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

Psychomotor retardation: What about the partial responders to magnetic transcranial stimulation in treatment resistant depression ?

OBJECTIVE

Psychomotor retardation is a core clinical component of Major Depressive Disorder responsible for disability and is known as a treatment response marker of biological treatments for depression. Our objective was to describe cognitive and motoric measures changes during a treatment by repetitive Transcranial Magnetic Stimulation (rTMS) within the THETAD-DEP trial for treatment-resistant depression (TRD), and compare those performances at the end of treatment and one month after between responders (>50% improvement on MADRS score), partial responders (25-50%) and non-reponders (no clinically relevant improvement). Our secondary aim was to investigate baseline psychomotor performances associated with non-response and response even partial.

METHODS

Fifty-four patients with treatment-resistant unipolar depression and treated by either high frequency 10 Hz rTMS or iTBS for 4 weeks (20 sessions) underwent assessment including French Retardation Rating Scale for Depression (ERD), Verbal Fluency test, and Trail Making Test A. before, just after treatment and one month later.

RESULTS

20 patients were responders (R, 21 partial responders (PR) and 13 non-responders (NR). rTMS treatment improved psychomotor performances in the R and PR groups unlike NR patients whose psychomotor performance was not enhanced by treatment. At baseline, participants, later identified as partial responders, showed significantly higher performances than non-responders.

CONCLUSION

Higher cognitivo-motor performances at baseline may be associated with clinical improvement after rTMS treatment. This work highlights the value of objective psychomotor testing for the identification of rTMS responders and partial responders, and thus may be useful for patient selection and protocol individualization such as treatment continuation for early partial responders.

The pattern glare and visual memory are disrupted in patients with major depressive disorder

BACKGROUND

Visual memory impairment is one of the most commonly complained symptoms in patients with major depressive disorder (MDD). Pattern glare is also a distorted visual phenomenon that puzzles patients with MDD. Nevertheless, how these two phenomena interact in MDD remains unknown. This study investigated the association between pattern glare and visual memory in MDD patients.

METHODS

Sixty-two patients with MDD and forty-nine age-, sex- and education level-matched healthy controls (HCs) were included in this study. The Pattern Recognition Memory (PRM) test and the Brief Visual Memory Test-Revised (BVMT-R) were applied to measure visual memory. The pattern glare test including three patterns with different spatial frequencies (SFs) was used to explore pattern glare levels.

RESULTS

Patients with MDD scored lower on the PRM-PCi, BVMT-R1, BVMT-R2, BVMT-R3, and BVMT-Rt and higher on the PRM-MCLd than HCs (all p < 0.05). Pattern glare scores for MDD patients were higher with mid-SF (p < 0.001), high-SF (p = 0.006) and mid-high SF differences (p = 0.01) than for HCs. A positive correlation between mid-SF and PRM-MCLd scores in all participants was observed (p = 0.01, r = 0.246). A negative correlation between mid-high difference scores and BVMT-R2 scores (p = 0.032, r = -0.317) was observed in HCs, but no significant correlation was observed in MDD patients.

CONCLUSIONS

The present study showed that visual memory and pattern glare are disrupted in MDD. Visual memory may be associated with pattern glare and needs to be studied in future work.

The anticholinergic burden is not associated with cognitive impairments in patients treated by electroconvulsive therapy for treatment-resistant depression

BACKGROUND

Electroconvulsive therapy (ECT) is the most effective non-pharmacological treatment for treatment-resistant depression (TRD) but can expose to transient cognitive impairments. Understanding factors underlying these cognitive side effects is important. This study investigated the impact of anticholinergic treatments on cognitive performances after ECT courses for TRD in naturalistic condition.

METHODS

Impact of anticholinergic burden (Anticholinergic Impregnation Scale, AIS) on cognitive changes (Montreal Cognitive Assessment, MoCA) adjusted on depression level (Montgomery and Asberg Depression Scale, MADRS) was investigated in 42 patients who received an ECT course between 2017 and 2020 for unipolar or bipolar TRD. Collection of daily treatments given during ECT was carried out via the computerized traceability of treatments validated by nurses.

RESULTS

Among the 31 treatments identified with an anticholinergic score, which represent only 38% of total treatments, the three most frequently given treatments were Lorazepam (47%), Venlafaxine (36%) and Cyamemazine (26%). Delayed recall was the most frequently impaired cognitive function after ECT courses. Using logistic regression, we found no association between the anticholinergic burden and the decrease in cognitive scores after ECT courses, adjusted on MADRS score evolution (p > 0.1). Conversely, improvement in MADRS scores were correlated with improvement in attention MoCA subscores.

LIMITATIONS

This is a retrospective monocentric study with a moderate sample size using anticholinergic scales to calculate the anticholinergic burden without plasma dosage.

CONCLUSION

Anticholinergic treatments did not seem to explain ECT-related cognitive impairments. This warrants further large prospective investigations including different measures of anticholinergic burden.

Functional and cognitive impairment in the first episode of depression: A systematic review

OBJECTIVES

To describe the cognitive and functional impairment in individuals with the first episode of major depressive disorder (MDD) as compared to controls and individuals with recurrent MDD. Also to describe the functional and cognitive trajectory after the first episode of MDD.

METHODS

A total of 52 studies were included in our systematic review. 32 studies compared the cognitive performance between first episode of depression (FED) and controls, 11 studies compared the cognitive performance between recurrent depression (RD) and FED, 10 compared global functioning between RD and FED, four studies assessed cognition in FED over time, and two studies assessed global functioning in FED over time.

RESULTS

The majority of studies (n = 22/32, 68.8%) found that FED subjects performed significantly worse than controls on cognitive tests, with processing speed (n = 12) and executive/working memory (n = 11) being the most commonly impaired domains. Seven out of 11 studies (63.6%) found that RD performed significantly worse than FED, with verbal learning and memory being the most commonly impaired domain (n = 4). Most studies (n = 7/10, 70%) did not find a significant difference in global functioning between RD and FED. In three of four longitudinal studies assessing cognition, subgroup analyses were used instead of directly assessing cognition in FED over time while the remaining study found significant cognitive declines over time in FED when compared to controls. The two longitudinal studies assessing functional trajectory found that functioning significantly improved over time, possibly due to the improvement of depressive symptoms.

CONCLUSION

There is strong evidence that cognitive impairment is present during the first episode of depression, and individuals with multiple episodes display greater cognitive impairment than individuals with a single episode. Future studies aimed at identifying predictors of cognitive and functional impairment after the first episode of depression are needed to describe the functional and cognitive trajectory of individuals with the first episode of MDD over time.

Using Network Parcels and Resting-State Networks to Estimate Correlates of Mood Disorder and Related Research Domain Criteria Constructs of Reward Responsiveness and Inhibitory Control

BACKGROUND

Resting-state graph-based network edges can be powerful tools for identification of mood disorders. We address whether these edges can be integrated with Research Domain Criteria (RDoC) constructs for accurate identification of mood disorder-related markers, while minimizing active symptoms of disease.

METHODS

We compared 132 individuals with currently remitted or euthymic mood disorder with 65 healthy comparison participants, ages 18-30 years. Subsets of smaller brain parcels, combined into three prominent networks and one network of parcels overlapping across these networks, were used to compare edge differences between groups. Consistent with the RDoC framework, we evaluated individual differences with performance measure regressors of inhibitory control and reward responsivity. Within an omnibus regression model, we predicted edges related to diagnostic group membership, performance within both RDoC domains, and relevant interactions.

