Duloxetine's modest short-term influences in subcortical structures of first episode drug-naïve patients with major depressive disorder and panic disorder

Enhanced interhemispheric resting-state functional connectivity of the visual network is an early treatment response of paroxetine in patients with panic disorder

This study aimed to detect alterations in interhemispheric interactions in patients with panic disorder (PD), determine whether such alterations could serve as biomarkers for the diagnosis and prediction of therapeutic outcomes, and map dynamic changes in interhemispheric interactions in patients with PD after treatment. Fifty-four patients with PD and 54 healthy controls (HCs) were enrolled in this study. All participants underwent clinical assessment and a resting-state functional magnetic resonance imaging scan at (i) baseline and (ii) after paroxetine treatment for 4 weeks. A voxel-mirrored homotopic connectivity (VMHC) indicator, support vector machine (SVM), and support vector regression (SVR) were used in this study. Patients with PD showed reduced VMHC in the fusiform, middle temporal/occipital, and postcentral/precentral gyri, relative to those of HCs. After treatment, the patients exhibited enhanced VMHC in the lingual gyrus, relative to the baseline data. The VMHC of the fusiform and postcentral/precentral gyri contributed most to the classification (accuracy = 87.04%). The predicted changes were accessed from the SVR using the aberrant VMHC as features. Positive correlations (p < 0.001) were indicated between the actual and predicted changes in the severity of anxiety. These findings suggest that impaired interhemispheric coordination in the cognitive-sensory network characterized PD and that VMHC can serve as biomarkers and predictors of the efficiency of PD treatment. Enhanced VMHC in the lingual gyrus of patients with PD after treatment implied that pharmacotherapy recruited the visual network in the early stages.

Alterations of brainstem volume in patients with first-episode and recurrent major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a prevalent mental health condition characterized by recurrent episodes in a substantial proportion of patients. The number of previous episodes is one of the most crucial predictors of depression recurrence. However, the underlying neural mechanisms remain unclear. To date, there have been limited neuroimaging studies investigating morphological changes of the brainstem in patients with first-episode MDD (FMDD) and recurrent MDD (RMDD). This study aimed to examine volumetric changes of individual brainstem regions in relation to the number of previous episodes and disease duration.

METHOD

A total of 111 individuals including 36 FMDD, 25 RMDD, and 50 healthy controls (HCs) underwent T1-weighted structural magnetic resonance imaging scans. A Bayesian segmentation algorithm was used to analyze the volume of each brainstem region, including the medulla oblongata, pons, midbrain, and superior cerebellar peduncle (SCP), as well as the whole brainstem volume. Analyses of variance (ANOVA) were performed to obtain brain regions with significant differences among three groups and then post hoc tests were calculated for inter-group comparisons. Partial correlation analyses were further conducted to identify associations between regional volumes and clinical features.

RESULTS

The ANOVA revealed significant brainstem volumetric differences among three groups in the pons, midbrain, SCP, and the whole brainstem (F = 3.996 ~ 5.886, adjusted p = 0.015 ~ 0.028). As compared with HCs, both groups of MDD patients showed decreased volumes in the pons as well as the entire brainstem (p = 0.002 ~ 0.034), however, only the FMDD group demonstrated a significantly reduced volume in the midbrain (p = 0.003). Specifically, the RMDD group exhibited significantly decreased SCP volume when comparing to both FMDD (p = 0.021) group and HCs (p = 0.008). Correlation analyses revealed that the SCP volumes were negatively associated with the number of depressive episodes (r=-0.36, p < 0.01) and illness duration (r=-0.28, p = 0.035) in patients with MDD.

CONCLUSION

The present findings provided evidence of decreased brainstem volume involving in the pathophysiology of MDD, particularly, volumetric reduction in the SCP might represent a neurobiological marker for RMDD. Further research is needed to confirm our observations and deepen our understanding of the neural mechanisms underlying depression recurrence.

Structural abnormalities in nucleus accumbens in patients with panic disorder

BACKGROUND

Although the pathogenesis of panic attacks has been well studied in patients with panic disorder (PD), the neurobiological basis of the long-term fear memories and avoidance behavior that are often observed in PD have not been well investigated. Recent animal studies have suggested that nucleus accumbens (NAcc) plays an important role in neurobiological basis of long-term fear memories and avoidance behavior.

