Anatomical MRI study of hippocampus and amygdala in patients with current and remitted major depression

The gray matter volume of the amygdala is correlated with the perception of melodic intervals: a voxel-based morphometry study

Music is not simply a series of organized pitches, rhythms, and timbres, it is capable of evoking emotions. In the present study, voxel-based morphometry (VBM) was employed to explore the neural basis that may link music to emotion. To do this, we identified the neuroanatomical correlates of the ability to extract pitch interval size in a music segment (i.e., interval perception) in a large population of healthy young adults (N = 264). Behaviorally, we found that interval perception was correlated with daily emotional experiences, indicating the intrinsic link between music and emotion. Neurally, and as expected, we found that interval perception was positively correlated with the gray matter volume (GMV) of the bilateral temporal cortex. More important, a larger GMV of the bilateral amygdala was associated with better interval perception, suggesting that the amygdala, which is the neural substrate of emotional processing, is also involved in music processing. In sum, our study provides one of first neuroanatomical evidence on the association between the amygdala and music, which contributes to our understanding of exactly how music evokes emotional responses.

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.

Neuropathology of stress

Environmental challenges are part of daily life for any individual. In fact, stress appears to be increasingly present in our modern, and demanding, industrialized society. Virtually every aspect of our body and brain can be influenced by stress and although its effects are partly mediated by powerful corticosteroid hormones that target the nervous system, relatively little is known about when, and how, the effects of stress shift from being beneficial and protective to becoming deleterious. Decades of stress research have provided valuable insights into whether stress can directly induce dysfunction and/or pathological alterations, which elements of stress exposure are responsible, and which structural substrates are involved. Using a broad definition of pathology, we here review the "neuropathology of stress" and focus on structural consequences of stress exposure for different regions of the rodent, primate and human brain. We discuss cytoarchitectural, neuropathological and structural plasticity measures as well as more recent neuroimaging techniques that allow direct monitoring of the spatiotemporal effects of stress and the role of different CNS structures in the regulation of the hypothalamic-pituitary-adrenal axis in human brain. We focus on the hypothalamus, hippocampus, amygdala, nucleus accumbens, prefrontal and orbitofrontal cortex, key brain regions that not only modulate emotions and cognition but also the response to stress itself, and discuss disorders like depression, post-traumatic stress disorder, Cushing syndrome and dementia.

Brain volumetric abnormalities in patients with anorexia and bulimia nervosa: a voxel-based morphometry study

Recent studies focussing on neuroimaging features of eating disorders have observed that anorexia nervosa (AN) is characterized by significant grey matter (GM) atrophy in many brain regions, especially in the cerebellum and anterior cingulate cortex. To date, no studies have found GM atrophy in bulimia nervosa (BN) or have directly compared patients with AN and BN. We used voxel-based morphometry (VBM) to characterize brain abnormalities in AN and BN patients, comparing them with each other and with a control group, and correlating brain volume with clinical features. We recruited 17 AN, 13 BN and 14 healthy controls. All subjects underwent high-resolution magnetic resonance imaging (MRI) with a T1-weighted 3D image. VBM analysis was carried out with the FSL-VBM 4.1 tool. We found no global atrophy, but regional GM reduction in AN with respect to controls and BN in the cerebellum, fusiform area, supplementary motor area, and occipital cortex, and in the caudate in BN compared to AN and controls. Both groups of patients had a volumetric increase bilaterally in somatosensory regions with respect to controls, in areas that are typically involved in the sensory-motor integration of body stimuli and in mental representation of the body image. Our VBM study documented, for the first time in BN patients, the presence of volumetric alterations and replicated previous findings in AN patients. We evidenced morphological differences between AN and BN, demonstrating in the latter atrophy of the caudate nucleus, a region involved in reward mechanisms and processes of self-regulation, perhaps involved in the genesis of the binge-eating behaviors of this disorder.

Antidepressant-like effects of erythropoietin: a focus on behavioural and hippocampal processes

Depression is a chronic and debilitating condition with a significant degree of relapse and treatment resistance that could stem, at least in part, from disturbances of neuroplasticity. This has led to an increased focus on treatment strategies that target brain derived neurotrophic factor (BDNF), synaptic plasticity and adult neurogenesis. In the current study we aimed to assess whether erythropoietin (EPO) would have antidepressant-like effects given its already established pro-trophic actions. In particular, we assessed whether EPO would diminish the deleterious effects of a social stressor in mice. Indeed, EPO induced anxiolytic and antidepressant-like responses in a forced swim test, open field, elevated-plus maze, and a novelty test, and appeared to blunt some of the negative behavioural effects of a social stressor. Furthermore, EPO promoted adult hippocampal neurogenesis, an important feature of effective antidepressants. Finally, a separate study using the mTOR inhibitor rapamycin revealed that antagonizing this pathway prevented the impact of EPO upon forced swim performance. These data are consistent with previous findings showing that the mTOR pathway and its neurogenic and synaptogenic effects might mediate the behavioral consequences of antidepressant agents. Our findings further highlight EPO as a possible adjunct treatment for affective disorders, as well as other stressor associated disorders of impaired neuroplasticity.

Cortical shape and curvedness analysis of structural deficits in remitting and non-remitting depression

In morphometric neuroimaging studies, the relationship between brain structural changes and the antidepressant treatment response in patients with major depressive disorder has been explored to search depression-trait biomarkers. Although patients were treated with serotonin-related drugs, whether the same treatment resulted in remission and non-remission in depressed patients is currently under investigation. We recruited 25 depressed patients and 25 healthy controls and acquired volumetric magnetic resonance imaging of each participant. We used the shape index and curvedness to classify cortical shapes and quantify shape complexities, respectively, in studying the pharmacological effect on brain morphology. The results showed that different regions of structural abnormalities emerged between remitting and non-remitting patients when contrasted with healthy controls. In addition to comparing structural metrics in each cortical parcellation, similar to the traditional voxel-based morphometric method, we highlighted the importance of structural integrity along the serotonin pathway in response to medication treatment. We discovered that disrupted serotonin-related cortical regions might cause non-remission to antidepressant treatment from a pharmacological perspective. The anomalous areas manifested in non-remitting patients were mainly in the frontolimbic areas, which can be used to differentiate remitting from non-remitting participants before medication treatment. Because non-remission is the failure to respond to treatment with serotonin-related drugs, our method may help clinicians choose appropriate medications for non-remitting patients.

Structural changes in hippocampal subfields in major depressive disorder: a high-field magnetic resonance imaging study

BACKGROUND

Magnetic resonance imaging (MRI) has shown lower hippocampal volume in major depressive disorder (MDD). Preclinical and postmortem studies show that chronic stress and MDD may affect hippocampal subfields differently, but MRI spatial resolution has previously been insufficient to measure subfield volumes.

METHODS

Twenty MDD participants (9 unmedicated and 11 medicated, both > 6 months) and 27 healthy control subjects were studied. We used T2-weighted two-dimensional fast spin echo and T1-weighted three-dimensional magnetization prepared rapid acquisition gradient-echo sequences at 4.7 T to compare hippocampal subfield volumes at .09 μL voxel volume.