RESULTS

There were several edges of mood disorder group, predominantly of greater connectivity across networks, different than those related to individual differences in inhibitory control and reward responsivity. Edges related to diagnosis and inhibitory control did not align well with prior literature, whereas edges in relation to reward responsivity constructs showed greater alignment with prior literature. Those edges in interaction between RDoC constructs and diagnosis showed a divergence for inhibitory control (negative interactions in default mode) relative to reward (positive interactions with salience and emotion network).

CONCLUSIONS

In conclusion, there is evidence that prior simple network models of mood disorders are currently of insufficient biological or diagnostic clarity or that parcel-based edges may be insufficiently sensitive for these purposes.

Reduced anterior cingulate cortex volume induced by chronic stress correlates with increased behavioral emotionality and decreased synaptic puncta density

Clinical and preclinical studies report that chronic stress induces behavioral deficits as well as volumetric and synaptic alterations in corticolimbic brain regions including the anterior cingulate cortex (ACC), amygdala (AMY), nucleus accumbens (NAc) and hippocampus (HPC). Here, we aimed to investigate the volumetric changes associated with chronic restraint stress (CRS) and link these changes to the CRS-induced behavioral and synaptic deficits. We first confirmed that CRS increases behavioral emotionality, defined as collective scoring of anxiety- and anhedonia-like behaviors. We then demonstrated that CRS induced a reduction of total brain volume which negatively correlated with behavioral emotionality. Region-specific analysis identified that only the ACC showed significant decrease in volume following CRS (p < 0.05). Reduced ACC correlated with increased behavioral emotionality (r = -0.56; p = 0.0003). Although not significantly altered by CRS, AMY and NAc (but not the HPC) volumes were negatively correlated with behavioral emotionality. Finally, using structural covariance network analysis to assess shared volumetric variances between the corticolimbic brain regions and associated structures, we found a progressive decreased ACC degree and increased AMY degree following CRS. At the cellular level, reduced ACC volume correlated with decreased PSD95 (but not VGLUT1) puncta density (r = 0.35, p < 0.05), which also correlated with increased behavioral emotionality (r = -0.44, p < 0.01), suggesting that altered synaptic strength is an underlying substrate of CRS volumetric and behavioral effects. Our results demonstrate that CRS effects on ACC volume and synaptic density are linked to behavioral emotionality and highlight key ACC structural and morphological alterations relevant to stress-related illnesses including mood and anxiety disorders.

Brain Structure and Subclinical Symptoms: A Dimensional Perspective of Psychopathology in the Depression and Anxiety Spectrum

Human psychopathology is the result of complex and subtle neurobiological alterations. Categorial DSM or ICD diagnoses do not allow a biologically founded and differentiated description of these diverse processes across a spectrum or continuum, emphasising the need for a scientific and clinical paradigm shift towards a dimensional psychiatric nosology. The subclinical part of the spectrum is, however, of special interest for early detection of mental disorders. We review the current evidence of brain structural correlates (grey matter volume, cortical thickness, and gyrification) in non-clinical (psychiatrically healthy) subjects with minor depressive and anxiety symptoms. We identified 16 studies in the depressive spectrum and 20 studies in the anxiety spectrum. These studies show effects associated with subclinical symptoms in the hippocampus, anterior cingulate cortex, and anterior insula similar to major depression and changes in amygdala similar to anxiety disorders. Precuneus and temporal areas as parts of the default mode network were affected specifically in the subclinical studies. We derive several methodical considerations crucial to investigations of brain structural correlates of minor psycho(patho)logical symptoms in healthy participants. And we discuss neurobiological overlaps with findings in patients as well as distinct findings, e.g. in areas involved in the default mode network. These results might lead to more insight into the early pathogenesis of clinical significant depression or anxiety and need to be enhanced by multi-centre and longitudinal studies.

Assessing Pragmatic Language Skills in Adults with Major Depressive Disorder: An Exploratory Study

INTRODUCTION

There is increasing evidence that major depressive disorder (MDD) is associated with significant pragmatic language impairments. However, there is a lack of studies that use standardized tools and simultaneously investigate all pragmatic language skills among MDD patients. The aim of this study was to propose a more thorough investigation of all pragmatic language skills in patients with MDD.

METHODS

Twenty adults (aged 22-65) with a DSM-5 diagnosis of MDD were assessed using BLED Santa Lucia (Batteria sul Linguaggio dell'Emisfero Destro Santa Lucia), a battery designed to evaluate pragmatic language skills (comprehension of inferences, of picture and written metaphors, of indirect requests, of humoristic expressions, and of prosody). The performance of the MDD participants on all BLED Santa Lucia subscales was compared to 20 healthy control subjects (aged 20-60) matched for gender, age, years of education, and employment status.

RESULTS

MDD patients performed poorer than controls in comprehension of inferences (p < 0.01), picture metaphors (p < 0.001), written metaphors (p < 0.001), indirect requests (p < 0.01), humoristic expression (p < 0.05), and prosody (p < 0.05).

CONCLUSIONS

All pragmatic language skills can be significantly impaired in MDD patients. A valid assessment of all pragmatic language skills can allow, for each patient, the definition of a specific profile of risk and protective factors before and during psychotherapy.

Performances on individual neurocognitive tests by people experiencing a current major depression episode: A systematic review and meta-analysis

BACKGROUND AND PURPOSES

Previous meta-analyses on neurocognitive test performances in depression have provided effect sizes for cognitive domains. Most domain effect sizes have medium to high variance heterogeneity. Restriction to each test performance could reduce variance and clarify differing test effect sizes. This systematic review and meta-analysis were done to 1. provide effect sizes for cognitive performances (test, subtest, or multiple measures within tests), and 2. investigate age as an effect modifier.

METHODS

Inclusion criteria were: 1. active major depression episode (MD), 2. a control group, 3 reported means and standard deviations, 4. non-computerized tests previously studied at least 3 times. Meta-analyses were performed using Cochrane Review Manager. Age under versus over 45 was investigated as an effect moderator.

RESULTS

Twenty-seven studies met criteria. MD patients performed significantly poorer on 16 of 16 neurocognitive measures (random effects d = -0.47 to -0.92 across tests). Variance was heterogeneous for 11 of 16 measures. Differences between cognitive measures were largely absent based on overlapping 95% confidence intervals. Effect sizes did not differ under versus over 45 years.

LIMITATIONS

Bias risk assessment showed limited control for subject selection, comparability of depressed and control groups, pre-morbid intelligence, drug treatment, and effort in testing.

CONCLUSIONS

The depression - cognition effect was in the moderate to large range regardless of test type. Variance heterogeneity was substantial despite exclusion of inactive depression and the absence of test pooling. The size of the depression - cognition effect was not a function of age.

Attention deficits in adults with Major depressive disorder: A systematic review and meta-analysis

Attention deficits have been proven in patients with major depressive disorder (MDD). However, a detailed characterization of attention deficits in MDD was unclear. The aim of current study was to explore the specific deficits of attention in different sub-domains of attention so as to produce an overall picture of contemporary research on this field. We performed a systematic review and meta-analysis of published researches. PubMed, EMBASE, Cochrane Library and review of references were searched up to October 2019. Studies using at least one objective measurement to assess attention performances of MDD patients were included. Effect sizes were calculated using random-effects models for attention outcomes. Publication bias was evaluated using Egger's test. Twenty-three eligible studies including 1371 MDD patients were enrolled in this meta-analysis. Significant deficit of global attention was observed. For the specific outcomes, MDD patients showed significant deficits in psychomotor speed/attention, auditory attention, visuo-spatial attention, sustained visual attention, ranging from small to moderate, but not in selective attention. Larger sample sizes and more detailed subgroup analyses based on features of patients should be conducted to produce a more accurate conclusion.

