Interplay between pro-inflammatory cytokines, childhood trauma, and executive function in depressed adolescents

A biobehavioural and social-structural model of inflammation and executive function in pediatric chronic health conditions

Evidence indicates that pediatric chronic health conditions (CHCs) often impair executive functioning (EF) and impaired EF undermines pediatric CHC management. This bidirectional relationship likely occurs due to biobehavioural and social-structural factors that serve to maintain this feedback loop. Specifically, biobehavioural research suggests that inflammation may sustain a feedback loop that links together increased CHC severity, challenges with EF, and lower engagement in health promoting behaviours. Experiencing social and environmental inequity also maintains pressure on this feedback loop as experiencing inequities is associated with greater inflammation, increased CHC severity, as well as challenges with EF and engagement in health promoting behaviours. Amidst this growing body of research, a model of biobehavioural and social-structural factors that centres inflammation and EF is warranted to better identify individual and structural targets to ameliorate the effects of CHCs on children, families, and society at large. This paper proposes this model, reviews relevant literature, and delineates actionable research and clinical implications.

The Insidious Influence of Stress: An Integrated Model of Stress, Executive Control, and Psychopathology

Although exposure to acute stress undoubtedly contributes to psychopathology, most individuals do not develop psychopathology following stress exposure. To explain this, biological, emotional, and cognitive responses to stress have been implicated, but individual differences in executive control (i.e., top-down control of cognition and behavior) measured in response to stress has only recently emerged as a potential factor contributing to psychopathology. In this review, we introduce a model-the integrated model of stress, executive control, and psychopathology-positing how the impairing effects of acute stress on executive control can contribute to psychopathology. We link to research on biological, emotional, and cognitive processes, all of which can be impacted by executive control, to propose a framework for how poorer executive control under conditions of acute stress can contribute to psychopathology. This integrated model is intended to further our understanding of who is more susceptible to the negative consequences of stress.

Prevalence and clinical correlates of abnormal glucose metabolism in young, first- episode and medication-naïve outpatients with major depressive disorder

BACKGROUNDS

The high co-morbidity of abnormal glucose metabolism in depressed patients has been extensively studied, but few studies have explored abnormal glucose metabolism in young patients with major depressive disorder (MDD). This study aimed to examine the prevalence and clinical correlates of abnormal glucose metabolism in young patients with first-episode medication-naïve (FEMN) MDD.

METHODS

A cross-sectional study was conducted on 1289 young Chinese outpatients with FEMN MDD. All subjects were assessed on the Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale (HAMA), Positive and Negative Syndrome Scale, and their sociodemographic information was collected, and blood pressure, blood glucose, lipid and thyroid hormone levels were measured.

RESULTS

The prevalence of abnormal glucose metabolism was 12.57% in young FEMN MDD outpatients. Thyroid stimulating hormone (TSH) levels and HAMA scale scores were associated with fasting blood glucose levels in patients with FEMN MDD (P<0.05), and TSH could differentiate patients with abnormal normal glucose metabolism from those without abnormal glucose metabolism (Area Under Curve of 0.774).

CONCLUSIONS

Our study showed a high prevalence of comorbid glucose metabolism abnormalities in young FEMN MDD outpatients. TSH may be a promising biomarker of abnormal glucose metabolism in young patients with FEMN MDD.

The association between victimization and inflammation: A meta-analysis

BACKGROUND

To meta-analyze the existing studies examining the association of childhood and adulthood victimization with inflammation and to explore the moderating variables that affect these relationships.

METHODS

Relevant work published before 28th February 2021 was identified by searching five major databases. We analyzed the cross-sectional data extracted from cross-sectional and longitudinal studies using the random-effects model to estimate the correlation (r) as the pooled effect size and further conducted subgroup analyses and sensitivity analyses.

RESULTS

A total of 37 articles finally met the inclusion criteria, including studies for C-reactive protein (CRP) (k = 23; N_CRP = 11,780), interleukin-6 (IL-6) (k = 31; N_IL-6 = 8943), and tumor necrosis factor-alpha (TNF-α) (k = 14; N_TNF-α = 4125). Overall, victimization has a significantly positive association with inflammation, with a small effect size (r = 0.122). Specifically, effect sizes were the largest for TNF-a (r = 0.152), followed by IL-6 (r = 0.119), and CRP (r = 0.084). Additionally, the effect sizes for victimization against children were r = 0.145 (k = 6) for childhood victimization - childhood inflammation, and r = 0.139 (k = 27) for childhood victimization - adulthood inflammation, which appear to be larger than that of victimization against adults (r = 0.039; k = 2).

