3D MRI studies of neuroanatomic changes in unipolar major depression: the role of stress and medical comorbidity

Parsing clinical and neurobiological sources of heterogeneity in depression

BACKGROUND

Patients with depression vary from one-another in their clinical and neuroimaging presentation, yet the relationship between clinical and neuroimaging sources of variation is poorly understood. Determining sources of heterogeneity in depression is important to gain insights into its diverse and complex neural etiology. This study aims to test if depression heterogeneity is characterized by subgroups that differ both clinically and neurobiologically and/or whether multiple neuroimaging profiles give rise to the same clinical presentation.

METHODS

This study utilizes population-based data from the UK Biobank over multiple imaging sites. Clinically dissociated groups were selected to isolate clinical characteristics of depression (symptoms of anhedonia, depressed mood, and somatic disturbance; severity indices of lifetime chronicity and acute impairment; and late onset). Residual neuroimaging heterogeneity within each group was assessed using neuroimaging driven clustering.

RESULTS

The clinically dissociated subgroups had significantly larger neuroimaging normative deviations than a comparison heterogeneous group and had distinct neuroimaging profiles from each other. Imaging driven clustering within each clinically dissociated group identified two stable subtypes within the acute impairment group that differed significantly in cognitive ability, despite identical clinical profiles.

CONCLUSIONS

The study identified distinct neuroimaging profiles related to particular clinical depression features that may explain inconsistencies in the literature and sub-clusters within the acute impairment group with cognitive differences that were only differentiable by neuroimaging. Our results provide evidence that multiple neuroimaging profiles may give rise to the same clinical presentation, emphasizing the presence of complex interactions between clinical and neuroimaging sources of heterogeneity.

White matter functional connectome gradient dysfunction in major depressive disorder

Background

Major depressive disorder (MDD) is a prevalent psychiatric disorder with disruptions in brain white matter (WM). While much research has focused on WM structure, the dysfunctional organization of WM in MDD remains poorly understood.

Methods

Using resting-state functional magnetic resonance imaging data from 48 MDD patients and 68 healthy controls (HC), we characterized the WM functional connectome gradients across participants and identified both global and regional alterations in MDD. Furthermore, we examined the relationship between gradient properties and depressive symptom severity. External validation and sensitivity analyses were finally conducted to ensure the reliability of results.

Results

The principal WM connectome gradient extended from the forceps major and superior longitudinal fasciculus to the uncinate fasciculus (UF) and anterior thalamic radiation (ATR), exhibiting a superficial-to-deep pattern in both groups. Compared to HC, MDD patients displayed a narrower gradient range and lower spatial variation, indicating a contracted WM hierarchy. At the tract-specific level, MDD patients exhibited lower gradient scores in the forceps minor, left ATR and UF, and bilateral cingulate gyrus and cingulum hippocampus, but higher gradient scores in the forceps major, bilateral inferior longitudinal fasciculus and superior longitudinal fasciculus. WM tract gradient patterns explained 37.2% of the variance in clinical severity, with the strongest contributions from the inferior fronto-occipital fasciculus, cingulum hippocampus, ATR, UF, and corticospinal tract.

Conclusions

These findings highlight altered WM functional connectome gradient in MDD and their association with clinical severity, offering novel insights into the neurobiological mechanisms of the disorder and potential biomarkers for symptom evaluation.

Alterations in gray matter volume and associated transcriptomics after electroconvulsive therapy in major depressive disorder

BACKGROUND

The antidepressant mechanism of electroconvulsive therapy (ECT) remains not clearly understood. This study aimed to detect the changes in gray matter volume (GMV) in patients with major depressive disorder (MDD) caused by ECT and exploratorily analyzed the potential functional mechanisms.

METHODS

A total of 24 patients with MDD who underwent eight ECT sessions were included in the study. Clinical symptom assessments and MRI scans were conducted and compared. Using whole-brain micro-array measurements provided by the Allen Human Brain Atlas (AHBA), regional gene expression profiles were calculated. The differential gene PLS1 was obtained through Partial Least Squares (PLS) regression analysis, and PLS1 was divided into positive contribution (PLS1+) and negative contribution (PLS1-) genes. Through gene function enrichment analysis, the functional pathways and cell types of PLS1 enrichment were identified.

RESULTS

Gray matter volume (GMV) in the somatosensory and motor cortices, occipital cortex, prefrontal cortex, and insula showed an increasing trend after ECT, while GMV in the temporal cortex, posterior cingulate cortex, and orbitofrontal cortex decreased. PLS1 genes were enriched in synapse- and cell-related biological processes and cellular components (such as 'pre- and post-synapse', 'synapse organization' etc.). A large number of genes in the PLS1+ list were involved in neurons (inhibitory and excitatory), whereas PLS1- genes were significantly involved in Astrocytes (Astro) and Microglia (Micro).

CONCLUSIONS

This study established a link between treatment-induced GMV changes and specific functional pathways and cell types, which suggests that ECT may exert its effects through synapse-associated functional and affect neurons and glial cells.

Structural and functional changes of Post-Stroke Depression: A multimodal magnetic resonance imaging study

This study investigated changes in gray matter volume (GMV), white matter microstructure, and spontaneous brain activity in post-stroke depression (PSD) using multiple MRI techniques, including neurite orientation dispersion and density imaging (NODDI). Changes in GMV, neurite density index (NDI), orientation dispersion index (ODI), fraction of isotropic water (ISO), diffusion tensor imaging (DTI) parameters, and the amplitude of frequency fluctuations (ALFF) were assessed between PSD (n = 20), post-stroke without depression (n = 20), and normal control (n = 20) groups. Receiver operating characteristic (ROC) curve analysis was performed to test the classification performance of the variant parameters of each MRI modality, each single MRI modality and multiple MRI modality. Compared to patients with post-stroke without depression (non-PSD), those with PSD showed increased ODI and ISO in the widespread white matter, as well as increased ALFF in the left pallidum. No significant differences in the GMV or DTI parameters were observed between the two groups. Furthermore, the ODI of the right superior longitudinal fasciculus and NODDI showed the best classification performance for PSD at their respective comparison level (the areas under the ROC curves (AUC) = 0.917(0.000), 0.933(0.000)). The model of NODDI-derived parameters combined with non-diffusion MRI modality parameters (i.e., GMV and ALFF) showed better diagnostic performance than that of DTI-derived parameters. These findings suggest that PSD is associated with structural and functional abnormalities that may contribute to depressive symptoms. Additionally, NODDI showed its advantages in the description of structural alterations in emotion-related white matter pathways and classification performance in PSD.

fMRI used to observe the acute craniocerebral response of esophageal cancer related depressive patients treated by rTMS: Initial experience

To observe the immediate craniocerebral response, changes of spontaneous nerve activity and functional connection after repeated transcranial magnetic stimulation (rTMS) in esophageal cancer patients with depression (ECPD) by functional magnetic resonance imaging (fMRI), and to explore the therapeutic effect, neuroactivity response and mechanism. Eleven patients with ECPD were enrolled to treated with single rTMS. The patients were examined by fMRI before and after the treatment. The changes of low frequency amplitude (ALFF) and the functional connection network between different brain regions of ALFF in patients were compared before and after rTMS treatment. Compared with those before rTMS treatment, the Hamilton Depression Rating Scale (HAMD) score decreased significantly after rTMS treatment (t = -7.63, P = .0001). The ALFF of bilateral putamen, left thalamus, left posterior cingulate gyrus and right middle temporal gyrus decreased significantly (P = .02). In addition, the functional connection between the cortex-limbic system-striatum-thalamus nerve loop increased in patients after rTMS treatment. rTMS may achieve the effect of rehabilitation treatment by improving the spontaneous neural activity and regulating the neural connection network of cortical-limbic systems-triatum-thalamus loop in ECPD.

Electroacupuncture attenuates depressive-like behaviors in poststroke depression mice through promoting hippocampal neurogenesis and inhibiting TLR4/NF-κB/NLRP3 signaling pathway

The aim of this study was to investigate the impact and underlying molecular mechanisms of electroacupuncture on mice with poststroke depression (PSD). Mice were randomly allocated into sham, PSD, and electroacupuncture groups. Mice in the PSD and electroacupuncture groups underwent middle cerebral artery occlusion (MCAO) surgery following with sedentary behavior. Electroacupuncture targeting Zusanli (ST36) acupoint was performed 24 h after MCAO for 4 weeks in electroacupuncture group. The sucrose preference test, forced swimming test, open field test, tail suspension test, elevated plus maze, Catwalk analysis, RNA sequencing, Nissl staining, Golgi staining, TUNEL staining, Edu labeling, and doublecortin staining were performed. Lymphocyte subsets in peripheral blood and the levels of IL-1β, IL-6, TNF-α, and expression of Iba1/CD86, Iba1/NLRP3, TLR4/p38/NF-κB/NLRP3 pathways in the hippocampus were detected. Electroacupuncture effectively protected against the development of depression-like symptoms. The number of granulosa cells and doublecortin-positive cells in the dentate gyrus (DG) were significantly decreased in PSD group, which were significantly upregulated ( P  < 0.01) by electroacupuncture. Electroacupuncture also significantly reduced ( P  < 0.05) TUNEL-positive cells in the DG and CA1. RNA-seq revealed that electroacupuncture may exert antidepressant effect by regulating the inflammation mediated by TLR4/NF-κB/NLRP3 pathway in hippocampus. Electroacupuncture remarkably elevated ( P  < 0.01) the ratio of CD4+ to CD8+ T cells and percentage of CD3-CD49b+ cells in CD45+CD49b+ cells in the peripheral blood. Electroacupuncture significantly reduced ( P  < 0.05) the high levels of IL-1β, IL-6, TNF-α, iba1, TLR4, p-p38, p-NF-κB, and NLRP3 and sedentary behavior. Electroacupuncture was observed to mitigate depression symptoms and increase hippocampal neurogenesis in mice with PSD, possibly by inhibiting TLR4/p38/NF-κB/NLRP3 pathways and improving the microglia-mediated inflammatory microenvironment in the hippocampus.