RESULTS

Unmedicated MDD participants had a lower dentate gyrus volume than control subjects or medicated MDD participants and a lower cornu ammonis (CA1-3) volume in the hippocampal body subregion than control subjects.

CONCLUSIONS

Hippocampal volumes in unmedicated MDD showed evidence of localization to specific subfields and subregions, findings that appear, on the surface, consistent with preclinical evidence for localized mechanisms of hippocampal neuroplasticity. Strengths include in vivo measurement of entire hippocampal subfields and separation between unmedicated and medicated MDD. Limitations include power to control for multiple comparisons and that MRI landmarks approximate the subfields defined by cellular microstructure.

The neuroprogressive nature of major depressive disorder: pathways to disease evolution and resistance, and therapeutic implications

In some patients with major depressive disorder (MDD), individual illness characteristics appear consistent with those of a neuroprogressive illness. Features of neuroprogression include poorer symptomatic, treatment and functional outcomes in patients with earlier disease onset and increased number and length of depressive episodes. In such patients, longer and more frequent depressive episodes appear to increase vulnerability for further episodes, precipitating an accelerating and progressive illness course leading to functional decline. Evidence from clinical, biochemical and neuroimaging studies appear to support this model and are informing novel therapeutic approaches. This paper reviews current knowledge of the neuroprogressive processes that may occur in MDD, including structural brain consequences and potential molecular mechanisms including the role of neurotransmitter systems, inflammatory, oxidative and nitrosative stress pathways, neurotrophins and regulation of neurogenesis, cortisol and the hypothalamic-pituitary-adrenal axis modulation, mitochondrial dysfunction and epigenetic and dietary influences. Evidence-based novel treatments informed by this knowledge are discussed.

Associations of current and remitted major depressive disorder with brain atrophy: the AGES-Reykjavik Study

BACKGROUND

To examine whether lifetime DSM-IV diagnosis of major depressive disorder (MDD), including age at onset and number of episodes, is associated with brain atrophy in older persons without dementia.

METHOD

Within the population-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, 4354 persons (mean age 76 ± 5 years, 58% women) without dementia had a 1.5-T brain magnetic resonance imaging (MRI) scan. Automated brain segmentation total and regional brain volumes were calculated. History of MDD, including age at onset and number of episodes, and MDD in the past 2 weeks was diagnosed according to DSM-IV criteria using the Mini-International Neuropsychiatric Interview (MINI).

RESULTS

Of the total sample, 4.5% reported a lifetime history of MDD; 1.5% had a current diagnosis of MDD (including 75% with a prior history of depression) and 3.0% had a past but no current diagnosis (remission). After adjusting for multiple covariates, compared to participants never depressed, those with current MDD (irrespective of past) had more global brain atrophy [B = -1.25%, 95% confidence interval (CI) -2.05 to -0.44], including more gray- and white-matter atrophy in most lobes, and also more atrophy of the hippocampus and thalamus. Participants with current, first-onset MDD also had more brain atrophy (B = -1.62%, 95% CI -3.30 to 0.05) whereas those remitted did not (B = 0.06%, 95% CI -0.54 to 0.66).

CONCLUSIONS

In older persons without dementia, current MDD, irrespective of prior history, but not remitted MDD was associated with widespread gray- and white-matter brain atrophy. Prospective studies should examine whether MDD is a consequence of, or contributes to, brain volume loss and development of dementia.

Organic bases of late-life depression: a critical update

Late-life depression (LLD) is frequently associated with cognitive impairment and increases the risk of subsequent dementia. Cerebrovascular disease, deep white matter lesions, Alzheimer disease (AD) and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, and a host of studies have looked at the interplay between cerebrovascular disease and LLD. This has resulted in new concepts of LLD, such as "vascular depression", but despite multiple magnetic resonance imaging (MRI) studies in this field, the relationship between structural changes in human brain and LLD is still controversial. While pathological findings of suicide in some elderly persons revealed multiple lacunes, small vessel cerebrovascular disease, AD-related lesions or multiple neurodegenerative pathologies, recent autopsy data challenged the role of subcortical lacunes and white matter lesions as major morphological substrates of depressive symptoms as well as poorer executive function and memory. Several neuropathological studies, including a personal clinico-pathological study in a small cohort of elderly persons with LLD and age-matched controls confirmed that lacunes, periventricular and deep white matter demyelination as well as AD-related lesions are usually unrelated to the occurrence of LLD. In the same line, neuropathological data show that early-onset depression is not associated with an acceleration of age-related neurodegenerative changes. Very recent data on the critical role of glia-modulating neuronal dysfunction and degeneration in depression are discussed.

Disrupted resting-state functional connectivity of the hippocampus in medication-naïve patients with major depressive disorder

BACKGROUND

The hippocampus has been reported to exhibit structural and functional alterations in patients with major depressive disorder (MDD). But functional relationships between this area and other regions remain unclear.

METHODS

Region of interest-based correlation analyses were performed in the resting-state functional magnetic resonance imaging data to examine differences in functional connectivity (FC) of the hippocampus between medication-naïve patients with MDD and healthy adults. Correlation analyses were done between clinical variables and the strength of FC in regions showing group differences.

RESULTS

Positive FC with the hippocampal-ROIs was seen in bilateral limbic system, subcortical areas, temporal lobe, medial and inferior prefrontal cortex while negative FC was observed in bilateral prefrontal cortex, parietal and occipital cortex and the cerebellum. Group comparison showed impaired functional connections of the hippocampus in MDD, with a lack of negative FC in left hippocampal-ROI to bilateral middle frontal gyrus, as well as decreased negative FC in right hippocampal-ROI to right inferior parietal cortex and the cerebellum. Negative correlations were seen between illness duration and the strength of FC in the prefrontal and parietal cortex.

LIMITATIONS

An optimized method taking individual variability of hippocampal volume into account is merited for the definition of seed regions and computation of FC. Further studies recruiting subjects with subthreshold depressive symptoms are needed.

CONCLUSIONS

Abnormal functional relationships between the hippocampus and cortical areas may underlie the pathophysiology of MDD.

Remodeling of axo-spinous synapses in the pathophysiology and treatment of depression

Dendritic spines provide a compartment for assembly and functional organization of synaptic machinery that plays a fundamental role in neuronal communication and neuroplasticity. Studies in humans as well as in animal models have demonstrated abnormal spine architecture in several psychiatric disorders, including depression and other stress-related illnesses. The negative impact of stress on the density and organization of spines is thought to contribute to the behavioral deficits caused by stress exposure. Moreover, there is now evidence that medication-induced recovery involves changes in synaptic plasticity and dendrite morphology, including increased expression of pre- and postsynaptic plasticity-related proteins, as well as the density and function of axo-spinous synapses. Here we review the evidence from brain imaging and postmortem studies demonstrating that depression is accompanied by structural and functional alterations of cortical and limbic brain regions, including the prefrontal cortex, hippocampus and amygdala. In addition, we present more direct evidence from basic research studies that exposure to stress alters spine morphology, function and plasticity and that antidepressants, particularly new rapid acting agents, reverse these effects. Elucidation of the signaling pathways and molecular mechanisms that control spine synapse assembly and plasticity will contribute to a better understanding of the pathophysiology of depression and development of novel, more effective therapeutic agents.

