Voxel-based analyses of gray/white matter volume and diffusion tensor data in major depression

Consensus Paper: Cerebellum and Emotion

Over the past three decades, insights into the role of the cerebellum in emotional processing have substantially increased. Indeed, methodological refinements in cerebellar lesion studies and major technological advancements in the field of neuroscience are in particular responsible to an exponential growth of knowledge on the topic. It is timely to review the available data and to critically evaluate the current status of the role of the cerebellum in emotion and related domains. The main aim of this article is to present an overview of current facts and ongoing debates relating to clinical, neuroimaging, and neurophysiological findings on the role of the cerebellum in key aspects of emotion. Experts in the field of cerebellar research discuss the range of cerebellar contributions to emotion in nine topics. Topics include the role of the cerebellum in perception and recognition, forwarding and encoding of emotional information, and the experience and regulation of emotional states in relation to motor, cognitive, and social behaviors. In addition, perspectives including cerebellar involvement in emotional learning, pain, emotional aspects of speech, and neuropsychiatric aspects of the cerebellum in mood disorders are briefly discussed. Results of this consensus paper illustrate how theory and empirical research have converged to produce a composite picture of brain topography, physiology, and function that establishes the role of the cerebellum in many aspects of emotional processing.

Microstructural Abnormalities of Basal Ganglia and Thalamus in Bipolar and Unipolar Disorders: A Diffusion Kurtosis and Perfusion Imaging Study

OBJECTIVE

Bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in subcorticalgray matter regions between BD and UD.

METHODS

Thirty-five BD patients, 30 UD patients and 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da), radial diffusivity (Dr) and cerebral blood flow (CBF) were measured by using regions-of-interest analysis in the caudate, putamen and thalamus of the subcortical gray matter regions.

RESULTS

UD exhibited differences from controls for DKI measures and CBF in the left putamen and caudate. BD showed differences from controls for DKI measures in the left caudate. Additionally, BD showed lower Ka in right putamen, higher MD in right caudate compared with UD. Receiver operating characteristic analysis revealed the Kr of left caudate had the highest predictive power for distinguishing UD from controls.

CONCLUSION

The two disorders may have overlaps in microstructural abnormality in basal ganglia. The change of caudate may serve as a potential biomarker for UD.

A Comparison of Neuroimaging Abnormalities in Multiple Sclerosis, Major Depression and Chronic Fatigue Syndrome (Myalgic Encephalomyelitis): is There a Common Cause?

There is copious evidence of abnormalities in resting-state functional network connectivity states, grey and white matter pathology and impaired cerebral perfusion in patients afforded a diagnosis of multiple sclerosis, major depression or chronic fatigue syndrome (CFS) (myalgic encephalomyelitis). Systemic inflammation may well be a major element explaining such findings. Inter-patient and inter-illness variations in neuroimaging findings may arise at least in part from regional genetic, epigenetic and environmental variations in the functions of microglia and astrocytes. Regional differences in neuronal resistance to oxidative and inflammatory insults and in the performance of antioxidant defences in the central nervous system may also play a role. Importantly, replicated experimental findings suggest that the use of high-resolution SPECT imaging may have the capacity to differentiate patients afforded a diagnosis of CFS from those with a diagnosis of depression. Further research involving this form of neuroimaging appears warranted in an attempt to overcome the problem of aetiologically heterogeneous cohorts which probably explain conflicting findings produced by investigative teams active in this field. However, the ionising radiation and relative lack of sensitivity involved probably preclude its use as a routine diagnostic tool.

White matter atrophy and myelinated fiber disruption in a rat model of depression

Brain imaging and postmortem studies have indicated that white matter abnormalities may contribute to the pathology and pathogenesis of depression. However, until now, no study has quantitatively investigated white matter changes in depression in rats. The current study used the chronic unpredictable stress (CUS) model of depression. Body weight and sucrose preference test (SPT) scores were assessed weekly. Upon successfully establishing the CUS animal model, all animals were tested using the SPT and the open field test (OFT). Then, transmission electron microscopy and unbiased stereological methods were used to investigate white matter changes in the rats. Compared with the control group, the body weight and sucrose preference of the CUS rats were significantly decreased (p < .001, p < .001, respectively). In the OFT, the total time spent and the total distance traveled in the inner area by the CUS rats were significantly lower than those of the control group (p = .002, p = .001, respectively). The stereological results revealed that white matter volume, the total volume, and the total length and mean diameter of myelinated fibers in the white matter of the CUS rats were significantly decreased compared to the control rats (p = .042, p = .038, p = .035, p = .019, respectively). The results of this study suggested that white matter atrophy and disruption of myelinated fibers in the white matter may contribute to the pathophysiology underlying depression, which might provide new targets for the development of novel therapeutic interventions for depression.

Brain Parenchymal Fraction in Healthy Adults-A Systematic Review of the Literature

Brain atrophy is an important feature of many neurodegenerative disorders. It can be described in terms of change in the brain parenchymal fraction (BPF). In order to interpret the BPF in disease, knowledge on the BPF in healthy individuals is required. The aim of this study was to establish a normal range of values for the BPF of healthy individuals via a systematic review of the literature. The databases PubMed and Scopus were searched and 95 articles, including a total of 9269 individuals, were identified including the required data. We present values of BPF from healthy individuals stratified by age and post-processing method. The mean BPF correlated with mean age and there were significant differences in age-adjusted mean BPF between methods. This study contributes to increased knowledge about BPF in healthy individuals, which may assist in the interpretation of BPF in the setting of disease. We highlight the differences between post-processing methods and the need for a consensus gold standard.

Alterations in the brainstem volume of patients with major depressive disorder and their relationship with antidepressant treatment

BACKGROUND

Morphologic changes of the brainstem in major depressive disorder (MDD) have rarely been reported in neuroimaging studies, even though, monoaminergic neurotransmitters are synthesized in several brainstem regions. We aimed to investigate volume changes in each region of the brainstem and their association with antidepressant use or the remission status of MDD.

METHODS

A total of 126 patients with MDD and 101 healthy controls underwent T1-weighted structural magnetic resonance imaging. We analyzed volumes of each brainstem region, including the medulla oblongata, pons, midbrain, and superior cerebellar peduncle, and the volume of the whole brainstem using the FreeSurfer.

RESULTS

The patients with MDD had significantly greater midbrain volumes (P=0.013) compared to healthy controls. In particular, drug-naïve patients with MDD had significantly greater brainstem volumes compared to healthy controls (P=0.007), while no significant findings were observed between the antidepressant treatment group and healthy controls. The remitted patient group had reduced pons (P=0.002) and midbrain (P=0.005) volumes compared to healthy controls, while the non-remitted MDD patient group had significantly greater midbrain volumes compared to the healthy controls (P=0.017).

LIMITATIONS

We could not distinguish gray versus white matter volumes changes in our analysis.

CONCLUSIONS

We observed that the midbrain is enlarged in patients with a current depressive episode, who are not undergoing antidepressant treatment. This volume then returns to normal after antidepressant treatment, and is even reduced, when the patient is in remission. Further studies are needed to confirm our observations.

Vascular depression consensus report - a critical update

BACKGROUND

Vascular depression is regarded as a subtype of late-life depression characterized by a distinct clinical presentation and an association with cerebrovascular damage. Although the term is commonly used in research settings, widely accepted diagnostic criteria are lacking and vascular depression is absent from formal psychiatric manuals such as the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition - a fact that limits its use in clinical settings. Magnetic resonance imaging (MRI) techniques, showing a variety of cerebrovascular lesions, including extensive white matter hyperintensities, subcortical microvascular lesions, lacunes, and microinfarcts, in patients with late life depression, led to the introduction of the term "MRI-defined vascular depression".