Structural development and brain asymmetry in the fronto-limbic regions in preschool-aged children

Early-life experiences play a crucial role in the development of the fronto-limbic regions, influencing both macro- and microstructural changes in the brain. These alterations profoundly impact cognitive, social-emotional functions. Recently, early limbic structural alterations have been associated with numerous neurological and psychiatric morbidities. Although identifying normative developmental trajectories is essential for determining brain alterations, only a few studies have focused on examining the normative trajectories in the fronto-limbic regions during preschool-aged children. The aim of this study was to investigate the structural-developmental trajectory of the fronto-limbic regions using the cortical thickness, volume, and subcortical volume in 57 healthy and typical preschool-aged children between 1 and 5 years and examined the early lateralization patterns during the development of the fronto-limbic regions. Regarding brain lateralization, remarkable asymmetry was detected in the volume of thalamus and the cortical regions excluding the lateral orbitofrontal cortex in the fronto-limbic regions. This study of preschool-aged children may fill the knowledge gaps regarding the developmental patterns and hemispheric asymmetries of the fronto-limbic regions between newborns and adolescents.

Psilocybin for dementia prevention? The potential role of psilocybin to alter mechanisms associated with major depression and neurodegenerative diseases

Major depression is an established risk factor for subsequent dementia, and depression in late life may also represent a prodromal state of dementia. Considering current challenges in the clinical development of disease modifying therapies for dementia, the focus of research is shifting towards prevention and modification of risk factors to alter the neurodegenerative disease trajectory. Understanding mechanistic commonalities underlying affective symptoms and cognitive decline may reveal biomarkers to aid early identification of those at risk of progressing to dementia during the preclinical phase of disease, thus allowing for timely intervention. Adult hippocampal neurogenesis (AHN) is a phenomenon that describes the birth of new neurons in the dentate gyrus throughout life and it is associated with spatial learning, memory and mood regulation. Microglia are innate immune system macrophages in the central nervous system that carefully regulate AHN via multiple mechanisms. Disruption in AHN is associated with both dementia and major depression and microgliosis is a hallmark of several neurodegenerative diseases. Emerging evidence suggests that psychedelics promote neuroplasticity, including neurogenesis, and may also be immunomodulatory. In this context, psilocybin, a serotonergic agonist with rapid-acting antidepressant properties has the potential to ameliorate intersecting pathophysiological processes relevant for both major depression and neurodegenerative diseases. In this narrative review, we focus on the evidence base for the effects of psilocybin on adult hippocampal neurogenesis and microglial form and function; which may suggest that psilocybin has the potential to modulate multiple mechanisms of action, and may have implications in altering the progression from major depression to dementia in those at risk.

Role of NLRP3 Inflammasome in Post-Spinal-Cord-Injury Anxiety and Depression: Molecular Mechanisms and Therapeutic Implications

The majority of research on the long-term effects of spinal cord injury (SCI) has primarily focused on neuropathic pain (NP), psychological issues, and sensorimotor impairments. Among SCI patients, mood disorders, such as anxiety and depression, have been extensively studied. It has been found that chronic stress and NP have negative consequences and reduce the quality of life for individuals living with SCI. Our review examined both human and experimental evidence to explore the connection between mood changes following SCI and inflammatory pathways, with a specific focus on NLRP3 inflammasome signaling. We observed increased proinflammatory factors in the blood, as well as in the brain and spinal cord tissues of SCI models. The NLRP3 inflammasome plays a crucial role in various diseases by controlling the release of proinflammatory molecules like interleukin 1β (IL-1β) and IL-18. Dysregulation of the NLRP3 inflammasome in key brain regions associated with pain processing, such as the prefrontal cortex and hippocampus, contributes to the development of mood disorders following SCI. In this review, we summarized recent research on the expression and regulation of components related to NLRP3 inflammasome signaling in mood disorders following SCI. Finally, we discussed potential therapeutic approaches that target the NLRP3 inflammasome and regulate proinflammatory cytokines as a way to treat mood disorders following SCI.

Altered MRI Diffusion Properties of the White Matter Tracts Connecting Frontal and Thalamic Brain Regions in First-Episode, Drug-Naïve Patients With Postpartum Depression

BACKGROUND

Although progress has been made in exploring postpartum depression (PPD), the involvement of cerebral structure connectivity in PPD patients keeps unclear.

PURPOSE

To explore structural connectivity alternations in mothers with PPD, diffusion tensor imaging (DTI) and automated fiber quantification (AFQ) were used to calculate brain white matter microstructure properties.

STUDY TYPE

Cross-sectional.

POPULATION

A total of 51 women with first-episode, treatment-näive PPD, and 49 matched healthy postpartum women (HPW) controls.

FIELD STRENGTH

A 3.0 T; single-shot echo-planar imaging sequence.

ASSESSMENT

DTI measurements of fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) were obtained for 18 specific white matter tracts. The relationship between PDD symptoms, hormone levels, and postpartum days was also investigated.

STATISTICAL TESTS

Two sample t test and Pearson's correlation analysis. The analysis was performed by using a permutation-based multiple-comparison correction approach, with the threshold of P < 0.05 (family wise error corrected [FWE-corrected]) separately across the four different outcome measures.

RESULTS

Women with PPD showed significantly increased FA and AD in right anterior thalamic radiation (ATR) tract and significantly increased FA and significantly reduced RD in the cingulum tract, compared to women without PPD. The RD values of right cingulum were significantly positively correlated with postpartum days in HPW (r = 0.39). There were no significant relationships between brain measures and hormone levels in either patients or controls.

DATA CONCLUSIONS

DTI measures have revealed altered integrity in the white matter of the cortical-thalamic circuits in women with PPD compared to HPW. Damage to these circuits may be a structural basis for the impaired emotional regulation and blunted mother-infant bonding in mothers with PPD and a potential target for the development of new treatments.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 3.

In vitro modeling of the neurobiological effects of glucocorticoids: A review

Hypothalamic-pituitary adrenal (HPA)axis dysregulation has long been implicated in stress-related disorders such as major depression and post-traumatic stress disorder. Glucocorticoids (GCs) are released from the adrenal glands as a result of HPA-axis activation. The release of GCs is implicated with several neurobiological changes that are associated with negative consequences of chronic stress and the onset and course of psychiatric disorders. Investigating the underlying neurobiological effects of GCs may help to better understand the pathophysiology of stress-related psychiatric disorders. GCs impact a plethora of neuronal processes at the genetic, epigenetic, cellular, and molecular levels. Given the scarcity and difficulty in accessing human brain samples, 2D and 3D in vitro neuronal cultures are becoming increasingly useful in studying GC effects. In this review, we provide an overview of in vitro studies investigating the effects of GCs on key neuronal processes such as proliferation and survival of progenitor cells, neurogenesis, synaptic plasticity, neuronal activity, inflammation, genetic vulnerability, and epigenetic alterations. Finally, we discuss the challenges in the field and offer suggestions for improving the use of in vitro models to investigate GC effects.

Cognitive rehabilitation for improving cognitive functions and reducing the severity of depressive symptoms in adult patients with Major Depressive Disorder: a systematic review and meta-analysis of randomized controlled clinical trials

INTRODUCTION

Nearly 40% of patients with Major Depressive Disorder (MDD) have been found to experience cognitive impairment in at least one domain. Cognitive impairment associated with MDD is disproportionately represented in patients that have not fully returned to psychosocial functioning. As awareness regarding cognitive dysfunction in MDD patients grows, so does the interest in developing newer treatments that specifically address these deficits.

METHOD

In the present study, we conduct a systematic review of controlled randomized clinical trials that used cognitive training and remediation interventions for improving cognitive functions and reducing symptom severity in adult patients with MDD. We selected studies published before March 2022 using search databases including PubMed, ScienceDirect, Scopus, and Google scholar. For conducting the meta-analysis, standard differences in means with the random effect model and with a 95% confidence interval of change in outcome measures from baseline to post-intervention between the cognitive rehabilitation and the control groups were calculated.

