Hippocampal volume, memory, and cortisol status in major depressive disorder: effects of treatment

Change in Cognitive Function over the Course of Major Depressive Disorder: A Systematic Review and Meta-analysis

Major depressive disorder (MDD) is associated with significant cognitive deficits during the acute and remitted stages. The aim of this systematic review and meta-analysis was to examine the course of cognitive function whilst considering demographic, treatment, or clinical features of MDD that could moderate the extent of cognitive change. Databases were searched to identify studies that reported on cognitive function in MDD with a ≥12-week test-retest interval. Relevant studies were pooled using random effects modelling to generate an inverse-variance, weighted, mean effect size estimate (Hedges' g) of cognitive change for each cognitive variable and for an overall composite cognitive domain. Of 6898 records, 99 eligible studies were identified from which 69 were meta-analysed, consisting of 4639 MDD patients (agemean = 40.25 years, female% = 64.62%) across 44 cognitive variables. In over 95% of cognitive variables, improvements were either of non-significant, negligible, or of a small magnitude, and when compared to matched healthy controls, the possibility of practice effects could not be precluded. Depressive symptom improvement and the number of previous depressive episodes moderated the extent of cognitive change, demonstrating state- and scar-like features for one-quarter of the cognitive domains. Further longitudinal studies are required to elucidate the MDD cognitive trajectory from initial onset. Findings nonetheless suggest that following pharmacological and non-pharmacological treatment, cognitive change in MDD is typically small, but the capacity for change may be less with episode recurrence. Targeting cognition early in the course of illness may facilitate better prognosis and support a more complete functional recovery.

A Brief Review on the Potential of Psychedelics for Treating Alzheimer's Disease and Related Depression

Alzheimer's disease (AD), the most common form of senile dementia, is poised to place an even greater societal and healthcare burden as the population ages. With few treatment options for the symptomatic relief of the disease and its unknown etiopathology, more research into AD is urgently needed. Psychedelic drugs target AD-related psychological pathology and symptoms such as depression. Using microdosing, psychedelic drugs may prove to help combat this devastating disease by eliciting psychiatric benefits via acting through various mechanisms of action such as serotonin and dopamine pathways. Herein, we review the studied benefits of a few psychedelic compounds that may show promise in treating AD and attenuating its related depressive symptoms. We used the listed keywords to search through PubMed for relevant preclinical, clinical research, and review articles. The putative mechanism of action (MOA) for psychedelics is that they act mainly as serotonin receptor agonists and induce potential beneficial effects for treating AD and related depression.

Antidepressive mechanisms of rhynchophylline in mice with chronic unpredictable stress-induced depression

ETHNOPHARMACOLOGICAL RELEVANCE

Uncaria rhynchophylla ([Mi] Jack) (gouteng) exerts antidepressive effects. Rhynchophylline (RH), a major component of U. rhynchophylla, exerts similar pharmacological effects to those of gouteng. Thus, RH may have antidepressive effects.

AIM OF THE STUDY

To investigate the anti-depressive effects of RH in chronic unpredictable mild stress (CUMS)-induced depressive mice. The anti-depressive mechanism of RH determined by measuring the 5-HT levels, the expressions of cAMP-response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in cortex and hippocampus.

MATERIALS AND METHODS

The behaviors of CUMS-induced depressive mice were measured using an open field test (OFT), forced swimming test (FST), and tail suspension test (TST). 5-HT levels were measured using an ELISA kits. The expressions of BDNF and CREB were determined using western blot test.

RESULTS

RH increased the frequency of rearing and grooming in the OFT and decreased the immobility time in the FST and TST. RH effectively increased the 5-HT level and BDNF and CREB expressions in the cortex and hippocampus.

CONCLUSION

Our findings indicate that the antidepressive mechanism of RH is related to increased levels of 5-HT from regulating CREB and BDNF expressions in cortex and hippocampus.

Association of childhood trauma with cognitive impairment and structural brain alterations in remitted patients with bipolar disorder

BACKGROUND

Cognitive impairment affects many patients with bipolar disorder (BD). No pro-cognitive treatment with robust efficacy exists partly due to limited insight into underlying neurobiological abnormalities.

METHODS

This magnetic resonance imaging (MRI) study investigates structural neuronal correlates of cognitive impairment in BD by comparing brain measures in a large sample of cognitively impaired versus cognitively intact patients with BD or cognitively impaired patients with major depressive disorder (MDD) and healthy controls (HC). Participants underwent neuropsychological assessments and MRI scans. The cognitively impaired and - intact BD and MDD patient groups were compared with each other and HC regarding prefrontal cortex measures, hippocampus shape/volume, and total cerebral white (WM) and grey matter (GM).

RESULTS

Cognitively impaired BD patients showed lower total cerebral WM volume than HC, which scaled with poorer global cognitive performance and more childhood trauma. Cognitively impaired BD patients also showed lower adjusted GM volume and thickness in the frontopolar cortex than HC but greater adjusted GM volume in the temporal cortex than cognitively normal BD patients. Cognitively impaired BD patients showed decreased cingulate volume than cognitively impaired MDD patients. Hippocampal measures were similar across all groups.

LIMITATIONS

The cross-sectional study design prevented insights into causal relationships.

CONCLUSIONS

Lower total cerebral WM and regional frontopolar and temporal GM abnormalities may constitute structural neuronal correlates of cognitive impairment in BD, of which the WM deficits scale with the degree of childhood trauma. The results deepen the understanding of cognitive impairment in BD and provide a neuronal target for pro-cognitive treatment development.

Polygenic Risk for Schizophrenia, Major Depression, and Post-traumatic Stress Disorder and Hippocampal Subregion Volumes in Middle Childhood

Studies demonstrate that individuals with diagnoses for Major Depressive Disorder (MDD), Post-traumatic Stress Disorder (PTSD), and Schizophrenia (SCZ) may exhibit smaller hippocampal gray matter relative to otherwise healthy controls, although the effect sizes vary in each disorder. Existing work suggests that hippocampal abnormalities in each disorder may be attributable to genetic liability and/or environmental variables. The following study uses baseline data from the Adolescent Brain and Cognitive Development[Formula: see text] Study (ABCD Study[Formula: see text]) to address three open questions regarding the relationship between genetic risk for each disorder and hippocampal volume reductions: (a) whether polygenic risk scores (PGRS) for MDD, PTSD, and SCZ are related to hippocampal volume; (b) whether PGRS for MDD, PTSD, and SCZ are differentially related to specific hippocampal subregions along the longitudinal axis; and (c) whether the association between PGRS for MDD, PTSD, and SCZ and hippocampal volume is moderated by sex and/or environmental adversity. In short, we did not find associations between PGRS for MDD, PTSD, and SCZ to be significantly related to any hippocampal subregion volumes. Furthermore, neither sex nor enviornmental adversity significantly moderated these associations. Our study provides an important null finding on the relationship genetic risk for MDD, PTSD, and SCZ to measures of hippocampal volume.

Memory and processing speed impairments in first-episode drug-naïve patients with major depressive disorder

BACKGROUND

Cognitive impairment, an intrinsic feature of major depressive disorder (MDD), affects daily and social functioning in depression patients. However, the cognitive impairment profile in MDD remains ambiguous because of the high heterogeneity of previous studies.