Metallic gold slows disease progression, reduces cell death and induces astrogliosis while simultaneously increasing stem cell responses in an EAE rat model of multiple sclerosis

Multiple sclerosis (MS) is the most common neurodegenerative disease in the Western world affecting younger, otherwise healthy individuals. Today no curative treatment exists. Patients suffer from recurring attacks caused by demyelination and underlying neuroinflammation, ultimately leading to loss of neurons. Recent research shows that bio-liberation of gold ions from metallic gold implants can ameliorate inflammation, reduce apoptosis and promote proliferation of neuronal stem cells (NSCs) in a mouse model of focal brain injury. Based on these findings, the present study investigates whether metallic gold implants affect the clinical signs of disease progression and the pathological findings in experimental autoimmune encephalomyelitis (EAE), a rodent model of MS. Gold particles 20-45 μm suspended in hyaluronic acid were bilaterally injected into the lateral ventricles (LV) of young Lewis rats prior to EAE induction. Comparing gold-treated animals to untreated and vehicle-treated ones, a statistically significant slowing of disease progression in terms of reduced weight loss was seen. Despite massive inflammatory infiltration, terminal deoxynucleotidyl transferase dUTP nick end labeling staining revealed reduced apoptotic cell death in disease foci in the brain stem of gold-treated animals, alongside an up-regulation of glial fibrillary acidic protein-positive reactive astrocytes near the LV and in the brain stem. Cell counting of frizzled-9 and nestin-stained cells showed statistically significant up-regulation of NSCs migrating from the subventricular zone. Additionally, the neuroprotective proteins Metallothionein-1 and -2 were up-regulated in the corpus callosum. In conclusion, this study is the first to show that the presence of small gold implants affect disease progression in a rat model of MS, increasing the neurogenic response and reducing the loss of cells in disease foci. Gold implants might thus improve clinical outcome for MS patients and further research into the long-term effects of such localized gold treatment is warranted.

Regional cortical thinning in patients with major depressive disorder: a surface-based morphometry study

This study uses surfaced-based morphometry to investigate cortical thinning and its functional correlates in patients with major depressive disorder (MDD). Subjects with MDD (N=36) and healthy control subjects (N=36) were enrolled in the study. Each subject received T1 structural magnetic resonance imaging (MRI), clinical evaluations, and neuropsychological examinations of executive functions with the Color Trail Test (CTT) and the Wisconsin Card Sorting Test (WCST). This study used an automated surface-based method (FreeSurfer) to measure cortical thickness and to generate the thickness maps for each subject. Statistical comparisons were performed using a general linear model. Compared with healthy controls, subjects with MDD showed the largest area of cortical thinning in the prefrontal cortex. This study also noted smaller areas of cortical thinning in the bilateral inferior parietal cortex, left middle temporal gyrus, left entorhinal cortex, left lingual cortex, and right postcentral gyrus. Regression analysis demonstrated cortical thinning in several frontoparietal regions, predicting worse executive performance measured by CTT 2, though the patterns of cortical thickness/executive performance correlation differed in healthy controls and MDD subjects. In conclusion, the results provide further evidence for the significant role of a prefrontal structural deficit and an aberrant structural/functional relationship in patients with MDD.

Pubertal stage and brain anatomy in girls

Studies of puberty have focused primarily on changes in hormones and on observable physical bodily characteristics. Little is known, however, about the nature of the relation between pubertal status and brain physiology. This is particularly important given findings that have linked the onset of puberty with both changes in cognitive functioning and increases in the incidence of depression and anxiety. The present study examined relations between pubertal stage, as assessed by Tanner staging, and brain anatomy in a sample of 54 girls aged 9-15 years. Brain morphometric analysis was conducted using high-resolution magnetic resonance imaging (MRI). The hippocampus and amygdala were manually traced on MRI scans in all participants. Stepwise regression analyses were conducted with total intracranial volume (ICV), age, and pubertal status as the predictor variables and hippocampus and amygdala volumes as outcome variables. Pubertal status was significantly associated with left amygdala volume, after controlling for both age and ICV. In addition, puberty was related to right hippocampus and amygdala volumes, after controlling for ICV. In contrast, no significant associations were found between age and hippocampal and amygdala volumes after controlling for pubertal status and ICV. These findings highlight the importance of the relation between pubertal status and morphometry of the hippocampus and amygdala, and of limbic and subcortical structures that have been implicated in emotional and social behaviors.

Increased hippocampal volumes in lithium treated adolescents with bipolar disorders: a structural MRI study

BACKGROUND

Structural neuroimaging studies in bipolar disorder (BD) have consistently identified several anatomical abnormalities in many brain areas related to mood regulation. Hippocampus is one of the key components of emotional regulatory networks in the brain. Evidence about hippocampal changes in BD is quite limited and inconsistent particularly for adolescent onset BD. It is aimed to compare hippocampus volumes of euthymic BD-I adolescents with healthy controls using structural MRI.

METHODS

Hippocampal volumes of seventeen youths between 13 and 19 age period with DSM-IV BD (seven boys) and twelve healthy comparison subjects (five boys) were compared using structural MRI. Differences in hippocampal volumes between groups were tested.

RESULTS

There was no significant difference between the right and left hippocampus volumes of patients with BD and the control group. However boys tended to have significantly larger right hippocampal volumes than girls both in BD and control group. Right hippocampal volumes were enlarged in lithium treated bipolar patients. This enlargement is not related to sex.

LIMITATIONS

Future, longitudinal follow-up studies need large enough sample sizes of both sexes and a sex-matched healthy comparison group to sort out developmental, gender and medication influences on brain structures over time in BD.

CONCLUSIONS

Lithium treatment in adolescent-onset BD has a significant effect on hippocampus volumes.

Cognitive and volumetric predictors of response to repetitive transcranial magnetic stimulation (rTMS) - a prospective follow-up study

As the prevalence of treatment resistant depression (TRD) continues to rise, it remains a clinically important issue to identify neurobiological-, patient- and treatment-related factors that could potentially predict response to treatment. Medial temporal lobe (MTL) structures, in particular the hippocampus and amygdala have been implicated in inferior treatment response. The role of related structures such as the entorhinal cortex and the impact of MTL abnormalities on neurocognitive function, however, have not been systematically examined. The current study investigated MTL abnormalities and neurocognitive characteristics of eventual treatment responders and non-responders to a course of repetitive transcranial magnetic stimulation (rTMS) in order to identify potential predictors of treatment outcome. Prior to rTMS treatment all patients underwent magnetic resonance imaging (MRI) and neuropsychological assessment. MRI analysis was conducted using FreeSurfer 5.0. There was a 50% response rate following up to a 6-week course of daily rTMS treatments. Treatment response was defined as 50% reduction in Hamilton Depression Rating Scale and BDI-II scores from baseline. There was no difference in pre-treatment neurocognitive profiles and MTL volumes between eventual treatment responders and non-responders. Smaller pre-treatment left hippocampus volume showed a trend towards predicting eventual subjective improvement in depressive symptomatology. Although preliminary, our findings suggest that structural abnormalities may have some potential for predicting outcome to rTMS.