RESULTS

The database search resulted in identifying 756 studies of interest, which ultimately 15 studies with 410 participants in the cognitive rehabilitation group and 339 participants in the control group were included. The meta-analysis of the data extracted from these studies, shows a moderate and significant effect on the executive function (d = 0.59 (95% CI, 0.25 to 0.93) p-value = 0.001, I2 = 15.2%), verbal learning (d = 0.45 (95% CI, 0.12 to 0.78) p-value = 0.007, I2 = 0.00%), and working memory (d = 0.41 (95% CI, 0.18 to 0.64) p-value < 0.001, I2 = 33%) of MDD patients. Although, there were no significant difference between intervention and control group in attention (d = 0.32 (95% CI, -0.01 to 0.66) p-value = 0.058, I2 = 0.00%) or depressive symptoms.

CONCLUSION

This systematic review and meta-analysis indicate that cognitive rehabilitation is an effective intervention for the executive function, verbal learning, and working memory of MDD patients. Due to the importance of these neuropsychological deficits in day-to-day life and the core symptoms of MDD, cognitive rehabilitation should be considered an important part of treating MDD. Further research in this area and concentrated on these particular deficits is warranted.

Prolonged Longitudinal Transcutaneous Auricular Vagus Nerve Stimulation Effect on Striatal Functional Connectivity in Patients with Major Depressive Disorder

BACKGROUND

Transcutaneous auricular vagus nerve stimulation (taVNS) is effective for treating major depressive disorder (MDD). We aimed to explore the modulating effect of prolonged longitudinal taVNS on the striatal subregions' functional connectivity (FC) in MDD patients.

METHODS

Sixteen MDD patients were enrolled and treated with taVNS for 8 weeks. Sixteen healthy control subjects (HCs) were recruited without intervention. The resting-state FC (rsFC) based on striatal subregion seed points and the Hamilton Depression Scale (HAMD) were evaluated in the MDD patients and HCs at baseline and after 8 weeks. A two-way ANCOVA test was performed on each rsFC metric to obtain the (group-by-time) interactions.

RESULTS

The rsFC values between the left ventral caudate (vCa) and right ventral prefrontal cortex (vPFC), and between the right nucleus accumbens (NAc) and right dorsal medial prefrontal cortex (dmPFC) and ventrolateral prefrontal cortex (vlPFC) are lower in the MDD patients compared to the HCs at baseline, and increase following taVNS; the rsFC values between the left vCa and right, superior occipital gyrus (SOG), and between the left dorsal caudate (dCa) and right cuneus are higher in MDD patients and decrease following taVNS.

CONCLUSIONS

Prolonged longitudinal taVNS can modulate the striatum rsFC with the prefrontal cortex, occipital cortex, temporal cortex, and intra-striatum, and these changes partly underlie any symptomatic improvements. The results indicate that prolonged longitudinal taVNS may produce beneficial treatment effects by modulating the cortical striatum circuitry in patients with MDD.

Abnormal regional homogeneity and functional connectivity in major depressive disorder patients with long-term remission: An exploratory study

This study was the first to explore whether abnormal spontaneous neuronal activities exist in patients in the long-term remission stage of major depressive disorder (MDD). We recruited 34 MDD patients (PTs) and 30 sex- and age-matched healthy controls (HCs). Resting-state functional magnetic resonance imaging (rs-fMRI) was employed to scan all subjects' brain regions, and independent two-sample t-test was used for regional homogeneity (ReHo) and functional connectivity (FC) analysis. Compared with the HCs, the ReHo of PTs increased in the right superior frontal gyrus and left middle frontal gyrus, and decreased in the right anterior and collateral cingulate gyrus, right middle frontal gyrus, right inferior parietal lobule. The cingulate gyrus as a mask showed that FC of the cingulate gyrus with the bilateral lingual gyrus and the right middle temporal gyrus decreased, and FC with the left supper frontal gyrus increased. The correlation analysis revealed no significant correlation between the abnormal ReHo and HAMD-24 scores in PTs. The ReHo of inferior parietal lobule and the duration of remission were positively correlated. We concluded that the spontaneous neuronal activities might be disrupted in MDD patients in the long-term remission stage. Our findings provided new reasons for MDD relapse.

Pharmacological targeting of cognitive impairment in depression: recent developments and challenges in human clinical research

Impaired cognition is often overlooked in the clinical management of depression, despite its association with poor psychosocial functioning and reduced clinical engagement. There is an outstanding need for new treatments to address this unmet clinical need, highlighted by our consultations with individuals with lived experience of depression. Here we consider the evidence to support different pharmacological approaches for the treatment of impaired cognition in individuals with depression, including treatments that influence primary neurotransmission directly as well as novel targets such as neurosteroid modulation. We also consider potential methodological challenges in establishing a strong evidence base in this area, including the need to disentangle direct effects of treatment on cognition from more generalised symptomatic improvement and the identification of sensitive, reliable and objective measures of cognition.

Prophylactic administration of rosmarinic acid ameliorates depression-associated cardiac abnormalities in Wistar rats: Evidence of serotonergic, oxidative, and inflammatory pathways

Psychiatric disorders and associated cardiac comorbidities have increased the risk of mortality worldwide. Researchers reported that depression increases the possibility of future cardiac abnormalities by approximately 30%. Therefore, there is an unmet need to develop therapeutic interventions to treat depression and associated cardiac abnormalities. The present study was conducted to evaluate the prophylactic effect of rosmarinic acid (RA) against chronic unpredictable stress (CUS)-induced depression associated cardiac abnormalities in Wistar rats. The CUS paradigm, which comprised several stressors, was employed for 40 days to induce depressive-like behavior and associated cardiac abnormalities in rats. Along with CUS, RA at a dose of 25 and 50 mg/kg was administered orally to two groups of animals for 40 days. Behavioral tests (forced swim test and sucrose consumption test) and molecular biomarkers (corticosterone and serotonin) were performed. Electrocardiography was performed before CUS (Day 0), Day 20, and Day 40 to study electrocardiogram parameters. Furthermore, changes in body weight, organ weight, tissue lipid peroxidation, glutathione, catalase, cTn-I, MMP-2, and proinflammatory cytokines (TNF-α and IL-6) were estimated. Our results showed that RA treatment caused a reduction in immobility period, adrenal hyperplasia, corticosterone level, tissue lipid peroxidation, cTn-I, MMP-2, proinflammatory cytokines, and QRS complex duration, while an increase in sucrose consumption, brain serotonin level, T-wave width, glutathione, and catalase activity as compared with the CUS-control group. The results of our study proved that RA administration ameliorates CUS-induced depression-associated cardiac abnormalities in rats via serotonergic, oxidative, and inflammatory pathways.

Neurotrophin Crosstalk in the Etiology and Treatment of Neuropsychiatric and Neurodegenerative Disease

This article reviews the current progress in our understanding of the mechanisms by which growth factors, including brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), and select neurotrophin-regulated gene products, such as VGF (non-acronymic) and VGF-derived neuropeptides, function in the central nervous system (CNS) to modulate neuropsychiatric and neurodegenerative disorders, with a discussion of the possible therapeutic applications of these growth factors to major depressive disorder (MDD) and Alzheimer’s disease (AD). BDNF and VEGF levels are generally decreased regionally in the brains of MDD subjects and in preclinical animal models of depression, changes that are associated with neuronal atrophy and reduced neurogenesis, and are reversed by conventional monoaminergic and novel ketamine-like antidepressants. Downstream of neurotrophins and their receptors, VGF was identified as a nerve growth factor (NGF)- and BDNF-inducible secreted protein and neuropeptide precursor that is produced and trafficked throughout the CNS, where its expression is greatly influenced by neuronal activity and exercise, and where several VGF-derived peptides modulate neuronal activity, function, proliferation, differentiation, and survival. Moreover, levels of VGF are reduced in the CSF of AD subjects, where it has been repetitively identified as a disease biomarker, and in the hippocampi of subjects with MDD, suggesting possible shared mechanisms by which reduced levels of VGF and other proteins that are similarly regulated by neurotrophin signaling pathways contribute to and potentially drive the pathogenesis and progression of co-morbid neuropsychiatric and neurodegenerative disorders, particularly MDD and AD, opening possible therapeutic windows.

The Neuromarketing Concept in Artificial Neural Networks: A Case of Forecasting and Simulation from the Advertising Industry

This research aims to examine a neural network (artificial intelligence) as an alternative model to examine the neuromarketing phenomenon. Neuromarketing is comparatively new as a technique for designing marketing strategies, especially advertising campaigns. Marketers have used a variety of different neuromarketing tools, for instance functional magnetic resonance imaging (fMRI), eye tracking, electroencephalography (EEG), steady-state probe topography (SSPT), and other expensive gadgets. Similarly, researchers have been using these devices to carry out their studies. Therefore, neuromarketing has been an expensive project for both companies and researchers. We employed 585 human responses and used the neural network (artificial intelligence) technique to examine the predictive consumer buying behavior of an effective advertisement. For this purpose, we employed two neural network applications (artificial intelligence) to examine consumer buying behavior, first taken from a 1–5 Likert scale. A second application was run to examine the predicted consumer buying behavior in light of the neuromarketing phenomenon. The findings suggest that a neural network (artificial intelligence) is a unique, cost-effective, and powerful alternative to traditional neuromarketing tools. This study has significant theoretical and practical implications for future researchers and brand managers in the service and manufacturing sectors.