DISCUSSION

This diagnosis, based on clinical and MRI findings, suggests that vascular lesions lead to depression by disruption of frontal-subcortical-limbic networks involved in mood regulation. However, despite multiple MRI approaches to shed light on the spatiotemporal structural changes associated with late life depression, the causal relationship between brain changes, related lesions, and late life depression remains controversial. While postmortem studies of elderly persons who died from suicide revealed lacunes, small vessel, and Alzheimer-related pathologies, recent autopsy data challenged the role of these lesions in the pathogenesis of vascular depression. Current data propose that the vascular depression connotation should be reserved for depressed older patients with vascular pathology and evident cerebral involvement. Based on current knowledge, the correlations between intra vitam neuroimaging findings and their postmortem validity as well as the role of peripheral markers of vascular disease in late life depression are discussed.

CONCLUSION

The multifold pathogenesis of vascular depression as a possible subtype of late life depression needs further elucidation. There is a need for correlative clinical, intra vitam structural and functional MRI as well as postmortem MRI and neuropathological studies in order to confirm the relationship between clinical symptomatology and changes in specific brain regions related to depression. To elucidate the causal relationship between regional vascular brain changes and vascular depression, animal models could be helpful. Current treatment options include a combination of vasoactive drugs and antidepressants, but the outcomes are still unsatisfying.

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.

Essential brain structural alterations in major depressive disorder: A voxel-wise meta-analysis on first episode, medication-naive patients

BACKGROUND

Because brain morphological abnormalities in major depressive disorder (MDD) may be modulated by medication and episodes, previous meta-analyses of voxel-based morphometry (VBM) studies therefore have been biased for including medicated patients or medication-free patients who had ever received drugs, as well as patients with different episodes. We sought to identify the essential morphological features without the interference of medication and episodes in MDD.

METHODS

Seed-based d Mapping was applied to analyze the gray matter differences between all first episode (FE), medication-naive MDD patients and healthy controls. Subgroup meta-analyses and meta-regression were used to explore the effects of methodology, demographics and clinical characteristics.

RESULTS

We identified 10 studies comprising 329 FE, medication-naive MDD patients and 340 healthy controls. Gray matter volumes were increased in the bilateral thalamus, cuneus, left paracentral lobule and medial superior frontal gyrus, and decreased in the right dorsolateral superior frontal gyrus, left insula and middle frontal gyrus in patients. Decreased volume in the right inferior temporal gyrus was only observed in patients with short illness duration and studies with threshold corrections. Moreover, there were different results between 3.0T MRI and 1.5T MRI studies. Meta-regression analyses revealed that mean age and the percentage of female patients were not significantly correlated with gray matter changes.

LIMITATIONS

There are heterogeneities in demographics, clinical features and analyzing methods of selected studies.

CONCLUSIONS

The present meta-analysis revealed that structural abnormalities in the fronto-limbic networks are the essential characteristics in MDD and could contribute to the high risk of suicide in patients.

Regional Coherence Changes in Alzheimer's Disease Patients with Depressive Symptoms: A Resting-State Functional MRI Study

Alzheimer's disease (AD) is characterized by progressive cognitive decline along with neuropsychiatric symptoms including depression and psychosis. Depression is a common psychiatric disorder occurring in people across the lifespan. Accumulating evidence indicates that depression may be a prodrome and/or a "risk factor" for AD. However, whether AD and depression share a common pathophysiological pathway is still unclear. The aim of this study was to identify regional alterations in brain function associated with depressive symptoms in mild AD patients. Thirty-two mild AD patients were evaluated using the Neuropsychiatric Inventory and Hamilton Depression Rating Scale, and were divided into two groups: 15 AD patients with depressive symptoms (D-AD) and 17 non-depressed AD (nD-AD) patients. Using the approach of regional homogeneity (ReHo), we characterized resting-state regional brain activity in D-AD and nD-AD patients. Compared with nD-AD patients, D-AD patients showed decreased ReHo in the right precentral gyrus, right superior frontal gyrus, right middle frontal gyrus, and right inferior frontal cortex. Our findings show regional brain activity alterations in D-AD patients. Thus, D-AD pathogenesis may be attributed to abnormal neural activity in multiple brain regions.

Cerebellar microstructural abnormalities in bipolar depression and unipolar depression: A diffusion kurtosis and perfusion imaging study

BACKGROUND

Depression in the context of bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in cerebellum between BD and UD.

METHODS

Patients with BD (n=35) and UD (n=30) during a depressive episode as well as 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The DKI parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr),fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da) and radial diffusivity (Dr) and 3D ASL parameters (i.e. cerebral blood flow) was measured by using regions-of-interest (ROIs) analysis in the superior cerebellar peduncles (SCP), middle cerebellar peduncles (MCP) and dentate nuclei (DN) of cerebellum.

RESULTS

Patients with UD exhibited significant differences from controls for DKI measures in bilateral SCP and MCP and cerebral blood flow (CBF) in bilateral SCP and left DN. Patients with BD exhibited significant differences from controls for DKI measures in the right MCP and left DN and CBF in the left DN. Patients with UD showed significantly lower MD values compared with patients with BD in the right SCP. Correlation analysis showed there were negative correlations between illness duration and MD and Dr values in the right SCP in UD.

LIMITATIONS

This study was cross-sectional and the sample size was not large. Parts of the patients included were under medication prior to MRI scanning.

CONCLUSIONS

Our findings provide new evidence of microstructural changes in cerebellum in BD and UD. The two disorders may have overlaps in microstructural abnormality in MCP and DN during the depressive period. Microstructural abnormality in SCP may be a key neurobiological feature of UD.

The impact of metabotropic glutamate receptors into active neurodegenerative processes: A "dark side" in the development of new symptomatic treatments for neurologic and psychiatric disorders

Metabotropic glutamate (mGlu) receptor ligands are under clinical development for the treatment of CNS disorders with high social and economic burden, such as schizophrenia, major depressive disorder (MDD), and Parkinson's disease (PD), and are promising drug candidates for the treatment of Alzheimer's disease (AD). So far, clinical studies have shown symptomatic effects of mGlu receptor ligands, but it is unknown whether these drugs act as disease modifiers or, at the opposite end, they accelerate disease progression by enhancing neurodegeneration. This is a fundamental issue in the treatment of PD and AD, and is also an emerging theme in the treatment of schizophrenia and MDD, in which neurodegeneration is also present and contribute to disease progression. Moving from in vitro data and preclinical studies, we discuss the potential impact of drugs targeting mGlu2, mGlu3, mGlu4 and mGlu5 receptor ligands on active neurodegeneration associated with AD, PD, schizophrenia, and MDD. We wish to highlight that our final comments on the best drug candidates are not influenced by commercial interests or by previous or ongoing collaborations with drug companies. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.

Abnormal functional connectivity density in first-episode, drug-naive adult patients with major depressive disorder

Previous studies have found evidence of brain functional connectivity (FC) changes with pre-selected region-of-interest (ROI) method in major depressive disorder (MDD). However, these studies could not completely exclude personal inequality when drawing ROIs manually and did not measure the total number of FC for each voxel. Here, we firstly applied functional connectivity density (FCD) mapping, a voxel-based analysis to locate the hubs with amount changes of FC between 22 first-episode, drug-naive adult MDD patients and 22 healthy control (HC) subjects. Both short-range (local) FCD and long-range (distal) FCD were measured. The relationships of FCD changes with Hamilton Depression Rating Scale (HAMD) scores and illness duration were also explored. Compared with the HC group, MDD patients showed significantly decreased short-range FCD in the left superior temporal gyrus (STG), the right orbital frontal cortex (OFC) and bilateral precuneus, while significantly decreased long-range FCD was found in bilateral middle occipital gyrus (MOG), superior occipital gyrus (SOG) and right calcarine. These results firstly demonstrated both local and distal alterations of connection amount at voxel level, and highlighted that the OFC, the precuneus, the STG and the visual cortex were important brain network hubs for first-episode, drug-naive adult MDD patients. Our findings were complementary for previous structural and functional studies in MDD patients, and provided new evidence of the dysfunction of connection hubs in the pathophysiology of MDD at voxel level.

