Prevalence of low-grade inflammation in depression: a systematic review and meta-analysis of CRP levels

Development of a clinical risk score system for peritoneal dialysis-associated peritonitis treatment failure

OBJECTIVE

This study aimed to construct a clinical risk score system for peritoneal dialysis-associated peritonitis (PDAP) treatment failure to provide a theoretical basis for clinical workers.

METHODS

A total of 161 PDAP individuals admitted to our hospital were included, among whom 70 cases were in the treatment-improved group and 87 cases were in the treatment failure group. We compared the general condition, clinical manifestations, and laboratory examination indicators of the two groups of individuals, used multivariate logistic regression analysis to identify the factors influencing PDAP treatment failure, and developed a clinical risk score system. The diagnostic performance of the risk score system was evaluated utilizing the receiver operating characteristic (ROC) curve.

RESULTS

Significant differences (P < 0.05) were observed between the two groups in terms of contamination, peritoneal fluid culture results, blood urea nitrogen (BUN) level, C-reactive protein (CRP) level, B-type natriuretic peptide (BNP) level, average residual urine (RU) volume, and urea clearance rate (UCR). Multivariate logistic regression analysis showed that BUN level, CRP level, BNP level, average RU volume, and UCR were independent risk factors affecting PDAP patient treatment outcomes (P < 0.05). The ROC curve analysis of the risk score system for predicting treatment failure in PDAP individuals showed an area under the curve of 0.895 [95% confidence interval (0.847-0.943)]. The optimal cut-off point was 2.5 points, with corresponding sensitivity and specificity of 88.5% and 74.3%, separately.

CONCLUSION

BUN level, CRP level, BNP level, average RU volume, and UCR are independent risk factors for PDAP treatment failure. The clinical risk score system based on these five independent risk factors can accurately predict the risk of treatment failure in PDAP individuals.

Major Depressive Disorder, Inflammation, and Nutrition: A Tricky Pattern?

Major depressive disorder (MDD) is a psychiatric disease associated with inflammation. The Western diet (WD) is a high-fat, high-sugar diet also associated with inflammation. We aimed to show whether the diet of MDD patients was a WD and could act as a risk factor in this context. We conducted a transversal study of MDD patients and controls (CTRLs) without comorbidities. We performed blood analyses including C-reactive protein (CRP), a diet anamnesis, and an advanced glycation end-product assessment. We found that 34.37% of MDD patients had a CRP level above 3 to 10 mg/L, which remained higher than CTRLs after adjustments (sex, BMI, age, smoking status). The MDD patients had an excess of sugar and saturated and trans fatty acids; a deficiency in n-3 polyunsaturated fatty acid, monounsaturated acid, dietary fibers, and antioxidants; a high glycemic load; and aggravating nutritional factors when compared to the CTRLs. We found correlations between nutritional factors and CRP in univariate/multivariate analysis models. Thus, MDD patients showed an elevated CRP level and a WD pattern that could contribute to sustaining an inflammatory state. Further studies are required to confirm this, but the results highlighted the importance of nutrition in the context of MDD.

Inflammatory hypotheses of sleep disturbance - depression link: Update and research agenda

Studies in human and experimental animal models support a role of inflammation in the aetiology of depression, yet the precise role played by sleep disturbance (i.e., difficulties falling or maintaining sleep) is poorly understood. Consistent evidence from prospective epidemiological studies suggests sleep disturbance as a predictor of major depression episodes and depression recurrence. In parallel, up to 20% of individuals with sleep disturbance have low-grade peripheral inflammation (i.e., CRP>3 mg/l), and preliminary longitudinal evidence showed that sleep disturbance may even predict the levels of inflammation. Therefore, it is possible that sleep disturbance may increase inflammation, which in turn may contribute (i.e., mediate) to the onset - or worsening - of depression. Alternatively, sleep disturbance may serve as a vulnerability factor and increase the risk of developing depressive symptoms when facing an immune challenge. The aim of this review was to summarise the state of the science on the role of sleep disturbance in contributing to depression-related inflammation. A research agenda is also proposed to advance the study of sleep disturbance in the psychoneuroimmunology of depression.

The prevalence and outcomes of depression in older HIV-positive adults in Northern Tanzania: a longitudinal study

Studies of depression and its outcomes in older people living with HIV (PLWH) are currently lacking in sub-Saharan Africa. This study aims to investigate the prevalence of psychiatric disorders in PLWH aged ≥ 50 years in Tanzania focussing on prevalence and 2-year outcomes of depression. PLWH aged ≥ 50 were systematically recruited from an outpatient clinic and assessed using the Mini-International Neuropsychiatric Interview (MINI). Neurological and functional impairment was assessed at year 2 follow-up. At baseline, 253 PLWH were recruited (72.3% female, median age 57, 95.5% on cART). DSM-IV depression was highly prevalent (20.9%), whereas other DSM-IV psychiatric disorders were uncommon. At follow-up (n = 162), incident cases of DSM-IV depression decreased from14.2 to 11.1% (χ2: 2.48, p = 0.29); this decline was not significant. Baseline depression was associated with increased functional and neurological impairment. At follow-up, depression was associated with negative life events (p = 0.001), neurological impairment (p < 0.001), and increased functional impairment (p = 0.018), but not with HIV and sociodemographic factors. In this setting, depression appears highly prevalent and associated with poorer neurological and functional outcomes and negative life events. Depression may be a future intervention target.