METHODS

Thirty-eight patients with PD and 38 matched healthy control subjects (HC) participated in this study. Differences in relative volumes and shape deformations of NAcc were evaluated between groups. Correlation analyses were conducted to quantify the association between structural abnormalities in the NAcc and trait, state anxiety measured by the State-Trait Anxiety Inventory (STAI).

RESULTS

Significant volume reductions were observed in the bilateral NAcc in the patients with PD, relative to the HC. In terms of shape differences, the PD patients demonstrated significant inward deformation of the NAcc bilaterally, compared to the HC. Degree of shape deformation in the right NAcc was associated with higher scores of the STAI-Trait, and STAI-State measures in the PD patients.

LIMITATIONS

All the patients received medication such as Psychotropic drug.

CONCLUSION

Patients with PD showed reduced volumes in the NAcc, especially in lateral regions, compared with HC. Furthermore, shape deformation in the right NAcc was associated with trait anxiety and state anxiety, which has been associated with avoidance behavior.

Distinguishing medication-free subjects with unipolar disorder from subjects with bipolar disorder: state matters

OBJECTIVES

Recent studies have indicated that pattern recognition techniques of functional magnetic resonance imaging (fMRI) data for individual classification may be valuable for distinguishing between major depressive disorder (MDD) and bipolar disorder (BD). Importantly, medication may have affected previous classification results as subjects with MDD and BD use different classes of medication. Furthermore, almost all studies have investigated only depressed subjects. Therefore, we focused on medication-free subjects. We additionally investigated whether classification would be mood state independent by including depressed and remitted subjects alike.

METHODS

We applied Gaussian process classifiers to investigate the discriminatory power of structural MRI (gray matter volumes of emotion regulation areas) and resting-state fMRI (resting-state networks implicated in mood disorders: default mode network [DMN], salience network [SN], and lateralized frontoparietal networks [FPNs]) in depressed (n=42) and remitted (n=49) medication-free subjects with MDD and BD.

RESULTS

Depressed subjects with MDD and BD could be classified based on the gray matter volumes of emotion regulation areas as well as DMN functional connectivity with 69.1% prediction accuracy. Prediction accuracy using the FPNs and SN did not exceed chance level. It was not possible to discriminate between remitted subjects with MDD and BD.

CONCLUSIONS

For the first time, we showed that medication-free subjects with MDD and BD can be differentiated based on structural MRI as well as resting-state functional connectivity. Importantly, the results indicated that research concerning diagnostic neuroimaging tools distinguishing between MDD and BD should consider mood state as only depressed subjects with MDD and BD could be correctly classified. Future studies, in larger samples are needed to investigate whether the results can be generalized to medication-naïve or first-episode subjects.

Clinical neuroimaging markers of response to treatment in mood disorders

Mood disorders (MD) are important and frequent psychiatric illness. The management of patients affected by these conditions represents an important factor of disability as well as a significant social and economic burden. The "in-vivo" studies can help researchers to understand the first developmental events of the pathology and to identify the molecular and non-molecular targets of therapies. However, they have strong limitations due to the fact that human brain circuitry can not be reproduced in animal models. In addition, these neural pathways are difficult to be selectively studied with the modern imaging (such as Magnetic Resonance and Positron Emitted Tomography/Computed Tomography) and non-imaging (such as electroencephalography, magnetoencephalography, transcranial magnetic stimulation and evoked potentials) methods. In comparison with other methods, the "in-vivo" imaging investigations have higher temporal and spatial resolution compared to the "in-vivo" non-imaging techniques. All these factors make difficult to fully understand the aetiology and pathophysiology of these disorders, and consequently hinder the analysis of the effects of pharmacological and non-pharmacological therapies, which have been demonstrated effective in clinical settings. In this review, we will focus our attention on the current state of the art of imaging in the assessment of treatment efficacy in MD. We will analyse briefly the actual classification of MD; then we will focus on the "in vivo" imaging methods used in research and clinical activity, the current knowledge about the neural models at the base of MD. Finally the last part of the review will focus on the analysis of the main markers of response to treatment.