The etiology of poststroke-depression: a hypothesis involving HPA axis

Approximately, one in three ischemic stroke survivors suffered from depression, namely, post-stroke depression (PSD). PSD affects functional rehabilitation and may lead to poor quality of life of patients. There are numerous explanations about the etiologies of PSD. Here, we speculated that PSD are likely to be the result of specific changes in brain pathology. We hypothesized that the stroke-induced hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis plays an important role in PSD. Stroke initiates a complex sequence of events in neuroendocrine system including HPA axis. The HPA axis is involved in the pathophysiology of depression, especially, the overactivity of the HPA axis occurs in major depressive disorder. This review summarizes the possible etiologies of PSD, focusing on the stroke-induced activation of HPA axis, mainly including the stress followed by severe brain damage and the proinflammatory cytokines release. The role of hyperactive of HPA axis in PSD was discussed in detail, which includes the role of high level corticotropin-releasing hormone in PSD, the effects of glucocorticoids on the alterations in specific brain structures, the expression of enzymes, excitotoxicity, the change in intestinal permeability, and the activation of microglia. The relationship between neuroendocrine regulation and inflammation was also described. Finally, the therapy of PSD by regulating HPA axis, neuroendocrine, and immunity was discussed briefly. Nevertheless, the change of HPA axis and the occurring of PSD maybe interact and promote on each other, and future investigations should explore this hypothesis in more depth.

Impaired allocentric spatial memory in patients with affective disorders

BACKGROUND

Memory disturbances are frequent in unipolar depression (UD) and bipolar disorder (BD) and may comprise important predisposing and maintaining factors. Previous studies have demonstrated hippocampal abnormalities in UD and BD but there is a lack of studies specifically assessing hippocampus-dependent memory.

METHODS

We used a virtual task to assess hippocampus-dependent (allocentric) vs non-hipppocampal (egocentric) spatial memory in remitted and partially remitted patients with UD or BD (N = 22) and a healthy control group (N = 32). Participants also completed a range of standard neuropsychological and functional assessments.

RESULTS

Participants in the UD/BD group showed selective impairments on high-load hippocampal (allocentric) memory compared to egocentric memory and this effect was independent of residual mood symptoms. Across both samples, both allocentric and egocentric spatial memory correlated with more general measures of memory and other aspects of cognition measured on standard neuropsychological tests but only high-load allocentric memory showed a significant relationship with functional capacity.

CONCLUSION

Results show a selective impairment in high-load allocentric spatial memory compared to egocentric memory in the patient group, suggesting impaired hippocampal functioning in patients with remitted UD/BD.

Volume of Amygdala Subregions and Plasma Levels of Brain-Derived Neurotrophic Factor and Cortisol in Patients with s/s Genotype of Serotonin Transporter Gene Polymorphism of First-Episode and Drug-Naive Major Depressive Disorder: An Exploratory Study

The amygdala is a prominent region of the brain that plays a critical role in the pathophysiology of major depressive disorder (MDD). The amygdala is formed from a collection of interconnected substructures (nuclei) that relay signals from multiple brain areas, which suggests that the amygdala has different functions depending on its subregion. There are two main alleles of serotonin transporter gene polymorphism (5-HTTLPR): a 44-bp insertion (l-allele) or deletion (s-allele). The transcriptional activity of the l-allele of the gene is twice that of the s-allele. The present study aimed to investigate the association between the volume of the whole amygdala and subregions of the amygdala in 25 first-episode and drug-naive patients with MDD and 46 healthy controls (HCs) with the s/s genotype of 5-HTTLPR and plasma levels of brain-derived neurotrophic factor (BDNF) or cortisol. No significant difference was observed in the amygdala total and subregion volumes between the HC and MDD groups. No significant difference was found in the plasma levels of BDNF and cortisol between the two groups. In addition, no correlations were found between the total and subregion amygdala volume and plasma levels of cortisol or BDNF.

Long-term consequences of COVID-19 on cognitive functioning up to 6 months after discharge: role of depression and impact on quality of life

Neurologic and psychiatric symptoms have been reported in the months following the infection with COVID-19. A low-grade inflammation has been associated both with depression and cognitive symptoms, suggesting a link between these disorders. The aim of the study is to investigate cognitive functioning 6 months following hospital discharge for COVID-19, the impact of depression, and the consequences on quality of life. Ninety-two COVID-19 survivors evaluated at 1-month follow-up, 122 evaluated at 3 months and 98 evaluated at 6 months performed neuropsychological and psychiatric evaluations and were compared with a healthy comparison group (HC) of 165 subjects and 165 patients with major depression (MDD). Cognitive performances were adjusted for age, sex, and education. Seventy-nine percent of COVID-19 survivors at 1 month and 75% at 3- and 6-month follow-up showed cognitive impairment in at least one cognitive function. No significant difference in cognitive performances was observed between 1-, 3-, and 6-months follow-up. COVID-19 patients performed worse than HC but better than MDD in psychomotor coordination and speed of information processing. No difference between COVID-19 survivors and MDD was observed for verbal fluency, and executive functions, which were lower than in HC. Finally, COVID-19 survivors performed the same as HC in working memory and verbal memory. The factor that most affected cognitive performance was depressive psychopathology which, in turn, interact with cognitive functions in determining quality of life. Our results confirm that COVID-19 sequelae include signs of cognitive impairment which persist up to 6 months after hospital discharge and affect quality of life.

Immediate Modulation of Transcutaneous Auricular Vagus Nerve Stimulation in Patients With Treatment-Resistant Depression: A Resting-State Functional Magnetic Resonance Imaging Study

BACKGROUND

Previous studies found that transcutaneous auricular vagus nerve stimulation (taVNS) was clinically effective in treating a case of treatment-resistant depression (TRD). However, the brain neural mechanisms underlying the immediate effects of taVNS treatment for TRD have not been elucidated.

MATERIALS AND METHODS

Differences in the amplitude of low-frequency fluctuations (ALFF) between TRD and healthy control (HC) groups were observed. The TRD group was treated with taVNS for 30 min, and changes in ALFF in the TRD group before and after immediate treatment were observed. The ALFF brain regions altered by taVNS induction were used as regions of interest to analyze whole-brain functional connectivity (FC) changes in the TRD group.

RESULTS

A total of 44 TRD patients and 44 HCs completed the study and were included in the data analysis. Compared with the HC group, the TRD group had increased ALFF in the left orbital area of the middle frontal gyrus. After taVNS treatment, ALFF in the left orbital area of the middle frontal gyrus and right middle frontal gyrus decreased in the TRD group, while ALFF in the right orbital area of the superior frontal gyrus increased. The FC in the left orbital area of the middle frontal gyrus with left middle frontal gyrus and the right inferior occipital gyrus was significantly increased.

CONCLUSION

Transcutaneous auricular vagus nerve stimulation demonstrates immediate modulation of functional activity in the emotional network, cognitive control network, and visual processing cortex, and may be a potential brain imaging biomarker for the treatment of TRD.

Elevated Systemic Inflammation Is Associated with Reduced Corticolimbic White Matter Integrity in Depression

(1) Background: Growing evidence indicates that inflammation can induce neural circuit dysfunction and plays a vital role in the pathogenesis of major depressive disorder (MDD). Nevertheless, whether inflammation affects the integrity of white matter pathways is only beginning to be explored. (2) Methods: We computed quantitative anisotropy (QA) from diffusion magnetic resonance imaging as an index of white matter integrity and regressed QA on C-reactive protein (CRP), controlling for age, sex, and BMI, in 176 participants with MDD. (3) Results: The QA values of several white matter tracts were negatively correlated with CRP concentration (standardized beta coefficient = -0.22, 95%CI = -0.38--0.06, FDR < 0.05). These tracts included the bilateral cortico-striatal tracts, thalamic radiations, inferior longitudinal fasciculi, corpus callosum (the forceps minor portion and the tapetum portion), cingulum bundles, and the left superior longitudinal fasciculus III. Importantly, the association remained robust after regressing up to twelve potential confounders. The bilateral fornix and a small portion of the thalamic radiation showed a positive association with CRP levels, but these associations did not remain significant after adjusting for confounders. (4) Conclusions: Peripheral inflammation may contribute to the etiology of MDD by impacting the microstructural integrity of brain corticolimbic white matter pathways.

Volumetric alterations in subregions of the amygdala in adults with major depressive disorder

BACKGROUND

Although major depressive disorder (MDD) has been associated with volumetric abnormalities in the amygdala, studies investigating the association between structural alterations of the amygdala and depression have yielded varying results. Since the amygdala comprises several subregions, it is difficult to detect subtle regional changes by measuring the total amygdala volume. This study aimed to examine the volume in each amygdala subregion in adults with and without a diagnosis of MDD.

METHODS

A total of 147 participants with a current history of major depression and 144 healthy participants ranging in age from 19 to 64 years underwent 3T magnetic resonance imaging scanning. Automatic segmentation of the nine nuclei of the amygdala was performed using FreeSurfer. One-way analysis of covariance, with individual volumes as dependent variables, and age, sex, and total intracranial volume as covariates, was performed to analyze volume differences.

