior temporal gyrus. Compared with LOD patients, young HC separately, EOD patients had significantly increased ReHo in the right inferior frontal triangular gyrus and the left postcentral gyrus. However, compared with young HC, EOD patients showed decreased ReHo in the right superior frontal gyrus/supplementary motor area and the right medial frontal gyrus. ReHo in the right inferior frontal triangular gyrus was negatively correlated with the severity of cognitive disturbance in LOD patients (r = -0.47, p = 0.002), but not in EOD patients (r = 0.21, p = 0.178). Conclusion: MDD patients with different onset ages may have different pathophysiological mechanisms; the EOD patients had more abnormal ReHo than LOD patients in the prefrontal lobe, especially the right inferior frontal triangular gyrus.

Study on neuropathological mechanisms of primary monosymptomatic nocturnal enuresis in children using cerebral resting-state functional magnetic resonance imaging

Primary monosymptomatic nocturnal enuresis (PMNE) is a heterogeneous disorder, which remains a difficult condition to manage due to lack of knowledge on the underlying pathophysiological mechanisms. Here we investigated the underlying neuropathological mechanisms of PMNE with functional MRI (fMRI), combining the amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and seed-based functional connectivity (seed-based FC) analyses. Compared to the control group, PMNE group showed decreased ALFF value in the left medial orbital superior frontal gyrus (Frontal_Med_Orb_L), and increased ReHo value in the left superior occipital gyrus (Occipital_Sup_L). With left thalamus as the seed, PMNE group showed significantly decreased functional connectivity to the left medial superior frontal gyrus (Frontal_Sup_Medial_L). We conclude that these abnormal brain activities are probably important neuropathological mechanisms of PMNE in children. Furthermore, this study facilitated the understanding of underlying pathogenesis of PMNE and may provide an objective basis for the effective treatment.

Treatment-naïve first episode depression classification based on high-order brain functional network

BACKGROUND

Recent functional connectivity (FC) studies have proved the potential value of resting-state functional magnetic resonance imaging (rs-fMRI) in the study of major depressive disorder (MDD); yet, the rs-fMRI-based individualized diagnosis of MDD is still challenging.

METHODS

We enrolled 82 treatment-naïve first episode depression (FED) adults and 72 matched normal control (NC). A computer-aided diagnosis framework was utilized to classify the FEDs from the NCs based on the features extracted from not only traditional "low-order" FC networks (LON) based on temporal synchronization of original rs-fMRI signals, but also "high-order" FC networks (HON) that characterize more complex functional interactions via correlation of the dynamic (time-varying) FCs. We contrasted a classifier using HON feature (C_HON) and compared its performance with using LON only (C_LON). Finally, an integrated classification model with both features was proposed to further enhance FED classification.

RESULTS

The C_HON had significantly improved diagnostic accuracy compared to the C_LON (82.47% vs. 67.53%). Joint classification further improved the performance (83.77%). The brain regions with potential diagnostic values mainly encompass the high-order cognitive function-related networks. Importantly, we found previously less-reported potential imaging biomarkers that involve the vermis and the crus II in the cerebellum.

LIMITATIONS

We only used one imaging modality and did not examine data from different subtypes of depression.

CONCLUSIONS

Depression classification could be significantly improved by using HON features that better capture the higher-level brain functional interactions. The findings suggest the importance of higher-level cerebro-cerebellar interactions in the pathophysiology of MDD.

Functional MRI reveals effects of high intraocular pressure on central nervous system in high-tension glaucoma patients

PURPOSE

To evaluate the effects of high intraocular pressure (IOP) on central nervous system in patients with high-tension glaucoma (HTG) by using resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Thirty-six patients with HTG and twenty age- and gender-matched healthy controls (HCs) were recruited and underwent IOP measurement and rs-fMRI scan. The whole brain regional homogeneity (ReHo) value was calculated among the enrolled subjects. Two-sample t tests with permutation test and threshold-free cluster enhancement was performed between HTG group and HCs. Correlation analyses between IOP and ReHo values were conducted.

RESULTS

Compared with HCs, HTG group showed increased ReHo values in the left lobule 8 of cerebellar hemisphere, left lobule 4 and 5 of cerebellar hemisphere and left fusiform gyrus (FG) (p < 0.05). HTG group showed decreased ReHo value in the left middle frontal gyrus (MFG) (p < 0.05). Intraocular pressure of the left eye in HTG group experienced a significant positive correlation with ReHo value of the left FG (r = 0.370, p = 0.026), IOP of the right eye in HTG group showed a significant negative correlation with ReHo value in the left MFG (r = -0.421, p = 0.011).

CONCLUSION

Resting-state fMRI ReHo analyses associated elevated IOP with abnormal regional activity in several brain regions related to higher visual function and visual memory consolidation. High-tension glaucoma patients also showed diminished integration of visual information and cerebellar function. These results may provide imaging support for pathophysiological research of HTG and may reveal new targets for the accurate treatment of HTG.