Variation of Circulating Brain-Derived Neurotrophic Factor (BDNF) in Depression: Relationships with Inflammatory Indices, Metabolic Status and Patients' Clinical Features

This study seeks to offer a contribution to the method of subtyping major depressed patients by exploring the possible relationships between circulating brain-derived neurotrophic factor (BDNF), different peripheral inflammatory/metabolic markers in the blood and clinical characteristics. Thirty-nine patients, thoroughly diagnosed according to the DSM-5 criteria, underwent a comprehensive set of evaluations encompassing structured interviews, rating scales and a panel of blood tests. Correlation and comparison analyses were carried out by means of non-parametric statistical tests. Concurrently, a principal component analysis was performed to explain biochemical variance. The findings of our research unveiled that leukocyte counts, their ratios and other inflammatory parameters are positively correlated with depression scores. Moreover, we found variations within the BDNF pools of depressed patients. Specifically, higher levels of platelet-poor plasma BDNF (PPP-BDNF) were correlated with augmented inflammatory markers in patients showing specific episode characteristics, whereas reduced platelet BDNF (PLT-BDNF) provided a better indication of the changes that were linked to a diagnosis of long-term depression. Our findings suggest that PPP-BDNF and PLT-BDNF might differentiate depression conditions. They also imply usefulness in appraising peripheral biomarker profiles in patients for a deeper characterization of major depressive episodes. At the same time, it is plausible that they might constitute novel avenues for developing more tailored therapeutic strategies for patients with MDs.

Elevated serum leptin is associated with attenuated reward anticipation in major depressive disorder independent of peripheral C-reactive protein levels

Major depressive disorder (MDD) is associated with immunologic and metabolic alterations linked to central processing dysfunctions, including attenuated reward processing. This study investigated the associations between inflammation, metabolic hormones (leptin, insulin, adiponectin), and reward-related brain processing in MDD patients with high (MDD-High) and low (MDD-Low) C-reactive protein (CRP) levels compared to healthy comparison subjects (HC). Participants completed a blood draw and a monetary incentive delay task during functional magnetic resonance imaging. Although groups did not differ in insulin or adiponectin concentrations, both MDD-High (Wilcoxon p = 0.004, d = 0.65) and MDD-Low (Wilcoxon p = 0.046, d = 0.53) showed higher leptin concentrations than HC but did not differ from each other. Across MDD participants, higher leptin levels were associated with lower brain activation during reward anticipation in the left insula (r = - 0.30, p = 0.004) and left dorsolateral putamen (r = -- 0.24, p = 0.025). In contrast, within HC, higher leptin concentrations were associated with higher activation during reward anticipation in the same regions (insula: r = 0.40, p = 0.007; putamen: r = 0.37, p = 0.014). Depression may be characterized by elevated pro-inflammatory signaling via leptin concentrations through alternate inflammatory pathways distinct to CRP.

Schizophrenia and the COVID-19 pandemic: A narrative review from the biomedical perspective

The outbreak of the Coronavirus Disease 2019 (COVID-19) pandemic in 2020 caused a rapid worsening of global mental health. Patients with severe mental disorders, including schizophrenia, are at higher risk of being infected. The neuroinvasive potential of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has been confirmed. The aim of this article was to present a narrative and comprehensive review of multidimensional associations between schizophrenia and COVID-19 with special emphasis on common biological pathways. Online searches were performed in the PubMed database and covered the publication period until September 17, 2022. Search terms included "psychosis", "schizophrenia", "inflammation" and "COVID-19". Viewed as a neuroinflammatory state, schizophrenia shares several neurobiological mechanisms with the COVID-19. Environmental stress, common comorbidities of schizophrenia and adverse effects of antipsychotic treatment are associated with the higher severity and mortality of the COVID-19. Additionally, more frequent relapses of psychosis have been observed, and might be related to lower treatment adherence. In the context of clinical manifestation, higher level of negative symptoms has been identified among patients with schizophrenia during the pandemic. Improvements in mental health care policy and treatment adjustment are necessary to protect people with schizophrenia who are the population that is particularly vulnerable to the consequences of the COVID-19 pandemic. Future research will show if prenatal infection with the SARS-CoV-2 increases a risk of psychosis.