RESULTS

Patients with MDD had significantly lower volumes of the entire amygdala and subregions, including the lateral nucleus and anterior amygdaloid area, than healthy volunteers (HCs). There were no significant associations between subregion volumes and antidepressant use, illness duration, or depression severity.

LIMITATIONS

Our cross-sectional design cannot provide a causal relationship between the volume change in the amygdala subregion and the risk of MDD.

CONCLUSION

Our findings suggest that specific amygdala subregions are more susceptible to volumetric alterations in patients with MDD than in HCs. These findings may advance our understanding of the neuroanatomic basis on MDD.

GABA System in Depression: Impact on Pathophysiology and Psychopharmacology

BACKGROUND

The pathophysiology of major depressive disorder (MDD), one of the major causes of worldwide disability, is still largely unclear, despite the increasing data reporting evidence of multiple alterations of different systems. Recently, there was a renewed interest in the signalling of gamma aminobutyric acid (GABA) - the main inhibitory neurotransmitter.

OBJECTIVE

The aim of this study was to review and comment on the available literature about the involvement of GABA in MDD, as well as on novel GABAergic compounds possibly useful as antidepressants.

METHODS

We carried out a narrative review through Pubmed, Google Scholar and Scopus, by using specific keywords.

RESULTS

The results, derived from various research tools, strongly support the presence of a deficiency of the GABA system in MDD, which appears to be restored by common antidepressant treatments. More recent publications would indicate the complex interactions between GABA and all the other processes involved in MDD, such as monoamine neurotransmission, hypothalamus-pituitary adrenal axis functioning, neurotrophism, and immune response. Taken together, all these findings seem to further support the complexity of the pathophysiology of MDD, possibly reflecting the heterogeneity of the clinical pictures.

CONCLUSION

Although further data are necessary to support the specificity of GABA deficiency in MDD, the available findings would suggest that novel GABAergic compounds might constitute innovative therapeutic strategies in MDD.

Grey matter volume abnormalities in the first depressive episode of medication-naïve adult individuals: a systematic review of voxel based morphometric studies

BACKGROUND

To identify the reliable and consistent grey matter volume (GMV) abnormalities associated with major depressive disorder (MDD), we excluded the influence of confounding clinical characteristics, comorbidities and brain degeneration on brain morphological abnormalities by inclusion of non-comorbid and non-geriatric drug-naïve MDD individuals experiencing first episode depressive.

METHODS

The PubMed, Scopus, Web of Science, Science Direct and Google scholar databases were searched for papers published in English up to April 2020.

RESULTS

A total of 21 voxel based morphometric (VBM) studies comparing 845 individuals in the first depressive episode and medication-naïve with 940 healthy control subjects were included. The results showed a grey matter volumes reductions in the orbitofrontal cortex (OFC), prefrontal cortex (PFC), frontal and temporal gyri, temporal pole, insular lobe, thalamus, basal ganglia, cerebellum, hippocampus, cingulate cortex, and amygdala. In addition, increased grey matter volumes in the postcentral gyrus, superior frontal gyrus, insula, basal ganglia, thalamus, amygdala, cuneus, and precuneus differentiated the first depressive episode in medication-naïve individuals from healthy subjects.

CONCLUSION

The present systematic review provided additional support for the involvement of grey matter structural abnormalities in limbic-cortical circuits as possibly specific structural abnormalities in the early stage of MDD.Key pointsDistinct brain regions in MDD patients might be associated with the early stages of illness, and thus it is critical to study the causal relationship between brain structures and the onset of the disease to improve the evaluation in clinic.Grey matter alterations in the fronto-limbic networks in the first episode, medication-naïve MDD might suggest that these abnormalities may play an important role in the neuropathophysiology of MDD at its onset.First episode, medically naïve depressive patients show grey matter volume alterations in brain regions mainly associated with emotion regulation including parietal-temporal regions, PFC, insular lobe, thalamus, basal ganglia, cerebellum and limbic structures that may be specific changes in early stage of MDD.Genotype-diagnosis interaction effects on brain morphology in the cortico-limbic-striatal circuits, including the PFC, amygdala, hippocampus and striatum that might be implicated in the dysfunctional regulation of emotion in first-episode MDD patients.Future longitudinal and prospective studies should be conducted to identify the core structural brain changes in people at-risk for MDD and explore the association of their brain volumes with symptom onset.

Facial Expression Recognition and ReHo Analysis in Major Depressive Disorder

Objective: To explore the characteristics of expression recognition and spontaneous activity of the resting state brain in major depressive disorder (MDD) patients to find the neural basis of expression recognition and emotional processing.

Methods: In this study, two of the six facial expressions (happiness, sadness, anger, fear, aversion, and surprise) were presented in quick succession using a short expression recognition test. The differences in facial expression recognition between MDD patients and healthy people were compared. Further, the differences in ReHo values between the two groups were compared using a resting-state functional magnetic resonance imaging (fMRI) scan to investigate the characteristics of spontaneous brain activity in the resting state and its relationship with clinical symptoms and the accuracy of facial expression recognition in patients with MDD.

Results: (1) The accuracy of facial expression recognition in patients with MDD was lower than that of the HC group. There were differences in facial expression recognition between the two groups in sadness-anger (p = 0.026), surprise-aversion (p = 0.038), surprise-happiness (p = 0.014), surprise-sadness (p = 0.019), fear-happiness (p = 0.027), and fear-anger (p = 0.009). The reaction time for facial expression recognition in the patient group was significantly longer than that of the HC group. (2) Compared with the HC group, the ReHo values decreased in the left parahippocampal gyrus, left thalamus, right putamen, left putamen, and right angular gyrus, and increased in the left superior frontal gyrus, left middle temporal gyrus, left medial superior frontal gyrus, and right medial superior frontal gyrus in the patient group. (3) Spearman correlation analysis showed no statistical correlation between ReHo and HAMD-17 scores in MDD patients (p > 0.05). The ReHo value of the left putamen was negatively correlated with the recognition of fear-surprise (r = −0.429, p = 0.016), the ReHo value of the right angular gyrus was positively correlated with the recognition of sadness-anger (r = 0.367, p = 0.042), and the ReHo value of the right medial superior frontal gyrus was negatively correlated with the recognition of fear-anger (r = −0.377, p = 0.037).

Conclusion: In view of the different performance of patients with MDD in facial expression tasks, facial expression recognition may have some suggestive effect on the diagnosis of depression and has clinical guiding significance. Many brain regions, including the frontal lobe, temporal lobe, striatum, hippocampus, and thalamus, in patients with MDD show extensive ReHo abnormalities in the resting state. These brain regions with abnormal spontaneous neural activity are important components of LCSPT and LTC circuits, and their dysfunctional functions cause disorder of emotion regulation. The changes in spontaneous activity in the left putamen, right angular gyrus, and right medial superior frontal gyrus may represent the abnormal pattern of spontaneous brain activity in the neural circuits related to emotion perception and may be the neural basis of facial expression recognition.

Uncovering the Roles of MicroRNAs in Major Depressive Disorder: From Candidate Diagnostic Biomarkers to Treatment Response Indicators

Major depressive disorder (MDD) is a recurrent debilitating illness that represents a major health burden due to its increasing worldwide prevalence, unclear pathological mechanism, nonresponsive treatment, and lack of reliable and specific diagnostic biomarkers. Recently, microRNA species (miRs) have gained particular interest because they have the ability to post-transcriptionally regulate gene expression by modulating mRNA stability and translation in a cohesive fashion. By regulating entire genetic circuitries, miRs have been shown to have dysregulated expression levels in blood samples from MDD patients, when compared to healthy subjects. In addition, antidepressant treatment (AD) also appears to alter the expression pattern of several miRs. Therefore, we critically and systematically reviewed herein the studies assessing the potential biomarker role of several candidate miRs for MDD, as well as treatment response monitoring indicators, in order to enrich the current knowledge and facilitate possible diagnostic biomarker development for MDD, which could aid in reducing both patients' burden and open novel avenues toward a better understanding of MDD neurobiology.

Neurological and Psychological Determinants of Depression, Anxiety, and Life Quality

Background:

This study aimed to determine the major neurological and psychological elements affecting depression, anxiety (DEPXITY), and the overall quality of life.

Methods:

This analytical descriptive study was carried out on 141 respondents with formal mood disorder diagnosis, with mental illness identity, with current depression and anxiety symptoms of at least moderate severity and people with mild symptoms. Data were analyzed using descriptive statistics, correlation test, reliability test, and separate regression models. Statistical significant level was set as 0.05.

Results:

The findings showed that external control by others on one's own life (EC) is the most significant factor (0.45) related to depression and the social conflict (SC) was found to be the most influential factor (0.28) for the anxiety. Internal control over own personal life (IC) is the most significant factor to cure or regulate some of the negative symptoms of the anxiety (−0.66). Good performance in personal life (PP) is a common positive factor to regulate both depression (DEP) and anxiety (XITY). This study shows that DEPXITY is associated with negative life quality.