Gray matter increases in fronto-parietal regions of depression patients with aripiprazole monotherapy: An exploratory study

We investigated the treatment effects of aripiprazole monotherapy in first-episode medication-naïve patients with major depressive disorder (MDD). The accompanying changes in the gray matter volume (GMV) were also explored.Fifteen patients completed the trial and received structural scans by 3-Tesla magnetic resonance imaging at baseline and partially responding state (sixth week). To account for the test-retest bias, 27 healthy controls were scanned twice within 6 weeks. We utilized optimized voxel-based morphometry with different comparisons between groups.The partially responding patients with MDD had greater GMV in left middle frontal gyrus and left superior parietal gyrus when compared with baseline. However, they had decreases in the GMV of right orbitofrontal gyrus and right inferior temporal gyrus after response. The partially responding patients with MDD still had residual GMV deficits in right superior frontal gyrus when compared with controls. However, the lack of second patient group without aripiprazole intervention would be a significant limitation to interpret the aripiprazole-specific effects on GMV.The changes in the GMV of fronto-parieto-temporal regions and residual GMV deficits in the superior frontal gyrus might represent "state-dependent brain changes" and "residual-deficit brain regions," respectively, for aripiprzole monotherapy in MDD.

Antidepressant-Like Effects of Fractions Prepared from Danzhi-Xiaoyao-San Decoction in Rats with Chronic Unpredictable Mild Stress: Effects on Hypothalamic-Pituitary-Adrenal Axis, Arginine Vasopressin, and Neurotransmitters

The aim of the present study was to investigate the antidepressant-like effects of two fractions, including petroleum ether soluble fraction (Fraction A, FA) and water-EtOH soluble fraction (Fraction B, FB) prepared from the Danzhi-xiaoyao-san (DZXYS) by using chronic unpredictable mild stress-induced depressive rat model. The results indicated that DZXYS could ameliorate the depression-like behavior in chronic stress model of rats. The inhibition of hyperactivity of HPA axis and the modulation of monoamine and amino acid neurotransmitters in the hippocampus may be the important mechanisms underlying the action of DZXYS antidepressant-like effect in chronically stressed rats.

Reduced volume of the nucleus accumbens in heroin addiction

The neural mechanisms of heroin addiction are still incompletely understood, even though modern neuroimaging techniques offer insights into disease-related changes in vivo. While changes on cortical structure have been reported in heroin addiction, evidence from subcortical areas remains underrepresented. Functional imaging studies revealed that the brain reward system and particularly the nucleus accumbens (NAcc) play a pivotal role in the pathophysiology of drug addiction. The aim of this study was to investigate whether there was a volume difference of the NAcc in heroin addiction in comparison to healthy controls. A further aim was to correlate subcortical volumes with clinical measurements on negative affects in addiction. Thirty heroin-dependent patients under maintenance treatment with diacetylmorphine and twenty healthy controls underwent structural MRI scanning at 3T. Subcortical segmentation analysis was performed using FMRIB's Integrated Registration and Segmentation Tool function of FSL. The State-Trait Anxiety Inventory and the Beck Depression Inventory were used to assess trait anxiety and depressive symptoms, respectively. A decreased volume of the left NAcc was observed in heroin-dependent patients compared to healthy controls. Depression score was negatively correlated with left NAcc volume in patients, whereas a positive correlation was found between the daily opioid dose and the volume of the right amygdala. This study indicates that there might be structural differences of the NAcc in heroin-dependent patients in comparison with healthy controls. Furthermore, correlations of subcortical structures with negative emotions and opioid doses might be of future relevance for the investigation of heroin addiction.

Imaging predictors of remission to anti-depressant medications in major depressive disorder

BACKGROUND

We review what is currently known about neuroimaging predictors of remission in major depressive disorder (MDD) after antidepressant medication (ADM) treatment.

METHODS

A systematic literature search found a total of twenty-seven studies comparing baseline neuroimaging findings in depressed patients who achieved remission with non-remitters following treatment with ADMs.

RESULTS

Eighteen of these studies utilised structural magnetic resonance imaging (MRI). These studies associated larger hippocampal (four studies) and cingulate volume (two studies) with remission. Two diffusion MRI studies identified a positive relationship between the fractional anisotropy of the cingulum bundle and remission. White matter signal hyperintensities were quantified in two papers - both observing decreased remission rates with increasing lesion burden. Nine studies on functional imaging met inclusion criteria - three using functional MRI, one with single photon emission computed tomography (SPECT), and five which evaluated patients with positron emission tomography (PET). These findings were not convergent, with different regions of interest interrogated.

LIMITATIONS

The studies were generally underpowered. Overall these data were heterogeneous with only a small number identifying concordant findings.