LIMITATIONS

Only a small number of studies on adult victimization were included. In addition, we only analyzed the cross-sectional relationship and did not have sufficient data to compare different types of victimization and single vs. multiple victimizations.

CONCLUSIONS

Victimization is associated with a heightened inflammatory response. As victimization against children may have a stronger effect than victimization against adults, prevention of victimization targeting the childhood period may be necessary. Studies with more robust methodologies (i.e., representative, longitudinal, and multi-country designs) are needed to confirm these findings and to unpack the underlying mechanisms.

Biomarkers in Child and Adolescent Depression

Despite the significant prevalence of Major Depressive Disorder in the pediatric population, the pathophysiology of this condition remains unclear, and the treatment outcomes poor. Investigating tools that might aid in diagnosing and treating early-onset depression seems essential in improving the prognosis of the future disease course. Recent studies have focused on searching for biomarkers that constitute biochemical indicators of MDD susceptibility, diagnosis, or treatment outcome. In comparison to increasing evidence of possible biomarkers in adult depression, the studies investigating this subject in the youth population are lacking. This narrative review aims to summarize research on molecular and biochemical biomarkers in child and adolescent depression in order to advocate future directions in the research on this subject. More studies on depression involving the youth population seem vital to comprehend the natural course of the disease and identify features that may underlie commonly observed differences in treatment outcomes between adults and children.

Longitudinal relations between impaired executive function and symptoms of psychiatric disorders in childhood

BACKGROUND

Malfunctioning of executive functions correlates with psychopathology in children. However, the directionality, the extent to which the relation varies for various disorders, and whether prospective relations afford causal interpretations are not known.

METHODS

A community sample of Norwegian children (n = 874) was studied biennially from the age of 6 to 14 years. Executive functions were assessed using the Behavior Rating Inventory of Executive Function Teacher-report and symptoms of psychopathology were assessed using the Preschool Age Psychiatric Assessment (age 6; parents) and Child and Adolescent Psychiatric Assessment (ages 8-14; children and parents). Prospective reciprocal relations were examined using a random intercept cross-lagged panel model that adjusts for all unobserved time-invariant confounders.

RESULTS

Even when time-invariant confounders were accounted for, reduced executive functions predicted increased symptoms of depressive disorders, anxiety disorders, attention-deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and conduct disorder (CD) 2 years later, even when previous changes in these symptoms were adjusted for. The level of prediction (B = .83, 95% CI [.37, 1.3]) was not different for different disorders or ages. Conversely, reduced executive functions were predicted by increased symptoms of all disorders (B = .01, 95% CI [.01, .02]).

CONCLUSIONS

Reduced executive functioning may be involved in the etiology of depression, anxiety, ADHD, and ODD/CD to an equal extent. Moreover, increased depression, anxiety, ADHD, and ODD/CD may negatively impact executive functioning.

Evaluation of Inflammatory Response System (IRS) and Compensatory Immune Response System (CIRS) in Adolescent Major Depression

Purpose

Nowadays, the role of two tightly interconnected systems, the inflammatory response system (IRS) and the compensatory immune response system (CIRS) in depression, is increasingly discussed. Various studies indicate pro-inflammatory activity in adolescent depression; however, there is an almost complete lack of findings about IRS and CIRS balance. Thus, we aimed to assess different IRS and CIRS indices, profiles, and IRS/CIRS ratios in drug-naïve MDD patients at adolescent age, with respect to sex.

Patients and Methods

One hundred MDD adolescents (40 boys, average age: 15.4±1.2 yrs.) and 60 controls (28 boys, average age: 15.3±1.5 yrs.) were examined. Evaluated parameters were 1. plasma levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon gamma, tumor necrosis factor alpha (TNF-α), soluble receptor of IL-6 (sIL-6R), soluble receptors of TNF-α (sTNF-R1, sTNF-R2); 2. profiles: IL-6 trans-signaling, M1 macrophage signaling, helper T lymphocytes (Th) 1 profile, regulatory T lymphocytes (Treg)+Th2, allIRS, and allCIRS; 3. IRS vs CIRS activity ratios: TNF-α/TNF-R1, TNF-α/TNF-R2, TNF-α/sTNF-Rs (ie sTNF-R1+sTNF-R2), Th1/Th2, Th1/Treg, Th1/Th2+Treg, M1/Th2, M1/Treg, M1/Treg+Th2, allIRS/allCIRS.