Identify abnormalities in resting-state brain function between first-episode, drug-naive major depressive disorder and remitted individuals: a 3-year retrospective study

This study aims to identify and characterize neurobiological markers for major depressive disorder (MDD) from resting-state brain functional MRI. We examined the abnormality in the regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) in first-episode, drug-naive major depressive disorder (fMDD), and remitted major depressive disorder (rMDD) and correlated these fluctuations with clinical markers of MDD. We conducted a retrospective study and reviewed the medical records of 43 patients with fMDD. Overall, 13 of the 43 patients who had at least 3 years of follow-up care and the 17-item Hamilton Depression rating scale less than 7 took no antidepressants for more than half a year at the end of the 3-year follow-up. We further chose a group of 14 healthy controls matched for age, sex and education level with patients with rMDD. Multiple comparison analysis was performed for ALFF and ReHo. The statistical significance level was set at P value of less than 0.05. We examined whether there were differences among the three groups in the whole-brain ALFF and ReHo during resting state. Compared with healthy controls, patients with fMDD showed significant decrease of ReHo in the right anterior lobe of cerebellum and significant increase of ReHo in the right inferior temporal gyrus, and significant decrease of ALFF in the left inferior parietal lobule and right caudate nucleus. Compared with patients with rMDD, those with fMDD showed significant increase of ReHo in the right fusiform gyrus and the left middle temporal gyrus, and significant increase of ALFF in the right superior temporal gyrus. Compared with healthy controls, patients with rMDD showed significant increase of ReHo in the right supramarginal and significant decrease of ReHo in the right precuneus, and significant decrease of ALFF in the right lingual gyrus and in the left superior frontal lobe. Only patients with fMDD showed the relatively robust increase in intrinsic activity of temporal gyrus. The temporal gyrus may play a critical role in depressive symptomatology. Abnormal right fusiform gyrus, left middle temporal gyrus, and right superior temporal gyrus alterations were present only in patients with rMDD but not in patients with fMDD, indicating that these alterations may be a therapeutic target for MDD. Abnormal right supramarginal, right precuneus, right lingual gyrus and left superior frontal lobe alterations were present only in patients with rMDD and not in healthy control, and thus may be used as a state marker of MDD.

Aberrant brain regional homogeneity in first-episode drug-naïve patients with major depressive disorder: A voxel-wise meta-analysis

BACKGROUND

Resting-state functional magnetic resonance imaging studies have reported aberrant brain regional homogeneity (ReHo) in patients with major depressive disorder (MDD). However, the findings across studies were confounded by medication status and different depressive episodes.

METHODS

A systematic literature search of the PubMed, Embase, and Web of Science databases was conducted. We conducted a quantitative voxel-wise meta-analysis of ReHo studies, using the Seed-based d Mapping approach, in first-episode drug-naïve patients with MDD.

RESULTS

We identified 10 studies with 12 datasets suitable for inclusion, consisting of 402 first-episode drug-naïve patients with MDD and 330 healthy controls. The most consistent and robust findings were that patients with MDD relative to healthy controls exhibited increased ReHo in the left hippocampus and decreased ReHo in the left orbitofrontal cortex.

LIMITATIONS

The patient samples included in our meta-analysis were all Chinese, thus limiting the applicability of the present findings to other populations.

CONCLUSIONS

ReHo alterations in these brain regions are likely to reflect the core disease-related functional abnormalities, which are implicated in emotional dysregulation and cognitive impairment that are seen in the early stage of MDD. These findings contribute to a better understanding of the neurobiological underpinnings of MDD, and the left hippocampus and orbitofrontal cortex could serve as specific regions of interest for further investigations.

Effects of stress on behavior and resting-state fMRI in rats and evaluation of Telmisartan therapy in a stress-induced depression model

BACKGROUND

The etiology of depression and its effective therapeutic treatment have not been clearly identified. Using behavioral phenotyping and resting-state functional magnetic resonance imaging (r-fMRI), we investigated the behavioral impact and cerebral alterations of chronic unpredictable mild stress (CUMS) in the rat. We also evaluated the efficacy of telmisartan therapy in this rodent model of depression.

METHODS

Thirty-two rats were divided into 4 groups: a control group(C group), a stress group(S group), a stress + telmisartan(0.5 mg/kg)group (T-0.5 mg/kg group) and a stress + telmisartan(1 mg/kg) group (T-1 mg/kg group). A behavioral battery, including an open field test (OFT), a sucrose preference test (SPT), and an object recognition test (ORT), as well as r-fMRI were conducted after 4 weeks of CUMS and telmisartan therapy. The r-fMRI data were analyzed using the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) approach. The group differences in the behavior and r-fMRI test results as well as the correlations between these 2 approaches were examined.