CONCLUSIONS

At present, the data remains inconsistent. The more promising biomarker of remission to ADMs appears to be hippocampal size, although this marker also has conflicting reports. Given remission should be the primary end-point of treatment, and that ADMs are the front-line treatment type for MDD, more focussed research is required to focus specifically on the imaging correlates of remission to ADMs.

Brain Structural Effects of Antidepressant Treatment in Major Depression

Depressive disorder is a very frequent and heterogeneous syndrome. Structural imaging techniques offer a useful tool in the comprehension of neurobiological alterations that concern depressive disorder. Altered brain structures in depressive disorder have been particularly located in the prefrontal cortex (medial prefrontal cortex and orbitofrontal cortex, OFC) and medial temporal cortex areas (hippocampus). These brain areas belong to a structural and functional network related to cognitive and emotional processes putatively implicated in depressive symptoms. These volumetric alterations may also represent biological predictors of response to pharmacological treatment. In this context, major findings of magnetic resonance (MR) imaging, in relation to treatment response in depressive disorder, will here be presented and discussed.

Hippocampal atrophy in major depression: a function of childhood maltreatment rather than diagnosis?

Reduced hippocampal volumes are probably the most frequently reported structural neuroimaging finding associated with major depressive disorder (MDD). However, it remains unclear whether altered hippocampal structure represents a risk factor for or a consequence of MDD. Reduced hippocampal volumes were consistently reported in subjects affected by childhood maltreatment. As the prevalence of childhood maltreatment is highly elevated in MDD populations, previous morphometric findings regarding hippocampal atrophy in MDD therefore might have been confounded by maltreatment experiences. The aim of this study was to differentiate the impact of childhood maltreatment from the influence of MDD diagnosis on hippocampal morphometry. Depressed patients (85) as well as 85 age- and sex-matched healthy controls underwent structural MRI. The Childhood Trauma Questionnaire was administered to estimate experiences of childhood maltreatment. Hippocampal volume and surface structure was examined by the use of two independent methods, automated segmentation (FSL-FIRST) and voxel-based morphometry (VBM8). In line with existing studies, MDD patients showed reduced hippocampal volumes, and childhood maltreatment was consistently associated with hippocampal volume loss in both, patients and healthy controls. However, no analysis revealed significant morphological differences between patients and controls if maltreatment experience was regressed out. Our results suggest that hippocampal alterations in MDD patients may at least partly be traced back to higher occurrence of early-life adverse experiences. Regarding the strong morphometric impact of childhood maltreatment and its distinctly elevated prevalence in MDD populations, this study provides an alternative explanation for frequently observed limbic structural abnormalities in depressed patients.

Improvements in white matter micro-structural integrity of right uncinate fasciculus and left fronto-occipital fasciculus of remitted first-episode medication-naïve panic disorder patients

OBJECTIVE

We designed this study to investigate neural correlates of white matter micro-structural integrity of remitted patients with first-episode, medication-naïve and very late-onset panic disorder.

METHOD

Twenty-one remitted patients with panic disorder completed treatment course with treatment of escitalopram (dose range around 10-15 mg/d). Twenty-one healthy controls were also enrolled into this study. Patients and controls all received 3-Tesla magnetic resonance imaging diffusion tensor imaging scanning at baseline and 6th week. We utilized FDT (FMRIB's Diffusion Toolbox v2.0) function of FSL (FMRIB Software Library) to calculate fractional anisotropy (FA). We compared FA values of patients and controls at baseline and 6th week to estimate the changes of FA of remitted patient group and inter-scan bias of controls. FA outputs of remitted patients and controls were compared by independent t test.

RESULTS

We found increased FA in some regions of right uncinate fasciculus and left fronoto-occipital fasciculus after remission in patient group (corrected p<0.05). Reduced FA of other regions of right uncinate fasciculus was still observed in remitted patients when they were compared to the control group.

CONCLUSION

Subtle changes of white matter micro-structural integrity after remission might represent neural correlates of treatment effects for first-episode, medication-naïve and very late-onset panic disorder.