Voxel-Based Meta-Analytical Evidence of Structural Disconnectivity in Major Depression and Bipolar Disorder

BACKGROUND

Identification of white matter microstructure differences and similarities between major depression and bipolar disorder is a necessary step to better understand the underlying brain abnormalities in affective disorders and target more effective treatments. However, research has not yet yielded robust conclusions. We report here a meta-analysis of diffusion tensor imaging studies in these conditions.

METHODS

A comprehensive literature search was conducted up to 2014 to identify studies comparing fractional anisotropy (FA) between patients and control subjects. Results were combined to identify white matter abnormalities in major depression (736 patients vs. 668 control subjects) and bipolar disorder (536 patients vs. 489 control subjects). Effect size comparison and conjunction analysis allowed identification of similarities and differences between the disorders.

RESULTS

A significant decrease in FA in the genu of the corpus callosum characterized both conditions. The comparison between unipolar and bipolar disorders revealed a greater decrease in FA in the left posterior cingulum in bipolar disorder. Studies that adopted tract-based spatial statistics methodology showed more pronounced reductions in these regions compared with voxel-based analyses.

CONCLUSIONS

Major depression and bipolar disorder are characterized by abnormalities in white matter tracts of the genu of the corpus callosum that connect the two hemispheres of the prefrontal cortex implicated in mood regulation. Bipolar disorder was associated with reduced white matter integrity in the left posterior cingulum, which may contribute to cognitive impairment described in this condition. Tract-based spatial statistics may be a more sensitive technique to detect white matter abnormalities in these regions compared with voxel-based analyses.

Computational meta-analysis of statistical parametric maps in major depression

OBJECTIVE

Several neuroimaging meta-analyses have summarized structural brain changes in major depression using coordinate-based methods. These methods might be biased toward brain regions where significant differences were found in the original studies. In this study, a novel voxel-based technique is implemented that estimates and meta-analyses between-group differences in grey matter from individual MRI studies, which are then applied to the study of major depression.

METHODS

A systematic review and meta-analysis of voxel-based morphometry studies were conducted comparing participants with major depression and healthy controls by using statistical parametric maps. Summary effect sizes were computed correcting for multiple comparisons at the voxel level. Publication bias and heterogeneity were also estimated and the excess of heterogeneity was investigated with metaregression analyses.

RESULTS

Patients with major depression were characterized by diffuse bilateral grey matter loss in ventrolateral and ventromedial frontal systems extending into temporal gyri compared to healthy controls. Grey matter reduction was also detected in the right parahippocampal and fusiform gyri, hippocampus, and bilateral thalamus. Other areas included parietal lobes and cerebellum. There was no evidence of statistically significant publication bias or heterogeneity.

CONCLUSIONS

The novel computational meta-analytic approach used in this study identified extensive grey matter loss in key brain regions implicated in emotion generation and regulation. Results are not biased toward the findings of the original studies because they include all available imaging data, irrespective of statistically significant regions, resulting in enhanced detection of additional areas of grey matter loss.

Subgenual anterior cingulate cortex and hippocampal volumes in depressed youth: The role of comorbidity and age

OBJECTIVES

Many studies have reported that adults with recurrent major depressive disorder (MDD) have smaller hippocampal volumes than control participants. The data are more variable in youth with MDD, where findings have been inconsistent and the effects of factors such as age and co-morbidity have not been systematically examined. This study therefore assessed hippocampus and subgenual anterior cingulate (sgACC) morphometry in 168 youth, aged 12-25, with or without MDD and comorbid anxiety.

METHODS

Structural magnetic resonance imaging (MRI) scans and clinical assessments were obtained from 80 participants with MDD (36 with comorbid anxiety disorder) and 88 age-matched control participants.

RESULTS

Participants with MDD had smaller right hippocampi than controls (p=.013). Older depressed participants (20.1-25 years) had smaller hippocampal volumes than younger ones (<20.1 years; p=.05); this age effect was not apparent in controls (p=.46). Depression scores, indexed by the HAMD17, correlated with hippocampal volumes in older depressed youth. Depressed participants with comorbid anxiety had smaller sgACC, but not hippocampal, volumes than those without anxiety (p=.042).

LIMITATIONS

Longitudinal, versus cross-sectional, studies can most optimally assess the influence of depression on neurodevelopmental profiles. Though our participants were largely treatment-naïve or in their first week of pharmacotherapy, a handful had extensive treatment histories; thus, treatment history may have influenced brain morphometry.

CONCLUSIONS

Age effects were apparent when hippocampal volumes of older and younger participants with MDD were compared; such differences were not apparent in healthy participants. Comorbid anxiety was associated with decreased sgACC volumes suggesting delayed or altered neurodevelopment in a key emotion regulation region.

A COMPREHENSIVE EXAMINATION OF WHITE MATTER TRACTS AND CONNECTOMETRY IN MAJOR DEPRESSIVE DISORDER

BACKGROUND

Major depressive disorder (MDD) is a debilitating disorder characterized by widespread brain abnormalities. The literature is mixed as to whether or not white matter abnormalities are associated with MDD. This study sought to examine fractional anisotropy (FA) in white matter tracts in individuals with MDD using diffusion tensor imaging (DTI).

METHODS

139 participants with MDD and 39 healthy controls (HC) in a multisite study were included. DTI scans were acquired in 64 directions and FA was determined in the brain using four methods: region of interest (ROI), tract-based spatial statistics (TBSS), and diffusion tractography. Diffusion connectometry was used to identify white matter pathways associated with MDD.

RESULTS

There were no significant differences when comparing FA in MDD and HC groups using any method. In the MDD group, there was a significant relationship between depression severity and FA in the right medial orbitofrontal cortex, and between age of onset of MDD and FA in the right caudal anterior cingulate cortex using the ROI method. There was a significant relationship between age of onset and connectivity in the thalamocortical radiation, inferior longitudinal fasciculus, and cerebellar tracts using diffusion connectometry.

CONCLUSIONS

The lack of group differences in FA and connectometry analysis may result from the clinically heterogenous nature of MDD. However, the relationship between FA and depression severity may suggest a state biomarker of depression that should be investigated as a potential indicator of response. Age of onset may also be a significant clinical feature to pursue when studying white matter tracts.

Single-Nucleotide Polymorphism of the FKBP5 Gene and Childhood Maltreatment as Predictors of Structural Changes in Brain Areas Involved in Emotional Processing in Depression

The gene expressing the FK506 binding protein 51 (FKBP5) is involved in the regulation of glucocorticoid receptor sensitivity. The rs1360780 SNP in this gene (T allele vs C homozygous) has been found to be associated with major depressive disorder (MDD). The aim of our study was to investigate whether this polymorphism might be associated with altered brain structure and function in a cohort of 40 patients with MDD and 43 healthy controls. A functional magnetic resonance imaging (fMRI) emotional attention task was employed. Diffusion tensor imaging (DTI) was also conducted, extracting mean diffusivity (MD) and fractional anisotropy (FA) from brain areas that showed functional differences between patients expressing the two alleles of the rs1360780 SNP. Finally, the effect of the interaction of childhood adversity as measured by the Childhood trauma Questionnaire (CTQ) and rs1360780 allele status was analyzed in relation to DTI measures using a general linear model. All results presented are family-wise error (FWE) corrected. Functional interactions were found between genotype and diagnosis (p<0.01). Patients carrying the high-risk allele, compared with patients not carrying it, showed reduced activity in the rolandic operculum, Heschl gyrus, insula, parahippocampal gyrus, posterior cingulate cortex, inferior frontal gyrus (p<0.05 for all measures); and increased MD and reduced FA measures in many of these regions (p<0.05). An interaction between CTQ scores and allele status was associated with DTI changes in the insula, rolandic operculum, and inferior frontal gyrus. Here, the presence of both the high-risk allele and higher CTQ scores was associated with higher MD and lower FA values (p<0.05). In conclusion, MDD patients expressing the T allele of rs1360780, compared with C homozygous patients, exhibit functional and structural differences in areas involved in emotional perception and inhibition. The interaction between the T allele and childhood maltreatment explained our structural findings in these regions, suggesting that their altered maturation and function might be influenced by early chronic stress in the presence of this genetic trait.