Results

MDD patients showed increased IL-4, IL-10, TNF-α, sIL-6R, Treg+Th2, allIRS, allCIRS, and TNF-α/sTNF-Rs, and decreased Th1/Th2+Treg. MDD females showed increased IL-10 and TNF-α compared to control females. MDD males showed increased IL-4, IL-10, sIL-6R, Treg+Th2, and TNF-α/TNF-R1 compared to control males. Increased sTNF-R1 was found in MDD males compared to MDD females. Positive correlations were found between CDI score and sIL-6R and IL-10 in the total group and between CDI score and IL-10 in adolescent males.

Conclusion

Our study for the first time extensively evaluated IRS and CIRS interactions revealing enhanced pro-inflammatory TNF-α signaling and IL-6 trans-signaling in association with increased IL-10- and IL-4-mediated anti-inflammatory activity in first-episode depression at the adolescent age. Moreover, results reflect the sex-specific simultaneous activation of IRS and CIRS pathways in adolescent depression.

Cytokine alterations in pediatric internalizing disorders: Systematic review and exploratory multi-variate meta-analysis

Pediatric internalizing disorders are prevalent and characterized by a maladaptive cognitive, emotional response to a perceived stressor. The hypothesized effect of this response is observable changes in behavior mediated by homeostatic inflammatory cytokines. The aim of this study was to synthesize the literature and analyze the effect of cytokines on pediatric internalizing disorders. Influential moderating variables, including mean body mass index, fasting status at blood collection, participant sex, cytokine type, mean age, percentage of sample medicated, and diagnosis, were also assessed. A systematic literature search was performed in electronic databases (Medline, PubMed, and PsycINFO) from January 1, 1980 to June 15, 2022. Case-control studies of pediatric internalizing disorders, specifically anxiety and depression, were reviewed for their association with peripheral cytokine levels. Meta-analyses were performed using a random effects multi-variate model and effect sizes were calculated using Hedge's g for IL-2, CRP, IL-6, TNF-α, IL-1β, IFN-γ, and IL-10. Thirty-three studies were reviewed and 28 studies were included in the meta-analysis (n = 1322 cases and n = 3617 controls). Peripheral cytokine levels were elevated in pediatric internalizing disorders compared to controls (Hedge's g = 0.19, p < 0.001). In the moderator analyses, depression diagnosis (Hedge's g = 0.18, p = 0.009) and non-fasting blood collection (Hedge's g = 0.20, p = 0.006) were significant. The meta-analytic findings are limited by methodological variation between studies, high heterogeneity, and low statistical power. Despite this, the findings suggest that elevated peripheral cytokine levels may play a role in the etiology and/or symptom maintenance of pediatric internalizing disorders.

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Depression diagnosis and non-fasting blood collection were observed to significantly influenced peripheral cytokine levels.

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No individual peripheral cytokines tested were associated with pediatric internalizing disorders.

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Overall, elevated peripheral cytokines were observed in pediatric internalizing disorders compared to controls.

Relationships between Depression and Executive Functioning in Adolescents: The Moderating Role of Unpredictable Home Environment

Although researchers have explored the link between depression and executive functioning (EF), the influence of early-life environmental and relational instability on this association has not been comprehensively assessed in adolescents. This cross-sectional study examined whether unpredictability of home environment in childhood moderated the relationship between depression and EF in adolescents. Participants were 138 adolescents aged 13 to 17 years (72% female; 47.8% White; 47.1% Hispanic). Diagnostic status (major depression versus healthy control) and depression severity were assessed using psycho-diagnostic interviews and self-reports from parents and adolescents. Participants also completed the Questionnaire of Unpredictability in Childhood (QUIC). EF was assessed using self-report (Behavior Rating Inventory of Executive Function, Second Edition; BRIEF2) and a battery of performance-based measures. Results showed that QUIC scores moderated the relationship between depression and BRIEF2 scores, such that high unpredictability was associated with poorer EF for adolescents exhibiting low depression severity. Participants with the highest levels of depression exhibited the poorest EF ratings, regardless of childhood unpredictability. Unpredictability was moderately associated with performance-based measures, but did not interact with depressive symptoms to predict complex performance-based EF. Recommendations include assessing for unpredictable childhood environment and acknowledging this risk factor for poor EF in youth with sub-threshold depression. Treatment implications are discussed with respect to family systems/parenting interventions, as mildly depressed adolescents growing up in unstable homes may be vulnerable to EF difficulties. Further, this study adds to the EF measurement literature by examining associations between self-report and performance-based EF instruments in a diverse sample of adolescents.