Structural and synaptic plasticity in stress-related disorders

Abstract Stress can have a lasting impact on the structure and function of brain circuitry that results in long-lasting changes in the behavior of an organism. Synaptic plasticity is the mechanism by which information is stored and maintained within individual synapses, neurons, and neuronal circuits to guide the behavior of an organism. Although these mechanisms allow the organism to adapt to its constantly evolving environment, not all of these adaptations are beneficial. Under prolonged bouts of physical or psychological stress, these mechanisms become dysregulated, and the connectivity between brain regions becomes unbalanced, resulting in pathological behaviors. In this review, we highlight the effects of stress on the structure and function of neurons within the mesocorticolimbic brain systems known to regulate mood and motivation. We then discuss the implications of these spine adaptations on neuronal activity and pathological behaviors implicated in mood disorders. Finally, we end by discussing recent brain imaging studies in human depression within the context of these basic findings to provide insight into the underlying mechanisms leading to neural dysfunction in depression.

Fronto-limbic volumetric changes in major depressive disorder

BACKGROUND

Fronto-limbic dysregulation in major depressive disorder (MDD) may be influenced by early life stress and antidepressant treatment. The present structural MRI study aimed to determine the relationship between amygdala, cingulate and subgenual prefrontal cortex volumes in MDD and their associations with child abuse and antidepressants.

METHODS

Right-handed subjects (21-50 years), meeting DSM-IV criteria for MDD, either with (n=19) or without (n=20) childhood sexual or physical abuse. Healthy controls (n=34) were matched for age, sex, education and smoking. 3D-MPRAGE images with a spatial resolution of 1.5 mm×1.0 mm×1.0 mm were acquired with a Siemens Sonata 1.5 T system. Volumes of subgenual prefrontal cortex, amygdala and affective, cognitive, superior and posterior divisions of cingulate cortex were analyzed using DISPLAY software using reliable volumetric protocols. Groups were compared using ANCOVA, with intracranial volume as a covariate.

RESULTS

MDD subjects had low cingulate (cognitive division) and high amygdala volumes. Low cingulate volume was related to abuse and treatment history. Amygdala volume was predicted by subgenual prefrontal and cingulate (cognitive division) volumes and the presence of paracingulate cortex.

LIMITATIONS

This study was cross sectional and the sample size was limited for subgroup and correlational analyses.

SUMMARY

Our data suggest that MDD may be associated with alterations in anterior cingulate cortex and amygdala. Morphological variation, early stress and stress-protective factors may contribute to differences in fronto-limbic structures in MDD.

Magnetic resonance imaging studies in unipolar depression: systematic review and meta-regression analyses

Previous meta-analyses of structural MRI studies have shown diffuse cortical and sub-cortical abnormalities in unipolar depression. However, the presence of duplicate publications, recruitment of particular age groups and the selection of specific regions of interest means that there is uncertainty about the balance of current research. Moreover, the lack of systematic exploration of highly significant heterogeneity has prevented the generalisability of finding. A systematic review and random-effects meta-analysis was carried out to estimate effect sizes. Possible publication bias, and the impact of various study design characteristics on the magnitude of the observed effect size were systematically explored. The aim of this study was 1) to include structural MRI studies systematically comparing unipolar depression with bipolar disorder and healthy volunteers; 2) to consider all available structures of interest without specific age limits, avoiding data duplication, and 3) to explore the influence of factors contributing to the measured effect sizes systematically with meta-regression analyses. Unipolar depression was characterised by reduced brain volume in areas involved in emotional processing, including the frontal cortex, orbitofrontal cortex, cingulate cortex, hippocampus and striatum. There was also evidence of pituitary enlargement and an excess of white matter hyperintensity volume in unipolar depression. Factors which influenced the magnitude of the observed effect sizes were differences in methods, clinical variables, pharmacological interventions and sample age.

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

We developed this study to follow up the hanges in subcortical structures after 6 weeks' treatment with therapy of duloxetine in first episode drug-naïve patients with major depressive disorder and panic disorder. Fifteen patients received duloxetine 60mg/d therapy for 6 weeks and achieved remission. They all underwent structural magnetic resonance imaging (MRI) of the brain at baseline and week 6. Fifteen healthy controls were also scanned twice at baseline and week 6 to exclude possible biases. Structural MRI data were preprocessed with FMRIB's Integrated Registration and Segmentation Tool function (FIRST version 1.2) of FSL (FMRIB Software Library; version 4.1.1) to perform subcortical segmentations of the brain using a shape and appearance model. Nonparametric corrections of these structural volumes in an F-test between pre- and post-treatment were used to identify the changes after duloxetine therapy. A false discovery correction of the F-test by FIRST was also performed. A paired t-test using SPSS was applied to confirm the changes in these structures. The patients had consistent changes of volumes in bilateral nucleus accumbens, left putamen, left hippocampus and brainstem after 6 weeks of treatment with duloxetine. There were no consistent changes in other subcortical structures. There were modest increases of the volumes of the above areas, which were not significant after false discovery correction by FIRST F-test comparisons. The volumetric increases were correlated with responses of clinical symptoms. The results suggested that duloxetine possibly contributed to modest increases in several subcortical areas of these patients with remission.

Structural neuroimaging studies in major depressive disorder. Meta-analysis and comparison with bipolar disorder

CONTEXT

Although differences in clinical characteristics exist between major depressive disorder (MDD) and bipolar disorder (BD), consistent structural brain abnormalities that distinguish the disorders have not been identified.

OBJECTIVES

To investigate structural brain changes in MDD using meta-analysis of primary studies; assess the effects of medication, demographic, and clinical variables; and compare the findings with those of a meta-analysis of studies on BD.

DATA SOURCES

The MEDLINE, EMBASE, and PsycINFO databases were searched for studies from January 1, 1980, to February 2, 2010.

STUDY SELECTION

Two hundred twenty-five studies that used magnetic resonance imaging or x-ray computed tomography to compare brain structure in patients with MDD with that of controls were included in an online database, and 143 that measured common brain structures were selected for meta-analysis.

DATA EXTRACTION

Twenty-five variables, including demographic and clinical data, were extracted from each study, when available. For the meta-analysis, mean structure size and standard deviation were extracted for continuous variables, and the proportion of patients and controls with an abnormality in brain structure was extracted for categorical variables.

DATA SYNTHESIS

Compared with the structure of a healthy brain, MDD was associated with lateral ventricle enlargement; larger cerebrospinal fluid volume; and smaller volumes of the basal ganglia, thalamus, hippocampus, frontal lobe, orbitofrontal cortex, and gyrus rectus. Patients during depressive episodes had significantly smaller hippocampal volume than patients during remission. Compared with BD patients, those with MDD had reduced rates of deep white matter hyperintensities, increased corpus callosum cross-sectional area, and smaller hippocampus and basal ganglia. Both disorders were associated with increased lateral ventricle volume and increased rates of subcortical gray matter hyperintensities compared with healthy controls.

CONCLUSIONS

The meta-analyses revealed structural brain abnormalities in MDD that are distinct from those observed in BD. These findings may aid investigators attempting to discriminate mood disorders using structural magnetic resonance imaging data.