The gray matter alterations in major depressive disorder and panic disorder: Putative differences in the pathogenesis

OBJECTIVE

This is a comprehensive study to establish a diagnosis-specific gray matter deficit model for major depressive disorder (MDD) and panic disorder (PD).

METHOD

We enrolled 53 patients with first-episode medication-naïve PD, 54 healthy controls and 53 patients with first-episode medication-naïve MDD in this study. They were age, handedness and gender matched. All participating subjects all received baseline structural scanning by the 3-Tesla magnetic resonance scanner. The optimized voxel-based morphometry was performed on the 3 groups of subjects and the ANOVA analysis was used to estimate the inter-group gray matter differences between each group.

RESULTS

The PD group had higher gray matter volume than MDD group in the right medial frontal cortex and right temporal gyrus. The PD group had gray matter reductions in the right inferior frontal gyrus and right insula. The MDD group had gray matter reductions in bilateral medial frontal cortex, right superior frontal gyrus, right superior temporal gyrus and bilateral cerebellums.

CONCLUSION

The gray matter alterations of fronto-insula and fronto-temporo-cerebellum regions probably would be specific for PD and MDD respectively. In addition, the differences of gray matter volume in the fronto-temporal regions would be helpful to differentiate MDD from PD.

Cortical Thickness in Individuals at High Familial Risk of Mood Disorders as They Develop Major Depressive Disorder

BACKGROUND

Frontal and temporal cortical thickness abnormalities have been observed in mood disorders. However, it is unknown whether cortical thickness abnormalities reflect early adverse effects of genetic and environmental risk factors predisposing to mood disorders or emerge at illness onset.

METHODS

Magnetic resonance imaging was conducted at baseline and after a 2-year follow-up interval in 111 initially unaffected young adults at high familial risk of mood disorders and 93 healthy control subjects (HC). During the follow-up period, 20 high-risk subjects developed major depressive disorder (HR-MDD), with the remainder remaining well (HR-well). Cortical surface reconstruction was applied to measure cortical thickness of frontal and temporal regions of interest. Mixed-effects models were used to investigate differences and longitudinal changes in cortical thickness.

RESULTS

Reduced cortical thickness in the right parahippocampal and fusiform gyrus across both time points was found in both high-risk groups. HR-MDD also had thinner parahippocampi than HR-well individuals. Over time, HR-well and HC individuals had progressive thickness reductions in the left inferior frontal and precentral gyrus, which were greater in HR-well subjects. HR-MDD showed left inferior frontal gyrus thickening relative to HR-well subjects and left precentral gyrus thickening relative to HR-well and HC individuals.

CONCLUSIONS

Reduced right parahippocampal and fusiform gyrus thickness are familial trait markers for vulnerability to mood disorders. Increased risk for mood disorders is associated with progressive cortical thinning in the left inferior frontal and precentral gyri in subjects who remain well. In contrast, onset of depression is associated with increasing left inferior frontal and precentral thickness.

Oligodendrocyte morphometry and expression of myelin - Related mRNA in ventral prefrontal white matter in major depressive disorder

White matter disturbance in the ventral prefrontal cortex (vPFC) in major depressive disorder (MDD) has been noted with diffusion tensor imaging (DTI). However, the cellular and molecular pathology of prefrontal white matter in MDD and potential influence of antidepressant medications is not fully understood. Oligodendrocyte morphometry and myelin-related mRNA and protein expression was examined in the white matter of the vPFC in MDD. Sections of deep and gyral white matter from the vPFC were collected from 20 subjects with MDD and 16 control subjects. Density and size of CNPase-immunoreactive (-IR) oligodendrocytes were estimated using 3-dimensional cell counting. While neither density nor soma size of oligodendrocytes was significantly affected in deep white matter, soma size was significantly decreased in the gyral white matter in MDD. In rhesus monkeys treated chronically with fluoxetine there was no significant effect on oligodendrocyte morphometry. Using quantitative RT-PCR to measure oligodendrocyte-related mRNA for CNPase, PLP1, MBP, MOG, MOBP, Olig1 and Olig2, in MDD there was a significantly reduced expression of PLP1 mRNA (which positively correlated with smaller sizes) and increased expression of mRNA for CNPase, OLIG1 and MOG. The expression of CNPase protein was significantly decreased in MDD. Altered expression of four myelin genes and CNPase protein suggests a mechanism for the degeneration of cortical axons and dysfunctional maturation of oligodendrocytes in MDD. The change in oligodendrocyte morphology in gyral white matter may parallel altered axonal integrity as revealed by DTI.

The papez circuit in first-episode, treatment-naive adults with major depressive disorder: combined atlas-based tract-specific quantification analysis and voxel-based analysis

Previous findings suggest that the Papez Circuit may have a role in major depressive disorders. We used atlas-based tract-specific quantification analysis and voxel-based analysis to examine the integrity of white matter tracts involved in mood regulation (including tracts in the Papez Circuit). Diffusion tensor imaging acquired from 35 first-episode, treatment-naive adults with major depressive disorders and 34 healthy adult controls were compared. Our statistical approach compared structural integrity of 11 major white matter tracts between the major depressive disorder and adult controls, as well as illness duration influence in patients. Fractional anisotropy was decreased in the hippocampal cingulum and in the anterior thalamic radiation according to both analytical approaches, all of which were important tracts included in the Papez Circuit. Our results support the role of the Papez Circuit in major depressive disorders with the minimal probability of false positive due to similar findings in both analyses that have complementary advantages. Dysfunction of the Papez Circuit may be a potential marker for studying the pathogenesis of major depressive disorders.

Discriminative analysis of Parkinson's disease based on whole-brain functional connectivity

Recently, there has been an increasing emphasis on applications of pattern recognition and neuroimaging techniques in the effective and accurate diagnosis of psychiatric or neurological disorders. In the present study, we investigated the whole-brain resting-state functional connectivity patterns of Parkinson's disease (PD), which are expected to provide additional information for the clinical diagnosis and treatment of this disease. First, we computed the functional connectivity between each pair of 116 regions of interest derived from a prior atlas. The most discriminative features based on Kendall tau correlation coefficient were then selected. A support vector machine classifier was employed to classify 21 PD patients with 26 demographically matched healthy controls. This method achieved a classification accuracy of 93.62% using leave-one-out cross-validation, with a sensitivity of 90.47% and a specificity of 96.15%. The majority of the most discriminative functional connections were located within or across the default mode, cingulo-opercular and frontal-parietal networks and the cerebellum. These disease-related resting-state network alterations might play important roles in the pathophysiology of this disease. Our results suggest that analyses of whole-brain resting-state functional connectivity patterns have the potential to improve the clinical diagnosis and treatment evaluation of PD.

The contribution of regional gray/white matter volume in preclinical depression assessed by the Automatic Thoughts Questionnaire: a voxel-based morphometry study

Negative automatic thought is a characteristic of depression that contributes toward the risk for episodes of depression. Evidence suggests that gray and white matter abnormalities are linked with depression, but little is known about the association between the negative cognitive experience and brain structure in preclinical depression. We examined the correlation between negative thought and gray (GMV)/white matter volume (WMV) in healthy individuals with preclinical depression. The participants were 309 university students with preclinical depression, as measured by their Automatic Thoughts Questionnaire (ATQ) scores. We collected brain MRIs and used voxel-based morphometry to analyze the correlation of regional GMV/WMV with the ATQ scores. The voxel-based morphometry results showed that the GMV of the right parahippocampal gyrus and fusiform gyrus and the WMV of the right superior temporal pole increased with the severity of depression. Furthermore, the corpus callosum volume decreased with the ATQ scores. This study implied that GMV increase and corpus callosum volume reduction may be associated with negative thought in nonclinical individuals, even at a preclinical depressed level.