Developmental trauma: Conceptual framework, associated risks and comorbidities, and evaluation and treatment

Children exposed to adverse childhood experiences (ACEs) and pervasive interpersonal traumas may go on to develop PTSD and, in most cases, will further undergo a significant shift in their developmental trajectory. This paper examines contemporary research on Developmental Trauma (DT), which is inextricably linked to disruptions in social cognition, physiological and behavioral regulation, and parent-child attachments. Developmental trauma associated with early experiences of abuse or neglect leads to multi-faceted and longstanding consequences and underscores critical periods of development, complex stress-mediated adaptations, and multilevel, trans-theoretical influences in the diagnostic formulation and treatment of traumatized children, adolescents, and adults. Psychological and medical correlates of Developmental Trauma Disorder are considered, and directions for future research are discussed.

Neuroinflammation, Early-Life Adversity, and Brain Development

The overarching objective is to review how early exposure to adversity interacts with inflammation to alter brain maturation. Both adversity and inflammation are significant risk factors for psychopathology. Literature relevant to the effects of adversity in children and adolescents on brain development is reviewed. These studies are supported by research in animals exposed to species-relevant stressors during development. While it is known that exposure to adversity at any age increases inflammation, the effects of inflammation are exacerbated at developmental stages when the immature brain is uniquely sensitive to experiences. Microglia play a vital role in this process, as they scavenge cellular debris and prune synapses to optimize performance. In essence, microglia modify the synapse to match environmental demands, which is necessary for someone with a history of adversity. Overall, by piecing together clinical and preclinical research areas, what emerges is a picture of how adversity uniquely sculpts the brain. Microglia interactions with the inhibitory neurotransmitter GABA (specifically, the subtype expressing parvalbumin) are discussed within contexts of development and adversity. A review of inflammation markers in individuals with a history of abuse is combined with preclinical studies to describe their effects on maturation. Inconsistencies within the literature are discussed, with a call for standardizing methodologies relating to the age of assessing adversity effects, measures to quantify stress and inflammation, and more brain-based measures of biochemistry. Preclinical studies pave the way for interventions using anti-inflammation-based agents (COX-2 inhibitors, CB2 agonists, meditation/yoga) by identifying where, when, and how the developmental trajectory goes awry.

Inflammation and depression in young people: a systematic review and proposed inflammatory pathways

Depression onset peaks during adolescence and young adulthood. Current treatments are only moderately effective, driving the search for novel pathophysiological mechanisms underlying youth depression. Inflammatory dysregulation has been shown in adults with depression, however, less is known about inflammation in youth depression. This systematic review identified 109 studies examining the association between inflammation and youth depression and showed subtle evidence for inflammatory dysregulation in youth depression. Longitudinal studies support the bidirectional association between inflammation and depression in youth. We hypothesise multiple inflammatory pathways contributing to depression. More research is needed on anti-inflammatory treatments, potentially tailored to individual symptom profiles.

The relationship between immune and cognitive dysfunction in mood and psychotic disorder: a systematic review and a meta-analysis

BACKGROUND

In psychotic and mood disorders, immune alterations are hypothesized to underlie cognitive symptoms, as they have been associated with elevated blood levels of inflammatory cytokines, kynurenine metabolites, and markers of microglial activation. The current meta-analysis synthesizes all available clinical evidence on the associations between immunomarkers (IMs) and cognition in these psychiatric illnesses.

METHODS

Pubmed, Web of Science, and Psycinfo were searched for peer-reviewed studies on schizophrenia spectrum disorder (SZ), bipolar disorder (BD), or major depressive disorder (MDD) including an association analysis between at least one baseline neuropsychological outcome measure (NP) and one IM (PROSPERO ID:CRD42021278371). Quality assessment was performed using BIOCROSS. Correlation meta-analyses, and random effect models, were conducted in Comprehensive Meta-Analysis version 3 investigating the association between eight cognitive domains and pro-inflammatory and anti-inflammatory indices (PII and AII) as well as individual IM.

RESULTS

Seventy-five studies (n = 29,104) revealed global cognitive performance (GCP) to be very weakly associated to PII (r = -0.076; p = 0.003; I² = 77.4) or AII (r = 0.067; p = 0.334; I² = 38.0) in the combined patient sample. Very weak associations between blood-based immune markers and global or domain-specific GCP were found, either combined or stratified by diagnostic subgroup (GCP x PII: SZ: r = -0.036, p = 0.370, I² = 70.4; BD: r = -0.095, p = 0.013, I² = 44.0; MDD: r = -0.133, p = 0.040, I² = 83.5). We found evidence of publication bias.

DISCUSSION

There is evidence of only a weak association between blood-based immune markers and cognition in mood and psychotic disorders. Significant publication and reporting biases were observed and most likely underlie the inflation of such associations in individual studies.