Depression related cerebral pathology and its relationship with cognitive functioning: A systematic review

BACKGROUND

Depression's relationship with cerebral abnormalities and cognitive decline is temporally dynamic. Despite clear clinical utility, understanding depression's effect on cerebral structures, cognitive impairment and the interaction between these symptoms has had limited consideration.

METHODS

This review summarised studies examining a clinical depression diagnosis or validated scales measuring depressive symptoms, data concerning amyloid-beta (Aβ) levels, brain structure and function focusing on hippocampal alterations, or white matter hyperintensities (WMH), and at least one validated neuropsychological test. Online database searches of: PsycINFO, EMBASE, MEDLINE, and Scopus were conducted to identify potential articles.

RESULTS

While depression was consistently associated with cross-sectionally cognitive decline across multiple domains, the neuropathological basis of this dysfunction remained unclear. Hippocampal, frontal, and limbic dysfunction as well as cortical thinning, WMH, and Aβ burden all provide inconsistent findings, likely due to depression subtypes. The consistency of these findings additionally decreases when examining this relationship longitudinally, as these results are further confounded by pre-dementia states. The therapeutic interventions examined were more efficacious in the younger compared with the older samples, who were characterised by greater WMH and Aβ burden.

LIMITATIONS

The limited number of longitudinal and interventional studies in addition to the heterogeneity of the samples restricts their generalisability.

CONCLUSIONS

Symptomatological differences between early-onset and late-onset depression (EOD and LOD) appear crucial in understanding whether late-life depression is the primary or secondary source of cerebral pathology. Though severe cognitive impairments and clearer neuropathological underpinnings are more characteristic of LOD than EOD, the inconsistency of valid biomarkers remains problematic.

The Impact of Stress and Major Depressive Disorder on Hippocampal and Medial Prefrontal Cortex Morphology

Volumetric reductions in the hippocampus and medial prefrontal cortex (mPFC) are among the most well-documented neural abnormalities in major depressive disorder (MDD). Hippocampal and mPFC structural reductions have been specifically tied to MDD illness progression markers, including greater number of major depressive episodes (MDEs), longer illness duration, and nonremission/treatment resistance. Chronic stress plays a critical role in the development of hippocampal and mPFC deficits, with some studies suggesting that these deficits occur irrespective of MDE occurrence. However, preclinical and human research also points to other stress-mediated neurotoxic processes, including enhanced inflammation and neurotransmitter disturbances, which may require the presence of an MDE and contribute to further brain structural decline as the illness advances. Specifically, hypothalamic-pituitary-adrenal axis dysfunction, enhanced inflammation and oxidative stress, and neurotransmitter abnormalities (e.g., serotonin, glutamate, gamma-aminobutyric acid) likely interact to facilitate illness progression in MDD. Congruent with stress sensitization models of MDD, with each consecutive MDE it may take lower levels of stress to trigger these neurotoxic pathways, leading to more pronounced brain volumetric reductions. Given that stress and MDD have overlapping and distinct influences on neurobiological pathways implicated in hippocampal and mPFC structural decline, further work is needed to clarify which precise mechanisms ultimately contribute to MDD development and maintenance.

Similar profiles of cognitive domain deficits between medication-naïve patients with bipolar II depression and those with major depressive disorder

BACKGROUND

Bipolar disorder (BD) II is more likely to be misdiagnosed as major depressive disorder (MDD) than other types of BD, leading to incorrect treatment and poor outcomes. Previous studies have shown inconsistent results regarding the differences in cognitive deficits between the two disorders. To eliminate the compounding effects of medication and aging, we sought to investigate changes in cognitive function in medication-naïve, non-late-life patients with BDII and MDD.

METHODS

Three subject groups were enrolled: 30 depressed BDII patients, 30 depressed MDD patients and 30 healthy controls. All subjects underwent a battery of cognitive tests to assess 8 cognitive domains. The cognitive domains were compared between the three subject groups. In BDII and MDD, the effect sizes were computed as evaluation parameters, weighing the degree of the cognitive deficits and the correlations between cognitive test deficits and clinical variables were also computed.

RESULTS

Compared with the controls, the BDII and MDD patients were characterized by similar deficits in psychomotor speed, working memory, visual memory, attention switching and verbal fluency. Moderate to severe deficits in the majority of cognitive tests were observed in the BDII and MDD patients. Furthermore, correlations between the modified Wisconsin Card Sorting Test total errors and age of onset in the BDII patients and between correct digit span responses (backward and total) and depressive severity were found in the MDD patients.

CONCLUSIONS

Our findings suggest that BDII and MDD patients may suffer from similar profiles of cognitive domain deficits that may not assist in distinguishing between the two disorders. In addition, cognitive deficits may be correlated with the age of onset and depressive severity in mood disorders.

Cortisol levels and cognitive profile in major depression: A comparison of currently and previously depressed patients

The association between depressive symptoms and elevated cortisol levels, and depression and cognitive functioning, has been less robust in outpatients with symptoms in the mild to moderate range. Furthermore, the association between elevated cortisol levels and cognitive functioning is unclear. In the present study, currently depressed (n = 37), previously depressed (n = 81) and never depressed controls (n = 50) were assessed on a range of neuropsychological measures. Salivary cortisol was measured in the morning and evening. Participants with current depression were non-hospitalized and had symptoms predominately in the mild to moderate range. Elevated salivary evening cortisol, but not morning cortisol, was significantly related to depressive symptoms. The difference in cortisol levels between the previously depressed group and the never depressed controls was not significant. The groups had significantly different cognitive profiles, with the currently depressed performing poorer on tasks related to working memory compared to the never depressed controls. Both the currently and previously depressed performed worse on attentional tasks. The findings indicate that outpatients with mild to moderate depression have elevated cortisol levels and limited mild cognitive impairments. Furthermore, mild impairments in attention may persist after remission, indicating that this could be a trait-marker in depression. The present study did not find support for a significant relationship between cortisol and cognitive functioning.

Global hippocampal atrophy in major depressive disorder: a meta-analysis of magnetic resonance imaging studies

INTRODUCTION

Major depressive disorder (MDD), an incapacitating mental disorder, is characterized by episodes of at least 2 weeks of apparent changes in mood, cognition, and neurovegetative functions. Many neuroimaging studies using magnetic resonance imaging (MRI) have examined morphometric changes in patients with MDD, but the results are not conclusive. This study aims to review the literature and perform a meta-analysis on hippocampal volume (HcV) in patients with MDD.

METHODS

Studies on HcV in patients with MDD diagnosis were identified from major databases (MEDLINE, EMBASE, The Cochrane Library, Scopus, PsycINFO, and SciELO) using the search terms depression, major depressive disorder, MDD, unipolar, magnetic resonance imaging, MRI, and hippocampus.

RESULTS

A meta-analysis of 29 studies fulfilling specific criteria was performed. The sample included 1327 patients and 1004 healthy participants. The studies were highly heterogeneous with respect to age, sex, age of onset, and average illness duration. However, the pooled effect size of depression was significant in both hippocampi. MDD was associated with right (-0.43; 95% confidence interval [95%CI] -0.66 to -0.21) and left (-0.40; 95%CI -0.66 to -0.15) hippocampal atrophy.

CONCLUSIONS

MDD seems to be associated with global HcV atrophy. Larger longitudinal follow-up studies designed to analyze the influence of sociodemographic variables on this relationship are required to yield better evidence about this topic.