Comparative efficacy of psychological interventions on immune biomarkers: A systematic review and network meta-analysis (NMA)

Psychological interventions are viable, cost-effective strategies for improving clinical and psychological impact of inflammation-related conditions. However, their efficacy on immune system function remains controversial. We performed a systematic review and frequentist random-effects network meta-analysis of randomised controlled trials (RCTs) assessing the effects of psychological interventions, against a control condition, on biomarkers of innate and adaptive immunity in adults. PubMed, Scopus, PsycInfo, and Web of Science were searched from inception up to Oct 17, 2022. Cohen's d at 95% confidence interval (CI) was calculated to assess the effect sizes of each class of intervention against active control conditions at post-treatment. The study was registered in PROSPERO (CRD42022325508). Of the 5024 articles retrieved, we included 104 RCTs reporting on 7820 participants. Analyses were based on 13 types of clinical interventions. Compared with the control conditions, cognitive therapy (d =  - 0.95, 95% CI: -1.64 to - 0.27), lifestyle (d =  - 0.51, 95% CI: -0.99 to - 0.02), and mindfulness-based (d =  - 0.38, 95% CI: -0.66 to - 0.09) interventions were associated with post-treatment reduction of proinflammatory cytokines and markers. Mindfulness-based interventions were also significantly associated with post-treatment increase in anti-inflammatory cytokines (d = 0.69, 95% CI: 0.09 to 1.30), while cognitive therapy was associated also with post-treatment increase in white blood cell count (d = 1.89, 95% CI: 0.05 to 3.74). Results on natural killer cells activity were non-significant. Grade of evidence was moderate for mindfulness and low-to-moderate for cognitive therapy and lifestyle interventions; however, substantial overall heterogeneity was detected in most of the analyses.

New Perspectives on Treatment of Depression in Coronary Heart Disease

ABSTRACT

It has been 35 years since we published a study in Psychosomatic Medicine showing that patients with coronary heart disease (CHD) and major depression were at twice the risk of having a cardiac event as were nondepressed patients (Carney et al. Psychosom Med. 1988;50:627-33). This small study was followed a few years later by a larger, more convincing report from Frasure-Smith et al. (JAMA. 1993;270:1819-25) showing that depression increased the rate of mortality in patients with a recent acute myocardial infarction. Since the 1990s, there have been many more studies of depression as a risk factor for cardiac events and cardiac-related mortality from all over the world, and many clinical trials designed to determine whether treating depression improves medical outcomes in these patients. Unfortunately, the effects of depression treatment in patients with CHD remain unclear. This article considers why it has been difficult to determine whether treatment of depression improves survival in these patients. It also proposes several lines of research to address this question, with the goal of definitively establishing whether treating depression can extend cardiac event-free survival and enhance quality of life in patients with CHD.

Sickness behaviour and depression: An updated model of peripheral-central immunity interactions

Current research into mood disorders indicates that circulating immune mediators participating in the pathophysiology of chronic somatic disorders have potent influences on brain function. This paradigm has brought to the fore the use of anti-inflammatory therapies as adjunctive to standard antidepressant therapy to improve treatment efficacy, particularly in subjects that do not respond to standard medication. Such new practice requires biomarkers to tailor these new therapies to those most likely to benefit but also validated mechanisms of action describing the interaction between peripheral immunity and brain function to optimize target intervention. These mechanisms are generally studied in preclinical models that try to recapitulate the human disease, MDD, through peripherally induced sickness behaviour. In this proposal paper, after an appraisal of the data in rodent models and their adherence to the data in clinical cohorts, we put forward a modified model of periphery-brain interactions that goes beyond the currently established view of microglia cells as the drivers of depression. Instead, we suggest that, for most patients with mild levels of peripheral inflammation, brain barriers are the primary actors in the pathophysiology of the disease and in treatment resistance. We then highlight data gaps in this proposal and suggest novel lines of research.

Development of a digital biomarker and intervention for subclinical depression: study protocol for a longitudinal waitlist control study

BACKGROUND

Depression remains a global health problem, with its prevalence rising worldwide. Digital biomarkers are increasingly investigated to initiate and tailor scalable interventions targeting depression. Due to the steady influx of new cases, focusing on treatment alone will not suffice; academics and practitioners need to focus on the prevention of depression (i.e., addressing subclinical depression).

AIM

With our study, we aim to (i) develop digital biomarkers for subclinical symptoms of depression, (ii) develop digital biomarkers for severity of subclinical depression, and (iii) investigate the efficacy of a digital intervention in reducing symptoms and severity of subclinical depression.

METHOD

Participants will interact with the digital intervention BEDDA consisting of a scripted conversational agent, the slow-paced breathing training Breeze, and actionable advice for different symptoms. The intervention comprises 30 daily interactions to be completed in less than 45 days. We will collect self-reports regarding mood, agitation, anhedonia (proximal outcomes; first objective), self-reports regarding depression severity (primary distal outcome; second and third objective), anxiety severity (secondary distal outcome; second and third objective), stress (secondary distal outcome; second and third objective), voice, and breathing. A subsample of 25% of the participants will use smartwatches to record physiological data (e.g., heart-rate, heart-rate variability), which will be used in the analyses for all three objectives.

DISCUSSION

Digital voice- and breathing-based biomarkers may improve diagnosis, prevention, and care by enabling an unobtrusive and either complementary or alternative assessment to self-reports. Furthermore, our results may advance our understanding of underlying psychophysiological changes in subclinical depression. Our study also provides further evidence regarding the efficacy of standalone digital health interventions to prevent depression. Trial registration Ethics approval was provided by the Ethics Commission of ETH Zurich (EK-2022-N-31) and the study was registered in the ISRCTN registry (Reference number: ISRCTN38841716, Submission date: 20/08/2022).