Associations of Early-Life Threat and Deprivation With Executive Functioning in Childhood and Adolescence: A Systematic Review and Meta-analysis

IMPORTANCE

Many studies have demonstrated an association between early-life adversity (ELA) and executive functioning in children and adolescents. However, the aggregate magnitude of this association is unknown in the context of threat and deprivation types of adversity and various executive functioning domains.

OBJECTIVE

To test the hypothesis that experiences of deprivation are more strongly associated with reduced executive functioning compared with experiences of threat during childhood and adolescence.

DATA SOURCES

Embase, ERIC, MEDLINE, and PsycInfo databases were searched from inception to December 31, 2020. Both forward and reverse snowball citation searches were performed to identify additional articles.

STUDY SELECTION

Articles were selected for inclusion if they (1) had a child and/or adolescent sample, (2) included measures of ELA, (3) measured executive functioning, (4) evaluated the association between adversity and executive functioning, (5) were published in a peer-reviewed journal, and (6) were published in the English language. No temporal or geographic limits were set. A 2-reviewer, blinded screening process was conducted.

DATA EXTRACTION AND SYNTHESIS

PRISMA guidelines were used to guide data extraction and article diagnostics (for heterogeneity, small study bias, and p-hacking). Article quality was assessed, and data extraction was performed by multiple independent observers. A 3-level meta-analytic model with a restricted maximum likelihood method was used. Moderator analyses were conducted to explore heterogeneity.

MAIN OUTCOMES AND MEASURES

Primary outcomes included measures of the 3 domains of executive functioning: cognitive flexibility, inhibitory control, and working memory.

RESULTS

A total of 91 articles were included, representing 82 unique cohorts and 31 188 unique individuals. Deprivation, compared with threat, was associated with significantly lower inhibitory control (F1,90 = 5.69; P = .02) and working memory (F1,54 = 5.78; P = .02). No significant difference was observed for cognitive flexibility (F1,36 = 2.38; P = .12). The pooled effect size of the association of inhibitory control with deprivation was stronger (Hedges g = -0.43; 95% CI, -0.57 to -0.29) compared with threat (Hedges g = -0.27; 95% CI, -0.46 to -0.08). The pooled effect size of the association of working memory with deprivation was stronger (Hedges g = -0.54; 95% CI, -0.75 to -0.33) compared with threat (Hedges g = -0.28; 95% CI, -0.51 to -0.05).

CONCLUSIONS AND RELEVANCE

Experiences of both threat and deprivation in childhood and adolescence were associated with reduced executive functioning, but the association was stronger for exposure to deprivation. Efforts to address the consequences of ELA for development should consider the associations between specific dimensions of adversity and specific developmental outcomes.

The role of inhibitory processes in the relationship between subsyndromal PTSD symptoms and aggressive behaviour

The issue of aggressive behaviours among military populations is important for a number of reasons, including the potential associated occupational, social and functional impacts. Controlled aggressive behaviour is an adaptive requirement of some military roles, however, this aggression can become maladaptive when uncontrolled, or contextually inappropriate. Elevated aggression among deployed veterans has been identified in a number of studies, although the reasons for it are not well understood. Deployed populations have elevated levels of stress and trauma exposure, have higher rates of childhood and other lifetime trauma exposures and have a heightened risk for subsyndromal or full PTSD. Both trauma exposure and PTSD have been found to be associated with executive function deficits, and increased anger and aggressive behaviours. The purpose of this paper was to explore the contribution of both early PTSD symptoms and cognitive disinhibition in predicting increased aggressive behaviour following deployment in a healthy active serving cohort. After controlling for pre-deployment PTSD symptoms and cognitive function, there were significant main effects of both PTSD symptoms and cognitive function on increased aggression at post-deployment. Furthermore, the positive association between PTSD symptoms and post-deployment aggression was moderated by response inhibition deficits in the domains of false positive errors as well as faster reaction times. Subsidiary analyses showed that the effects of increased reaction time in particular increased the likelihood of PTSD symptoms being coupled with increased aggression. These findings highlight the potential effects of repeated occupational stress exposure and point to possible cognitive adaptations and long-term risk for disorder.

Linking childhood trauma and cytokine levels in depressed adolescents

BACKGROUND

Evidence supports raised circulating levels of inflammatory mediators, such as interleukin-6 (IL-6) and tumor necrosis factor (TNFα), among clinically depressed adults, although preliminary findings in adolescents are mixed. Independently, meta-analyses identify correlations between childhood trauma and elevated cytokine levels in adulthood. Here, we examine the possible role of individual differences in exposure to childhood trauma in contributing to variability in cytokine levels in depressed adolescents.