METHODS

Four cognitive domains, including memory, processing speed, executive function (EF), and attention, were assessed in 184 first-episode drug-naïve (FEDN) MDD patients and matched 71 healthy controls (HCs). The effects of demographic and depressive factors on cognitive performance were analyzed using various statistical methods, including multi-factor analysis of variance, Mann-Whitney U test, and Spearman's rank correlation. In addition, the impact of depression severity on cognitive function was further assessed using subgroup analyses and partial correlation analyses.

RESULTS

Age and education significantly impacted most cognitive performances, and depression severity appeared to influence processing speed. Moreover, cognitive scores in memory and processing speed, rather than in EF and attention, were significantly different between FEDN MDD patients and HCs after controlling for sex, age, educational attainment, household income, and body mass index.

LIMITATIONS

The number of HCs was relatively small, which may have slightly reduced the study's statistical power.

CONCLUSIONS

Age and educational attainment have confirmative confounding effects greater than those of depression in most cognitive functions. More importantly, memory and processing speed were impaired in MDD after strictly controlling for confounders. These findings provide new information for understanding the pattern of cognitive impairment and offer clues for further exploring the pathogenesis of cognitive abnormalities in MDD.

Hair Cortisol Concentration as a Biomarker of Symptoms of Depression in the Perinatal Period

Pregnancy is a sensitive period when women experience major hormonal and psychological changes. A high prevalence of the symptoms of depression and manifested major depression rates have been reported during this period, leading to negative outcomes both for mothers and the offspring. Despite its prevalence, the aetiology of depression is not yet fully understood. Nonetheless, alterations in cortisol levels have been proposed as a reliable biomarker to identify pregnant women at risk of perinatal depression. Hair cortisol has recently been extensively used in bio-psychological studies as a suitable non-invasive biomarker for several neuropsychiatric disorders. Various studies have published evidence regarding the relationship between cortisol fluctuations during the perinatal period, measured both in hair and in other substrates, and the onset of perinatal symptoms of depression. This current review provides an overview of cortisol level changes measured in women's hair during pregnancy or the postpartum period and its association with perinatal symptoms of depression. Further studies, including repetitive measurement of both hair cortisol and depression throughout the prenatal period, must be performed to clarify the relationship between cortisol levels and perinatal symptoms of depression.

Variation in Thyroid-Stimulating Hormone and Cognitive Disorders in Unmedicated Middle-Aged Patients with Major Depressive Disorder: A Proton Magnetic Resonance Spectroscopy Study

Background

Middle-aged (45-59 years old) patients with major depressive disorder (MDD) have a predilection for dementia and cognitive disorders (CDs); however, the characteristics and mechanisms of CDs in these patients remain unclear. There are also known connections between thyroid-stimulating hormone (TSH), brain biochemical metabolism, and cognitive function (CF); however, there is scanty of information about these connections in middle-aged MDD patients.

Methods

Cognitive assessment was performed on 30 first-episode, untreated middle-aged patients with MDD and 30 well-matched healthy controls (HCs) using the MATRICS Consensus Cognitive Battery (MCCB). N-acetyl aspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios in the prefrontal cortex (PFC) and cerebellum were also obtained via proton magnetic resonance spectroscopy (¹H-MRS), and the TSH level was measured by chemiluminescence analysis.

Results

MDD patients presented significantly lower processing speed, working memory, verbal learning, reasoning problem-solving, visual learning, and composite cognition scores than controls, with a statistically lower NAA/Cr ratio in the right cerebellum. Age was positively related to reasoning problem-solving in the MDD group (r = 0.6249, p = 0.0220). Education also showed a positive association with visual learning, social cognition, and composite cognition. The 24-item Hamilton Depression Rating Scale (HDRS-24) score was negatively related to all domains of CF. TSH levels were markedly decreased in the MDD group, and a positive connection was determined between the NAA/Cr ratio in the right PFC and the TSH level.

Conclusions

Middle-aged MDD patients have multidimensional CDs. There are changes in PFC and cerebellar biochemical metabolism in middle-aged patients with MDD, which may be related to CDs or altered TSH levels.

Memory-related neurophysiological mechanisms in the hippocampus underlying stress susceptibility

Stress-induced psychiatric symptoms, such as increased anxiety, decreased sociality, and depression, differ considerably across individuals. The cognitive model of depression proposes that biased negative memory is a crucial determinant in the development of mental stress-induced disorders. Accumulating evidence from both clinical and animal studies has demonstrated that such biased memory processing could be triggered by the hippocampus, a region well known to be involved in declarative memories. This review mainly describes how memory-related neurophysiological mechanisms in the hippocampus and their interactions with other related brain regions are involved in the regulation of stress susceptibility and discusses potential interventions to prevent and treat stress-related psychiatric symptoms. Further neurophysiological insights based on memory mechanisms are expected to devise personalized prevention and therapy to confer stress resilience.

Prediction of residual cognitive disturbances by early response of depressive symptoms to antidepressant treatments in patients with major depressive disorder

BACKGROUND

Patients with major depressive disorder (MDD) frequently retain cognitive disturbances after recovery from mood symptoms. We investigated the relationship between early response of mood symptoms and/or remission, and residual cognitive disturbances after 6 months of antidepressant treatment.

METHODS

518 patients with MDD were followed up for 6 months after antidepressant treatment initiation (first-line or switch from a previous drug). Subjective and objective cognitive disturbances were assessed by the Perceived Deficits Questionnaire - Depression (PDQ-D) and digit symbol substitution test (DSST), respectively. Depressive symptoms, as well as remission and early response to treatment, were assessed using the Montgomery-Asberg Depression Rating Scale (MADRS). Multivariable linear and logistic regression models were used to adjust for confounders.

RESULTS

Early response of depressive mood (≥50% reduction in MADRS score at month 1) was related with fewer residual subjective cognitive symptoms, as evaluated by the PDQ-D at month 6 (p<0.001). Likewise, early remission status at month 2 was inversely associated with PDQ-D scores at month 6 (p<0.001). Among patients with baseline DSST scores of ≥1 standard deviation below the norm, early response/remission was associated with better performance on the DSST at month 6 (p<0.05).

LIMITATIONS

The cohort may not be representative of the general MDD patient population, and the possible influence of concomitant medications was not evaluated.

CONCLUSIONS

These findings suggest that early improvements in depressive symptoms predict better cognitive outcomes in patients with MDD. Grouping of patients by mood and cognition status in early stages of antidepressant treatments may facilitate efforts to improve long-term functional outcomes.