Corpus callosum atrophy associated with the degree of cognitive decline in patients with Alzheimer's dementia or mild cognitive impairment: a meta-analysis of the region of interest structural imaging studies

Individual structural neuroimaging studies of the corpus callosum (CC) in Alzheimer's disease (AD) and mild cognitive impairment (MCI) with the region of interest (ROI) analysis have yielded inconsistent findings. The aim of this study was to conduct a meta-analysis of structural imaging studies using ROI technique to measure the CC midsagittal area changes in patients with AD or MCI. Databases of PubMed, the Cochrane Library, the ISI Web of Science, and Science Direct from inception to June 2014 were searched with key words "corpus callosum" or "callosal", plus "Alzheimer's disease" or "mild cognitive impairment". Twenty-three studies with 603 patients with AD, 146 with MCI, and 638 healthy controls were included in this meta-analysis. Effect size was used to measure the difference between patients with AD or MCI and healthy controls. Significant callosal atrophy was found in MCI patients with an effect size of -0.36 (95% CI, -0.57 to -0.14; P = 0.001). The degree of the CC atrophy in mild AD was less severe than that in moderate AD with a mean effect size -0.69 (95% CI, -0.89 to -0.49) versus -0.92 (95% CI, -1.16 to -0.69), respectively. Comparing with healthy controls, patients with MCI had atrophy in the anterior portion of the CC (i.e., rostrum and genu). In contrast, patients with AD had atrophy in both anterior and posterior portions (i.e., splenium). These results suggest that callosal atrophy may be related to the degree of cognitive decline in patients with MCI and AD, and it may be used as a biomarker for patients with cognitive deficit even before meeting the criteria for AD.

The associations of depression and hypertension with brain volumes: Independent or interactive?

Independent studies on major depressive disorder (MDD) and hypertension, suggest overlapping abnormalities in brain regions associated with emotional and autonomic processing. However, the unique and interactive effects of MDD and hypertension have never been studied in a single sample. Brain volume in these areas may be an explanatory link in the comorbidity between MDD and hypertension. Voxel-based morphometry was used to test for main effects of MDD (N = 152) and hypertension (N = 82) and their interactions on gray and white matter volumes. Voxel-wise results are reported at p < .05 FWE corrected for the spatial extent of the whole brain and a-priori regions of interest (ROIs: hippocampus, anterior cingulate cortex (ACC) and inferior frontal gyrus (IFG)). In addition, analyses on the extracted total volumes of our ROIs were performed. Interactive effects in the mid-cingulate cortex (MCC) (p FWE = .01), cerebellum (p FWE = .01) and in the ACC total ROI volume (p = .02) were found. MDD in the presence, but not in the absence of hypertension was associated with lower volumes in the ACC and MCC, and with a trend towards larger gray matter volume in the cerebellum. No associations with white matter volumes were observed. Results suggest that the combination of MDD and hypertension has a unique effect on brain volumes in areas implicated in the regulation of emotional and autonomic functions. Brain volume in these regulatory areas may be an explanatory link in the comorbidity between hypertension and MDD.

Illness progression, recent stress, and morphometry of hippocampal subfields and medial prefrontal cortex in major depression

BACKGROUND

Longitudinal studies of illness progression in patients with major depressive disorder (MDD) indicate that the onset of subsequent depressive episodes becomes increasingly decoupled from external stressors. A possible mechanism underlying this phenomenon is that multiple episodes induce long-lasting neurobiological changes that confer increased risk for recurrence. Prior morphometric studies have frequently reported volumetric reductions in patients with MDD--especially in medial prefrontal cortex (mPFC) and the hippocampus--but few studies have investigated whether these changes are exacerbated by prior episodes.

METHODS

In a sample of 103 medication-free patients with depression and control subjects with no history of depression, structural magnetic resonance imaging was performed to examine relationships between number of prior episodes, current stress, hippocampal subfield volume and cortical thickness. Volumetric analyses of the hippocampus were performed using a recently validated subfield segmentation approach, and cortical thickness estimates were obtained using vertex-based methods. Participants were grouped on the basis of the number of prior depressive episodes and current depressive diagnosis.

RESULTS

Number of prior episodes was associated with both lower reported stress levels and reduced volume in the dentate gyrus. Cortical thinning of the left mPFC was associated with a greater number of prior depressive episodes but not current depressive diagnosis.

CONCLUSIONS

Collectively, these findings are consistent with preclinical models suggesting that the dentate gyrus and mPFC are especially vulnerable to stress exposure and provide evidence for morphometric changes that are consistent with stress-sensitization models of recurrence in MDD.

DISC1 gene and affective psychopathology: a combined structural and functional MRI study

The gene Disrupted-In-Schizophrenia-1 (DISC1) has been indicated as a determinant of psychopathology, including affective disorders, and shown to influence prefrontal cortex (PFC) and hippocampus functioning, regions of major interest for affective disorders. We aimed to investigate whether DISC1 differentially modulates brain function during executive and memory processing, and morphology in regions relevant for depression and anxiety disorders (affective disorders). 128 participants, with (n = 103) and without (controls; n = 25) affective disorders underwent genotyping for Ser704Cys (with Cys-allele considered as risk-allele) and structural and functional (f) Magnetic Resonance Imaging (MRI) during visuospatial planning and emotional episodic memory tasks. For both voxel-based morphometry and fMRI analyses, we investigated the effect of genotype in controls and explored genotypeXdiagnosis interactions. Results are reported at p < 0.05 FWE small volume corrected. In controls, Cys-carriers showed smaller bilateral (para)hippocampal volumes compared with Ser-homozygotes, and lower activation in the anterior cingulate cortex (ACC) and dorsolateral PFC during visuospatial planning. In anxiety patients, Cys-carriers showed larger (para)hippocampal volumes and more ACC activation during visuospatial planning. In depressive patients, no effect of genotype was observed and overall, no effect of genotype on episodic memory processing was detected. We demonstrated that Ser704Cys-genotype influences (para)hippocampal structure and functioning the dorsal PFC during executive planning, most prominently in unaffected controls. Results suggest that presence of psychopathology moderates Ser704Cys effects.

Gray matter volume abnormalities in depressive patients with and without anxiety disorders

Comorbidity with anxiety disorder is a relatively common occurrence in major depressive disorder. However, the unique and shared neuroanatomical characteristics of depression and anxiety disorders have not been fully identified. The aim of this study was to identify gray matter abnormalities and their clinical correlates in depressive patients with and without anxiety disorders. We applied voxel-based morphometry and region-of-interest analyses of gray matter volume (GMV) in normal controls (NC group, n = 28), depressive patients without anxiety disorder (DP group, n = 18), and depressive patients with anxiety disorder (DPA group, n = 20). The correlations between regional GMV and clinical data were analyzed. The DP group showed decreased GMV in the left insula (INS) and left triangular part of the inferior frontal gyrus when compared to the NC group. The DPA group showed greater GMV in the midbrain, medial prefrontal cortex, and primary motor/somatosensory cortex when compared to the NC group. Moreover, the DPA group showed greater GMV than the DP group in the frontal, INS, and temporal lobes. Most gray matter anomalies were significantly correlated with depression severity or anxiety symptoms. These correlations were categorized into 4 trend models, of which 3 trend models (ie, Models I, II, and IV) revealed the direction of the correlation between regional GMV and depression severity to be the opposite of that between regional GMV and anxiety symptoms. Importantly, the left INS showed a trend Model I, which might be critically important for distinguishing depressive patients with and without anxiety disorder. Our findings of gray matter abnormalities, their correlations with clinical data, and the trend models showing opposite direction may reflect disorder-specific symptom characteristics and help explain the neurobiological differences between depression and anxiety disorder.