Cognitive impairment and medial temporal lobe structure in young adults with a depressive episode

BACKGROUND

Cognitive deficits are common in patients with a depressive episode although the predictors for their development and severity remain elusive. We investigated whether subjective and objective cognitive impairment in young depressed adults would be associated with cortical thinning in medial temporal subregions.

METHODS

High-resolution magnetic resonance imaging, cortical unfolding data analysis, and comprehensive assessments of subjective and objective cognitive abilities were performed on 27 young patients with a depressive episode (mean age: 29.0 ± 5.8 years) and 23 older participants without a history of a depressive disorder but amnestic mild cognitive impairment (68.5 ± 6.6 years) or normal cognition (65.2 ± 8.7 years).

RESULTS

Thickness reductions in parahippocampal, perirhinal and fusiform cortices were associated with subjective memory deficits only among young patients with a depressive episode and a measurable cognitive impairment.

LIMITATIONS

Long-term longitudinal data would be desirable to determine the trajectories of cognitive impairment associated with depression in patients with or without cortical structure changes.

CONCLUSIONS

The presence of clinically significant cognitive deficits in young people with a depressive episode may identify a patient population with extrahippocampal cortical thinning.

The impact from the aftermath of chronic stress on hippocampal structure and function: Is there a recovery?

Chronic stress results in functional and structural changes to the brain and especially the hippocampus. Decades of research have provided insights into the mechanisms by which chronic stress impairs hippocampal-mediated cognition and the corresponding reduction of hippocampal CA3 apical dendritic complexity. Yet, when chronic stress ends and time passes, which we refer to as a "post-stress rest period," hippocampal-mediated spatial memory deficits begin to improve and CA3 apical dendritic arbors increase in complexity. The processes by which the hippocampus improves from a chronically stressed state are not simply the reversal of the mechanisms that produced spatial memory deficits and CA3 apical dendritic retraction. This review will discuss our current understanding of how a chronically stressed hippocampus improves after a post-stress rest period. Untangling the mechanisms that allow for this post-stress plasticity is a critical next step in understanding how to promote resilience in the face of stressors.

Evaluation of the benefits of exercise on cognition in major depressive disorder

BACKGROUND

Cognitive impairment is increasingly recognized as a significant symptom in patients with major depressive disorder (MDD). While exercise is already recommended in many treatment guidelines for patients with MDD and has been shown to improve cognition in other disorders (e.g., Alzheimer's, Parkinson's, schizophrenia), limited research is available evaluating the effect of exercise on cognition in MDD.

METHODS

We provide a narrative review of existing literature regarding the effect(s) of exercise on cognition across several neurodegenerative and psychiatric diseases, and particularly in MDD, with specific emphasis on study design and methodology that may impair adequate synthesis of the results. We also describe mechanisms by which exercise may improve cognition in depression and other brain disorders.

RESULTS

Of existing studies with MDD, data are equivocal, as some are supportive of improved cognition, whereas others demonstrate no benefit. Several limitations were noted, including insufficiently-powered designs, variability in interventions examined (e.g., aerobic, anaerobic, mind-body) or control groups, lack of attention to the status of baseline cognitive impairment, and/or heterogeneity across outcome measures and clinical characteristics.

CONCLUSIONS

While preliminary results suggest the potential for exercise as a beneficial treatment or augmentation strategy for impaired cognition in MDD, the aforementioned limitations necessitate further investigation.

Relationship between the hippocampal shape abnormality and serum cortisol levels in first-episode and drug-naïve major depressive disorder patients

BACKGROUND

We aimed to investigate the relationship between the hippocampal shape deformations and the serum cortisol levels in first-episode and drug-naïve major depression disorder (MDD) patients.

METHODS

Thirty first-episode and drug-naïve MDD patients and 40 healthy subjects were recruited. High-resolution T1-weighted imaging and morning blood samples for cortisol measurement were obtained from all MDD patients and healthy subjects. In the hippocampal shape analysis, we compared the hippocampal shape between MDD patients and healthy subjects and evaluated the linear correlation between hippocampal shape deformations and the serum cortisol levels in MDD patients and healthy subjects.

RESULTS

MDD patients showed significant inward deformations predominantly in the cornu ammonis (CA) 1 and subiculum in bilateral hippocampi compared to healthy subjects (false discovery rate (FDR) corrected, P < .05). Furthermore, in MDD patients, a significant linear correlation between inward deformations and high cortisol levels were found predominantly in the CA1 and subiculum, extending into the CA2-3 (FDR-corrected, P < .05), whereas no significant linear correlation was observed in healthy subjects.

CONCLUSIONS

The serum cortisol levels are therefore considered to be associated with hippocampal shape abnormalities in MDD.

Neuropsychological changes in melancholic and atypical depression: A systematic review

There is not a consensus as to whether neuropsychological profiling can distinguish depressive subtypes. We aimed to systematically review and critically analyse the literature on cognitive function in patients with melancholic and atypical depression. We searched in databases PubMed, SCOPUS, Web of Knowledge and PsycInfo for papers comparing the neuropsychological performance of melancholic patients (MEL) to non-melancholic depressive patients (NMEL), including atypical depressives, and healthy controls (HC). All studies were scrutinised to determine the main methodological characteristics and particularly possible sources of bias influencing the results reported, using the STROBE statement checklist. We also provide effect size of the results reported for contrasts between MEL; patients and NMEL patients. Seventeen studies were included; most of them demonstrated higher neuropsychological impairments of MEL patients compared to both NMEL patients and HC on tasks requiring memory, executive function, attention and reaction time. Detailed analysis of the methodologies used in the studies revealed significant variability especially regarding the participants' sociodemographic characteristics, clinical characteristics of patients and differences in neuropsychological assessment. These findings suggest that MEL may have a distinct and impaired cognitive performance compared to NMEL depressive patients on tasks involving verbal and visual memory, executive function, sustained attention and span, as well as psychomotor speed, this last especially when cognitive load is increased. Additional studies with adequate control of potentially confounding variables will help to clarify further differences in the neuropsychological functioning of depressive subtypes.

Effects of cortisol on hippocampal subfields volumes and memory performance in healthy control subjects and patients with major depressive disorder

Overactivity of the hypothalamic-pituitary-adrenal (HPA) axis in major depressive disorder (MDD) is among the most consistently replicated biological findings in psychiatry. Magnetic resonance imaging (MRI) studies have consistently demonstrated that hippocampal (HC) volume is decreased in patients with MDD. The improved spatial resolution of high field strength MRI has recently enabled measurements of HC subfield volumes in vivo. The main goal of the present study was to examine the relationship between cortisol concentrations over a day and HC subfield volumes in patients with MDD compared to healthy controls and to investigate whether diurnal cortisol measures are related to memory performance. Fourteen MDD patients with moderate or severe episodes were recruited, together with 14 healthy controls. Imaging was performed using a 4.7T whole-body imaging system. HC subfields and subregions were segmented manually using previously defined protocol. Memory performance was assessed using the Wechsler Memory Scale IV. The salivary cortisol levels were measured over the course of one day. We found that cortisol awakening response to 8h (CAR-8h) was higher in MDD patients compared to controls and that this increase in CAR-8h in MDD patients correlated negatively with left total Cornu Ammonis (CA)1-3 and left HC head volume. In healthy controls mean cortisol levels were negatively associated with right total CA1-3, right HC head, and right total HC volume. In addition, in healthy controls higher CAR-8h was related to worse performance on the immediate content memory. These results provide the first in vivo evidence of the negative associations between cortisol level, CA1-3 HC subfield volume and memory performance in patients with MDD and healthy controls.