Mitochondria-wide association study observed significant interactions of mitochondrial respiratory and the inflammatory in the development of anxiety and depression

The aim of this study was to investigate the possible interaction of mitochondrial dysfunction and inflammatory cytokines in the risk of anxiety and depression. We utilized the UK Biobank for the sample of this study. A mitochondria-wide association(MiWAS) and interaction analysis was performed to investigate the interaction effects of mitochondrial DNA (mtDNA)×C-reactive protein (CRP) on the risks of self-reported anxiety (N = 72,476), general anxiety disorder (GAD-7) scores (N = 80,853), self-reported depression (N = 80,778), Patient Health Questionnaire (PHQ-9) scores (N = 80,520) in total samples, females and males, respectively, adjusting for sex, age, Townsend deprivation index (TDI), education score, alcohol intake, smoking and 10 principal components. In all, 25 mtSNPs and 10 mtSNPs showed significant level of association with self-reported anxiety and GAD-7 score respectively. A total of seven significant mtDNA × CRP interactions were found for anxiety, such as m.3915G>A(MT-ND1) for self-reported anxiety in total subjects (P = 6.59 × 10^-3), m.4561T>C(MT-ND2) (P = 3.04 × 10^-3) for GAD-7 score in total subjects. For depression, MiWAS identified 17 significant mtSNPs for self-reported depression and 14 significant mtSNPs for PHQ-9 scores. 17 significant mtDNA associations (2 for self-reported depression and 15 for PHQ-9 score) was identified, such as m.14869G>A(MT-CYB; P = 2.22 × 10^-3) associated with self-reported depression and m.4561T>C (MT-ND2; P value = 3.02 × 10^-8) associated with PHQ-9 score in all subjects. In addition, 5 common mtDNA shared with anxiety and depression were found in MiWAS, and 4 common mtDNA variants were detected to interact with CRP for anxiety and depression, such as m.9899T>C(MT-CO3). Our study suggests the important interaction effects of mitochondrial function and CRP on the risks of anxiety and depression.

A sex-specific genome-wide association study of depression phenotypes in UK Biobank

There are marked sex differences in the prevalence, phenotypic presentation and treatment response for major depression. While genome-wide association studies (GWAS) adjust for sex differences, to date, no studies seek to identify sex-specific markers and pathways. In this study, we performed a sex-stratified genome-wide association analysis for broad depression with the UK Biobank total participants (N = 274,141), including only non-related participants, as well as with males (N = 127,867) and females (N = 146,274) separately. Bioinformatics analyses were performed to characterize common and sex-specific markers and associated processes/pathways. We identified 11 loci passing genome-level significance (P < 5 × 10-8) in females and one in males. In both males and females, genetic correlations were significant between the broad depression GWA and other psychopathologies; however, correlations with educational attainment and metabolic features including body fat, waist circumference, waist-to-hip ratio and triglycerides were significant only in females. Gene-based analysis showed 147 genes significantly associated with broad depression in the total sample, 64 in the females and 53 in the males. Gene-based analysis revealed "Regulation of Gene Expression" as a common biological process, but suggested sex-specific molecular mechanisms. Finally, sex-specific polygenic risk scores (PRSs) for broad depression outperformed total and the opposite sex PRSs in the prediction of broad major depressive disorder. These findings provide evidence for sex-dependent genetic pathways for clinical depression as well as for health conditions comorbid with depression.

Higher immune-related gene expression in major depression is independent of CRP levels: results from the BIODEP study

Compelling evidence demonstrates that some individuals suffering from major depressive disorder (MDD) exhibit increased levels of inflammation. Most studies focus on inflammation-related proteins, such as serum or plasma C-reactive protein (CRP). However, the immune-related modifications associated with MDD may be not entirely captured by CRP alone. Analysing mRNA gene expression levels, we aimed to identify broader molecular immune-related phenotypes of MDD. We examined 168 individuals from the non-interventional, case-control, BIODEP study, 128 with a diagnosis of MDD and 40 healthy controls. Individuals with MDD were further divided according to serum high-sensitivity (hs)CRP levels (n = 59 with CRP <1, n = 33 with CRP 1-3 and n = 36 with CRP >3 mg/L). We isolated RNA from whole blood and performed gene expression analyses using RT-qPCR. We measured the expression of 16 immune-related candidate genes: A2M, AQP4, CCL2, CXCL12, CRP, FKBP5, IL-1-beta, IL-6, ISG15, MIF, GR, P2RX7, SGK1, STAT1, TNF-alpha and USP18. Nine of the 16 candidate genes were differentially expressed in MDD cases vs. controls, with no differences between CRP-based groups. Only CRP mRNA was clearly associated with serum CRP. In contrast, plasma (proteins) IL-6, IL-7, IL-8, IL-10, IL-12/IL-23p40, IL-16, IL-17A, IFN-gamma and TNF-alpha, and neutrophils counts, were all differentially regulated between CRP-based groups (higher in CRP >3 vs. CRP <1 and/or controls), reflecting the gradient of CRP values. Secondary analyses on MDD individuals and controls with CRP values <1 mg/L (usually interpreted as 'no inflammation') confirmed MDD cases still had significantly different mRNA expression of immune-related genes compared with controls. These findings corroborate an immune-related molecular activation in MDD, which appears to be independent of serum CRP levels. Additional biological mechanisms may then be required to translate this mRNA signature into inflammation at protein and cellular levels. Understanding these mechanisms will help to uncover the true immune abnormalities in depression, opening new paths for diagnosis and treatment.