METHODS

52 depressed adolescents and 20 healthy adolescents completed measures of childhood trauma and provided blood for the assessment of plasma IL-6 and TNFα. Cross-sectional associations of childhood trauma and cytokine measures were assessed in both depressed and healthy adolescents, along with exploratory analysis of childhood trauma subtypes. Longitudinal relationships between childhood trauma and cytokine measures were also studied in an exploratory fashion within a subset of depressed participants (n = 36).

RESULTS

Higher childhood trauma (particularly emotional abuse) was positively associated with TNFα in depressed adolescents. Childhood trauma was not linked to longitudinal changes in cytokine levels.

DISCUSSION

In depressed adolescents, childhood trauma may relate to higher levels of the proinflammatory cytokine TNFα and contribute to heterogeneity in cytokine elevation among depressed adolescents. Such findings may ultimately help guide more effective individualized treatments for adolescents with depression.

Neurofilament Light Chain Is a Novel Biomarker for Major Depression and Related Executive Dysfunction

BACKGROUND

Evidence suggests that major depressive disorder is related to neuroaxonal injury and that neurofilament light chain (NfL) is a biomarker of neuroaxonal injury. In addition, proinflammatory cytokines have been reported to be associated with major depression and neuroaxonal injury.

METHODS

Forty patients with major depression and 40 age- and sex-matched healthy control participants were enrolled for the measurement of NfL and proinflammatory cytokines and assessment of executive function. General linear models were used to examine the association between NfL levels, proinflammatory cytokine levels, and executive function.

RESULTS

Patients with major depressive disorder exhibited significantly higher NfL levels (P = .007) than the control participants. NfL levels were positively related to log-transformed levels of tumor necrosis factor-α (P = .004). Higher levels of NfL (P = .002) and tumor necrosis factor-α (P = .013) were associated with greater deficits in executive function.

DISCUSSION

NfL was a novel biomarker for major depressive disorder and related executive dysfunction. Further studies are necessary to elucidate the role of NfL in the pathophysiology of major depression and related cognitive impairment.

Molecular Biomarkers for Pediatric Depressive Disorders: A Narrative Review

Depressive disorder in childhood and adolescence is a highly prevalent mood disorder that tends to recur throughout life. Untreated mood disorders can adversely impact a patient’s quality of life and cause socioeconomic loss. Thus, an accurate diagnosis and appropriate treatment is crucial. However, until now, diagnoses and treatments were conducted according to clinical symptoms. Objective and biological validation is lacking. This may result in a poor outcome for patients with depressive disorder. Research has been conducted to identify the biomarkers that are related to depressive disorder. Cumulative evidence has revealed that certain immunologic biomarkers including brain-derived neurotrophic factor (BDNF) and cytokines, gastrointestinal biomarkers, hormones, oxidative stress, and certain hypothalamus-pituitary axis biomarkers are associated with depressive disorder. This article reviews the biomarkers related to the diagnosis and treatment of pediatric depressive disorders. To date, clinical biomarker tests are not yet available for diagnosis or for the prediction of treatment prognosis. However, cytokines such as Interleukin-2, interferon-gamma, tumor necrosis factor-alpha, and BDNF have shown significant results in previous studies of pediatric depressive disorder. These biomarkers have the potential to be used for diagnosis, prognostic assessment, and group screening for those at high risk.

Alterations in 'inflammatory' pathways in the rat prefrontal cortex as early biological predictors of the long-term negative consequences of exposure to stress early in life

Early life stress, especially when experienced during the first period of life, affects the brain developmental trajectories leading to an enhanced vulnerability for stress-related psychiatric disorders later in life. Although both clinical and preclinical studies clearly support this association, the biological pathways deregulated by such exposure, and the effects in shaping the neurodevelopmental trajectories, have so far been poorly investigated. By using the prenatal stress (PNS) model, a well-established rat model of early life stress, we performed transcriptomic analyses in the prefrontal cortex of rats exposed or not to PNS and sacrificed at different postnatal days (PNDs 21, 40, 62). We first investigated the long-lasting mechanisms and pathways affected in the PFC. We have decided to focus on the prefrontal cortex because we have previously shown that this brain region is highly sensitive to PNS exposure. We found that adult animals exposed to PNS show alterations in 389 genes, mainly involved in stress and inflammatory signalling. We then wanted to establish whether PNS exposure could also affect the neurodevelopmental trajectories in order to identify the most critical temporal window. We found that PNS rats show the most significant changes during adolescence (between PND 40 versus PND 21), with alterations of several pathways related to stress, inflammation and metabolism, which were maintained until adulthood.