Influence of age of onset on limbic and paralimbic structures in depression

AIM

Major depressive disorder (MDD) onset during childhood/adolescence is associated with a greater illness burden and distinct clinical profile. However, limited research exists on the effect of age of MDD onset on volumetric abnormalities in para/limbic structures during adulthood.

METHODS

Subgenual anterior cingulate cortex (sgACC), hippocampus and caudate nucleus volumes were measured by manual tracing in depressed individuals (n = 45) and healthy controls (HC; n = 19). Volumetric comparisons were carried out between HC and MDD patients divided into those with pediatric (≤ 18 years; n = 17) and adult onset (≥ 19 years; n = 28).

RESULTS

The adult MDD-onset group had smaller sgACC volumes than the pediatric-onset and HC groups (age, sex controlled). No differences in caudate and hippocampus volumes existed. sgACC and hippocampal volumes were inversely correlated with depression severity.

CONCLUSIONS

Surprisingly, pediatric MDD-onset was not associated with more pronounced sgACC, hippocampus and caudate volume reductions. Nevertheless, age of illness onset appears to be a meaningful dimension of study in efforts to understand the neurobiological heterogeneity of MDD.

Brain morphometric biomarkers distinguishing unipolar and bipolar depression. A voxel-based morphometry-pattern classification approach

IMPORTANCE

The structural abnormalities in the brain that accurately differentiate unipolar depression (UD) and bipolar depression (BD) remain unidentified.

OBJECTIVES

First, to investigate and compare morphometric changes in UD and BD, and to replicate the findings at 2 independent neuroimaging sites; second, to differentiate UD and BD using multivariate pattern classification techniques.

DESIGN, SETTING, AND PARTICIPANTS

In a 2-center cross-sectional study, structural gray matter data were obtained at 2 independent sites (Pittsburgh, Pennsylvania, and Münster, Germany) using 3-T magnetic resonance imaging. Voxel-based morphometry was used to compare local gray and white matter volumes, and a novel pattern classification approach was used to discriminate between UD and BD, while training the classifier at one imaging site and testing in an independent sample at the other site. The Pittsburgh sample of participants was recruited from the Western Psychiatric Institute and Clinic at the University of Pittsburgh from 2008 to 2012. The Münster sample was recruited from the Department of Psychiatry at the University of Münster from 2010 to 2012. Equally divided between the 2 sites were 58 currently depressed patients with bipolar I disorder, 58 age- and sex-matched unipolar depressed patients, and 58 matched healthy controls.

MAIN OUTCOMES AND MEASURES

Magnetic resonance imaging was used to detect structural differences between groups. Morphometric analyses were applied using voxel-based morphometry. Pattern classification techniques were used for a multivariate approach.

RESULTS

At both sites, individuals with BD showed reduced gray matter volumes in the hippocampal formation and the amygdala relative to individuals with UD (Montreal Neurological Institute coordinates x = -22, y = -1, z = 20; k = 1938 voxels; t = 4.75), whereas individuals with UD showed reduced gray matter volumes in the anterior cingulate gyrus compared with individuals with BD (Montreal Neurological Institute coordinates x = -8, y = 32, z = 3; k = 979 voxels; t = 6.37; all corrected P < .05). Reductions in white matter volume within the cerebellum and hippocampus were found in individuals with BD. Pattern classification yielded up to 79.3% accuracy (P < .001) by differentiating the 2 depressed groups, training and testing the classifier at one site, and up to 69.0% accuracy (P < .001), training the classifier at one imaging site (Pittsburgh) and testing it at the other independent sample (Münster). Medication load did not alter the pattern of results.

CONCLUSIONS AND RELEVANCE

Individuals with UD and those with BD are differentiated by structural abnormalities in neural regions supporting emotion processing. Neuroimaging and multivariate pattern classification techniques are promising tools to differentiate UD from BD and show promise as future diagnostic aids.

White matter integrity and late-life depression in community-dwelling individuals: diffusion tensor imaging study using tract-based spatial statistics

BACKGROUND

Late-life depression has been associated with white matter changes in studies using the regions of interest approach.

AIMS

To investigate the cross-sectional and longitudinal relationship between white matter integrity and depression in community-dwelling individuals using diffusion tensor imaging with tract-based spatial statistics.

METHOD

The sample comprised 381 participants aged between 72 and 92 years who were assessed twice within 2 years. Depressive symptoms were measured with the Geriatric Depression Scale. Tract-based spatial statistics were applied to investigate white matter integrity in currently depressed v. non-depressed elderly people and in those with a history of depression v. no history of depression. The relationship between white matter integrity and development of depressive symptoms after 2 years were analysed with logistic regression.

RESULTS

Individuals with current depression had widespread white matter integrity reduction compared with non-depressed elderly people. Significant fractional anisotropy reductions were found in 45 brain areas with the most notable findings in the frontal lobe, association and projection fibres. A history of depression was not associated with reduced fractional anisotropy. White matter changes in the superior frontal gyrus, posterior thalamic radiation, superior longitudinal fasciculus and in the body of corpus callosum predicted depression at follow-up.

CONCLUSIONS

Reduced white matter integrity is associated with late-life depression and predicts future depressive symptoms whereas a history of depression is not related to white matter changes. Disruption to white matter integrity may be a biomarker to predict late-life depression.

Reduced gray matter volume in the anterior cingulate, orbitofrontal cortex and thalamus as a function of mild depressive symptoms: a voxel-based morphometric analysis

BACKGROUND

Studies investigating structural brain abnormalities in depression have typically employed a categorical rather than dimensional approach to depression [i.e., comparing subjects with Diagnostic and Statistical Manual of Mental Disorders (DSM)-defined major depressive disorder (MDD) v. healthy controls]. The National Institute of Mental Health, through their Research Domain Criteria initiative, has encouraged a dimensional approach to the study of psychopathology as opposed to an over-reliance on categorical (e.g., DSM-based) diagnostic approaches. Moreover, subthreshold levels of depressive symptoms (i.e., severity levels below DSM criteria) have been found to be associated with a range of negative outcomes, yet have been relatively neglected in neuroimaging research.

METHOD

To examine the extent to which depressive symptoms--even at subclinical levels--are linearly related to gray matter volume reductions in theoretically important brain regions, we employed whole-brain voxel-based morphometry in a sample of 54 participants.

RESULTS

The severity of mild depressive symptoms, even in a subclinical population, was associated with reduced gray matter volume in the orbitofrontal cortex, anterior cingulate, thalamus, superior temporal gyrus/temporal pole and superior frontal gyrus. A conjunction analysis revealed concordance across two separate measures of depression.

CONCLUSIONS

Reduced gray matter volume in theoretically important brain regions can be observed even in a sample that does not meet DSM criteria for MDD, but who nevertheless report relatively elevated levels of depressive symptoms. Overall, these findings highlight the need for additional research using dimensional conceptual and analytic approaches, as well as further investigation of subclinical populations.

Resting-state functional connectivity abnormalities in first-onset unmedicated depression

Depression is closely linked to the morphology and functional abnormalities of multiple brain regions; however, its topological structure throughout the whole brain remains unclear. We collected resting-state functional MRI data from 36 first-onset unmedicated depression patients and 27 healthy controls. The resting-state functional connectivity was constructed using the Automated Anatomical Labeling template with a partial correlation method. The metrics calculation and statistical analysis were performed using complex network theory. The results showed that both depressive patients and healthy controls presented typical small-world attributes. Compared with healthy controls, characteristic path length was significantly shorter in depressive patients, suggesting development toward randomization. Patients with depression showed apparently abnormal node attributes at key areas in cortical-striatal-pallidal-thalamic circuits. In addition, right hippocampus and right thalamus were closely linked with the severity of depression. We selected 270 local attributes as the classification features and their P values were regarded as criteria for statistically significant differences. An artificial neural network algorithm was applied for classification research. The results showed that brain network metrics could be used as an effective feature in machine learning research, which brings about a reasonable application prospect for brain network metrics. The present study also highlighted a significant positive correlation between the importance of the attributes and the intergroup differences; that is, the more significant the differences in node attributes, the stronger their contribution to the classification. Experimental findings indicate that statistical significance is an effective quantitative indicator of the selection of brain network metrics and can assist the clinical diagnosis of depression.