Effect of fluvoxamine on plasma interleukin-6 in patients with major depressive disorder: a prospective follow-up study

Introduction

Major depressive disorder (MDD) is associated with low-grade inflammation, and anti-inflammatory treatment can help improve depressive symptoms. A recent study found that fluvoxamine (FLV) can reduce Interleukin-6 (IL-6) production via sigma-1 receptor in inflammation models. However, the anti- IL-6 effect of FLV in treating patients with MDD and whether it can contribute to antidepressant effects remain unclear.

Methods

A total of 65 patients with MDD and 34 healthy controls were recruited at baseline, and 50 patients completed the FLV treatment for 2 months. We assessed depression and anhedonia and collected plasma IL-6 levels at baseline, 1 month, and 2 months after baseline. This study evaluated the changes in clinical measures and IL-6 during treatment and analyzed their association. Further subgroup analyses were conducted in patients with MDD with high, medium, or low IL-6.

Results

Depression and anhedonia were significantly improved in patients with MDD, while the IL-6 did not significantly change after the FLV treatment. However, IL-6 significantly declined after the FLV treatment among patients with MDD with higher baseline IL-6. No significant associations were found between the changes in depressive symptoms and IL-6.

Conclusion

Our study provided preliminary evidence suggesting that the anti-IL-6 effect of FLV might not play a vital role in its antidepressant treatment, at least in patients with MDD with low inflammation. However, for patients with MDD with higher IL-6, FLV can help reduce IL-6 significantly in the antidepressant treatment, which may help guide the individual treatment of MDD with higher IL-6 levels.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT04160377, identifier NCT04160377.

Depression after stoma surgery: a systematic review and meta-analysis

BACKGROUND

Depression is the leading cause of global disability and can develop following the change in body image and functional capacity associated with stoma surgery. However, reported prevalence across the literature is unknown. Accordingly, we performed a systematic review and meta-analysis aiming to characterise depressive symptoms after stoma surgery and potential predictive factors.

METHODS

PubMed/MEDLINE, Embase, CINAHL and Cochrane Library were searched from respective database inception to 6 March 2023 for studies reporting rates of depressive symptoms after stoma surgery. Risk of bias was assessed using the Downs and Black checklist for non-randomised studies of interventions (NRSIs), and Cochrane RoB2 tool for randomised controlled trials (RCTs). Meta-analysis incorporated meta-regressions and a random-effects model.

REGISTRATION

PROSPERO, CRD42021262345.

RESULTS

From 5,742 records, 68 studies were included. According to Downs and Black checklist, the 65 NRSIs were of low to moderate methodological quality. According to Cochrane RoB2, the three RCTs ranged from low risk of bias to some concerns of bias. Thirty-eight studies reported rates of depressive symptoms after stoma surgery as a proportion of the respective study populations, and from these, the median rate across all timepoints was 42.9% 42.9% (IQR: 24.2-58.9%). Pooled scores for respective validated depression measures (Hospital Anxiety and Depression Score (HADS), Beck Depression Inventory (BDI), and Patient Health Questionnaire-9 (PHQ-9)) across studies reporting those scores were below clinical thresholds for major depressive disorder according to severity criteria of the respective scores. In the three studies that used the HADS to compare non-stoma versus stoma surgical populations, depressive symptoms were 58% less frequent in non-stoma populations. Region (Asia-Pacific; Europe; Middle East/Africa; North America) was significantly associated with postoperative depressive symptoms (p = 0.002), whereas age (p = 0.592) and sex (p = 0.069) were not.

CONCLUSIONS

Depressive symptoms occur in almost half of stoma surgery patients, which is higher than the general population, and many inflammatory bowel disease and colorectal cancer populations outlined in the literature. However, validated measures suggest this is mostly at a level of clinical severity below major depressive disorder. Stoma patient outcomes and postoperative psychosocial adjustment may be enhanced by increased psychological evaluation and care in the perioperative period.

A facile indole probe for ultrasensitive immunosensor fabrication toward C-reactive protein sensing

C-reactive protein (CRP) is a protein biomarker for acute phase response. Herein, we fabricate a highly sensitive electrochemical immunosensor for CRP on a screen-printed carbon electrode (SPCE) with indole as a novel electrochemical probe and Au nanoparticles for signal amplification. Amongst, indole appeared as transparent nanofilms on the electrode surface, and underwent a one-electron and one-proton transfer to form oxindole during the oxidation process. Upon optimization of experimental conditions, a logarithmic correlation between CRP concentration (0.0001-100 μg∙mL^-1) and response current was revealed with a detection limit of 0.03 ng∙mL^-1 and a sensitivity of 5.7055 μA∙μg^-1∙mL∙cm^-2. The sensor exhibited exceptionally distinction selectivity, reproducibility and stability of the electrochemical immunosensor studied. The recovery rate of CRP in human serum samples determined by the standard addition method, ranged between 98.2-102.2%. Overall, the developed immunosensor is promising, and has the potential for CRP detection in real human serum samples.