Demonstration of decreased gray matter concentration in the midbrain encompassing the dorsal raphe nucleus and the limbic subcortical regions in major depressive disorder: an optimized voxel-based morphometry study

BACKGROUND

Previous neuroimaging studies in patients with major depressive disorder (MDD) have reported changes in several brain areas, such as the medial and dorsolateral orbital cortex, amygdala, hippocampus, and basal ganglia. However, the results of these studies are inconsistent, and relatively few studies have been conducted using voxel-based morphometry (VBM) to detect gray matter concentration (GMC) abnormalities in patients with MDD.

METHODS

We examined 47 MDD patients and 51 healthy controls to investigate structural abnormalities using a 1.5 T magnetic resonance imaging system, which was normalized to a customized T1 template and segmented with optimized VBM. Analysis of covariance with age and gender as covariates was adopted for the VBM statistics; the level of statistical significance was set at P<0.05 for the corrected false discovery rate.

RESULTS

Decreased GMC was found in MDD patients in the bilateral amygdalae, hippocampi, fusiform gyri, lingual gyri, insular gyri, middle-superior temporal gyri, thalami, cingulate gyri, the central lobule of the cerebellum, and the midbrain encompassing the dorsal raphe nuclei (DRN).

LIMITATIONS

Half of our study subjects were taking antidepressants. This may have been a potential confounding factor if any of the medications affected cortical volume.

CONCLUSIONS

The results suggest that the GMC of several regions associated with emotion regulation was lower in MDD patients. In particular, we found decreased GMC in the DRN. These findings may provide a better understanding of the anatomical properties of the neural mechanisms underlying the etiology of MDD.

The effects of antidepressants on human brain as detected by imaging studies. Focus on major depression

Recent brain imaging studies have shed light on understanding the pathogenesis of mood disorders. Evidence of structural, chemical, and functional brain changes, particularly in prefrontal cortex, cingulate, and amygdala, has been revealed in major depressive disorder (MDD). Furthermore, imaging techniques have been applied to monitor the effects of antidepressants (ADs) both in the brains of healthy volunteers and MDD patients. Although with some discrepancies due to the differences in study designs and patient samples, imaging findings have shown that ADs, particularly those having effects on the serotonergic system, modulate the volumes, functions and biochemistry of brain structures, i.e. dorsolateral prefrontal cortex, anterior cingulate and amygdala, which have been demonstrated abnormal in MDD by earlier imaging studies. This paper reviews imaging studies conducted in MDD patients and healthy controls treated with different ADs.

Hippocampus and amygdalar volumes in patients with somatization disorder

In regard to somatization disorder which covers an important section of our patient population, there is no systematic structural magnetic resonance imaging (MRI) study in the literature. Therefore, we aimed to use structural MRI to evaluate the hippocampus amygdalar complex which is associated with both stress and regulation of emotion that are main basis clinical presentation of somatization disorder in the patients with somatization disorder. Totally 40 subjects (20 patients with somatization disorder and 20 healthy controls) were enrolled. Intracranial volume (ICV), whole brain volume, gray and white matter volumes, and hippocampus and amygdalar volumes of the subjects were measured. In regard to unadjusted mean volumes of measured structures, the patients had significantly smaller mean volumes of the left and right amygdala. However, two groups did not differ significantly in terms of whole brain, total gray and white matter or hippocampus volumes. The repeated measures ANCOVA predicting left and right amygdala volumes demonstrated a significant main effect of diagnostic group. In conclusion, the findings of the present study revealed that the patients with somatization disorder had significantly smaller mean volumes of the left and right amygdala without any differences in regard to whole brain, total gray and white matter or hippocampus volumes. On the basis of the current findings, it seems reasonable to evaluate that abnormalities in connectivity and/or metabolism dimensions and to examine the effects of drugs or psychotherapeutic approaches could be especially informative.

Biomarkers for major depression and its delineation from neurodegenerative disorders

Major depressive disorders (MDD) are among the most debilitating diseases worldwide and occur with a high prevalence in elderly individuals. Neurodegenerative diseases (in particular Alzheimer's disease, AD) do also show a strong age-dependent increase in incidence and prevalence among the elderly population. A high number of geriatric patients with MDD show cognitive deficits and a very high proportion of AD patients present co-morbid MDD, which poses difficult diagnostic and prognostic questions. Especially in prodromal and in very early stages of AD, it is almost impossible to differentiate between pure MDD and MDD with underlying AD. Here, we give a comprehensive review of the literature on the current state of candidate biomarkers for MDD ("positive MDD markers") and briefly refer to established and validated diagnostic AD biomarkers in order to rule out underlying AD pathophysiology in elderly MDD subjects with cognitive impairments ("negative MDD biomarkers"). In summary, to date there is no evidence for positive diagnostic MDD biomarkers and the only way to delineate MDD from AD is to use "negative MDD" biomarkers. Because of this highly unsatisfactory current state of MDD biomarker research, we propose a research strategy targeting to detect and validate positive MDD biomarkers, which is based on a complex (genetic, molecular and neurophysiological) biological model that incorporates current state of the art knowledge on the pathobiology of MDD. This model delineates common pathways and the intersection between AD and MDD. Applying these concepts to MDD gives hope that positive MDD biomarkers can be successfully identified in the near future.

Altered empathic responding in major depressive disorder: relation to symptom severity, illness burden, and psychosocial outcome

Individuals with major depressive disorder (MDD) demonstrate deficits in multiple social cognitive domains; however, systematic investigations of empathic responding have not been performed. Twenty patients with MDD completed two measures of empathy, the Interpersonal Reactivity Index (IRI: Davis, 1980, 1983) and the Toronto Empathy Questionnaire (TEQ: Spreng et al., 2009). Relative to matched controls, patients with MDD reported significantly reduced levels of empathy measured broadly on the TEQ and specifically in cognitive ('Perspective Taking') and affective ('Empathic Concern') domains captured by the IRI. A higher illness burden (i.e., greater number of past depressive episodes) was associated with greater reductions in perspective taking ability. This study provides early evidence of impaired empathic abilities in patients with MDD that may worsen with illness progression. Alternatively, reductions in perspective taking ability may contribute to a more severe course of illness in this population. Further longitudinal work is needed to characterize the relation between social cognitive performance and social functioning in this population.

Neural correlates of treatment outcome in major depression

There is a need to identify clinically useful biomarkers in major depressive disorder (MDD). In this context the functional connectivity of the orbitofrontal cortex (OFC) to other areas of the affect regulation circuit is of interest. The aim of this study was to identify neural changes during antidepressant treatment and correlates associated with the treatment outcome. In an exploratory analysis it was investigated whether functional connectivity measures moderated a response to mirtazapine and venlafaxine. Twenty-three drug-free patients with MDD were recruited from the Department of Psychiatry and Psychotherapy of the Ludwig-Maximilians University in Munich. The patients were subjected to a 4-wk randomized clinical trial with two common antidepressants, venlafaxine or mirtazapine. Functional connectivity of the OFC, derived from functional magnetic resonance imaging with an emotional face-matching task, was measured before and after the trial. Higher OFC connectivity with the left motor areas and the OFC regions prior to the trial characterized responders (p<0.05, false discovery rate). The treatment non-responders were characterized by higher OFC-cerebellum connectivity. The strength of response was positively correlated with functional coupling between left OFC and the caudate nuclei and thalami. Differences in longitudinal changes were detected between venlafaxine and mirtazapine treatment in the motor areas, cerebellum, cingulate gyrus and angular gyrus. These results indicate that OFC functional connectivity might be useful as a marker for therapy response to mirtazapine and venlafaxine and to reconstruct the differences in their mechanism of action.