Aerobic Exercise as a Tool to Improve Hippocampal Plasticity and Function in Humans: Practical Implications for Mental Health Treatment

Aerobic exercise (AE) has been widely praised for its potential benefits to cognition and overall brain and mental health. In particular, AE has a potent impact on promoting the function of the hippocampus and stimulating neuroplasticity. As the evidence-base rapidly builds, and given most of the supporting work can be readily translated from animal models to humans, the potential for AE to be applied as a therapeutic or adjunctive intervention for a range of human conditions appears ever more promising. Notably, many psychiatric and neurological disorders have been associated with hippocampal dysfunction, which may underlie the expression of certain symptoms common to these disorders, including (aspects of) cognitive dysfunction. Augmenting existing treatment approaches using AE based interventions may promote hippocampal function and alleviate cognitive deficits in various psychiatric disorders that currently remain untreated. Incorporating non-pharmacological interventions into clinical treatment may also have a number of other benefits to patient well being, such as limiting the risk of adverse side effects. This review incorporates both animal and human literature to comprehensively detail how AE is associated with cognitive enhancements and stimulates a cascade of neuroplastic mechanisms that support improvements in hippocampal functioning. Using the examples of schizophrenia and major depressive disorder, the utility and implementation of an AE intervention to the clinical domain will be proposed, aimed to reduce cognitive deficits in these, and related disorders.

Altered hippocampal function in major depression despite intact structure and resting perfusion

BACKGROUND

Hippocampal volume reductions in major depression have been frequently reported. However, evidence for functional abnormalities in the same region in depression has been less clear. We investigated hippocampal function in depression using functional magnetic resonance imaging (fMRI) and neuropsychological tasks tapping spatial memory function, with complementing measures of hippocampal volume and resting blood flow to aid interpretation.

METHOD

A total of 20 patients with major depressive disorder (MDD) and a matched group of 20 healthy individuals participated. Participants underwent multimodal magnetic resonance imaging (MRI): fMRI during a spatial memory task, and structural MRI and resting blood flow measurements of the hippocampal region using arterial spin labelling. An offline battery of neuropsychological tests, including several measures of spatial memory, was also completed.

RESULTS

The fMRI analysis showed significant group differences in bilateral anterior regions of the hippocampus. While control participants showed task-dependent differences in blood oxygen level-dependent (BOLD) signal, depressed patients did not. No group differences were detected with regard to hippocampal volume or resting blood flow. Patients showed reduced performance in several offline neuropsychological measures. All group differences were independent of differences in hippocampal volume and hippocampal blood flow.

CONCLUSIONS

Functional abnormalities of the hippocampus can be observed in patients with MDD even when the volume and resting perfusion in the same region appear normal. This suggests that changes in hippocampal function can be observed independently of structural abnormalities of the hippocampus in depression.

The volumetric and shape changes of the putamen and thalamus in first episode, untreated major depressive disorder

Previous MRI studies confirmed abnormalities in the limbic-cortical-striatal-pallidal-thalamic (LCSPT) network or limbic-cortico-striatal-thalamic-cortical (LCSTC) circuits in patients with major depressive disorder (MDD), but few studies have investigated the subcortical structural abnormalities. Therefore, we sought to determine whether focal subcortical grey matter (GM) changes might be present in MDD at an early stage. We recruited 30 first episode, untreated patients with major depressive disorder (MDD) and 26 healthy control subjects. Voxel-based morphometry was used to evaluate cortical grey matter changes, and automated volumetric and shape analyses were used to assess volume and shape changes of the subcortical GM structures, respectively. In addition, probabilistic tractography methods were used to demonstrate the relationship between the subcortical and the cortical GM. Compared to healthy controls, MDD patients had significant volume reductions in the bilateral putamen and left thalamus (FWE-corrected, p < 0.05). Meanwhile, the vertex-based shape analysis showed regionally contracted areas on the dorsolateral and ventromedial aspects of the bilateral putamen, and on the dorsal and ventral aspects of left thalamus in MDD patients (FWE-corrected, p < 0.05). Additionally, a negative correlation was found between local atrophy in the dorsal aspects of the left thalamus and clinical variables representing severity. Furthermore, probabilistic tractography demonstrated that the area of shape deformation of the bilateral putamen and left thalamus have connections with the frontal and temporal lobes, which were found to be related to major depression. Our results suggested that structural abnormalities in the putamen and thalamus might be present in the early stages of MDD, which support the role of subcortical structure in the pathophysiology of MDD. Meanwhile, the present study showed that these subcortical structural abnormalities might be the potential trait markers of MDD.

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Structural abnormalities in putamen and thalamus might be the potential trait marker of MDD at the early stage.

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The abnormality of LCSTC circuits, or LCSPT circuit, may contribute to the pathophysiology of MDD.

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The shape analysis is more sensitive to subtle structural changes than volumetric and VBM analysis.

Molecular, Functional, and Structural Imaging of Major Depressive Disorder

Major depressive disorder (MDD) is a significant cause of morbidity and mortality worldwide, correlating with genetic susceptibility and environmental risk factors. Molecular, functional, and structural imaging approaches have been increasingly used to detect neurobiological changes, analyze neurochemical correlates, and parse pathophysiological mechanisms underlying MDD. We reviewed recent neuroimaging publications on MDD in terms of molecular, functional, and structural alterations as detected mainly by magnetic resonance imaging (MRI) and positron emission tomography. Altered structure and function of brain regions involved in the cognitive control of affective state have been demonstrated. An abnormal default mode network, as revealed by resting-state functional MRI, is likely associated with aberrant metabolic and serotonergic function revealed by radionuclide imaging. Further multi-modal investigations are essential to clarify the characteristics of the cortical network and serotonergic system associated with behavioral and genetic variations in MDD.

Hippocampal subfield analysis in medication-naïve female patients with major depressive disorder

BACKGROUND

Hippocampal volume loss is known as the best-replicated finding of structural brain imaging studies on major depressive disorder (MDD). Several evidences suggest localized mechanisms of hippocampal neuroplasticity lead the brain imaging studies on the hippocampus and MDD to perform analyses in the subfield level. The aim of this study was to investigate the differences in total and subfield hippocampal volumes, between medication-naïve female MDD patients and healthy controls, through automated segmentation and volumetric methods.

METHODS

Twenty medication-naïve female patients diagnosed with MDD and 21 age-matched healthy controls, underwent T1-weighted structural magnetic resonance scanning. Total volumes of both hippocampi and subfield regions were calculated by the automated procedure for volumetric measures implemented in FreeSurfer and automated segmentation method by Van Leemput et al.

RESULTS

We observed patients to have significantly smaller volumes of the left hippocampus, subiculum, cornu ammonis 2-3, cornu ammonis 4-dentate gyrus, and right subiculum compared to healthy controls. There were no significant predictors for these subfield region volumes among the illness burden-related parameters including duration of illness, number of depressive episodes, severity of depressive symptoms and memory performances.

LIMITATIONS

Our findings relied on the data of only female participants.

CONCLUSIONS

We found significant volume reductions in several hippocampal subfield regions in medication-naïve female MDD patients. Our results are consistent with neurobiological evidences on hippocampal neuroplasticity in MDD, and replicate previous findings that suggest morphologic changes of hippocampal subfields in MDD patients.