Conclusions:

The lack of internal control and the control by others on one's own personal life are associated with impaired cognitive, affective, and behavioral functioning. The results of this study can also be a good indicator and confirmation that the medial prefrontal cortex is able with the support of IC and PP to coordinate self-appraisal processes by regulating activity in the posterior cingulate cortex area of the brain.

Early Life Irradiation-Induced Hypoplasia and Impairment of Neurogenesis in the Dentate Gyrus and Adult Depression Are Mediated by MicroRNA- 34a-5p/T-Cell Intracytoplasmic Antigen-1 Pathway

Early life radiation exposure causes abnormal brain development, leading to adult depression. However, few studies have been conducted to explore pre- or post-natal irradiation-induced depression-related neuropathological changes. Relevant molecular mechanisms are also poorly understood. We induced adult depression by irradiation of mice at postnatal day 3 (P3) to reveal hippocampal neuropathological changes and investigate their molecular mechanism, focusing on MicroRNA (miR) and its target mRNA and protein. P3 mice were irradiated by γ-rays with 5Gy, and euthanized at 1, 7 and 120 days after irradiation. A behavioral test was conducted before the animals were euthanized at 120 days after irradiation. The animal brains were used for different studies including immunohistochemistry, CAP-miRSeq, Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) and western blotting. The interaction of miR-34a-5p and its target T-cell intracytoplasmic antigen-1 (Tia1) was confirmed by luciferase reporter assay. Overexpression of Tia1 in a neural stem cell (NSC) model was used to further validate findings from the mouse model. Irradiation with 5 Gy at P3 induced depression in adult mice. Animal hippocampal pathological changes included hypoplasia of the infrapyramidal blade of the stratum granulosum, aberrant and impaired cell division, and neurogenesis in the dentate gyrus. At the molecular level, upregulation of miR-34a-5p and downregulation of Tia1 mRNA were observed in both animal and neural stem cell models. The luciferase reporter assay and gene transfection studies further confirmed a direct interaction between miR-43a-5p and Tia1. Our results indicate that the early life γ-radiation-activated miR-43a-5p/Tia1 pathway is involved in the pathogenesis of adult depression. This novel finding may provide a new therapeutic target by inhibiting the miR-43a-5p/Tia1 pathway to prevent radiation-induced pathogenesis of depression.

Effect of Cold Stress on Neurobehavioral and Physiological Parameters in Rats

Objective: Cold stress is an important current issue and implementing control strategies to limit its sometimes harmful effects is crucial. Cold is a common stressor that can occur in our work and our occupational or leisure time activities every day. There are substantial studies on the effects of chronic stress on memory and behavior, although, the cognitive changes and anxiety disorders that can occur after exposure to chronic intermittent cold stress are not completely characterized. Therefore, the present study was undertaken with an aim to investigate the effects of chronic intermittent cold stress on body weight, food intake and working memory, and to elucidate cold stress related anxiety disorders using cognitive and behavioral test batteries. Methods: We generated a cold stress model by exposing rats to chronic intermittent cold stress for 5 consecutive days and in order to test for the potential presence of sex differences, a comparable number of male and female rats were tested in the current study. Then, we measured the body weights, food intake and the adrenal glands weight. Working memory and recognition memory were assessed using the Y maze and the Novel Object Recognition (NOR) tasks. While, sex differences in the effects of chronic stress on behavior were evaluated by the elevated plus maze (EPM), open field maze (OF), and Marble burying (MB) tests. Results: We found that 2 h exposure to cold (4°C) resulted in an increase in the relative weight of the adrenal glands in male rats. Given the same chronic stress 5 days of cold exposure (2 h per day), increased weight gain in male rats, while females showed decreased food intake and no change in body weight. Both sexes successfully performed the Y maze and object recognition (OR) tasks, indicating intact spatial working memory performance and object recognition abilities in both male and female rats. In addition, we have shown that stress caused an increase in the level of anxiety in male rats. In contrast, the behavior of the female rats was not affected by cold exposure. Conclusion: Overall, the current results provide preliminary evidence that chronic intermittent cold stress model may not be an efficient stressor to female rats. Females exhibit resilience to cold exposure that causes an increase in the level of anxiety in male rats, which demonstrates that they are affected differently by stress and the gender is an important consideration in experimental design.

Psychobiological mechanisms underlying the mood benefits of meditation: A narrative review

Psychological stressors can lead to distress and result in autonomic arousal and activation of a stress response. Ongoing or persistent stress can disrupt the stress response feedback mechanisms and result in elevated cortisol and pro-inflammatory cytokines which can cause damage to brain regions involved in the regulation of mood and emotion. We propose that the magnitude of the stress response experienced in response to psychological stressors depends on a number of modifiable psychological processes including an individual’s level of self-compassion, dispositional mindfulness, tendency to ruminate and attentional bias. We further propose that the stress response elected by psychological stressors can be meditated by influencing these modifiable psychological processes, and that meditation practices can decrease stress and improve mood by decreasing stress reactivity on a psychological, physiological and neurobiological level. We explore this in a narrative review.

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Meditation decreases blood pressure, heart rate, cortisol and cytokine levels.

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Meditation increases self-compassion, dispositional mindfulness and meta-cognition.

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Meditation improves attention and memory.

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Meditation results in brain changes in regions related to emotion regulation.

Fronto-limbic neuroimaging biomarkers for diagnosis and prediction of treatment responses in major depressive disorder

The neuroimaging is an important tool for understanding the biomarkers and predicting treatment responses in major depressive disorder (MDD). The potential biomarkers and prediction of treatment response in MDD will be addressed in the review article. The brain regions of cognitive control and emotion regulation, such as the frontal and limbic regions, might represent the potential targets for MDD biomarkers. The potential targets of frontal lobes might include anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC). For the limbic system, hippocampus and amygdala might be the potentially promising targets for MDD. The potential targets of fronto-limbic regions have been found in the studies of several major neuroimaging modalities, such as the magnetic resonance imaging, near-infrared spectroscopy, electroencephalography, positron emission tomography, and single-photon emission computed tomography. Additional regions, such as brainstem and midbrain, might also play a part in the MDD biomarkers. For the prediction of treatment response, the gray matter volumes, white matter tracts, functional representations and receptor bindings of ACC, DLPFC, OFC, amygdala, and hippocampus might play a role in the prediction of antidepressant responses in MDD. For the response prediction of psychotherapies, the fronto-limbic, reward regions, and insula will be the potential targets. For the repetitive transcranial magnetic stimulation, the DLPFC, ACC, limbic, and visuospatial regions might represent the predictive targets for treatment. The neuroimaging targets of MDD might be focused in the fronto-limbic regions. However, the neuroimaging targets for the prediction of treatment responses might be inconclusive and beyond the fronto-limbic regions.

The relation of depression with structural brain abnormalities and cognitive functioning: the Maastricht study

BACKGROUND

Individuals with depression often experience widespread and persistent cognitive deficits, which might be due to brain atrophy and cerebral small vessel disease (CSVD). We therefore studied the associations between depression, markers of brain atrophy and CSVD, and cognitive functioning.

METHODS

We used cross-sectional data from the population-based Maastricht study (n = 4734; mean age 59.1 ± 8.6 years, 50.2% women), which focuses on type 2 diabetes. A current episode of major depressive disorder (MDD, n = 151) was assessed by the Mini-International Neuropsychiatric Interview. Volumes of cerebral spinal fluid, white matter, gray matter and white matter hyperintensities, presence of lacunar infarcts and cerebral microbleeds, and total CSVD burden were assessed by 3 T magnetic resonance imaging. Multiple linear and logistic regression analyses tested the associations between MDD, brain markers and cognitive functioning in memory, information processing speed, and executive functioning & attention, and presence of cognitive impairment. Structural equation modeling was used to test mediation.

RESULTS

In fully adjusted models, MDD was associated with lower scores in information processing speed [mean difference = -0.18(-0.28;-0.08)], executive functioning & attention [mean difference = -0.13(-0.25;-0.02)], and with higher odds of cognitive impairment [odds ratio (OR) = 1.60(1.06;2.40)]. MDD was associated with CSVD in participants without type 2 diabetes [OR = 1.65(1.06;2.56)], but CSVD or other markers of brain atrophy or CSVD did not mediate the association with cognitive functioning.

CONCLUSIONS

MDD is associated with more impaired information processing speed and executive functioning & attention, and overall cognitive impairment. Furthermore, MDD was associated with CSVD in participants without type 2 diabetes, but this association did not explain an impaired cognitive profile.

Stress increases blood beta-hydroxybutyrate levels and prefrontal cortex NLRP3 activity jointly in a rodent model

Aim

This study aimed to assess the response of endogenous beta‐hydroxybutyrate to psychological stress, and its association with nucleotide‐binding domain, leucine‐rich repeat, pyrin domain‐containing 3 (NLRP3) inflammasome, and stress‐induced behavior.

Methods

Male C57BL/6J mice were subjected to 1‐hour restraint stress to examine changes in the endogenous beta‐hydroxybutyrate and active NLRP3 levels in the prefrontal cortex. Subsequently, we created a depression model applying 10‐day social defeat stress to the male C57BL/6J mice.