Modulation of interhemispheric functional coordination in electroconvulsive therapy for depression

Considerable evidence suggests that depression is related to interhemispheric functional coordination deficits. For depression, electroconvulsive therapy (ECT) is the most rapid and effective therapy, but its underlying mechanism remains unknown. The aim of this study was to explore the impact of ECT on the interhemispheric functional coordination in depression patients. We used resting-state functional magnetic resonance imaging to observe the change of interhemispheric functional coordination with the method of voxel-mirrored homotopic connectivity (VMHC) in 11 depressed patients before and after ECT, compared with 15 healthy controls. The results showed that, compared with depression patients before ECT, VMHC was significantly increased in superior frontal gyri (BA 8), middle frontal gyri (two clusters: BA 8/9 and BA 10) and angular gyri (BA 39) in depression patients after ECT. Compared with healthy controls, VMHC in those areas was significantly lower in the middle frontal gyri (BA 8/9) and angular gyri (BA 39) in depression patients before ECT, but no significant difference was observed in the superior frontal gyri (BA 8) and middle frontal gyri (BA 10). There was no significant correlation between the changes of Hamilton Depression Rating Scale scores and changed VMHC values in those four areas in depression patients. The results suggest that ECT selectively modulated interhemispheric functional coordination in depression patients. Such may play an important mechanistic role in the treatment of depression, and may afford a useful avenue for optimizing treatment.

Pontine microbleeds and depression in stroke

OBJECTIVES

Depression is the most common affective disorder following stroke yet the neuroanatomical model of poststroke depression (PSD) remains unclear. This study examined the association between PSD and cerebral microbleeds (CMBs) and hypothesized that CMBs in specific regions would be associated with PSD.

METHODS

Of the 4766 patients with first ever or recurrent acute ischemic stroke admitted to the Acute Stroke Unit of the Prince of Wales Hospital between June 2004 and October 2010, 229 met the entry criteria and formed the study sample. Patients with a Geriatric Depression Scale score of 7 or above were classified as having PSD. The presence and location of CMBs were evaluated with magnetic resonance imaging.

RESULTS

Compared to the non-PSD group, patients with PSD were more likely to have pontine CMBs (32.0% vs 18.2%; P = .019). The presence of pontine CMBs remained an independent predictor of PSD in the multivariate analysis, with an odds ratio of 2.2 (P = .016).

CONCLUSION

The results suggest that pontine CMBs are associated with a higher risk of developing PSD.

Towards mapping the brain connectome in depression: functional connectivity by perfusion SPECT

Several studies have demonstrated altered brain functional connectivity in the resting state in depression. However, no study has investigated interregional networking in patients with persistent depressive disorder (PDD). The aim of this study was to assess differences in brain perfusion distribution and connectivity between large groups of patients and healthy controls. Participants comprised 91 patients with PDD and 65 age- and sex-matched healthy controls. Resting state perfusion was investigated by single photon emission computed tomography, and group differences were assessed by Statistical Parametric Mapping. Brain connectivity was explored through a voxel-wise interregional correlation analysis using as covariate of interest the normalized values of clusters of voxels in which perfusion differences were found in group analysis. Significantly increased regional brain perfusion distribution covering a large part of the cerebellum was observed in patients as compared with controls. Patients showed a significant negative functional connectivity between the cerebellar cluster and caudate, bilaterally. This study demonstrated inverse relative perfusion between the cerebellum and the caudate in PDD. Functional uncoupling may be associated with a dysregulation between the role of the cerebellum in action control and of the caudate in action selection, initiation and decision making in the patients. The potential impact of the resting state condition and the possibility of mitochondrial impairment are discussed.

Insular and hippocampal gray matter volume reductions in patients with major depressive disorder

Background

Major depressive disorder is a serious psychiatric illness with a highly variable and heterogeneous clinical course. Due to the lack of consistent data from previous studies, the study of morphometric changes in major depressive disorder is still a major point of research requiring additional studies. The aim of the study presented here was to characterize and quantify regional gray matter abnormalities in a large sample of clinically well-characterized patients with major depressive disorder.

Methods

For this study one-hundred thirty two patients with major depressive disorder and 132 age- and gender-matched healthy control participants were included, 35 with their first episode and 97 with recurrent depression. To analyse gray matter abnormalities, voxel-based morphometry (VBM8) was employed on T1 weighted MRI data. We performed whole-brain analyses as well as a region-of-interest approach on the hippocampal formation, anterior cingulate cortex and amygdala, correlating the number of depressive episodes.

Results

Compared to healthy control persons, patients showed a strong gray-matter reduction in the right anterior insula. In addition, region-of-interest analyses revealed significant gray-matter reductions in the hippocampal formation. The observed alterations were more severe in patients with recurrent depressive episodes than in patients with a first episode. The number of depressive episodes was negatively correlated with gray-matter volume in the right hippocampus and right amygdala.

Conclusions

The anterior insula gray matter structure appears to be strongly affected in major depressive disorder and might play an important role in the neurobiology of depression. The hippocampal and amygdala volume loss cumulating with the number of episodes might be explained either by repeated neurotoxic stress or alternatively by higher relapse rates in patients showing hippocampal atrophy.

Cerebral anatomical changes in female asthma patients with and without depression compared to healthy controls and patients with depression

BACKGROUND

Population-based studies have demonstrated that asthma patients with depression symptoms are more likely to have poor asthma control and worse asthma outcomes. However, the underlying mechanism of the relationship between asthma and depression is still unclear. The present study aimed to examine the cerebral anatomical changes in female asthma patients with and without depression.

METHODS

Using structural magnetic resonance imaging (MRI) and a voxel-based morphometry technique, the primary effects of and the interaction between asthma and depression were analyzed. The cerebral gray matter volume (GMV) was compared between the groups. Correlation analyses between the GMV value of the brain regions and the clinical parameters were completed.

RESULTS

The interaction effect of asthma and depression was found on the right superior temporal gyrus (STG) and the left middle temporal gyrus. Patients with both asthma and depression showed less GMV in the right STG, the bilateral precuneus, and the right superior frontal gyrus compared to patients with asthma only. The GMV of the right STG showed a decrement form among the asthma only group, healthy controls and asthma plus depression group. In patients with asthma and depression, the volume of the right STG was positively correlated with PD20 (r = 0.714, p = 0.047) and negatively correlated with the nocturnal awakening score in the Asthma Control Test (r = -0.061, p = 0.038).

CONCLUSION

Current findings provided convergent evidence to support the critical role of the right STG in the brain mechanism that mediates asthma and depression.

Frontal-insula gray matter deficits in first-episode medication-naïve patients with major depressive disorder

OBJECTIVE

This study is designed to investigate the gray matter volume (GMV) deficits in patients with first-episode medication-naïve major depressive disorder (MDD).

METHODS

We enrolled 38 patients with first-episode medication-naïve MDD and 27 controls in this project. Voxel-based morphometry was used to compare GMV differences between two groups. Besides, the relationship between GMV of patients and the severity of clinical symptoms was estimated to confirm the role of GMV deficits in clinical symptoms. The correlation between total GMV and illness duration was also performed to elucidate the impacts of untreated duration on the GMV.

RESULTS

We found that first-episode medication-naïve MDD patients had significant GMV deficits in bilateral superior frontal gyri, left middle frontal gyrus, left medial frontal gyrus and left insula. The GMV of patient group was negatively correlated with the severity of clinical symptoms and the illness duration.