Religious factors and hippocampal atrophy in late life

Despite a growing interest in the ways spiritual beliefs and practices are reflected in brain activity, there have been relatively few studies using neuroimaging data to assess potential relationships between religious factors and structural neuroanatomy. This study examined prospective relationships between religious factors and hippocampal volume change using high-resolution MRI data of a sample of 268 older adults. Religious factors assessed included life-changing religious experiences, spiritual practices, and religious group membership. Hippocampal volumes were analyzed using the GRID program, which is based on a manual point-counting method and allows for semi-automated determination of region of interest volumes. Significantly greater hippocampal atrophy was observed for participants reporting a life-changing religious experience. Significantly greater hippocampal atrophy was also observed from baseline to final assessment among born-again Protestants, Catholics, and those with no religious affiliation, compared with Protestants not identifying as born-again. These associations were not explained by psychosocial or demographic factors, or baseline cerebral volume. Hippocampal volume has been linked to clinical outcomes, such as depression, dementia, and Alzheimer's Disease. The findings of this study indicate that hippocampal atrophy in late life may be uniquely influenced by certain types of religious factors.

Chronic stress, cognitive functioning and mental health

This review aims to discuss the evidence supporting the link between chronic stress, cognitive function and mental health. Over the years, the associations between these concepts have been investigated in different populations. This review summarizes the findings that have emerged from older populations as well as from populations suffering from pathological aging, namely Mild Cognitive Impairment and Alzheimer's Disease. Although older adults are an interesting population to study in terms of chronic stress, other stress-related diseases can occur throughout the lifespan. The second section covers some of these stress-related diseases that have recently received a great deal of attention, namely burnout, depression, and post-traumatic stress disorder. Given that chronic stress contributes to the development of certain pathologies by accelerating and/or exacerbating pre-existing vulnerabilities that vary from one individual to the other, the final section summarizes data obtained on potential variables contributing to the association between chronic stress and cognition.

Brain anatomy of major depression II. Focus on amygdala

Here, we briefly summarize the most consistent structural magnetic resonance imaging (MRI) studies on amygdala in major depression and debate the effects of clinical variables on amygdalar morphology.

The hippocampus in major depression: evidence for the convergence of the bench and bedside in psychiatric research?

Major depressive disorder (MDD) has until recently been conceptualized as an episodic disorder associated with 'chemical imbalances' but no permanent brain changes. Evidence has emerged in the past decade that MDD is associated with small hippocampal volumes. This paper reviews the clinical and biological correlates of small hippocampal volumes based on literature searches of PubMed and EMBASE and discusses the ways in which these data force a re-conceptualization of MDD. Preclinical data describe the molecular and cellular effects of chronic stress and antidepressant treatment on the hippocampus, providing plausible mechanisms through which MDD might be associated with small hippocampal volumes. Small hippocampal volumes are associated with poor clinical outcome and may be a mechanism through which MDD appears to be a risk factor for Alzheimer's disease. The pathways through which stress may be linked to MDD, the emergence of chronicity or treatment resistance in MDD and the association between MDD and memory problems may be at least partially understood by dissecting the association with depression and changes in the hippocampus. MDD must be re-conceived as a complex illness, associated with persistent morphological brain changes that are detectable before illness onset and which may be modified by clinical and treatment variables.

The prefrontal-limbic network in depression: Modulation by hypothalamus, basal ganglia and midbrain

The anterior cingulate cortex, amygdala and hippocampus form part of an interconnected prefrontal neocortical and limbic archicortical network that is dysregulated in major depressive disorders (MDD). Modulation of this prefrontal-limbic network (PLN) is principally through the hypothalamus, basal ganglia and midbrain. Here the likely mechanisms by which these modulations are affected are described and the implications of their failure for depression associated with suicidal diathesis, late-life and psychoses discussed.

Survey of protocols for the manual segmentation of the hippocampus: preparatory steps towards a joint EADC-ADNI harmonized protocol

Manual segmentation from magnetic resonance imaging (MR) is the gold standard for evaluating hippocampal atrophy in Alzheimer's disease (AD). Nonetheless, different segmentation protocols provide up to 2.5-fold volume differences. Here we surveyed the most frequently used segmentation protocols in the AD literature as a preliminary step for international harmonization. The anatomical landmarks (anteriormost and posteriormost slices, superior, inferior, medial, and lateral borders) were identified from 12 published protocols for hippocampal manual segmentation ([Abbreviation] first author, publication year: [B] Bartzokis, 1998; [C] Convit, 1997; [dTM] deToledo-Morrell, 2004; [H] Haller, 1997; [J] Jack, 1994; [K] Killiany, 1993; [L] Lehericy, 1994; [M] Malykhin, 2007; [Pa] Pantel, 2000; [Pr] Pruessner, 2000; [S] Soininen, 1994; [W] Watson, 1992). The hippocampi of one healthy control and one AD patient taken from the 1.5T MR ADNI database were segmented by a single rater according to each protocol. The accuracy of the protocols' interpretation and translation into practice was checked with lead authors of protocols through individual interactive web conferences. Semantically harmonized landmarks and differences were then extracted, regarding: (a) the posteriormost slice, protocol [B] being the most restrictive, and [H, M, Pa, Pr, S] the most inclusive; (b) inclusion [C, dTM, J, L, M, Pr, W] or exclusion [B, H, K, Pa, S] of alveus/fimbria; (c) separation from the parahippocampal gyrus, [C] being the most restrictive, [B, dTM, H, J, Pa, S] the most inclusive. There were no substantial differences in the definition of the anteriormost slice. This survey will allow us to operationalize differences among protocols into tracing units, measure their impact on the repeatability and diagnostic accuracy of manual hippocampal segmentation, and finally develop a harmonized protocol.

Manic episodes are associated with grey matter volume reduction - a voxel-based morphometry brain analysis

OBJECTIVE

To investigate whether the lifetime number of affective episodes or illness duration is associated with changes in local grey matter volume, in patients with bipolar I disorder without comorbid conditions.

METHOD

Magnetic resonance imaging scans of 55 patients with bipolar I disorder were analysed using VBM.

RESULTS

Smaller grey matter volume in the inferior frontal gyri of the dorsolateral prefrontal cortices (DLPFC) correlated significantly to the lifetime number of manic episodes. No association between local grey matter volume and the lifetime number of depression episodes or illness duration was found.

CONCLUSION

We found strong evidence for a linear correlation between a decrease in DLPFC volume and the lifetime number of manic episodes in patients with bipolar I disorder. Interestingly, DLPFC is known to be important for executive functions and the findings in this study might hence be linked to the executive cognitive deficits associated with bipolar disorder.

Cortisol awakening response and hippocampal volume: vulnerability for major depressive disorder?