The interaction between kynurenine pathway, suicidal ideation and augmentation therapy with minocycline in patients with treatment-resistant depression

BACKGROUND AND AIMS

We investigated kynurenine pathway (KP) metabolites levels and their association with suicidal ideation in patients with treatment-resistant depression (TRD) and elevated peripheral inflammation. The effect of antidepressant augmentation with minocycline on KP metabolites was tested.

METHODS

We analysed data from MINocycline in DEPression, a 4-week, randomized, placebo controlled (1:1) trial of minocycline added to antidepressant treatment in 39 TRD patients (n = 18 minocycline; n = 21 placebo) with C-reactive protein (CRP) ⩾1 mg/L. At baseline and at week 4, we collected data on suicidality (Beck Depression Inventory) and blood samples to measure inflammatory markers and KP metabolites. We tested (1) the association of KP metabolites ratios with inflammatory markers and suicidal ideation at baseline and (2) the role of suicidality and treatment (minocycline vs placebo) in affecting KP changes over time.

RESULTS

At baseline, kynurenine/tryptophan (KYN/TRP) ratio positively correlated with high-sensitivity CRP (Spearman's ρ = 0.35, p = 0.02) and IL-10, (ρ = 0.41, p = 0.009); and tumour necrosis factor was positively correlated with quinolinic acid/3-hydroxykynurenine ratio (ρ = 0.55, p < 0.001). Moreover, participants with suicidal ideation showed higher levels of KYN/TRP (U = 143.000, p = 0.02) than those without suicidal ideation. There was no significant effect of minocycline on KP metabolites changes from baseline to week 4. However, in the minocycline group, the number of participants with suicidal thoughts decreased from 44.4% (8/18) to 22.2% (4/18).

CONCLUSION

Increased KP neurotoxic metabolites are associated with elevated peripheral inflammation in depressed individuals, particularly in those with suicidal ideation. Targeting KP in this population could be a potential effective personalized approach. Whether this includes minocycline should be investigated in future larger trials.

Chronic stress, neuroinflammation, and depression: an overview of pathophysiological mechanisms and emerging anti-inflammatories

In a subset of patients, chronic exposure to stress is an etiological risk factor for neuroinflammation and depression. Neuroinflammation affects up to 27% of patients with MDD and is associated with a more severe, chronic, and treatment-resistant trajectory. Inflammation is not unique to depression and has transdiagnostic effects suggesting a shared etiological risk factor underlying psychopathologies and metabolic disorders. Research supports an association but not necessarily a causation with depression. Putative mechanisms link chronic stress to dysregulation of the HPA axis and immune cell glucocorticoid resistance resulting in hyperactivation of the peripheral immune system. The chronic extracellular release of DAMPs and immune cell DAMP-PRR signaling creates a feed forward loop that accelerates peripheral and central inflammation. Higher plasma levels of inflammatory cytokines, most consistently interleukin IL-1β, IL-6, and TNF-α, are correlated with greater depressive symptomatology. Cytokines sensitize the HPA axis, disrupt the negative feedback loop, and further propagate inflammatory reactions. Peripheral inflammation exacerbates central inflammation (neuroinflammation) through several mechanisms including disruption of the blood-brain barrier, immune cellular trafficking, and activation of glial cells. Activated glial cells release cytokines, chemokines, and reactive oxygen and nitrogen species into the extra-synaptic space dysregulating neurotransmitter systems, imbalancing the excitatory to inhibitory ratio, and disrupting neural circuitry plasticity and adaptation. In particular, microglial activation and toxicity plays a central role in the pathophysiology of neuroinflammation. Magnetic resonance imaging (MRI) studies most consistently show reduced hippocampal volumes. Neural circuitry dysfunction such as hypoactivation between the ventral striatum and the ventromedial prefrontal cortex underlies the melancholic phenotype of depression. Chronic administration of monoamine-based antidepressants counters the inflammatory response, but with a delayed therapeutic onset. Therapeutics targeting cell mediated immunity, generalized and specific inflammatory signaling pathways, and nitro-oxidative stress have enormous potential to advance the treatment landscape. Future clinical trials will need to include immune system perturbations as biomarker outcome measures to facilitate novel antidepressant development. In this overview, we explore the inflammatory correlates of depression and elucidate pathomechanisms to facilitate the development of novel biomarkers and therapeutics.

Hesperidin may improve depressive symptoms by binding NLRP3 and influencing the pyroptosis pathway in a rat model

OBJECTIVE

Major depressive disorder (MDD) is a debilitating psychiatric disorder which is common and endangers human physical and mental health. Studies have shown that hesperidin could improve the symptoms of depression with unclear mechanisms.

METHOD

In this study, hesperidin was administered to chronic unpredictable mild stress (CUMS) depressed mice before behavioral test, network pharmacology analysis, RNA expression microarray analysis, pathway validation and molecular docking experiments.