Interaction of Serum Copper and Neurometabolites on Executive Dysfunction in Unmedicated Patients With Major Depressive Disorder

Objective: The mechanism of executive function (EF) impairment in major depressive disorder (MDD) remains unclear. Previous studies have demonstrated that altered serum copper levels and neurometabolic alterations may be associated with the psychopathology and cognitive impairment of MDD. While, their inter-relationships in MDD remain uncertain. The present study aims to assess whether the interaction between serum copper levels and neurometabolic alterations is involved in the deficit of executive function (EF) in patients with unmedicated MDD. Methods: Serum copper levels and EFs were measured in 41 MDD patients and 50 control subjects. EFs were evaluated by Trail Making Test, Part-B (TMT-B), Digit Symbol Substitution Test (DSST), Wisconsin Card Sorting Task (WCST), and Semantic Verbal Fluency testing (SVFT). Additionally, 41 patients and 41 healthy controls underwent proton magnetic resonance spectroscopy (¹H-MRS) to obtain ratios of N-acetyl aspartate to creatine (NAA/Cr) and choline-containing compounds to creatine (Cho/Cr) in the lenticular nucleus (LN) of basal ganglia (BG). Finally, association and interaction analysis were conducted to investigate their inter-relationships. Results: The results showed that patients performed worse in the DSST, WCST, TMT-B time and SVFT. Moreover, patients had higher serum copper levels, but lower NAA/Cr ratios in left LN of BG than healthy controls. In patients, serum copper levels were found to significantly negative associated with Categories Completed (CC) number of WCST (r = -0.408, p = 0.008), and positive associated with the Total Errors (TE) and Nonperseverative Errors (PE) number of WCST (r = 0.356, p = 0.023; r = -0.356, p = 0.022). In addition, the NAA/Cr ratios of left LN were found to significantly negative associated with VFS (r = -0.401, p = 0.009), as well as negative associated with serum copper levels (r = -0.365, p = 0.019). Finally, the interaction between copper and NAA may as influencing factors for SVFT and CC number of WCST in patients. Conclusion: Our results indicated that the interaction of abnormal copper levels and NAA/Cr neurometabolic disruption of the LN may impact executive dysfunction, and this may relevant to the pathophysiology of executive impairment in MDD patients.

The Association Between Adverse Childhood Experiences and Inflammation in Patients with Major Depressive Disorder: A Systematic Review

BACKGROUND

Replicated evidence has documented elevated levels of pro-inflammatory cytokines in populations with major depressive disorder (MDD). However, childhood trauma, a risk factor for MDD, has been separately shown to also impact inflammatory systems; its potential moderating effect on inflammation in MDD has been less frequently investigated.

METHODS

We systematically searched the PubMed, Google Scholar, Scopus, Web of Science, and PsycINFO databases between database inception to June 19th, 2019 using the search string: (Childhood trauma or Adverse childhood experiences or childhood abuse or childhood rape or physical abuse or emotional abuse) AND (Inflammation or inflammatory cytokines or interleukin-6 or tumor necrosis factor-alpha or c-reactive protein) AND (Major Depressive Disorder or Depression).

RESULTS

We identified nine articles that evaluated inflammatory biomarkers in MDD populations with adverse childhood experiences (ACE). Eight articles evaluated IL-6, three articles evaluated CRP, and five articles evaluated TNF-α. The strongest effects were observed for IL-6; six studies reported significantly elevated levels of IL-6 in MDD and ACE patients compared to healthy controls and/or MDD-only populations. Meanwhile, only three studies found TNF-α to be significantly elevated in the MDD and ACE cohort. In contrast, MDD-ACE populations did not exhibit significantly elevated CRP.

LIMITATIONS

The methodological heterogeneity amongst studies was very high.

CONCLUSION

The current review suggests that MDD and ACE subpopulations present elevated levels of IL-6 compared to MDD-only and healthy control populations. Therefore, research should consider whether elevated inflammation in MDD is just an epiphenomenon of previous ACE and whether MDD-ACE subgroups are more likely to respond to immune-inflammatory targeted intervention.