BACKGROUND

Major depressive disorder is associated with dysregulated basal cortisol levels and small hippocampal (HC) volume. However, it is still debated whether these phenomena are a consequence of the illness or whether they may represent a vulnerability marker existing before the illness onset. Here, we aimed to examine this notion of vulnerability by assessing whether abnormalities in basal cortisol secretion and HC volumes are already present in a sample of healthy young adults who showed varying levels of depressive tendencies, but at subclinical levels.

METHODS

We recruited healthy young men and women from the local university. On the basis of depression scores derived from standard questionnaires, three groups were formed: a control group (n = 27), a subclinical group (n = 23), and a high-risk subclinical group (n = 9). The participants underwent a magnetic resonance imaging scan and collected saliva samples for the assessment of diurnal cortisol levels.

RESULTS

Both the subclinical and the high-risk subclinical group failed to show a significant increase in cortisol levels after awakening. The high-risk subclinical group also showed a lower area-under-the-curve increase of cortisol levels after awakening compared with control subjects. In addition, this group also had smaller total HC volume compared with control subjects.

CONCLUSIONS

The findings from this subclinical sample suggest that dysregulated cortisol awakening response and small HC volume may constitute vulnerability factors for major depressive disorder. Further investigations are needed to discern the mechanisms that may underlie these phenomena.

Evidence for GABAergic inhibitory deficits in major depressive disorder

Converging evidence suggests that deficits in gamma-aminobutyric acid (GABA) functioning are implicated in the pathophysiology of major depressive disorder (MDD). This is highlighted by research investigating cortical inhibition (CI), a process whereby GABAergic interneurons selectively attenuate pyramidal neurons. Transcranial magnetic stimulation (TMS) paradigms evaluate this marker of neuronal inhibitory activity in the cortex. This review will examine the neuroanatomic and neurophysiological evidence from neuroimaging, molecular, treatment, and TMS studies linking dysfunctional GABAergic neurotransmission to MDD.

Hippocampal volumetrics in treatment-resistant depression and schizophrenia: the devil's in de-tail

Studies of patients with major depressive disorder (MDD) and schizophrenia (SCH) have revealed reduced hippocampal volumes, but findings have been inconsistent due to sample and measurement differences. The current study sought to measure this structure in a large sample of MDD, SCH, and healthy subjects, using a strict measurement protocol, to elucidate morphological-specific volumetric differences. Patients with treatment-resistant MDD (N = 182) and treatment-resistant SCH with auditory-verbal hallucinations (N = 52), and healthy controls (N = 76) underwent psychiatric assessments and brain MRI. The findings indicate that (1) MDD and SCH patients have reduced total hippocampal volume which was marked in the tails (more so in patients with MDD), (2) region of interest estimation protocols and sample characteristics may help explain volumetric differences between previous SCH studies.

Orbitofrontal volume reductions during emotion recognition in patients with major depression

BACKGROUND

Major depressive disorder is associated with both structural and functional alterations in the emotion regulation network of the central nervous system. The relation between structural and functional changes is largely unknown. Therefore, we sought to determine the relation between structural differences and functional alterations during the recognition of emotional facial expressions.

METHODS

We examined 13 medication-free patients with major depression and 15 healthy controls by use of structural T1-weighted high-resolution magnetic resonance imaging (MRI) and functional MRI during 1 session. We set the statistical threshold for the analysis of imaging data to p < 0.001 (uncorrected).

RESULTS

As shown by voxel-based morphometry, depressed patients had reductions in orbitofrontal cortex volume and increases in cerebellar volume. Additionally, depressed patients showed increased activity during emotion recognition in the middle frontal cortex, caudate nucleus, precuneus and lingual gyrus. Within this cerebral network, the orbitofrontal volumes were negatively correlated in depressed patients but not in healthy controls with changes in blood oxygen level-dependent signal in the middle frontal gyrus, caudate nucleus, precuneus and supplementary motor area.

LIMITATIONS

Our results are limited by the relatively small sample size.

CONCLUSIONS

This combined functional and structural MRI study provides evidence that the orbitofrontal cortex is a key area in major depression and that structural changes result in functional alterations within the emotional circuit. Whether these alterations in the orbitofrontal cortex are also related to persistent emotional dysfunction in remitted mental states and, therefore, are related to the risk of depression needs further exploration.

Structural changes in the hippocampus in major depressive disorder: contributions of disease and treatment

BACKGROUND

Previous magnetic resonance imaging (MRI) studies of patients with major depressive disorder (MDD) have consistently shown bilateral and unilateral reductions in hippocampal volume relative to healthy controls. Recent structural MRI studies have addressed the question of whether changes in the volume of hippocampal subregions may be associated with MDD.

METHODS

We used a comprehensive and reliable 3-dimensional tracing protocol that enables delineation of hippocampal subregions (head, body, tail) to study changes in the hippocampus of patients with MDD. We recruited 39 MDD patients (16 medicated, 23 unmedicated) and 34 healthy age- and sex-matched controls. We acquired images using a magnetization-prepared rapid acquisition gradient echo sequence on a 1.5-T scanner with a spatial resolution of 1.5 mm x 0.5 mm x 0.5 mm. We performed volumetric analyses, blinded to diagnosis, using the interactive software package Display. All volumes were adjusted for intracranial volume.

RESULTS

We found a significant reduction in the volume of the hippocampal tail bilaterally, right hippocampal head and right total hippocampus in MDD patients. Medicated MDD patients showed increased hippocampal body volume compared with both healthy controls and unmedicated patients.

LIMITATIONS

This study was cross-sectional. Further prospective studies are needed to determine the direct effect of antidepressant treatment.

CONCLUSION

Our results suggest that decreased hippocampal tail and hippocampal head volumes could be trait changes, whereas hippocampal body changes may be dependent on treatment. We showed that long-term antidepressant treatment may affect hippocampal volume in patients with MDD.

Impaired off-line memory consolidation in depression

Sleep is critically involved in the consolidation of procedural memory. In major depression (MD) and during antidepressant pharmacotherapy, changes in sleep EEG are well documented. Here, we test if off-line motor memory consolidation is impaired in MD. 50 medicated patients with an acute episode of MD, 50 normal controls and 12 patients with a remitted episode of MD were assessed using a sequential finger tapping task before and after a night of sleep. Although depressed patients and control subjects did not differ in practice-dependent learning, healthy subjects showed markedly overnight improvements in tapping performance of 18% while patients failed to show any improvement. This pattern became even more striking when the subjects were divided by an age threshold of 30years: In the 30+yrs group the healthy subjects showed 16% overnight increase in motor performance, whereas the patients showed -10% overnight decrease. In contrast, patients and controls in the </=30yrs group showed virtually the same motor performance, as well as remitted patients and controls in the 30+yrs group. In addition, the younger controls showed stronger overnight improvements than the older controls. This pattern might be interpreted as a synergistic interaction between age and depression: Off-line motor memory consolidation is not affected in young patients, but severely impaired in older patients with an acute episode of MD. This impairment seems to recover after remission from depression.