Cognitive Dysfunction in Major Depressive Disorder. A Translational Review in Animal Models of the Disease

Major Depressive Disorder (MDD) is the most common psychiatric disease, affecting millions of people worldwide. In addition to the well-defined depressive symptoms, patients suffering from MDD consistently complain about cognitive disturbances, significantly exacerbating the burden of this illness. Among cognitive symptoms, impairments in attention, working memory, learning and memory or executive functions are often reported. However, available data about the heterogeneity of MDD patients and magnitude of cognitive symptoms through the different phases of MDD remain difficult to summarize. Thus, the first part of this review briefly overviewed clinical studies, focusing on the cognitive dysfunctions depending on the MDD type. As animal models are essential translational tools for underpinning the mechanisms of cognitive deficits in MDD, the second part of this review synthetized preclinical studies observing cognitive deficits in different rodent models of anxiety/depression. For each cognitive domain, we determined whether deficits could be shared across models. Particularly, we established whether specific stress-related procedures or unspecific criteria (such as species, sex or age) could segregate common cognitive alteration across models. Finally, the role of adult hippocampal neurogenesis in rodents in cognitive dysfunctions during MDD state was also discussed.

Dentate gyrus volume and memory performance in major depressive disorder

BACKGROUND

Magnetic resonance imaging (MRI) has shown lower hippocampal volume in major depressive disorder (MDD). Patients with MDD have consistently demonstrated worse performance than healthy controls a number of memory tests. Memory functions within the hippocampus in healthy younger subjects appear to be linked to cornu ammonis (CA1-3) and dentate gyrus (DG) subfields. Therefore, the main goal of the present study was to investigate whether memory deficits in MDD patients are related to reduction in hippocampal subfields volumes, particularly DG and CA 1-3.

METHODS

15 MDD patients meeting DSM-IV criteria for MDD with moderate or severe episodes were recruited, together with 15 healthy controls. We used T2-weighted 2D Fast Spin Echo (FSE) and T1-weighted 3D MPRAGE sequences at 4.7 T to compare hippocampal subfield volumes at 0.09 μl voxel volume. Participants were administered the Wechsler Memory Scale.

RESULTS

MDD patients underperformed in several episodic visual memory tasks, as well as in visual working memory, compared to healthy controls. Global hippocampal volumes were similar between groups; however, MDD patients showed significantly reduced DG volumes within the hippocampal body. Duration of depression correlated with MDD patients׳ total volumes in the hippocampal body and CA1-3 and DG subfields within it.

LIMITATIONS

Our study sample was relatively small and the majority of patients were on antidepressant treatment.

CONCLUSIONS

Our findings suggest that DG volumes in particular may be worthy of further study to further elucidate their precise role in MDD, both by itself as well as in relation to memory.

Now you see it, now you don't: Testing environments modulate the association between hippocampal volume and cortisol levels in young and older adults

The hypothalamic pituitary adrenal axis production of the stress hormone cortisol interacts with the hippocampal formation and impacts memory function. A growing interest is to determine whether hippocampal volume (HV) predicts basal and/or reactive cortisol levels in young and older adults. Recent evidence shows that contextual features in testing environments might be stressful and inadvertently induce a stress response in young and/or older populations. This latter result suggests that variations in testing environments might influence associations between HV and cortisol levels in young and older adults. To this end, we investigated 28 healthy young adults (ages 18-35) and 32 healthy older adults (ages 60-75) in two different environments constructed to be more or less stressful for each age group (Favoring-Young versus Favoring-Old conditions). Cortisol levels were repeatedly assessed in each environment, and young and older participants underwent an anatomical magnetic resonance imaging scan for subsequent assessment of HV. Results in both age groups showed that HV was significantly associated with cortisol levels only in the unfavorable stressful testing conditions specific for each age group. This association was absent when testing environments were designed to decrease stress for each age group. These findings are fundamental in showing that unless the nature of the testing environment is taken into consideration, detected associations between HV and cortisol levels in both young and older populations might be confounded by environmental stress.

The development of an RDoC-based treatment program for adolescent depression: "Training for Awareness, Resilience, and Action" (TARA)

Major depressive disorder (MDD) is one of the current leading causes of disability worldwide. Adolescence is a vulnerable period for the onset of depression, with MDD affecting 8–20% of all youth. Traditional treatment methods have not been sufficiently effective to slow the increasing prevalence of adolescent depression. We therefore propose a new model for the treatment of adolescent depression – Training for Awareness, Resilience, and Action (TARA) – that is based on current understanding of developmental and depression neurobiology. The TARA model is aligned with the Research Domain Criteria (RDoC) of the National Institute of Mental Health. In this article, we first address the relevance of RDoC to adolescent depression. Second, we identify the major RDoC domains of function involved in adolescent depression and organize them in a way that gives priority to domains thought to be driving the psychopathology. Third, we select therapeutic training strategies for TARA based on current scientific evidence of efficacy for the prioritized domains of function in a manner that maximizes time, resources, and feasibility. The TARA model takes into consideration the developmental limitation in top-down cognitive control in adolescence and promotes bottom-up strategies such as vagal afference to decrease limbic hyperactivation and its secondary effects. The program has been informed by mindfulness-based therapy and yoga, as well as modern psychotherapeutic techniques. The treatment program is semi-manualized, progressive, and applied in a module-based approach designed for a group setting that is to be conducted one session per week for 12 weeks. We hope that this work may form the basis for a novel and more effective treatment strategy for adolescent depression, as well as broaden the discussion on how to address this challenge.

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.

Cognitive dysfunction in unipolar depression: implications for treatment

OBJECTIVE

The primary objective of this review is to examine the literature assessing abnormalities in neural circuitry and cognition early in the course of major depressive disorder (MDD) and the impact of these features on treatment selection and long-term outcomes.

DATA SOURCES

English language and peer-reviewed publications were obtained by PubMed/Medline (www.pubmed.org) searches using combinations of major depressive disorder, major depression, or unipolar depression and "first episode", early, cognition, cognitive, executive function and memory. The terms bipolar and psychosis were excluded from the searches. These searches yielded 409 records.

STUDY SELECTION

A total of 12 studies, systematic reviews and meta-analyses were selected that evaluated learning, memory and executive function in individuals with major depressive disorder. Additional publications meeting these criteria were identified from the bibliographies of the 12 selected articles and from the "related citations" section of PubMed.

RESULTS

Difficulty in concentrating and indecisiveness are reported as among the most troubling symptoms by patients with MDD and may limit functional recovery. Cognitive deficits in memory and decision-making are present early in the course of MDD and may be accompanied by structural abnormalities in the hippocampus and prefrontal cortex involved in cognitive functions. Although resolution of cognitive symptoms of depression lags behind recovery from mood symptoms in many patients, preliminary evidence suggests they may improve with antidepressant therapy, but can also persist residually.

CONCLUSIONS

New strategies that target cognitive symptoms of depression in addition to mood symptoms are needed to improve long-term outcomes, particularly functional recovery.

Nonhuman primate models of depression: effects of early experience and stress

Depression causes significant morbidity in the human population. The Diathesis-Stress/Two-Hit model of depression hypothesizes that stress interacts with underlying (probably genetic) predispositions to produce a central nervous system that is primed to express psychopathology when confronted with stressful experiences later in life. Nonhuman primate (NHP) studies have been extensively utilized to test this model. NHPs are especially useful for studying effects of early experience, because many aspects of NHP infancy are similar to humans, whereas development occurs at an accelerated rate and therefore allows for more rapid assessment of experimental variables. In addition, the ability to manipulate putative risk factors, including introducing experimental stress during development, allows inference of causality not possible with human studies. This manuscript reviews experimental paradigms that have been utilized to model early adverse experience in NHPs, including peer-rearing, maternal separation, and variable foraging. It also provides examples of how this model has been used to investigate the effects of early experience on later neurobiology, physiology, and behavior associated with depression. We conclude that the NHP offers an excellent model to research mechanisms contributing to the Diathesis-Stress/Two-Hit model of depression.