A cluster analytic approach to examining the role of cortisol in the development of post-traumatic stress and dysphoria in adult traumatic injury survivors

Identification of specific risk factors for posttraumatic stress disorder (PTSD) versus depression after trauma has been challenging, in part due to the high comorbidity of these disorders. As exposure to trauma triggers activation of the hypothalamic-pituitary-adrenal (HPA)-axis, examining atypical stress responses via HPA-axis hormones, namely cortisol, may help in the delineation of these disorders. Indeed, extant research demonstrates that, following stress, individuals with chronic PTSD exhibit hypocortisolism (e.g., lower cortisol response than controls), while those with chronic depression exhibit hypercortisolism (e.g., higher response than controls). Less is known about the role of cortisol and these seemingly disparate profiles immediately following traumatic injury as well as whether cortisol can be used as a predictor of future development of PTSD versus depression symptoms. In this study cortisol was measured blood from 172 traumatic injury survivors during hospitalization (on average 2.5 days post-injury). PTSD and depression severity were assessed from Clinician Assessed PTSD Scale (CAPS-5) six-eight months later using a two-factor dimensional approach that measures trauma-specific symptoms of PTSD versus dysphoria (akin to depression). Cluster analysis was used to group individuals based on post-injury cortisol, PTSD, and dysphoria. Results demonstrated that trauma survivors who only developed symptoms of dysphoria at six months (with minimal symptoms of PTSD) were differentiated by high post-injury cortisol compared to other groups. By contrast, individuals who developed symptoms of both PTSD and dysphoria were differentiated by low post-injury cortisol and most severe symptoms of PTSD. Findings provide support for the presence of subgroups of trauma survivors defined, in part, by post-trauma cortisol.

Age-dependent brain morphometry in Major Depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a complex disorder that affects nearly 264 million people worldwide. Structural brain abnormalities in multiple neuroanatomical networks have been implicated in the etiology of MDD, but the degree to which MDD affects brain structure during early to late adulthood is unclear.

METHODS

We examined morphometry of brain regions commonly implicated in MDD, including the amygdala, hippocampus, anterior cingulate gyrus, lateral orbitofrontal gyrus, subgenual cortex, and insular cortex subregions, from early to late adulthood. Harmonized measures for gray matter (GM) volume and cortical thickness of each region were estimated cross-sectionally for 305 healthy controls (CTLs) and 247 individuals with MDD (MDDs), collated from four research cohorts. We modeled the nonlinear associations of age with GM volume and cortical thickness using generalized additive modeling and tested for age-dependent group differences.

RESULTS

Overall, all investigated regions exhibited smaller GM volume and thinner cortical measures with increasing age. Compared to age matched CTLs, MDDs had thicker cortices and greater GM volume from early adulthood until early middle age (average 35 years), but thinner cortices and smaller GM volume during and after middle age in the lateral orbital gyrus and all insular subregions. Deviations of the MDD and CTL models for both GM volume and cortical thickness in these regions started as early as age 18.

CONCLUSIONS

The analyses revealed that brain morphometry differences between MDDs and CTLs are dependent on age and brain region. The significant age-by-group interactions in the lateral orbital frontal gyrus and insular subregions make these regions potential targets for future longitudinal studies of MDD.

Hair glucocorticoids are associated with childhood adversity, depressive symptoms and reduced global and lobar grey matter in Generation Scotland

Hypothalamic-pituitary-adrenal (HPA) axis dysregulation has been commonly reported in major depressive disorder (MDD), but with considerable heterogeneity of results; potentially due to the predominant use of acute measures of an inherently variable/phasic system. Chronic longer-term measures of HPA-axis activity have yet to be systematically examined in MDD, particularly in relation to brain phenotypes, and in the context of early-life/contemporaneous stress. Here, we utilise a temporally stable measure of cumulative HPA-axis function (hair glucocorticoids) to investigate associations between cortisol, cortisone and total glucocorticoids with concurrent measures of (i) lifetime-MDD case/control status and current symptom severity, (ii) early/current-life stress and (iii) structural neuroimaging phenotypes, in N = 993 individuals from Generation Scotland (mean age = 59.1 yrs). Increased levels of hair cortisol were significantly associated with reduced global and lobar brain volumes with reductions in the frontal, temporal and cingulate regions (βrange = -0.057 to -0.104, all PFDR < 0.05). Increased levels of hair cortisone were significantly associated with MDD (lifetime-MDD status, current symptoms, and severity; βrange = 0.071 to 0.115, all PFDR = < 0.05), with early-life adversity (β = 0.083, P = 0.017), and with reduced global and regional brain volumes (global: β = -0.059, P = 0.043; nucleus accumbens: β = -0.075, PFDR = 0.044). Associations with total glucocorticoids followed a similar pattern to the cortisol findings. In this large community-based sample, elevated glucocorticoids were significantly associated with MDD, with early, but not later-life stress, and with reduced global and regional brain phenotypes. These findings provide important foundations for future mechanistic studies to formally explore causal relationships between early adversity, chronic rather than acute measures of glucocorticoids, and neurobiological associations relevant to the aetiology of MDD.

How do serotonergic psychedelics treat depression: The potential role of neuroplasticity

Depression is a common mental disorder and one of the leading causes of disability around the world. Monoaminergic antidepressants often take weeks to months to work and are not effective for all patients. This has led to a search for a better understanding of the pathogenesis of depression as well as to the development of novel antidepressants. One such novel antidepressant is ketamine, which has demonstrated both clinically promising results and contributed to new explanatory models of depression, including the potential role of neuroplasticity in depression. Early clinical trials are now showing promising results of serotonergic psychedelics for depression; however, their mechanism of action remains poorly understood. This paper seeks to review the effect of depression, classic antidepressants, ketamine, and serotonergic psychedelics on markers of neuroplasticity at a cellular, molecular, electrophysiological, functional, structural, and psychological level to explore the potential role that neuroplasticity plays in the treatment response of serotonergic psychedelics.

Comparative Proteomic Characterization of Ventral Hippocampus in Susceptible and Resilient Rats Subjected to Chronic Unpredictable Stress

Chronic stress is an essential factor leading to depression. However, there exist individual differences in people exposed to the same stressful stimuli. Some people display negative psychology and behavior, while others are normal. Given the importance of individual difference, finding differentially expressed proteins in stress-resistant and stress-susceptible groups has great significance for the study of pathogenesis and treatment of depression. In this study, stress-susceptible rats and stress-resilient rats were first distinguished by sucrose preference test. These stress-susceptible rats also displayed depression-like behaviors in forced swimming test and open field test. Then, we employed label-free quantitative proteomics to analyze proteins in the ventral hippocampus. There were 4,848 proteins totally identified. Based on statistical analysis, we found 276 differentially expressed proteins. Bioinformatics analysis revealed that the biological processes of these differential proteins were related to mitochondrion organization, protein localization, coenzyme metabolic process, cerebral cortex tangential migration, vesicle-mediated transport, and so on. The KEGG pathways were mainly involved in metabolic pathways, axon guidance, autophagy, and tight junction. Furthermore, we ultimately found 20 stress-susceptible proteins and two stress-resilient proteins. These stress-related proteins could not only be potential biomarkers for depression diagnosis but also contribute to finding new therapeutic targets and providing personalized medicine.

Hippocampus shape deformation: a potential diagnostic biomarker for chronic back pain in women

ABSTRACT

Sex differences in the quality and prevalence of chronic pain are manifold, with women generally presenting higher incidence and severity. Uncovering chronic pain-related sex differences inform neural mechanisms and may lead to novel treatment routes. In a multicenter morphological study (total n = 374), we investigated whether the shape of subcortical regions would reflect sex differences in back pain. Given the hormone-dependent functions of the hippocampus, and its role in the transition to chronic pain, this region constituted our primary candidate. We found that the anterior part of the left hippocampus (alHP) presented outer deformation in women with chronic back pain (CBP), identified in CBP in the United States (n = 77 women vs n = 78 men) and validated in a Chinese data set (n = 29 women vs n = 58 men with CBP, in contrast to n = 53 female and n = 43 male healthy controls). Next, we examined this region in subacute back pain who persisted with back pain a year later (SBPp; n = 18 women vs n = 18 men) and in a subgroup with persistent back pain for 3 years. Weeks after onset of back pain, there was no deformation within alHP, but at 1 and 3 years women exhibited a trend for outer deformation. The alHP partly overlapped with the subiculum and entorhinal cortex, whose functional connectivity, in healthy subjects, was associated with emotional and episodic memory related terms (Neurosynth, reverse inference). These findings suggest that in women the alHP undergoes anatomical changes with pain persistence, highlighting sexually dimorphic involvement of emotional and episodic memory-related circuitry with chronic pain.