Results

One‐hour restraint stress rapidly increased beta‐hydroxybutyrate levels in the blood. The active NLRP3 levels in the prefrontal cortex also increased significantly. A correlation was found between the increased beta‐hydroxybutyrate levels in the blood and the active NLRP3 levels in the prefrontal cortex. The mice exposed to social defeat stress exhibited depression‐ and anxiety‐like behavioral changes in the open field, social interaction, and forced swim tests. There was a correlation between these behavioral changes and endogenous beta‐hydroxybutyrate levels. Among the social defeat model mice, those with high beta‐hydroxybutyrate levels tended to have more depression‐ and anxiety‐like behavior.

Conclusions

The increased blood beta‐hydroxybutyrate levels due to psychological stress correlate with the active NLRP3 levels in the prefrontal cortex, suggesting that the increased beta‐hydroxybutyrate levels due to stress may reflect a reaction to brain inflammation. In addition, mice with higher blood beta‐hydroxybutyrate levels tend to exhibit increased depression‐ and anxiety‐like behaviors; thus, an increase in blood beta‐hydroxybutyrate levels due to stress may indicate stress vulnerability.

Psychological stress increased blood beta‐hydroxybutyrate (BHB) levels. Mice with higher blood BHB levels tend to exhibit increased depression‐ and anxiety‐like behaviors. The increased blood BHB levels correlate with the active NLRP3 levels in the prefrontal cortex, suggesting that increased blood BHB levels may represent stress vulnerability.

Intrinsic brain abnormalities of irritable bowel syndrome with diarrhea: a preliminary resting-state functional magnetic resonance imaging study

Background

The aim of the present study was to explore the brain active characteristics of patients with irritable bowel syndrome with diarrhea (IBS-D) using resting-state functional magnetic resonance imaging technology.

Methods

Thirteen IBS-D patients and fourteen healthy controls (HC) were enrolled. All subjects underwent head MRI examination during resting state. A voxel-based analysis of fractional amplitude of low frequency fluctuation (fALFF) maps between IBS-D and HC was performed using a two-sample t-test. The relationship between the fALFF values in abnormal brain regions and the scores of Symptom Severity Scale (IBS-SSS) were analyzed using Pearson correlation analysis.

Results

Compared with HC, IBS-D patients had lower fALFF values in the left medial superior frontal gyrus and higher fALFF values in the left hippocampus and right precuneus. There was a positive correlation between the duration scores of IBS-SSS and fALFF values in the right precuneus.

Conclusion

The altered fALFF values in the medial superior frontal gyri, left hippocampus and right precuneus revealed changes of intrinsic neuronal activity, further revealing the abnormality of gut-brain axis of IBS-D.

Task MRI-Based Functional Brain Network of Major Depression

This chapter will focus on task magnetic resonance imaging (MRI) to understand the biological mechanisms and pathophysiology of brain in major depressive disorder (MDD), which would have minor alterations in the brain function. Therefore, the functional study, such as task MRI functional connectivity, would play a crucial role to explore the brain function in MDD. Different kinds of tasks would determine the alterations in functional connectivity in task MRI studies of MDD. The emotion-related tasks are linked with alterations in anterior cingulate cortex, insula, and default mode network. The emotional memory task is linked with amygdala-hippocampus alterations. The reward-related task would be related to the reward circuit alterations, such as fronto-straital. The cognitive-related tasks would be associated with frontal-related functional connectivity alterations, such as the dorsolateral prefrontal cortex, anterior cingulate cortex, and other frontal regions. The visuo-sensory characteristics of tasks might be associated with the parieto-occipital alterations. The frontolimbic regions might be major components of task MRI-based functional connectivity in MDD. However, different scenarios and tasks would influence the representations of results.

Decision Models and Technology Can Help Psychiatry Develop Biomarkers

Why is psychiatry unable to define clinically useful biomarkers? We explore this question from the vantage of data and decision science and consider biomarkers as a form of phenotypic data that resolves a well-defined clinical decision. We introduce a framework that systematizes different forms of phenotypic data and further introduce the concept of decision model to describe the strategies a clinician uses to seek out, combine, and act on clinical data. Though many medical specialties rely on quantitative clinical data and operationalized decision models, we observe that, in psychiatry, clinical data are gathered and used in idiosyncratic decision models that exist solely in the clinician's mind and therefore are outside empirical evaluation. This, we argue, is a fundamental reason why psychiatry is unable to define clinically useful biomarkers: because psychiatry does not currently quantify clinical data, decision models cannot be operationalized and, in the absence of an operationalized decision model, it is impossible to define how a biomarker might be of use. Here, psychiatry might benefit from digital technologies that have recently emerged specifically to quantify clinically relevant facets of human behavior. We propose that digital tools might help psychiatry in two ways: first, by quantifying data already present in the standard clinical interaction and by allowing decision models to be operationalized and evaluated; second, by testing whether new forms of data might have value within an operationalized decision model. We reference successes from other medical specialties to illustrate how quantitative data and operationalized decision models improve patient care.

Vascular depression for radiology: A review of the construct, methodology, and diagnosis

Vascular depression (VD) as defined by magnetic resonance imaging (MRI) has been proposed as a unique subtype of late-life depression. The VD hypothesis posits that cerebrovascular disease, as characterized by the presence of MRI-defined white matter hyperintensities, contributes to and increases the risk for depression in older adults. VD is also accompanied by cognitive impairment and poor antidepressant treatment response. The VD diagnosis relies on MRI findings and yet this clinical entity is largely unfamiliar to neuroradiologists and is rarely, if ever, discussed in radiology journals. The primary purpose of this review is to introduce the MRI-defined VD construct to the neuroradiology community. Case reports are highlighted in order to illustrate the profile of VD in terms of radiological, clinical, and neuropsychological findings. A secondary purpose is to elucidate and elaborate on the measurement of cerebrovascular disease through visual rating scales and semi- and fully-automated volumetric methods. These methods are crucial for determining whether lesion burden or lesion severity is the dominant pathological contributor to VD. Additionally, these rating methods have implications for the growing field of computer assisted diagnosis. Since VD has been found to have a profile that is distinct from other types of late-life depression, neuroradiologists, in conjunction with psychiatrists and psychologists, should consider VD in diagnosis and treatment planning.

Volumetric MRI analysis of hippocampal subregions in Cushing's disease: A model for glucocorticoid neural modulation

Several preclinical studies have demonstrated neuronal effects of glucocorticoids on the hippocampus (HC), a limbic structure with anterior–posterior anatomical and functional segmentation. We propose a volumetric magnetic resonance imaging analysis of hippocampus head (HH), body (HB) and tail (HT) using Cushing's disease (CD) as model, to investigate whether there is a differential sensitivity to glucocorticoid neuronal damage in these segments. We found a significant difference in the HH bilaterally after 12 months from trans-sphenoidal surgical selective resection of the adrenocorticotropic hormone (ACTH)-secreting pituitary micro-adenomas. This pre–post surgery difference could contribute to better understand the pathopysiology of CD as an in vivo model for stress-related hypercortisolemic neuropsychiatric disorders.

Aberrant interhemispheric functional connectivity in first-episode, drug-naïve major depressive disorder

Many studies have indicated that depression is associated with impairment of the topological organization of the brain functional network, which may lead to disruption of mood and cognition in depressive patients. The abnormality of homotopic connectivity provides a basis for the clinical manifestations of depression, such as emotional and cognitive disorders. Several studies have investigated the abnormal imbalance of homotopic regions between the hemispheres in depressive patients. However, the reported findings are inconsistent. Additionally, the published studies have focused on only the grey matter when investigating functional connectivity abnormalities of the bilateral cerebral hemispheres in major depressive disorder (MDD). The aim of this study is to investigate functional connectivity abnormalities of the bilateral cerebral hemispheres in patients with first-episode, drug-naïve MDD using a voxel-mirrored homotopic connectivity (VMHC) method. Based on DSM-IV diagnostic criteria, 23 first-episode, drug-naïve MDD patients were recruited, together with 20 gender- and age-matched healthy normal controls. A Philips Achieva 3.0 T MRI scanner was used to acquire brain functional images at resting state as well as high-resolution structural images. The functional images were preprocessed by using Data Processing Assistant for Resting-State Functional MR Imaging toolkit and SPM8.VMHC between the bilateral hemispheres was computed and compared between the MDD and control groups. The correlation between the VMHC values of the abnormal homotopy function areas and the Hamilton Depression Rating Scale (HAMD) was evaluated in the MDD patients. Compared with the control group, the MDD patients showed significantly decreased VMHC values in the bilateral brain regions including the insular, putamen, and frontal white matter. The MDD patients did not exhibit increased VMHC values in any brain regions compared with the normal controls. In addition, a negative correlation was observed between the VMHC value in the frontal lobe white-matter and the HAMD in the MDD patients. Abnormalities in brain homotopic functional connectivity observed in this study may indicate abnormal neural circuits related to aberrant cognition and emotional processing in MDD. Although the physiological significance underlaying abnormal VMHC in white matter in the frontal lobe needs further research, our study new angle to investigate the role of white-matter abnormalities in MDD as well as other psychiatric disorders.