Gray matter and intrinsic network changes in the posterior cingulate cortex after selective serotonin reuptake inhibitor intake

Preclinical studies have demonstrated that serotonin (5-HT) challenge changes neuronal circuitries and microarchitecture. However, evidence in human subjects is missing. Pharmacologic magnetic resonance imaging (phMRI) applying selective 5-HT reuptake inhibitors (SSRIs) and high-resolution structural and functional brain assessment is able to demonstrate the impact of 5-HT challenge on neuronal network morphology and functional activity. To determine how SSRIs induce changes in gray matter and neuronal activity, we conducted a longitudinal study using citalopram and escitalopram. Seventeen healthy subjects completed a structural and functional phMRI study with randomized, cross-over, placebo-controlled, double-blind design. Significant gray matter increases were observed (among other regions) in the posterior cingulate cortex (PCC) and the ventral precuneus after SSRI intake of 10days, while decreases were observed within the pre- and postcentral gyri (all P<0.05, family-wise error [FWE] corrected). Furthermore, enhanced resting functional connectivity (rFC) within the ventral precuneus and PCC was associated with gray matter increases in the PCC (all FWE Pcorr<0.05). Corroborating these results, whole-brain connectivity density, measuring the brain's functional network hubs, was significantly increased after SSRI-intake in the ventral precuneus and PCC (all FWE Pcorr<0.05). Short-term administration of SSRIs changes gray matter structures, consistent with previous work reporting enhancement of neuroplasticity by serotonergic neurotransmission. Furthermore, increased gray matter in the PCC is associated with increased functional connectivity in one of the brain's metabolically most active regions. Our novel findings provide convergent evidence for dynamic alterations of brain structure and function associated with SSRI pharmacotherapy.

Antidepressant-like effects of shuyusan in rats exposed to chronic stress: effects on hypothalamic-pituitary-adrenal function

This study was to investigate antidepressant activities of Shuyusan (a Chinese herb), using a rats model of depression induced by unpredictable chronic mild stress (UCMS). The administration groups were treated with Shuyusan decoction for 3 weeks and compared with fluoxetine treatment. In order to understand the potential antidepressant-like activities of Shuyusan, tail suspension test (TST) and forced swimming test (FST) were used as behavioral despair study. The level of corticotropin-releasing factor (CRH), adrenocorticotropic hormone (ACTH), corticosterone (CORT) and hippocampus glucocorticoid receptor expression were examined. After modeling, there was a significant prolongation of immobility time in administration groups with the TST and FST. High-dose Shuyusan could reduce the immobility time measured with the TST and FST. The immobility time in high-dose herbs group and fluoxetine group was increased significantly compared with the model group. After 3 weeks herbs fed, the serum contents level of CRH, ACTH, and CORT in high-dose herb group was significantly decreased compared to the model group. The result indicated that Shuyusan had antidepressant activity effects on UCMS model rats. The potential antidepressant effect may be related to decreasing glucocorticoid levels activity, regulating the function of HPA axis, and inhibiting glucocorticoid receptor expression in hippocampus.

Revise the revised? New dimensions of the neuroanatomical hypothesis of panic disorder

In 2000, Gorman et al. published a widely acknowledged revised version of their 1989 neuroanatomical hypothesis of panic disorder (PD). Herein, a 'fear network' was suggested to mediate fear- and anxiety-related responses: panic attacks result from a dysfunctional coordination of 'upstream' (cortical) and 'downstream' (brainstem) sensory information leading to heightened amygdala activity with subsequent behavioral, autonomic and neuroendocrine activation. Given the emergence of novel imaging methods such as fMRI and the publication of numerous neuroimaging studies regarding PD since 2000, a comprehensive literature search was performed regarding structural (CT, MRI), metabolic (PET, SPECT, MRS) and functional (fMRI, NIRS, EEG) studies on PD, which will be reviewed and critically discussed in relation to the neuroanatomical hypothesis of PD. Recent findings support structural and functional alterations in limbic and cortical structures in PD. Novel insights regarding structural volume increase or reduction, hyper- or hypoactivity, laterality and task-specificity of neural activation patterns emerged. The assumption of a generally hyperactive amygdala in PD seems to apply more to state than trait characteristics of PD, and involvement of further areas in the fear circuit, such as anterior cingulate and insula, is suggested. Furthermore, genetic risk variants have been proposed to partly drive fear network activity. Thus, the present state of knowledge generally supports limbic and cortical prefrontal involvement as originally proposed in the neuroanatomical hypothesis. Some modifications might be suggested regarding a potential extension of the fear circuit, genetic factors shaping neural network activity and neuroanatomically informed clinical subtypes of PD potentially guiding future treatment decisions.