Association Between Elevated Depressive Symptoms and Cognitive Function Moderated by APOE4 Status: Framingham Offspring Study

BACKGROUND

Depression and Apolipoprotein E4 (APOE4) are associated with decreased cognitive function and differences in brain structure.

OBJECTIVE

This study investigated whether APOE4 status moderates the association between elevated depressive symptoms, cognitive function, and brain structure.

METHODS

Stroke- and dementia-free participants (n = 1,968) underwent neuropsychological evaluation, brain MRI, and depression screening. Linear and logistic regression was used to examine all associations. Secondary analyses were performed using interaction terms to assess effect modification by APOE4 status.

RESULTS

Elevated depressive symptoms were associated with lower cognitive performance in several domains. In stratified analyses, elevated depressive symptoms were associated with poorer visual short- and long-term memory performance for APOE4 + participants. Elevated depressive symptoms were not associated with any brain structure in this study sample.

CONCLUSION

Elevated depressive symptoms impact cognitive function in non-demented individuals. Having the APOE4 allele may exacerbate the deleterious effects of elevated depressive symptoms on visual memory performance. Screening for elevated depressive symptoms in both research studies and clinical practice may be warranted to avoid false positive identification of neurodegeneration, particularly among those who are APOE4 + .

Differential Susceptibility to the Impact of the COVID-19 Pandemic on Working Memory, Empathy, and Perceived Stress: The Role of Cortisol and Resilience

There are important individual differences in adaptation and reactivity to stressful challenges. Being subjected to strict social confinement is a distressful psychological experience leading to reduced emotional well-being, but it is not known how it can affect the cognitive and empathic tendencies of different individuals. Cortisol, a key glucocorticoid in humans, is a strong modulator of brain function, behavior, and cognition, and the diurnal cortisol rhythm has been postulated to interact with environmental stressors to predict stress adaptation. The present study investigates in 45 young adults (21.09 years old, SD = 6.42) whether pre-pandemic diurnal cortisol indices, overall diurnal cortisol secretion (AUCg) and cortisol awakening response (CAR) can predict individuals' differential susceptibility to the impact of strict social confinement during the Coronavirus Disease 2019 (COVID-19) pandemic on working memory, empathy, and perceived stress. We observed that, following long-term home confinement, there was an increase in subjects' perceived stress and cognitive empathy scores, as well as an improvement in visuospatial working memory. Moreover, during confinement, resilient coping moderated the relationship between perceived stress scores and pre-pandemic AUCg and CAR. In addition, in mediation models, we observed a direct effect of AUCg and an indirect effect of both CAR and AUCg, on change in perceived self-efficacy. These effects were parallelly mediated by the increase in working memory span and cognitive empathy. In summary, our findings reveal the role of the diurnal pattern of cortisol in predicting the emotional impact of the COVID-19 pandemic, highlighting a potential biomarker for the identification of at-risk groups following public health crises.

Body mass index and variability in hippocampal volume in youth with major depressive disorder

BACKGROUND

The hippocampus has been implicated in major depressive disorder (MDD), in both adults and youth. However, possible sources of variability for the hippocampus have not been well delineated. Here, we explored the relationship between body mass index (BMI) and hippocampal volume in youth with MDD.

METHODS

Twenty-two controls (9 male, 13 female, 12-24 years), 24 youth with MDD and normal BMI (12 male, 12 female, 14-24 years), and 20 youth with MDD and high BMI (14 male, 6 female, 13-22 years) underwent magnetic resonance (MR) imaging and spectroscopy (1H-MRS). Hippocampal volume was determined through manual tracing of high-resolution anatomical T1 scans, and LCModel quantified neurochemical concentrations. Intracranial volume was used as a covariate in analysis to control for effects of brain volume on hippocampus.

RESULTS

In youth with MDD and normal BMI, right hippocampal volume was reduced (p = 0.006, Bonferroni) and a trend for reduced left hippocampal volume was noted when compared to healthy controls (p = 0.054, Bonferroni). Left hippocampal volumes were negatively associated with BMI in youth with MDD and high BMI group (r = -0.593, p = 0.006). No associations were found between the right hippocampus and BMI and there were no group differences for metabolite concentrations.

LIMITATIONS

Larger sample sizes would enable researchers to explore overweight vs obese groups and effect of sex in MDD-BMI groups.

CONCLUSIONS

BMI may account for some of the variability observed in previous studies of hippocampal volume in MDD, and therefore BMI impacts should be considered in future analyses.

Neurogenesis and Neuroplasticity in Major Depression: Its Therapeutic Implication

The neurochemical model of depression, based on monoaminergic theories, does not allow on its own to understand the mechanism of action of antidepressants. This approach does not explain the gap between the immediate biochemical modulations induced by antidepressants and the time required for their clinical action. Several hypotheses have been developed to try to explain more precisely the action of these molecules, each of them involving mechanisms of receptor regulation. At the same time, data on the neuroanatomy of depression converge toward the existence of specific lesions of this pathology. This chapter aims to provide an overview of recent advances in understanding the mechanisms of neural plasticity involved in pathophysiology depression and in its treatment.

The relationship between hippocampal subfield volumes and autobiographical memory persistence

Structural integrity of the human hippocampus is widely acknowledged to be necessary for the successful encoding and retrieval of autobiographical memories. However, evidence for an association between hippocampal volume and the ability to recall such memories in healthy individuals is mixed. Here we examined this issue further by combining two approaches. First, we focused on the anatomically distinct subregions of the hippocampus where more nuanced associations may be expressed compared to considering the whole hippocampal volume. A manual segmentation protocol of hippocampal subregions allowed us to separately calculate the volumes of the dentate gyrus/CA4, CA3/2, CA1, subiculum, pre/parasubiculum and uncus. Second, a critical feature of autobiographical memories is that they can span long time periods, and so we sought to consider how memory details persist over time by conducting a longitudinal study whereby participants had to recall the same autobiographical memories on two visits spaced 8 months apart. Overall, we found that there was no difference in the total number of internal (episodic) details produced at Visits 1 and 2. However, further probing of detail subcategories revealed that specifically the amount of subjective thoughts and emotions included during recall had declined significantly by the second visit. We also observed a strong correlation between left pre/parasubiculum volume and the amount of autobiographical memory internal details produced over time. This positive relationship was evident for particular facets of the memories, with remembered events, perceptual observations and thoughts and emotions benefitting from greater volume of the left pre/parasubiculum. These preliminary findings expand upon existing functional neuroimaging evidence by highlighting a potential link between left pre/parasubiculum volume and autobiographical memory. A larger pre/parasubiculum appears not only to protect against memory decay, but may possibly enhance memory persistence, inviting further scrutiny of the role of this brain region in remote autobiographical memory retrieval.