Neural correlates of cognitive remediation in patients with mood disorders

Little is known about the brain changes that mediate improvement following cognitive remediation. We used neuropsychological tests and functional magnetic resonance imaging to study working memory and recollection memory in patients with mood disorders, before (PRE) and after (POST) 10 weeks of cognitive remediation. Thirty-eight patients completed a recollection memory task at PRE (28 had complete PRE and POST scans) and 35 patients completed an n-back working memory task at PRE (23 had complete PRE and POST scans). We also compared patients at PRE with two groups of healthy controls subjects (n=18 for the recollection memory task and n=15 for the working memory task). At PRE, compared to controls, patients had (i) poorer backward digit span scores, (ii) lower accuracy scores and weaker frontopolar activation during the 2-back condition, and (iii) poorer recollection scores and altered medial temporal activation on the recollection memory task. Following remediation, patients (i) improved on the backward digit span, (ii) activation increased in lateral and medial prefrontal, superior temporal, and lateral parietal regions in the 2-back condition, and (iii) recollection-related activation increased in the bilateral hippocampus. Improvements in 2-back accuracy correlated with activation increases in lateral and medial prefrontal and lateral parietal regions, and improved recollection scores correlated with activation increases in the left hippocampus. PRE-POST improvements on the backward digit span correlated with PRE-POST improvements in 2-back task accuracy; however, there was no direct association between improvement on the backward digit span following training and change in functional activation. These findings suggest that cognitive remediation may lead to behavioural improvements on tests of working memory. The relation between behavioural change and changes in functional activation following remediation requires further study.

A follow-up study of first episode major depressive disorder. Impairment in inhibition and semantic fluency-potential predictors for relapse?

The present study investigated the Executive Functions (EF) of inhibition, mental flexibility and phonemic and semantic fluency in a 1-year follow-up assessment of patients diagnosed with first episode Major Depressive Disorder (MDD). In the acute phase, the patient group performed significantly poorer compared to the control group (CG) in inhibition and semantic fluency. The present study pursued these findings from the acute phase to see if the impairment seen in inhibition and semantic fluency in the acute phase normalized or persisted in the follow-up assessment. In addition, the present study investigated the association between poor inhibition and semantic fluency performance and the experience of relapse during the 1-year period. Twenty eight patients and 28 individually matched control subjects were included. EF was reassessed using three tests from the Delis Kaplan Executive Function System (D-KEFS).

RESULTS

There was a significant decrease in depression severity score from the acute phase, showing that most of the patients were in remission in the follow-up assessment. RESULTS showed a sustained impairment in inhibition and semantic fluency in the patient group. However, the performance in inhibition was more severe when an additional requirement of mental flexibility was included. There were no group differences in the other EF functions measured. Further, patients with a relapse in the course of 1 year performed significantly poorer in inhibition/switching at inclusion compared to patients that did not relapse and the CG. This relationship was not found for semantic fluency. Poor performance in inhibition and semantic fluency are prolonged despite symptom reduction in patients with a first episode of MDD. Moreover, although based on a small sample of patients, the present study showed that there may be a relationship between impaired ability in the EF of inhibition/switching and vulnerability for the experience of relapse.

Major depressive disorder is associated with broad impairments on neuropsychological measures of executive function: a meta-analysis and review

Cognitive impairments are now widely acknowledged as an important aspect of major depressive disorder (MDD), and it has been proposed that executive function (EF) may be particularly impaired in patients with MDD. However, the existence and nature of EF impairments associated with depression remain strongly debated. Although many studies have found significant deficits associated with MDD on neuropsychological measures of EF, others have not, potentially due to low statistical power, task impurity, and diverse patient samples, and there have been no recent, comprehensive, meta-analyses investigating EF in patients with MDD. The current meta-analysis uses random-effects models to synthesize 113 previous research studies that compared participants with MDD to healthy control participants on at least one neuropsychological measure of EF. Results of the meta-analysis demonstrate that MDD is reliably associated with impaired performance on neuropsychological measures of EF, with effect sizes ranging from 0.32 to 0.97. Although patients with MDD also have slower processing speed, motor slowing alone cannot account for these results. In addition, some evidence suggests that deficits on neuropsychological measures of EF are greater in patients with more severe current depression symptoms, and those taking psychotropic medications, whereas evidence for effects of age was weaker. The results are consistent with the theory that MDD is associated with broad impairment in multiple aspects of EF. Implications for treatment of MDD and theories of EF are discussed. Future research is needed to establish the specificity and causal link between MDD and EF impairments.

Altered hippocampal formation shape in first-episode depressed patients at 5-year follow-up

It is generally accepted that patients with major depressive disorder have smaller hippocampus size compared to healthy people. However, it is still not known if this situation exists before the onset of the disease or is a result of the toxic mechanism created by the depression itself. The findings of the long-term follow-up studies of first-episode depressed patients might contribute to solve the ongoing problem. In this study, the hippocampus of 18 first-episode patients who were followed-up for 5 years, were compared with those of healthy controls. There were no volumetric differences among groups neither at the baseline nor after 5 years of follow-up. However, shape analyses, using high dimensional mapping methods, revealed regional structural changes in the head and tail of the hippocampal formation in CA1 and subiculum regions in patients at the follow-up. Furthermore, a significant negative correlation was found with the number of days in depression without antidepressant treatment in the CA1 region in the head and tail of the hippocampal formation bilaterally. The findings of this study support the hypothesis that pathophysiological processes of depression induce structural alterations in depressed patients.

Stress-related depression: neuroendocrine, genetic, and therapeutical aspects

OBJECTIVE

To summarize current concepts on neuroendocrine and genetic principles underlying stress-related depression and to discuss the challenges of personalized treatment in depression.

METHODS

Review of the literature pertaining to genetic and neuroendocrine basis of stress-related depression including aspects of treatment response with a focus on the hypothalamus-pituitary-adrenal (HPA) axis.

RESULTS

There is increasing evidence that genetic polymorphisms and dysregulation of the HPA axis are associated with the pathophysiology of stress-related depression. Individual stress hormone reactivity seems to be determined by a combination of genetic and environmental factors, contributing to both, resilience or vulnerability.

CONCLUSIONS

Although substantial progress has been made, current knowledge is still limited. Further basic and clinical research is needed to identify specific subgroups and to minimize heterogeneity of the depression phenotype. A better characterization is essential to detect genetic and functional predictors of antidepressant treatment response to follow the vision of personalized therapy in psychiatry.

Detection of the acute effects of hydrocortisone in the hippocampus using pharmacological fMRI

Impaired hippocampal function is believed to be important in the pathogenesis of depression. The hippocampus contains a high concentration of both mineralocorticoid (MR) and glucocorticoid receptors (GR), and the experimental administration of corticosteroids has been reported to mimic memory impairments seen in depression. Using pharmacological functional magnetic resonance imaging (phMRI) we investigated whether hippocampal function is altered after acute administration of hydrocortisone. Changes in BOLD signal following infusion of 100mg hydrocortisone given as a rapid intravenous bolus were measured in 14 healthy volunteers in a within-subject placebo-controlled crossover design. Subsequently, subjects completed an n-back task during an fMRI scan. Hydrocortisone infusion caused a significant, time-dependent increase in fMRI BOLD signal in hippocampus reaching a maximal effect at 11-19min. The n-back task increased BOLD signal in prefrontal and parietal cortical areas and decreased it in the hippocampus. After hydrocortisone the left hippocampal decrease in BOLD signal was attenuated with the magnitude of attenuation correlating with the increase seen after hydrocortisone infusion. No difference in behavioural task performance was observed. The results suggest acute hydrocortisone has rapid direct and modulatory influences on hippocampal function, probably acting through non-genomic GR or MR signalling. Hydrocortisone infusion phMRI may be a useful tool to investigate hippocampal corticosteroid receptor function in depression.