CONCLUSION

A pattern of GMV deficits in fronto-insula might represent the biomarker for first-episode medication-naïve MDD.

A diffusion tensor imaging study of suicide attempters

BACKGROUND

Few studies have examined white matter abnormalities in suicide attempters using diffusion tensor imaging (DTI). This study sought to identify white matter regions altered in individuals with a prior suicide attempt.

METHODS

DTI scans were acquired in 13 suicide attempters with major depressive disorder (MDD), 39 non-attempters with MDD, and 46 healthy participants (HP). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were determined in the brain using two methods: region of interest (ROI) and tract-based spatial statistics (TBSS). ROIs were limited a priori to white matter adjacent to the caudal anterior cingulate cortex, rostral anterior cingulate cortex, dorsomedial prefrontal cortex, and medial orbitofrontal cortex.

RESULTS

Using the ROI approach, suicide attempters had lower FA than MDD non-attempters and HP in the dorsomedial prefrontal cortex. Uncorrected TBSS results confirmed a significant cluster within the right dorsomedial prefrontal cortex indicating lower FA in suicide attempters compared to non-attempters. There were no differences in ADC when comparing suicide attempters, non-attempters and HP groups using ROI or TBSS methods.

CONCLUSIONS

Low FA in the dorsomedial prefrontal cortex was associated with a suicide attempt history. Converging findings from other imaging modalities support this finding, making this region of potential interest in determining the diathesis for suicidal behavior.

Microstructural white-matter abnormalities associated with treatment resistance, severity and duration of illness in major depression

BACKGROUND

Although white-matter abnormalities have been reported in middle-aged patients with major depressive disorder (MDD), few data are available on treatment-resistant MDD and the influence of relevant variables related to clinical burden of illness is far from being well established.

METHOD

The present study examined white-matter microstructure in a sample of 52 patients with MDD in different stages (treatment-resistant/chronic MDD, n = 18; remitted-recurrent MDD, n = 15; first-episode MDD, n = 19) and 17 healthy controls, using diffusion tensor imaging with a tract-based spatial statistics approach. Groups were comparable in age and gender distribution, and results were corrected for familywise error (FWE) rate.

RESULTS

Widespread significant reductions of fractional anisotropy (FA) - including the cingulum, corpus callosum, superior and inferior longitudinal fascicule - were evident in treatment-resistant/chronic MDD compared with first-episode MDD and controls (p < 0.05, FWE-corrected). Decreased FA was observed within the ventromedial prefrontal region in treatment-resistant/chronic MDD even when compared with the remitted-recurrent MDD group (p < 0.05, FWE-corrected). Longer duration of illness (β = -0.49, p = 0.04) and higher depression severity (at a trend level: β = -0.26, p = 0.06) predicted lower FA in linear multiple regression analysis at the whole-brain level. The number of previous episodes and severity of symptoms were significant predictors when focused on the ventromedial prefrontal area (β = -0.28, p = 0.04; and β = -0.29, p = 0.03, respectively). Medication effects were controlled for in the analyses and results remained unaltered.

CONCLUSIONS

Our findings support the notion that disruptions of white-matter microstructure, particularly in fronto-limbic networks, are associated with resistance to treatment and higher current and past burden of depression.

Cortical thickness in youth with major depressive disorder

BACKGROUND

Studies in adults with major depressive disorder (MDD) have implicated dysregulation of frontal-limbic circuits in the symptomology of this disorder. We hypothesized that the middle frontal gyrus (MFG; a core portion of the dorsolateral prefrontal cortex or DLPFC) and the anterior cingulate (caudal), regions implicated in emotive and cognitive control, would display a reduced cortical thickness in youth with MDD as compared to healthy, non-depressed adolescents.

METHODS

Sixteen healthy control adolescents (17.19 ± 1.87 years; 7 males, 9 females) and thirty MDD participants (16.89 ± 2.01 years; 9 males, 21 females) underwent magnetic resonance imaging (MRI). Cortical thickness analysis was carried out using FreeSurfer software.

RESULTS

Counter to our hypothesis, we observed thicker right and left rostral MFG in MDD adolescents as compared to controls (p = 0.004 and p = 0.005, respectively). Furthermore, the left caudal anterior cingulate cortex was thicker in MDD subjects as compared to controls (p = 0.009). In MDD subjects, there was a significant inverse correlation between age and left MFG thickness (r = -0.45, p = 0.001).

CONCLUSIONS

These results have implications for the developmental trajectory of the frontal lobe in adolescent MDD. The MFG is implicated in the frontal-limbic circuits underlying executive functioning and their interaction with affective processing. Alterations in this region are likely involved with the symptoms of MDD. Limitations include a small sample size and cross sectional design.

Depressive symptoms and neuroanatomical structures in community-dwelling women: A combined voxel-based morphometry and diffusion tensor imaging study with tract-based spatial statistics

Depressive symptoms, even at a subclinical level, have been associated with structural brain abnormalities. However, previous studies have used regions of interest or small sample sizes, limiting the ability to generalize the results. In this study, we examined neuroanatomical structures of both gray matter and white matter associated with depressive symptoms across the whole brain in a large sample. A total of 810 community-dwelling adult participants underwent measurement of depressive symptoms with the Center for Epidemiologic Studies Depression Scale (CES-D). The participants were not demented and had no neurological or psychiatric history. To examine the gray and white matter volume, we used structural MRI scans and voxel-based morphometry (VBM); to examine the white matter integrity, we used diffusion tensor imaging with tract-based spatial statistics (TBSS). In female participants, VBM revealed a negative correlation between bilateral anterior cingulate gray matter volume and the CES-D score. TBSS showed a CES-D-related decrease in fractional anisotropy and increase in radial and mean diffusivity in several white matter regions, including the right anterior cingulum. In male participants, there was no significant correlation between gray or white matter volume or white matter integrity and the CES-D score. Our results indicate that the reduction in gray matter volume and differences in white matter integrity in specific brain regions, including the anterior cingulate, are associated with depressive symptoms in women.

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We studied neuroanatomical structures associated with subclinical depression.

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The analysis was performed across the whole brain in a large sample.

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Anterior cingulate gray matter volume reduction was revealed by VBM.

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Broad white matter integrity differences were revealed by DTI with TBSS.

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Both changes were seen only in females but not in males.

Tractography of the brainstem in major depressive disorder using diffusion tensor imaging

Background

The brainstem is the main region that innervates neurotransmitter release to the Hypothalamic-Pituitary Adrenal (HPA) axis and fronto-limbic circuits, two key brain circuits found to be dysfunctional in Major Depressive Disorder (MDD). However, the brainstem’s role in MDD has only been evaluated in limited reports. Using Diffusion Tensor Imaging (DTI), we investigated whether major brainstem white matter tracts that relate to these two circuits differ in MDD patients compared to healthy controls.

Methods

MDD patients (n = 95) and age- and gender-matched controls (n = 34) were assessed using probabilistic tractography of DTI to delineate three distinct brainstem tracts: the nigrostriatal tract (connecting brainstem to striatum), solitary tract (connecting brainstem to amygdala) and corticospinal tract (connecting brainstem to precentral cortex). Fractional anisotropy (FA) was used to measure the white matter integrity of these tracts, and measures were compared between MDD and control participants.

Results

MDD participants were characterized by a significant and specific decrease in white matter integrity of the right solitary tract (p<0.009 using independent t-test), which is a “bottom up” afferent pathway that connects the brainstem to the amygdala. This decrease was not related to symptom severity.

Conclusions

The results provide new evidence to suggest that structural connectivity between the brainstem and the amygdala is altered in MDD. These results are interesting in light of predominant theories regarding amygdala-mediated emotional reactivity observed in functional imaging studies of MDD. The characterization of altered white matter integrity in the solitary tract in MDD supports the possibility of dysfunctional brainstem-amygdala connectivity impacting vulnerable circuits in MDD.