Sex differences in brain metabolites in anxiety and mood disorders

Gender differences in mood and anxiety disorders are well-established. However, the neural basis of these differences is not clear yet, especially in terms of brain metabolism. Indeed, although several proton Magnetic Resonance Spectroscopy (¹H MRS) investigations reported different metabolic levels in both depression and anxiety disorders, which have been also linked to symptoms severity and response to treatment, the role of gender on these differences have not been explored yet. Therefore, this study aims at investigating the role of sex in neurometabolic alterations associated with both mood and anxiety disorders. A 3T single-voxel ¹H MRS acquisition of the dorsolateral prefrontal cortex was acquired from 14 Major Depressive Disorder, 10 Generalized Anxiety Disorder (GAD), 11 Panic Disorder (PD), patients and 16 healthy controls (HC). Among males, PD patients showed significantly lower GPC+PC (also observed in GAD+PD) and Glu levels compared to HC. Finally, a significant group x sex interaction effect was observed in the GPC+PC and Glu levels. We proved the presence of an association between sex and brain metabolites in anxiety spectrum.

Volumetric brain differences in clinical depression in association with anxiety: a systematic review with meta-analysis

BACKGROUND

Structural differences associated with depression have not been confirmed in brain regions apart from the hippocampus. Comorbid anxiety has been inconsistently assessed, and may explain discrepancies in previous findings. We investigated the link between depression, comorbid anxiety and brain structure.

METHODS

We followed Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines (PROSPERO CRD42018089286). We searched the Cochrane Library, MEDLINE, PsycInfo, PubMed and Scopus, from database inception to Sept. 13, 2018, for MRI case-control studies that reported brain volumes in healthy adults and adults with clinical depression. We summarized mean volumetric differences using meta-analyses, and we assessed demographics, depression factors and segmentation procedure as moderators using meta-regressions.

RESULTS

We included 112 studies in the meta-analyses, assessing 4911 healthy participants and 5934 participants with depression (mean age 49.8 yr, 68.2% female). Volume effects were greater in late-onset depression and in multiple episodes of depression. Adults with depression and no comorbidity showed significantly lower volumes in the putamen, pallidum and thalamus, as well as significantly lower grey matter volume and intracranial volume; the largest effects were in the hippocampus (6.8%, p < 0.001). Adults with depression and comorbid anxiety showed significantly higher volumes in the amygdala (3.6%, p < 0.001). Comorbid anxiety lowered depression effects by 3% on average. Sex moderated reductions in intracranial volume.

LIMITATIONS

High heterogeneity in hippocampus effects could not be accounted for by any moderator. Data on symptom severity and medication were sparse, but other factors likely made significant contributions.

CONCLUSION

Depression-related differences in brain structure were modulated by comorbid anxiety, chronicity of symptoms and onset of illness. Early diagnosis of anxiety symptomatology will prove crucial to ensuring effective, tailored treatments for improving long-term mental health and mitigating cognitive problems, given the effects in the hippocampus.

Sex differences in the cognitive function of first-diagnosed, drug-naïve depressed patients: An observational case-control study

BACKGROUND

Major depressive disorder (MDD) is a severe mental illness with high prevalence and recurrence rates. Cognitive impairments are found in most depressed patients, but systematic assessment of sex differences in cognitive deficits remains to be investigated.

METHODS

A total of 69 first-diagnosed, drug-naïve depressed outpatients (males/females = 28/41; average age: 27.51±8.82 years) and 57 healthy controls (HCs) (males/females = 26/31; average age: 29.05±8.69 years) were recruited. Cognitive function, measured by repeatable battery for the assessment of neuropsychological status [RBANS] scores, was compared between depressed patients and healthy controls in males and females.

RESULTS

Immediate memory, delayed memory and RBANS total score were significantly decreased in depressed patients compared with healthy controls. Moreover, among patients with first-diagnosed, drug-naïve depression, females had lower visuospatial and constructional scores than males, whereas among controls, females had higher language scores than males. Interestingly, impaired attention was negatively associated with the Beck Depression Inventory-II (BDI-II) score in female patients, but not in male patients.

CONCLUSION

Female patients with first-diagnosed, drug-naïve depression had more serious cognitive impairment than male patients in the visuospatial and constructional categories. Cognitive impairment was associated with depression severity only in female patients. These observations build the basis for future investigation of sex differences in cognitive impairment of depressed patients.

Early life maltreatment and depression: Mediating effect of maternal hair cortisol concentration on child abuse potential

INTRODUCTION

Maternal early life maltreatment (ELM) and history of depression can bear a risk for adverse development in the child. One neurobiological pathway for the transmission of both maternal ELM and remitted depression (MDD) might be altered maternal cortisol levels. In the present study, we examine (1) main and interacting effects of maternal ELM and remitted MDD on hair cortisol concentration (HCC) in mothers, whether (2) maternal HCC explains the association between maternal ELM or remitted MDD and maternal child abuse potential, and (3) whether maternal child abuse potential as well as maternal HCC are associated with maternal report of child well-being.

METHODS

The current study involved 127 mother-child dyads. Maternal history of ELM and psychopathology were assessed via the Mini International Neuropsychiatric Interview (M.I.N.I.) and Childhood Experience and Care (CECA) interview. The Child Abuse Potential Inventory (CAPI) was used to assess maternal child abuse and neglect potential. We applied the Kidscreen-27 parent report to study child well-being. To assess HCC, hair strands were taken from the mothers. To test the research questions, a two-factorial analysis of covariance, mediation analysis using ordinary least squares regressions with bootstrapping, and Pearson correlations were calculated.

RESULTS

Mothers with ELM had significantly increased HCC. There was no effect of remitted MDD on HCC, nor an interaction effect of both factors. HCC was a significant mediator of the association between maternal ELM and maternal child abuse potential. Maternal child abuse potential as well as HCC were significantly associated with reduced child well-being.

DISCUSSION

Our data suggest that adverse experiences in childhood are associated with altered HPA-axis functioning reflected in increased levels of HCC. HPA-axis activity is not altered in mothers with remitted MDD. From a clinical point of view, one might speculate that the partially mediating effect of maternal HCC could indicate a starting point in the prevention of the intergenerational cycle of abuse.

Overlapping Neurobiological Substrates for Early-Life Stress and Resilience to Psychosis

Early-life stress, such as childhood maltreatment, is a well-known etiological factor in psychopathology, including psychosis. Exposure to early-life stress disrupts the neurodevelopment of widespread brain systems, including key components of the hypothalamic-pituitary-adrenal axis stress response, such as the amygdala, hippocampus, and medial prefrontal cortex, as well as key components of the brain's reward system, such as the nucleus accumbens and orbitofrontal cortex. These disruptions have a considerable impact on the function of emotion and reward circuitry, which play a central role in the emergence and severity of psychosis. While this overlap may provide insight into the pathophysiology of psychosis, it also provides unique opportunities to elucidate neurobiological substrates that may promote resilience to psychosis. In this review, we discuss the hypothalamic-pituitary-adrenal axis stress response, discuss the disruption in the neurodevelopment of emotion and reward processing associated with early stress exposures, and examine how this circuitry may contribute to resilience to psychotic disorders.