A meta-analysis of cognitive deficits in first-episode Major Depressive Disorder

BACKGROUND

Recurrent-episode Major Depressive Disorder (MDD) is associated with a number of neuropsychological deficits. To date, less is known about whether these are present in the first-episode. The current aim was to systematically evaluate the literature on first-episode MDD to determine whether cognition may be a feasible target for early identification and intervention.

METHODS

Electronic database searches were conducted to examine neuropsychological studies in adults (mean age greater than 18 years old) with a first-episode of MDD. Effect sizes were pooled by cognitive domain. Using meta-regression techniques, demographic and clinical factors potentially influencing heterogeneity of neuropsychological outcome were also investigated.

RESULTS

The 15 independent samples reviewed yielded data for 644 patients with a mean age of 39.36 years (SD=10.21). Significant cognitive deficits were identified (small to medium effect sizes) for psychomotor speed, attention, visual learning and memory, and all aspects of executive functioning. Symptom remission, inpatient status, antidepressant use, age and educational attainment, each significantly contributed to heterogeneity in effect sizes in at least one cognitive domain.

LIMITATIONS

Reviewed studies were limited by small sample sizes and often did not report important demographic and clinical characteristics of patients.

CONCLUSIONS

The current meta-analysis was the first to systematically demonstrate reduced neuropsychological functioning in first-episode MDD. Psychomotor speed and memory functioning were associated with clinical state, whereas attention and executive functioning were more likely trait-markers. Demographic factors were also associated with heterogeneity across studies. Overall, cognitive deficits appear to be feasible early markers and targets for early intervention in MDD.

Association between subcortical volumes and verbal memory in unmedicated depressed patients and healthy controls

Research has shown poor performance on verbal memory tasks in patients with major depressive disorder relative to healthy controls, as well as structural abnormalities in the subcortical structures that form the limbic-cortical-striatal-pallidal-thalamic circuitry. Few studies, however, have attempted to link the impairments in learning and memory in depression with these structural abnormalities, and of those which have done so, most have included patients medicated with psychotropic agents likely to influence cognitive performance. This study thus examines the relationship between subcortical structural abnormalities and verbal memory using the California Verbal Learning Test (CVLT) in unmedicated depressed patients. A T1 weighted magnetic resonance imaging scan and the CVLT were obtained on 45 subjects with major depressive disorder and 44 healthy controls. Using the FMRIB's Integrated Registration and Segmentation Tool (FIRST) volumes of selected subcortical structures were segmented and correlated with CVLT performance. Depressed participants showed significantly smaller right thalamus and right hippocampus volumes than healthy controls. Depressed participants also showed impaired performance on global verbal learning ability, and appeared to depend upon an inferior memory strategy (serial clustering). Measures of serial clustering were correlated significantly with right hippocampal volumes in depressed participants. Our findings indicate that depressed participants and healthy controls differ in the memory strategies they employ, and that while depressed participants had a smaller hippocampal volume, there was a positive correlation between volume and use of an inferior memory strategy. This suggests that larger hippocampal volume is related to better memory recall in depression, but specifically with regard to utilizing an inferior memory strategy.

Association of amygdala volumes with cortisol secretion in unipolar depressed patients

Major depressive disorder (MDD) is accompanied by morphological changes of brain structures which are of great importance in the neural circuitry mediating depression like the hippocampus and the amygdala. Hyperactivity of the hypothalamic-pituitary-adrenocortical (HPA) system resulting in enhanced glucocorticoid secretion can often be observed during depression and has been thought to play an important role in inducing these morphological changes. We used magnetic resonance imaging to investigate alterations of amygdala and hippocampal volumes in 86 in-patients with unipolar depression and 87 healthy controls, and we then correlated amygdala and hippocampal volumes of 76 in-patients with the area under the curve of cortisol secretion in the dexamethasone/corticotropin releasing hormone (Dex/CRH) test at baseline and during short-term antidepressant therapy. In line with recently published studies both left and right amygdala volumes of patients in a first depressive episode were smaller than those of healthy controls. Patients with recurrent depressive episodes showed a reduction of hippocampal volumes, while amygdala volumes were normal. Larger left and right amygdala volumes correlated with a more pronounced reduction of HPA activity, measured by the cortisol secretion in the combined DEX/CRH test, during antidepressant therapy in patients with recurrent depressive episodes.

Increased stress reactivity is associated with reduced hippocampal activity and neuronal integrity along with changes in energy metabolism

Patients suffering from major depression have repeatedly been reported to have dysregulations in hypothalamus-pituitary-adrenal (HPA) axis activity along with deficits in cognitive processes related to hippocampal and prefrontal cortex (PFC) malfunction. Here, we utilized three mouse lines selectively bred for high (HR), intermediate, or low (LR) stress reactivity, determined by the corticosterone response to a psychological stressor, probing the behavioral and functional consequences of increased vs. decreased HPA axis reactivity on the hippocampus and PFC. We assessed performance in hippocampus- and PFC-dependent tasks and determined the volume, basal activity, and neuronal integrity of the hippocampus and PFC using in vivo manganese-enhanced magnetic resonance imaging and proton magnetic resonance spectroscopy. The hippocampal proteomes of HR and LR mice were also compared using two-dimensional gel electrophoresis and mass spectrometry. HR mice were found to have deficits in the performance of hippocampus- and PFC-dependent tests and showed decreased N-acetylaspartate levels in the right dorsal hippocampus and PFC. In addition, the basal activity of the hippocampus, as assessed by manganese-enhanced magnetic resonance imaging, was reduced in HR mice. The three mouse lines, however, did not differ in hippocampal volume. Proteomic analysis identified several proteins that were differentially expressed in HR and LR mice. In accordance with the notion that N-acetylaspartate levels, in part, reflect dysfunctional mitochondrial metabolism, these proteins were found to be involved in energy metabolism pathways. Thus, our results provide further support for the involvement of a dysregulated HPA axis and mitochondrial dysfunction in the etiology and pathophysiology of affective disorders.

Total antioxidant status correlates with cognitive impairment in patients with recurrent depressive disorder

Depressive disorder is a multifactorial diseases, that one of the typical feature are cognitive impairments. The aim of this study was to determine the total antioxidant status (TAS) in patients with recurrent depressive disorder (rDD) and to define relationship between plasma levels of TAS and the cognitive performance.

DESIGN AND METHODS

the study comprised 74 subjects: patients with rDD (n = 45) and healthy subjects (n = 29). Cognitive function assessment was based on: Trail Making Test, The Stroop Test, Verbal Fluency Test and Auditory Verbal Learning Test. Statistically significant differences were found in the intensity of depression symptoms, measured by the Hamilton Depression Rating Scale (HDRS) on therapy onset versus the examination results after 8 weeks of treatment (p < 0.001). The level of TAS was substantially higher in patients with rDD (p = 0.01). For rDD patients, elevated TAS levels were associated with worse cognitive test performance. The higher was the concentration of plasma TAS, the greater was the severity of depressive symptoms measured by HDRS before and after pharmacotherapy. (1) Higher concentration of plasma TAS in rDD patients is associated with the severity of depressive symptoms. (2) Elevated levels of plasma TAS are related to impairment of short-term declarative memory, long-term declarative-memory, verbal fluency and working memory.

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.