RESULTS

we found that hesperidin intervention could significantly improve the depressive symptoms and downregulate the expression level of pyroptosis pathway including caspase 1 (Casp1), interleukin 18 (IL18), interleukin-1β (IL-1β) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3). In addition, we found that hesperidin could possibly bind to NLRP3.

CONCLUSIONS

Our study demonstrated that hesperidin had huge potential as anti-depressive neuroprotectant, and may play a role in treating MDD by regulating NLRP3-mediated pyroptosis.

Baseline C-reactive protein levels are predictive of treatment response to a neuroimmune modulator in individuals with an alcohol use disorder: a preliminary study

Background: Inflammation is implicated in alcohol use disorder (AUD). Ibudilast, a neuroimmune modulator, shows promise for the treatment of AUD. Elevated inflammation, indicated by high levels of C-reactive protein (CRP), represents a possible subtype of AUD, which may be associated with treatment response to ibudilast.Objectives: The current study evaluated CRP as a predictor of treatment response to ibudilast; hypothesizing that ibudilast would be more effective at reducing drinking and alcohol cue-reactivity in individuals with higher CRP levels.Methods: This is a secondary analysis of a clinical trial of ibudilast for AUD, which found that ibudilast reduced heavy drinking in individuals with AUD. Fifty-one individuals were randomized to receive ibudilast (n = 24 [16 M/8F]) or placebo (n = 27 [18 M/9F]) for two weeks. Participants provided blood samples at baseline to assess CRP levels, completed daily assessments of alcohol use, and an fMRI alcohol cue-reactivity task at study mid-point. Models tested the effects of medication, CRP levels, and their interaction on drinks per drinking day and alcohol cue-reactivity.Results: There was a significant interaction between medication and CRP (F = 3.80, p = .03), such that the ibudilast high CRP group had fewer drinks per drinking day compared to the ibudilast low CRP group. CRP moderated the effect of medication on brain activation in a cluster extending from the left inferior frontal gyrus to the right-dorsal striatum (Z = 4.55, p < .001). This interaction was driven by attenuated cue-reactivity in the ibudilast high CRP group relative to the ibudilast low CRP and placebo high CRP groups.Conclusions: This study serves as an initial investigation into predictors of clinical response to ibudilast treatment and suggests that a baseline proinflammatory profile may enhance clinical efficacy.

Investigating the relationship between early life adversity, inflammation and alcohol use

Early life adversity (ELA) has long-lasting and potentially harmful effects on adult mental and physical health, including a higher likelihood of developing psychiatric conditions such as depression, anxiety and alcohol use disorder (AUD). It has been suggested that inflammation may play a role in linking ELA to the development of AUD. Here, we evaluated a number of predictive factors of high sensitivity C-reactive protein (hsCRP), a key inflammatory marker, and the potential mediating role of hsCRP in the relationship between ELA and alcohol misuse in adulthood. Data was collected from participants who participated in NIAAA screening protocols between January 2013 and December 2019. In this secondary analysis, we first tested, via multiple linear regression, potential predictors of hsCRP levels among adults with AUD (N = 781) and non-AUD (N = 440) individuals. We subsequently conducted mediation analyses to evaluate the potential role of hsCRP in the relationship between early life stress and alcohol use. Regression analysis showed that stress in early life, but not childhood trauma, significantly predicted increased hsCRP levels in adulthood (p < 0.05). Additionally, a greater amount of alcohol drinking, but not a diagnosis of AUD, significantly predicted increased hsCRP levels (p < 0.05). Furthermore, hsCRP mediated the relationship between early life stress and alcohol consumption. Early life stress and heavier alcohol drinking both predicted increased hsCRP levels; however, an AUD diagnosis did not. Elevated inflammation, due to and/or predicted by greater early life stress, may contribute to the development of unhealthy alcohol use in adulthood.

Cognitive function in early-phase schizophrenia-spectrum disorder: IQ subtypes, brain volume and immune markers

BACKGROUND

Evidence suggests that cognitive subtypes exist in schizophrenia that may reflect different neurobiological trajectories. We aimed to identify whether IQ-derived cognitive subtypes are present in early-phase schizophrenia-spectrum disorder and examine their relationship with brain structure and markers of neuroinflammation.

METHOD

161 patients with recent-onset schizophrenia spectrum disorder (<5 years) were recruited. Estimated premorbid and current IQ were calculated using the Wechsler Test of Adult Reading and a 4-subtest WAIS-III. Cognitive subtypes were identified with k-means clustering. Freesurfer was used to analyse 3.0 T MRI. Blood samples were analysed for hs-CRP, IL-1RA, IL-6 and TNF-α.

RESULTS

Three subtypes were identified indicating preserved (PIQ), deteriorated (DIQ) and compromised (CIQ) IQ. Absolute total brain volume was significantly smaller in CIQ compared to PIQ and DIQ, and intracranial volume was smaller in CIQ than PIQ (F(2, 124) = 6.407, p = 0.002) indicative of premorbid smaller brain size in the CIQ group. CIQ had higher levels of hs-CRP than PIQ (F(2, 131) = 5.01, p = 0.008). PIQ showed differentially impaired processing speed and verbal learning compared to IQ-matched healthy controls.