Application of Noninvasive Vagal Nerve Stimulation to Stress-Related Psychiatric Disorders

BACKGROUND

Vagal Nerve Stimulation (VNS) has been shown to be efficacious for the treatment of depression, but to date, VNS devices have required surgical implantation, which has limited widespread implementation.

METHODS

New noninvasive VNS (nVNS) devices have been developed which allow external stimulation of the vagus nerve, and their effects on physiology in patients with stress-related psychiatric disorders can be measured with brain imaging, blood biomarkers, and wearable sensing devices. Advantages in terms of cost and convenience may lead to more widespread implementation in psychiatry, as well as facilitate research of the physiology of the vagus nerve in humans. nVNS has effects on autonomic tone, cardiovascular function, inflammatory responses, and central brain areas involved in modulation of emotion, all of which make it particularly applicable to patients with stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD) and depression, since dysregulation of these circuits and systems underlies the symptomatology of these disorders.

RESULTS

This paper reviewed the physiology of the vagus nerve and its relevance to modulating the stress response in the context of application of nVNS to stress-related psychiatric disorders.

CONCLUSIONS

nVNS has a favorable effect on stress physiology that is measurable using brain imaging, blood biomarkers of inflammation, and wearable sensing devices, and shows promise in the prevention and treatment of stress-related psychiatric disorders.

Nucleus Reuniens Lesion and Antidepressant Treatment Prevent Hippocampal Neurostructural Alterations Induced by Chronic Mild Stress in Male Rats

The hippocampus-prefrontal cortex circuit plays a major role in stress and in the neurobiology of depression and its treatment. Disruption of this circuit by lesioning the thalamic nucleus reuniens (RE) has been shown to prevent the detrimental effects of chronic mild stress on prefrontal cortex neuroplasticity indices in male rats. However, it remains unknown whether hippocampal neurostructural response to stress is modified by RE lesion. In the present study, adult male rats were subjected to the chronic mild stress model of depression and were treated with either vehicle or an antidepressant (i.e. sertraline). Moreover, a group of animals was subjected to RE lesion before stress exposure with or without sertraline treatment. We demonstrated that chronic mild stress induced hippocampal CA1 dendritic atrophy and this was prevented by pre-stress RE lesion to the same extent that antidepressant treatment reversed it. The present findings highlight the importance of hippocampal-prefrontal cortex communication in chronic stress effects on hippocampal neuroplasticity and contribute to the elucidation of the role of RE in neurostructural changes underlying stress-driven depression and its treatment.

Prognosis and Improved Outcomes in Major Depression: A Review

(Reprinted from Transl Psychiatry. 2019 Apr 3; 9(1):127. Open access; is licensed under a Creative Commons Attribution 4.0 International License).

Prospective study of hippocampal volume and function in human subjects treated with corticosteroids

Purpose.

Decreased hippocampal volume reported in neuropsychiatric and endocrine disorders is considered a result of putative neuronal damage mediated by corticosteroids. This is the first prospective study of hippocampal volume and function in patients treated with corticosteroids.

Methods.

14 subjects treated systemically with prednisone or betamethasone for dermatological or rheumatic disorders underwent prospective neurocognitive testing (Auditory Verbal Learning Test—AVLT, Trail Making Test—TMT, Digit Span—DS) and nine of them also repeated magnetic resonance volumetry.

Results.

The mean duration of treatment between the first and the second assessment was 73 ± 38 days with mean daily dose of 37 ± 17 mg prednisone and 193 ± 29 days, with mean daily dose of 24 ± 15 mg prednisone between the first and the third assessment. There was a trend towards decreases in total AVLT scores and an improvement in the TMT and DS, but no significant changes in the volumes of the right or the left hippocampi between the assessments. Prednisone dose did not correlate with the hippocampal volume change.

Conclusion.

We observed a trend for decline in verbal memory despite improvement in psychomotor speed, attention/working memory and no macroscopic hippocampal volume changes during 36–238 days of treatment with therapeutic doses of corticosteroids.

Impact of GRIK4 gene polymorphisms on cognitive dysfunction in patients with major depression

An increasing body of research has focused on the functions of the glutamate receptor ionotropic kainate 4 (GRIK4) gene in treatment for depression, memory, as well as neurodegenerative diseases. It is widely recognized that major depressive disorder (MDD) patients often display cognitive dysfunctions, which do not strictly correlate with the severity of depressive symptoms, and in some individuals persist after clinical remission. However, little is known regarding the particular role of GRIK4 in cognitive functions of patients suffering from a MDD. The current study therefore sought to examine the impact of GRIK4 polymorphism on cognitive functions in MDD patients. A total of 217 MDD patients participated in this study. Their depressive severity was determined with the 17-item Hamilton Depression Rating Scale, and cognitive functions were evaluated using the Stroop Neuropsychological Screening Test, tests of visual reproduction and immediate logical memory, and the verbal fluency test (VFT). All patients were genotyped to determine GRIK4 polymorphisms. Results of VFT revealed statistical differences among all single-nucleotide polymorphism (SNP) genotypes. In the Stroop-color-word test, only rs6589847 was discovered to be statistically different. No significant difference was found in the Stroop-color task scores, the visual reproduction test, or the immediate logical memory test. GRIK4 polymorphism exerted a significant effect on long-term memory retrieval and selective attention, but did not affect immediate memory.

Opposing effects of cortisol on learning and memory in children using spatial versus response-dependent navigation strategies

Previous studies showed that healthy young adults who spontaneously use caudate nucleus-dependent strategies on a virtual navigation task, have significantly lower basal levels of cortisol compared with adults who use hippocampus-dependent spatial navigation strategies. In the current paper, we assessed the relation between basal cortisol levels and learning using a virtual navigation task in children. We show that basal cortisol level has a differential effect on learning and memory between children using spatial and response navigation strategies. Specifically, cortisol was found to be beneficial for learning performance in children using spatial strategies, such that higher levels of cortisol were associated with more efficient learning in a virtual maze. In contrast, cortisol had a deleterious effect on learning the virtual maze in children using response strategies, such that higher cortisol levels were associated with increased spatial working memory errors. Based on these results, individual differences in navigation strategy could help explain contradictory results in the literature showing that cortisol can have either a positive or negative association with learning and memory performance.

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

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

Hippocampal tail volume as a predictive biomarker of antidepressant treatment outcomes in patients with major depressive disorder: a CAN-BIND report

Finding a clinically useful neuroimaging biomarker that can predict treatment response in patients with major depressive disorder (MDD) is challenging, in part because of poor reproducibility and generalizability of findings across studies. Previous work has suggested that posterior hippocampal volumes in depressed patients may be associated with antidepressant treatment outcomes. The primary purpose of this investigation was to examine further whether posterior hippocampal volumes predict remission following antidepressant treatment. Magnetic resonance imaging (MRI) scans from 196 patients with MDD and 110 healthy participants were obtained as part of the first study in the Canadian Biomarker Integration Network in Depression program (CAN-BIND 1) in which patients were treated for 16 weeks with open-label medication. Hippocampal volumes were measured using both a manual segmentation protocol and FreeSurfer 6.0. Baseline hippocampal tail (Ht) volumes were significantly smaller in patients with depression compared to healthy participants. Larger baseline Ht volumes were positively associated with remission status at weeks 8 and 16. Participants who achieved early sustained remission had significantly greater Ht volumes compared to those who did not achieve remission by week 16. Ht volume is a prognostic biomarker for antidepressant treatment outcomes in patients with MDD.