Behavioral and neurobiological consequences of prolonged glucocorticoid exposure in rats: relevance to depression

Stress is a critical environmental trigger for the development of clinical depression, yet little is known about the specific neurobiological mechanisms by which stress influences the development of depressive symptomatology. Animal models provide an efficient way to study the etiology of human disorders such as depression, and a number of preclinical models have been developed to assess the link between stress, glucocorticoids, and depressive behavior. These mode ls typically make use of repeated exposure to physical or psychological stressors in rodents or other small laboratory animals. This review focuses primarily on a recently developed preclinical model of depression that uses exogenous administration of the stress hormone corticosterone (CORT) in rodents instead of exposure to physical or psychological stressors. Repeated CORT administration in rats or mice produces reliable behavioral and neurobiological alterations that parallel many of the core symptoms and neurobiological changes associated with human depression. This provides an opportunity to study behavior and neurobiology in the same animal, so that the neurobiological factors that underlie specific symptoms can be identified. Taken together, these findings suggest that exogenous CORT administration is a useful method for studying the relationship between stress, glucocorticoids, and depression. Further study with this model may provide important new data regarding the neurobiological bases of depression.

Sustained stress-induced changes in mice as a model for chronic depression

RATIONALE

Major depression is a chronic disabling disorder, often preceded by stress. Despite emerging clinical interest in mechanisms perpetuating episodes of depression and/or establishing increased vulnerability for relapse, little attention has been paid to address these aspects in experimental models. Here, we studied the long-term neuroadaptive effects of chronic mild stress (CMS) as well as the effectiveness of a course of an antidepressant treatment.

METHODS

CMS was applied for 6 weeks, and paroxetine was administered from the third week and continued for 2 weeks thereafter. In order to validate our CMS procedure, we first studied short-term (24 h after CMS) hippocampal cell proliferation and neurogenesis, along with anhedonic-like behaviour. Subsequently, we examined the long-term (one month after CMS) anhedonia, hippocampal neurogenesis, the regulation of c-Fos immunoreactivity and neurotransmitter levels in different areas as well as cortical spine density and hippocampal expression of synaptic proteins.

RESULTS

CMS induced a decrease in short-term neurogenesis that was fully recovered in the long term. In addition, CMS-induced lasting anhedonia and region-specific changes in neuronal activity (c-Fos immunoreactivity) and neurotransmitter (glutamate and GABA) levels. Repeated paroxetine reverted these effects with the exception of decreased neuronal activity in the dentate gyrus (DG) and GABA levels in the ventral hippocampus. Moreover, CMS downregulated the GAD65 and VGLUT1 expressions.

CONCLUSION

This study shows region-specific long-term neurobiological adaptations induced by CMS and residual hippocampal signs after paroxetine treatment. We propose the use of this model to study molecular mechanisms involved in chronic depression and vulnerability for relapse.

Hippocampus, glucocorticoids and neurocognitive functions in patients with first-episode major depressive disorders

The aim of this study was to determine whether there was any relationship between hippocampal volume, and glucocorticoid regulation, and cognitive dysfunctions in drug-naïve major depressive disorder (MDD) patients during their first episode. Twenty drug-free female MDD patients in their first episode and 15 healthy females as control subjects were included in the study. All subjects underwent 3.0 Tesla (T) magnetic resonance imaging (MRI), comprehensive neuropsychological testing and dexamethasone suppression tests (DST). The volumes of the right and left hippocampus of the patients were found to be significantly smaller than those of the controls. Patients were found to have significantly lower scores on measures of attention, working memory, psychomotor speed, executive functions, and visual and verbal memory fields. The performance of the patients only in the recollection memory and memory of reward-associated rules were positively correlated with hippocampal volumes. The volumes of the left and right hippocampus did not correlate with basal or post-dexamethasone cortisol levels. Our findings indicate that depressed patients have smaller hippocampi even in the earlier phase of their illness. Further research efforts are needed to explain the mechanisms that are responsible for the small hippocampus in depressed patients.

Differences in hippocampal volume between major depression and schizophrenia: a comparative neuroimaging study

Several studies have demonstrated that structural brain change is detectable in the hippocampus in both patients, with schizophrenia and major depression. Only few studies, however, compared both clinical disease entities directly and no larger study has tried to take different disease stages into account. The objectives of this study are to investigate whether hippocampal volumes are reduced in patients with schizophrenia and those with major depression with the same duration of illness compared to healthy controls and to assess further changes at different disease stages. A total of 319 inpatients and healthy controls were enrolled and investigated with magnetic resonance imaging (MRI). Hippocampal volumes were measured using the segmentation software BRAINS. Bilateral hippocampal volume reductions were detected in both schizophrenic and depressed patients compared to healthy control (HC) subjects. Although younger, schizophrenic (SZ) patients showed in their MRI scans significant bilaterally reduced hippocampal volumes compared to patients with major depression. Although the hippocampal reductions were similar at the onset of symptomatic manifestation of both diseases, there was a further significant reduction of the left hippocampus in the recurrently ill SZ subgroup. The data suggest rather dynamic structural brain alterations in schizophrenia compared to major depression. Here, the presented application of the comparative neuroscience approach, by the use of large neuroimaging MRI databases, seems highly valuable. In the field of psychiatry, with its still controversial operationalized descriptive diagnostic entities, the cross-nosological approach provides a helpful tool to better elucidate the still unknown brain pathologies and their underlying molecular mechanisms beyond a single nosological entity.

[Cholinesterase inhibitors and depression in the elderly]

BACKGROUND

Depression in the elderly is characterized by an atypical expression with delusion, major anxiety, behaviour disorders, somatic complains or cognitive impairment. These clinical aspects are suspected to be at the origin of the poor response to antidepressants observed in these cases. It is currently indicated to add sedative medicines to antidepressants, when a major anxiety is associated with depression, or an antipsychotic in the delusional forms of the depression. However, it is not consensually established that cholinesterase inhibitors can be helpful in depression with cognitive impairment. Cholinesterase inhibitors are efficient among patients with Alzheimer disease. They improve cognitive performances and slow down the degenerative process during the first years of treatment. Today, new findings on neurobiological mechanisms of depression involve a located degenerative process, with some similar anomalies in the brain in both depression and pre-Alzheimer states. New therapeutic trials have shown that cholinesterase inhibitors can be also efficient on depressed symptoms among patients with Alzheimer disease. These evidences support the hypothesis that the association of cholinesterase inhibitors to antidepressants can bring more benefits to depressed elderly patients.

AIM

Through a review of the literature and a case report, we tried to specify whether cholinesterase inhibitors can be useful in the treatment of depression among the elderly.

CASE REPORT

We report the case of a 68-year-old man who had presented, four years ago, a second episode of major depression with a cognitive impairment. Treated with an antidepressant (venlafaxine), the improvement was poor with major anxiety, slow thoughts, and an evidence of a persistent cognitive impairment. Despite normal cerebral scanning images, we decided to add a cholinesterase inhibitor (donepezil) to the same antidepressant. With this association, we rapidly obtained a total remission from depression with restitution of cognitive performances. This state is still maintained until today (four years after the last depressive episode) with no new mood relapses. Recent cerebral scanning images did not show any degenerative process.

CONCLUSION

The association of cholinesterase inhibitors and an antidepressant seems a good alternative, when the response to antidepressant is partial in depression with cognitive impairment in the elderly. However, further therapeutic trials are still needed, to prove the usefulness of cholinesterase inhibitors among depressed elderly patients.