The importance of identifying functional Val158Met polymorphism in catechol-O- Methyltransferase when assessing MRI-based volumetric measurements in major depressive disorder

Many studies have shown volumetric differences in the hippocampus between COMT gene polymorphisms and other studies have shown differences between depressed patients and controls; yet, few studies have been completed to identify the volumetric differences when taking both factors into consideration. Using voxel-based morphology (VBM) we investigated, in major depressive disorder (MDD) patients and healthy controls, the relationship between COMT gene polymorphism and volumetric abnormalities. Data from 60 MDD patients and 25 healthy controls were included in this study. Volumetric measurements and genotyping of COMTval158met polymorphism were conducted to determine its impact on gray matter volume (GMV) in the hippocampus and amygdala using a Met dominant model (Val/Val vs Met/Val & Met/Met). In the analysis, a significant difference in the right hippocampus (p = 0.015), right amygdala (p = 0.003) and entire amygdala (p = 0.019) was found between the interaction of diagnosis and genotype after MRI scanner, age and sex correction. Healthy controls (HC) with the Met dominant genotype exhibited a larger right hippocampal, right amygdalar and entire amydgalar volume than MDD patients with the Met dominant genotype. Conversely, HC with the Val/Val genotype displayed a lower right hippocampal, right amygdalar and entire amygdalar volume than their MDD counterparts. This study shows that COMT polymorphism and depression may have a confounding effect on neuroimaging studies.

Promising Neuroimaging Biomarkers in Depression

The neuroimaging has been applied in the study of pathophysiology in major depressive disorder (MDD). In this review article, several kinds of methodologies of neuroimaging would be discussed to summarize the promising biomarkers in MDD. For the magnetic resonance imaging (MRI) and magnetoencephalography field, the literature review showed the potentially promising roles of frontal lobes, such as anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC). In addition, the limbic regions, such as hippocampus and amygdala, might be the potentially promising biomarkers for MDD. The structures and functions of ACC, DLPFC, OFC, amygdala and hippocampus might be confirmed as the biomarkers for the prediction of antidepressant treatment responses and for the pathophysiology of MDD. The functions of cognitive control and emotion regulation of these regions might be crucial for the establishment of biomarkers. The near-infrared spectroscopy studies demonstrated that blood flow in the frontal lobe, such as the DLPFC and OFC, might be the biomarkers for the field of near-infrared spectroscopy. The electroencephalography also supported the promising role of frontal regions, such as the ACC, DLPFC and OFC in the biomarker exploration, especially for the sleep electroencephalogram to detect biomarkers in MDD. The positron emission tomography (PET) and single-photon emission computed tomography (SPECT) in MDD demonstrated the promising biomarkers for the frontal and limbic regions, such as ACC, DLPFC and amygdala. However, additional findings in brainstem and midbrain were also found in PET and SPECT. The promising neuroimaging biomarkers of MDD seemed focused in the fronto-limbic regions.

Activation of WNT and CREB signaling pathways in human neuronal cells in response to the Omega-3 fatty acid docosahexaenoic acid (DHA)

A subset of individuals with major depressive disorder (MDD) elects treatment with complementary and alternative medicines (CAMs), including the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Previous studies in rodents suggest that DHA modulates neurodevelopmental processes, including adult neurogenesis and neuroplasticity, but the molecular and cellular mechanisms of DHA's potential therapeutic effect in the context of human neurobiology have not been well established. Here we sought to address this knowledge gap by investigating the effects of DHA using human iPSC-derived neural progenitor cells (NPCs) and post-mitotic neurons using pathway-selective reporter genes, multiplexed mRNA expression profiling, and a panel of metabolism-based viability assays. Finally, real-time, live-cell imaging was employed to monitor neurite outgrowth upon DHA treatment. Overall, these studies showed that DHA treatment (0-50 μM) significantly upregulated both WNT and CREB signaling pathways in human neuronal cells in a dose-dependent manner with 2- to 3-fold increases in pathway activation. Additionally, we observed that DHA treatment enhanced survival of iPSC-derived NPCs and differentiation of post-mitotic neurons with live-cell imaging, revealing increased neurite outgrowth with DHA treatment within 24 h. Taken together, this study provides evidence that DHA treatment activates critical pathways regulating neuroplasticity, which may contribute to enhanced neuronal cell viability and neuronal connectivity. The extent to which these pathways represent molecular mechanisms underlying the potential beneficial effects of omega-3 fatty acids in MDD and other brain disorders merits further investigation.

Bayesian Generative Models for Knowledge Transfer in MRI Semantic Segmentation Problems

Automatic segmentation methods based on deep learning have recently demonstrated state-of-the-art performance, outperforming the ordinary methods. Nevertheless, these methods are inapplicable for small datasets, which are very common in medical problems. To this end, we propose a knowledge transfer method between diseases via the Generative Bayesian Prior network. Our approach is compared to a pre-train approach and random initialization and obtains the best results in terms of Dice Similarity Coefficient metric for the small subsets of the Brain Tumor Segmentation 2018 database (BRATS2018).

Dopaminergic impact of cART and anti-depressants on HIV neuropathogenesis in older adults

The success of combination antiretroviral therapy (cART) has transformed HIV infection into a chronic condition, resulting in an increase in the number of older, cART-treated adults living with HIV. This has increased the incidence of age-related, non-AIDS comorbidities in this population. One of the most common comorbidities is depression, which is also associated with cognitive impairment and a number of neuropathologies. In older people living with HIV, treating these overlapping disorders is complex, often creating pill burden or adverse drug-drug interactions that can exacerbate these neurologic disorders. Depression, NeuroHIV and many of the neuropsychiatric therapeutics used to treat them impact the dopaminergic system, suggesting that dopaminergic dysfunction may be a common factor in the development of these disorders. Further, changes in dopamine can influence the development of inflammation and the regulation of immune function, which are also implicated in the progression of NeuroHIV and depression. Little is known about the optimal clinical management of drug-drug interactions between cART drugs and antidepressants, particularly in regard to dopamine in older people living with HIV. This review will discuss those interactions, first examining the etiology of NeuroHIV and depression in older adults, then discussing the interrelated effects of dopamine and inflammation on these disorders, and finally reviewing the activity and interactions of cART drugs and antidepressants on each of these factors. Developing better strategies to manage these comorbidities is critical to the health of the aging, HIV-infected population, as the older population may be particularly vulnerable to drug-drug interactions affecting dopamine.

Aberrant brain network topology in fronto-limbic circuitry differentiates euthymic bipolar disorder from recurrent major depressive disorder

INTRODUCTION

Previous studies have established graph theoretical analysis of functional network connectivity (FNC) as a potential tool to detect neurobiological underpinnings of psychiatric disorders. Despite the promising outcomes in studies that examined FNC aberrancies in bipolar disorder (BD) and major depressive disorder (MDD), there is still a lack of research comparing both mood disorders, especially in a nondepressed state. In this study, we used graph theoretical network analysis to compare brain network properties of euthymic BD, euthymic MDD and healthy controls (HC) to evaluate whether these groups showed distinct features in FNC.

METHODS

We collected resting-state functional magnetic resonance imaging (fMRI) data from 20 BD patients, 15 patients with recurrent MDD as well as 30 age- and gender-matched HC. Graph theoretical analyses were then applied to investigate functional brain networks on a global and regional network level.

RESULTS

Global network analysis revealed a significantly higher mean global clustering coefficient in BD compared to HC. We further detected frontal, temporal and subcortical nodes in emotion regulation areas such as the limbic system and associated regions exhibiting significant differences in network integration and segregation in BD compared to MDD patients and HC. Participants with MDD and HC only differed in frontal and insular network centrality.

CONCLUSION

In conclusion, our findings indicate that a significantly altered brain network topology in the limbic system might be a trait marker specific to BD. Brain network analysis in these regions may therefore be used to differentiate euthymic BD not only from HC but also from patients with MDD.

Major Depressive Disorder in Neuroimaging: What is Beyond Fronto-limbic Model?

Background:

The major depressive disorder (MDD) is a chronic illness with major manifestations in cognitive, social and occupational functions. The pathophysiological model is an intrigue issue for scientists to understand the origin of MDD.

Objective:

In the beginning, the cortico-limbic-striato-pallidal-thalamic model has been proposed to link the clinical symptoms with the abnormalities in brain structure and function. However, the model is still evolving due to recent advances in the neuroimaging techniques, especially for functional magnetic resonance imaging (fMRI). The recent findings in the fMRI studies in MDD showed the importance of fronto-limbic model for the modulations between cognitive function and primitive and negative emotions.

Method:

This review will focus on the literature of fMRI studies in MDD with findings not in the fronto-limbic structures.

Results:

Additional regions beyond the fronto-limbic model have been observed in some literature of MDD. Some regions in the parietal, temporal and occipital lobes have been shown with the alterations in gray matter, white matter and brain function. The importance of sensory detection, visuospatial function, language reception, motor response and emotional memories in these regions might provide the clues to understand the cognitive misinterpretations related to altered reception of outside information, behavioral responses related to biased cognition and emotional memories and clinical symptoms related to the significant alterations of interactions between different brain regions.

Conclusion:

Future studies to establish a more comprehensive model for MDD will be warranted, especially for the model beyond the fronto-limbic structures.