Brain structural effects of treatments for depression and biomarkers of response: a systematic review of neuroimaging studies

Antidepressive pharmacotherapy (AD), electroconvulsive therapy (ECT) and cognitive behavioural therapy (CBT) are effective treatments for major depressive disorder. With our review, we aim to provide a systematic overview of neuroimaging studies that investigate the effects of AD, ECT and CBT on brain grey matter volume (GMV) and biomarkers associated with response. After a systematic database research on PubMed, we included 50 studies using magnetic resonance imaging and investigating (1) changes in GMV, (2) pre-treatment GMV biomarkers associated with response, or (3) the accuracy of predictions of response to AD, ECT or CBT based on baseline GMV data. The strongest evidence for brain structural changes was found for ECT, showing volume increases within the temporal lobe and subcortical structures - such as the hippocampus-amygdala complex, anterior cingulate cortex (ACC) and striatum. For AD, the evidence is heterogeneous as only 4 of 11 studies reported significant changes in GMV. The results are not sufficient in order to draw conclusions about the structural brain effects of CBT. The findings show consistently that higher pre-treatment ACC volume is associated with response to AD, ECT and CBT. An association of higher pre-treatment hippocampal volume and response has only been reported for AD. Machine learning approaches based on pre-treatment whole brain patterns reach accuracies of 64-90% for predictions of AD or ECT response on the individual patient level. The findings underline the potential of brain biomarkers for the implementation in clinical practice as an additive feature within the process of treatment selection.

The impact of depression and anxiety treatment on biological aging and metabolic stress: study protocol of the MOod treatment with antidepressants or running (MOTAR) study

BACKGROUND

Depressive and anxiety disorders have shown to be associated to premature or advanced biological aging and consequently to adversely impact somatic health. Treatments with antidepressant medication or running therapy are both found to be effective for many but not all patients with mood and anxiety disorders. These interventions may, however, work through different pathophysiological mechanisms and could differ in their impact on biological aging and somatic health. This study protocol describes the design of an unique intervention study that examines whether both treatments are similarly effective in reducing or reversing biological aging (primary outcome), psychiatric status, metabolic stress and neurobiological indicators (secondary outcomes).

METHODS

The MOod Treatment with Antidepressants or Running (MOTAR) study will recruit a total of 160 patients with a current major depressive and/or anxiety disorder in a mental health care setting. Patients will receive a 16-week treatment with either antidepressant medication or running therapy (3 times/week). Patients will undergo the treatment of their preference and a subsample will be randomized (1:1) to overcome preference bias. An additional no-disease-no-treatment group of 60 healthy controls without lifetime psychopathology, will be included as comparison group for primary and secondary outcomes at baseline. Assessments are done at week 0 for patients and controls, and at week 16 and week 52 for patients only, including written questionnaires, a psychiatric and medical examination, blood, urine and saliva collection and a cycle ergometer test, to gather information about biological aging (telomere length and telomerase activity), mental health (depression and anxiety disorder characteristics), general fitness, metabolic stress-related biomarkers (inflammation, metabolic syndrome, cortisol) and genetic determinants. In addition, neurobiological alterations in brain processes will be assessed using structural and functional Magnetic Resonance Imaging (MRI) in a subsample of at least 25 patients per treatment arm and in all controls.

DISCUSSION

This intervention study aims to provide a better understanding of the impact of antidepressant medication and running therapy on biological aging, metabolic stress and neurobiological indicators in patients with depressive and anxiety disorders in order to guide a more personalized medicine treatment.

TRIAL REGISTRATION

Trialregister.nl Number of identification: NTR3460, May 2012.

Left fimbria atrophy is associated with hippocampal metabolism in female major depressive disorder patients

Despite the high incidence of major depressive disorder (MDD) in females, the detailed neurobiology mechanism remains not fully understood. Increasing evidence showed that MDD was associated with hippocampal volumetric abnormality with different subfields demonstrating various alteration features. However, the linkage between hippocampal atrophy with its biochemical information remains unclear. In this study, we aim to investigate the relationship between bilateral hippocampal subfields volumetric and metabolic information in female MDD patients, using a combined T1weighted magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (H-MRS) technology. There are 15 female MDD patients and 12 matched healthy controls involved in the study. We found a significant decrease in left fimbria volume in MDD group, which was negatively correlated with left hippocampal choline level. In addition, the left hippocampal creatine concentration in patients was negatively correlated with left fimbria volume. Moreover, the NAA level in left hippocampus was negatively correlated with MDD clinical symptomology including anxiety and depression scores. Our findings suggest that the altered coupling between hippocampal structural and metabolic features might contribute to the etiology of female MDD patients.

Neurobiological mechanisms underlying sex-related differences in stress-related disorders: Effects of neuroactive steroids on the hippocampus

Men and women differ in their vulnerability to a variety of stress-related illnesses, but the underlying neurobiological mechanisms are not well understood. This is likely due to a comparative dearth of neurobiological studies that assess male and female rodents at the same time, while human neuroimaging studies often don't model sex as a variable of interest. These sex differences are often attributed to the actions of sex hormones, i.e. estrogens, progestogens and androgens. In this review, we summarize the results on sex hormone actions in the hippocampus and seek to bridge the gap between animal models and findings in humans. However, while effects of sex hormones on the hippocampus are largely consistent in animals and humans, methodological differences challenge the comparability of animal and human studies on stress effects. We summarise our current understanding of the neurobiological mechanisms that underlie sex-related differences in behavior and discuss implications for stress-related illnesses.

Effects of a mental stress challenge on brain function in coronary artery disease patients with and without depression

OBJECTIVE

Coronary artery disease (CAD) patients with comorbid depression show an increase in mortality compared to cardiac patients without depression, but the mechanisms mediating this effect remain obscure. One possible explanation for this finding is that depressed patients with CAD exhibit an increased vulnerability to stress. The purpose of this study was to assess the effects of stress and depression on brain function and to explore its relationship with myocardial ischemia in CAD patients.

METHODS

Patients with CAD and depression (N = 13) and CAD without depression (N = 15) underwent imaging of the brain with positron emission tomography and [O-15] water and imaging of the heart with single photon emission computed tomography (SPECT) and [Tc-99m] sestamibi under mental stress task and control conditions.

RESULTS

CAD patients with depression compared to nondepressed showed decreased function with mental stress in the rostral anterior cingulate, the hippocampus, parts of the dorsolateral temporal and parietal cortex, the cerebellum, and the uncus, with increased blood flow in the parahippocampus, visual association cortex, and posterior cingulate. Depressed CAD patients who became ischemic during a mental stress task had relative decreases in the caudal and posterior cingulate, orbitofrontal cortex, and cerebellum, and increased activation in the parietal cortex and precuneus/visual association cortex compared to nonischemic depressed CAD patients.