Dysregulation of inflammation, neurobiology, and cognitive function in PTSD: an integrative review

Compelling evidence from animal and human research suggest a strong link between inflammation and posttraumatic stress disorder (PTSD). Furthermore, recent findings support compromised neurocognitive function as a key feature of PTSD, particularly with deficits in attention and processing speed, executive function, and memory. These cognitive domains are supported by brain structures and neural pathways that are disrupted in PTSD and which are implicated in fear learning and extinction processes. The disruption of these supporting structures potentially results from their interaction with inflammation. Thus, the converging evidence supports a model of inflammatory dysregulation and cognitive dysfunction as combined mechanisms underpinning PTSD symptomatology. In this review, we summarize evidence of dysregulated inflammation in PTSD and further explore how the neurobiological underpinnings of PTSD, in the context of fear learning and extinction acquisition and recall, may interact with inflammation. We then present evidence for cognitive dysfunction in PTSD, highlighting findings from human work. Potential therapeutic approaches utilizing novel pharmacological and behavioral interventions that target inflammation and cognition also are discussed.

Disrupted intrinsic functional connectivity of the cognitive control network underlies disease severity and executive dysfunction in first-episode, treatment-naive adolescent depression

BACKGROUND

Previous neuroimaging studies have showed that imbalanced functional integration of distributed large-scale brain networks is associated with pathophysiological characteristics of major depressive disorder (MDD). However, the association between network integrative disturbances and clinical features and cognitive functions remains largely unclear in adolescent MDD. This study investigated the neural correlates of abnormal functional connectivity networks with clinical and cognitive characteristics in adolescent MDD.

METHODS

Twenty-eight first-episode, treatment-naive adolescents with MDD and 24 well-matched healthy controls (HCs) underwent functional magnetic resonance imaging (fMRI) and a battery of cognitive tests. A seed-based functional connectivity (FC) approach was used to depict connectivity patterns of the cognitive control network (CCN), affective network (AN) and default mode network (DMN), whose between-group differences were correlated with clinical variables and cognitive functions in the patients.

RESULTS

Compared with the HCs, the MDD patients exhibited impaired executive functions. The FC analysis revealed lower CCN FC with the temporal, parietal and frontal regions and the limbic system, higher AN FC with the temporal and occipital regions and the cerebellum, and lower DMN FC with the cerebellum and insula. Interestingly, the decreased CCN FC was related to disease severity (with the inferior frontal gyrus) and executive dysfunctions (with the middle cingulate gyrus and supramarginal gyrus) in the patients.

LIMITATIONS

The main limitations were the relatively small sample size and suboptimal imaging parameters.

CONCLUSION

Functional alteration of CCN during the developmentally sensitive period may be important in the neurobiology of adolescent MDD.

C-reactive protein and response to lurasidone treatment in children and adolescents with bipolar I depression: Results from a placebo-controlled trial

This study sought to investigate associations between levels of high-sensitivity c-reactive protein (hsCRP) prior to treatment and change in depressive symptoms and cognition in a short-term, double-blind, placebo-controlled study of lurasidone in children and adolescents with bipolar I depression. Patients 10-17 years of age with a DSM-5 diagnosis of bipolar I depression were randomized to 6 weeks of double-blind treatment with flexibly dosed lurasidone (20-80 mg/day) (n = 173) or placebo (n = 170). The primary efficacy measure was change from baseline to week 6 in the Children's Depression Rating Scale, Revised (CDRS-R). Treatment response was defined as 50% or greater improvement on the CDRS-R from baseline to week 6. Cognitive function was evaluated with the computerized Brief Cogstate Battery at baseline and week 6. Analyses were adjusted for baseline BMI, as well as age. HsCRP was evaluated as a logarithmically transformed continuous variable and as a categorical variable dichotomized into lower (<1 mg/L) and higher (≥1 mg/L) subgroups. A significant interaction was found between baseline hsCRP and treatment group for change in CDRS-R score at study endpoint, with larger placebo-corrected effect sizes for lurasidone in the higher baseline hsCRP group (≥1 mg/L). A significant BMI-by-hsCRP-by-treatment interaction was found for response rate with higher baseline hsCRP levels associated with greater antidepressant response to lurasidone (vs. placebo) in the normal BMI range subgroup (NNT = 2 in higher hsCRP vs. NNT = 5 in lower hsCRP groups) but not in the overweight/obese patients (NNT = 6 in higher hsCRP vs. NNT = 5 in lower hsCRP). Similarly, a significant interaction effect was observed for the combination of hsCRP and BMI on the procognitive effect of lurasidone, with higher baseline hsCRP levels being associated with improvement in cognitive function for lurasidone (vs placebo) in the normal BMI range subgroup but not in overweight/obese patients. These results suggest that young patients with bipolar depression with normal weight and higher levels of pre-treatment CRP may show a greater placebo-adjusted improvement in depressive symptoms and cognitive performance when treated with lurasidone. If these findings are confirmed in future prospective studies, CRP and BMI may prove to be useful diagnostic and predictive biomarkers in the treatment with lurasidone of children and adolescents with bipolar depression.