RESULTS

CUMS reduced the number of rearings and the total moved distance in OFT, the sucrose preference in SPT, and novel object recognition ability in ORT. The telmisartan treatment (1 mg/kg) significantly improved B-A/B + A in the ORT and improved latency scores in the OFT and SPT. The S group exhibited a decreased ReHo in the motor cortex and pons, but increased ReHo in the thalamus, visual cortex, midbrain, cerebellum, hippocampus, hypothalamus, and olfactory cortex compared to the C group. Telmisartan (1 mg/kg)reversed or attenuated the stress-induced changes in the motor cortex, midbrain, thalamus, hippocampus, hypothalamus, visual cortex, and olfactory cortex. A negative correlation was found between OFT rearing and ReHo values in the thalamus. Two positive correlations were found between ORT B-A and the ReHo values in the olfactory cortexand pons.

CONCLUSIONS

Telmisartan may be an effective complementary drug for individuals with depression who also exhibit memory impairments. Stress induced widespread regional alterations in the cerebrum in ReHo measures while telmissartan can reverse part of theses alterations. These data lend support for future research on the pathology of depression and provide a new insight into the effects of telmisartan on brain function in depression.

Altered resting-state connectivity within default mode network associated with late chronotype

Current evidence suggests late chronotype individuals have an increased risk of developing depression. However, the underlying neural mechanisms of this association are not fully understood. Forty-six healthy, right-handed individuals free of current or previous diagnosis of depression, family history of depression or sleep disorder underwent resting-state functional Magnetic Resonance Imaging (rsFMRI). Using an Independent Component Analysis (ICA) approach, the Default Mode Network (DMN) was identified based on a well validated template. Linear effects of chronotype on DMN connectivity were tested for significance using non-parametric permutation tests (applying 5000 permutations). Sleep quality, age, gender, measures of mood and anxiety, time of scan and cortical grey matter volume were included as covariates in the regression model. A significant positive correlation between chronotype and functional connectivity within nodes of the DMN was observed, including; bilateral PCC and precuneus, such that later chronotype (participants with lower rMEQ scores) was associated with decreased connectivity within these regions. The current results appear consistent with altered DMN connectivity in depressed patients and weighted evidence towards reduced DMN connectivity in other at-risk populations which may, in part, explain the increased vulnerability for depression in late chronotype individuals. The effect may be driven by self-critical thoughts associated with late chronotype although future studies are needed to directly investigate this.

Brain structure alterations in depression: Psychoradiological evidence

Depression is the leading cause of disability around the world, but little is known about its pathology. Currently, the diagnosis of depression is made based on clinical manifestations, with little objective evidence. Magnetic resonance imaging (MRI) has been used to investigate the pathological changes in brain anatomy associated with this disorder. MRI can identify structural alterations in depressive patients in vivo, which could make considerable contributions to clinical diagnosis and treatment. Numerous studies that focused on gray and white matter have found significant brain region alterations in major depressive disorder patients, such as in the frontal lobe, hippocampus, temporal lobe, thalamus, striatum, and amygdala. The results are inconsistent and controversial because of the different demographic and clinical characteristics. However, some regions overlapped; thus, we think that there may be a "hub" in MDD and that an impairment in these regions contributes to disease severity. Brain connections contain both structural connections and functional connections, which reflect disease from a different view and support that MDD may be caused by the interaction of multiple brain regions. According to previous reports, significant circuits include the frontal-subcortical circuit, the suicide circuit, and the reward circuit. As has been recognized, the pathophysiology of major depressive disorder is complex and changeable. The current review focuses on the significant alterations in the gray and white matter of patients with the depressive disorder to generate a better understanding of the circuits. Moreover, identifying the nuances of depressive disorder and finding a biomarker will make a significant contribution to the guidance of clinical diagnosis and treatment.

Resting-state functional changes in the precuneus within first-episode drug-naive patients with MDD

BACKGROUND

Major depressive disorder (MDD) is a leading psychiatric disorder that has a lack of biomarkers for a diagnosis.

PURPOSE

The objective of this study was to examine the structural and functional change in the precuneus within first-episode drug naive patients with MDD.

METHODS

Thirty-two first episode drug-naive patients with MDD and thirty healthy controls (HCs) were recruited in this study; the structural MRI and fMRI data were collected using the 3.0 T Trio Siemens System. All the patients were interviewed using the HAMD-17.

RESULTS

The difference between gray matter volume within the two groups was not observed. Results indicated that the low-frequency fluctuations (ALFF), fractional ALFF (fALFF) and regional homogeneity values of the precuneus within first-episode drug-naive patients with MDD were lower than the HCs. In addition, the fALFF value of the MDD was negatively and statistically significantly correlated with the HAMD-17 total score (P<0.05).

CONCLUSION

The current study found abnormal activity of the precuneus at resting state in first-episode drug-naive patients with MDD, indicating that activity within the precuneus may be a potential biomarker for the diagnosis of MDD.