CONCLUSIONS

These findings are consistent with dysfunction in a network of brain regions involved in the stress response in patients with comorbid CAD and depression that has direct and indirect links to the heart, suggesting a pathway by which stress and depression could lead to increased risk of heart disease related morbidity and mortality. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Hippocampal Subfields in Acute and Remitted Depression-an Ultra-High Field Magnetic Resonance Imaging Study

BACKGROUND

Studies investigating hippocampal volume changes after treatment with serotonergic antidepressants in patients with major depressive disorder yielded inconsistent results, and effects on hippocampal subfields are unclear.

METHODS

To detail treatment effects on total hippocampal and subfield volumes, we conducted an open-label study with escitalopram followed by venlafaxine upon nonresponse in 20 unmedicated patients with major depressive disorder. Before and after 12 weeks treatment, we measured total hippocampal formation volumes and subfield volumes with ultra-high field (7 Tesla), T1-weighted, structural magnetic resonance imaging, and FreeSurfer. Twenty-eight remitted patients and 22 healthy subjects were included as controls. We hypothesized to detect increased volumes after treatment in major depressive disorder.

RESULTS

We did not detect treatment-related changes of total hippocampal or subfield volumes in patients with major depressive disorder. Secondary results indicated that the control group of untreated, stable remitted patients, compared with healthy controls, had larger volumes of the right hippocampal-amygdaloid transition area and right fissure at both measurement time points. Depressed patients exhibited larger volumes of the right subiculum compared with healthy controls at MRI-2. Exploratory data analyses indicated lower baseline volumes in the subgroup of remitting (n = 10) vs nonremitting (n = 10) acute patients.

CONCLUSIONS

The results demonstrate that monoaminergic antidepressant treatment in major depressive disorder patients was not associated with volume changes in hippocampal subfields. Studies with larger sample sizes to detect smaller effects as well as other imaging modalities are needed to further assess the impact of antidepressant treatment on hippocampal subfields.

Negative Mental States and Their Association to the Cognitive Function of Nurses

Abstract. Nurses’ inherently stressful occupation leaves them at a higher risk of developing negative mental states (stress, anxiety, and depression). However, research examining the effect of negative mental states on these health professionals’ cognitive performance is sparse. Thus, the present study aimed to assess the link between negative mental states and cognitive performance in nurses ( n = 53). Negative mental state data was obtained using the Depression Anxiety Stress Scale, brain activity was measured using electroencephalography, and finally, cognitive performance was assessed using the Cognistat and the Mini-Mental State Examination. Significant negative correlations ( p < .05) were observed between anxiety and attention, and all three negative mental states and memory performance. Electroencephalographic changes indicated that increases in anxiety were significantly associated ( p < .05) with decreases in gamma reactivity at fronto-central sites. The current study suggests that higher levels of negative mental states are associated with domain-specific cognitive impairments, and variations in gamma reactivity; possibly reflecting less optimal cortical functioning.

Examining HPA-axis functioning as a mediator of the relationship between depression and cognition across the adult lifespan

Altered HPA-axis functioning is a hypothesized mechanism for worsened cognition in depression. The current study examines the indirect effects of depression on processing speed, executive functioning, and memory as a function of the HPA-axis. 38 individuals with a depression diagnosis and 50 healthy controls (HCs) aged 18-86 underwent neuropsychological testing and at-home diurnal salivary cortisol collection. Depression was assessed via structured clinical interviews and rating scales. Cognitive composite scores were derived from factor analysis. Daytime cortisol exposure was estimated using area under the curve (AUC). Depression was associated with higher cortisol levels and slower processing speed . A significant suppression effect of AUC was present on the relationship between depression and processing speed. Limitations include the cross-sectional design and limited sample heterogeneity. Though poorly modulated HPA-axis is one proposed mechanism of cognitive alterations in depression, our results did not support this conclusion for processing speed. Alternative mechanisms should be considered to inform interventions to target cognitive alterations in depression.

Functional disconnectivity of the hippocampal network and neural correlates of memory impairment in treatment-resistant depression

BACKGROUND

Major depressive disorder (MDD) is a disabling neuropsychiatric condition associated with cognitive impairment. Neuroimaging studies have consistently linked memory deficits with hippocampal atrophy in MDD patients. However, there has been a paucity of research examining how the hippocampus functionally contributes to memory impairments in MDD. The present study examined whether hippocampal networks distinguish treatment-resistant depression (TRD) patients from healthy controls (HCs), and whether these networks underlie declarative memory deficits in TRD. We hypothesized that functional connectivity (FC) of the posterior hippocampus would correlate preferentially with memory in patients, whereas FC pattern of the anterior and intermediate hippocampus would correlate with emotion-mediated regions and show a significant correlation with memory.

METHODS

Resting-state functional magnetic resonance imaging (fMRI) scans were acquired in 56 patients and 42 age- and sex-matched HCs. We parcellated the hippocampus into three subregions based on a sparse representation-based method recently developed by our group. FC networks of hippocampal subregions were compared between patients and HCs and correlated with clinical measures and cognitive performance.

RESULTS

Decreased connectivity of the right intermediate hippocampus (RIH) with the limbic regions was a distinguishing feature between TRD and HCs. These functional abnormalities were present in the absence of structural volumetric differences. Furthermore, lower right amygdalar connectivity to the RIH related to a longer current depressive episode. Declarative memory deficits in TRD were significantly associated with left posterior and right intermediate hippocampal FC patterns.

LIMITATIONS

Our patient samples were treatment-resistant, the conclusions from this study cannot be generalized to all MDD patients directly. Task-based imaging studies are needed to demonstrate hippocampal engagement in the memory deficits of patients. Finally, our findings are strongly in need of replication in independent validation samples.

CONCLUSIONS

These findings demonstrate a transitional property of the intermediate hippocampal subregion between its anterior and posterior counterparts in TRD patients, and provide new insights into the neural network-level dysfunction of the hippocampus in TRD.

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.

CA, Kasper S. Prognosis and improved outcomes in major depression: a review

Treatment outcomes for major depressive disorder (MDD) need to be improved. Presently, no clinically relevant tools have been established for stratifying subgroups or predicting outcomes. This literature review sought to investigate factors closely linked to outcome and summarize existing and novel strategies for improvement. The results show that early recognition and treatment are crucial, as duration of untreated depression correlates with worse outcomes. Early improvement is associated with response and remission, while comorbidities prolong course of illness. Potential biomarkers have been explored, including hippocampal volumes, neuronal activity of the anterior cingulate cortex, and levels of brain-derived neurotrophic factor (BDNF) and central and peripheral inflammatory markers (e.g., translocator protein (TSPO), interleukin-6 (IL-6), C-reactive protein (CRP), tumor necrosis factor alpha (TNFα)). However, their integration into routine clinical care has not yet been fully elucidated, and more research is needed in this regard. Genetic findings suggest that testing for CYP450 isoenzyme activity may improve treatment outcomes. Strategies such as managing risk factors, improving clinical trial methodology, and designing structured step-by-step treatments are also beneficial. Finally, drawing on existing guidelines, we outline a sequential treatment optimization paradigm for selecting first-, second-, and third-line treatments for acute and chronically ill patients. Well-established treatments such as electroconvulsive therapy (ECT) are clinically relevant for treatment-resistant populations, and novel transcranial stimulation methods such as theta-burst stimulation (TBS) and magnetic seizure therapy (MST) have shown promising results. Novel rapid-acting antidepressants, such as ketamine, may also constitute a paradigm shift in treatment optimization for MDD.