CONCLUSIONS

The findings add validity of a neurodevelopmental subtype of schizophrenia identified by comparing estimated premorbid and current IQ and characterised by smaller premorbid brain volume and higher measures of low-grade inflammation (CRP).

Long-term benzodiazepine prescription in treatment-resistant depression: A national FACE-TRD prospective study

BACKGROUND

Benzodiazepine long-term use (BLTU) is a public health challenge. We lack data on the consequences of LBTU on the trajectory of treatment-resistant depression (TRD).

OBJECTIVE

To determine the prevalence of BLTU in a nationwide non-selected population of patients with TRD, to determine the rate of patients succeeding at withdrawing benzodiazepines at one year and to determine if persistent BLTU is associated with poorer mental health outcomes.

METHOD

The FACE-TRD cohort is a national cohort of TRD patients recruited in 13 resistant depression expert centers between 2014 and 2021 and followed-up at one year. A standardized one-day long comprehensive battery was carried out, including trained-clinician and patient-reported outcomes, and patients were reevaluated at one year.

RESULTS

At baseline, 45.2% of the patients were classified in the BLTU group. In multivariate analysis, compared to patients without BLTU, patients with BLTU were more frequently classified in the "low physical activity" group (adjusted odds ratio (aOR) = 1.885, p = 0.036), and had higher primary healthcare consumption (B = 0.158, p = 0.031) independently of age, sex and antipsychotic consumption. We found no significant difference for personality traits, suicidal ideation, impulsivity, childhood trauma exposure, earlier age at first major depressive episode, anxiety and sleep disorders (all p > 0.05). Despite recommendations for withdrawal, <5% of BLTU patients withdraw benzodiazepines during the one-year follow-up. Persistent BLTU at one-year was associated with higher depression severity (B = 0.189, p = 0.029), higher clinical global severity (B = 0.210, p = 0.016), higher state-anxiety (B = 0.266, p = 0.003), impaired sleep quality (B = 0.249, p = 0.008), increased peripheral inflammation (B = 0.241, p = 0.027), lower functioning level (B = -0.240, p = 0.006), decreased processing speed (B = -0.195, p = 0.020) and verbal episodic memory (B = -0.178, p = 0.048), higher absenteeism and productivity loss (B = 0.595, p = 0.016) and lower subjective global health status (B = -0.198, p = 0.028).

CONCLUSION

Benzodiazepines are over-prescribed in TRD (in almost a half of the patients). Despite recommendations for withdrawal and psychiatric follow-up, <5% of patients successfully stopped taking benzodiazepines at one-year. Maintaining BLTU may contribute to the worsening of clinical and cognitive symptoms and of daily functioning in TRD patients. Progressive and planed withdrawal of benzodiazepines seems therefore strongly recommended in TRD patients with BLTU. Pharmacological and non-pharmacological alternatives should be promoted when possible.

Association of positive psychological well-being with circulating inflammatory markers: A systematic review and meta-analysis

Accumulating evidence shows a protective effect of positive psychological well-being (PPWB) on health outcomes. However, the underlying mechanisms remain poorly understood. One pathway relates to enhanced immune functioning (Boehm, 2021). The aim of this project was to conduct a systematic review and meta-analysis of the association between PPWB and circulating inflammatory biomarkers and determine the magnitude of this association. After examining 748 references, 29 studies were included. Results from over 94'700 participants revealed a significant association between PPWB and reduced levels of interleukin (IL)-6 (r=-0.05; P<.001) and C-reactive protein (CRP) (r=-0.06; P<.001) with a heterogeneity of I² = 31.5% and I² = 84.5%, respectively. Only the association of PPWB with CRP was independent of co-variates included in the individual studies (r=-0.04; P=.027),. The findings of this systematic review and meta-analysis suggest that PPWB is associated with lower levels of inflammatory biomarkers IL-6 and CRP in the circulation. Such relationships with inflammatory biomarkers may partly explain positive effects of PPWB on health.

Eveningness chronotype and depressive affective temperament associated with higher high-sensitivity C-reactive protein in unipolar and bipolar depression

BACKGROUND

Several studies investigated the role of inflammation in the etiopathogenesis of mood disorders. The aim of our cross-sectional study is evaluating baseline high-sensitivity C-reactive-protein (hsCRP) levels in a cohort of unipolar and bipolar depressive inpatients, in relation with psychopathological, temperamental and chronotype features.

METHODS

Among 313 screened inpatients, we retrospectively recruited 133 moderate-to-severe depressive patients who were assessed for hsCRP levels, chronotype with Morningness-Eveningness Questionnaire (MEQ) and affective temperament with Temperament Evaluation of Memphis, Pisa, Paris and San Diego (TEMPS).

LIMITATIONS

The cross-sectional and retrospective design of the study, the small sample size, the exclusion of hypomanic, maniac and euthymic bipolar patients.

RESULTS

hsCRP levels were significantly higher among those with previous suicide attempt (p = 0.05), death (p = 0.018) and self-harm/self-injury thoughts (p = 0.011). Linear regression analyses, adjusted for all covariates, demonstrated that higher scores at the TEMPS-M depressive, while lower scores at the hyperthymic and irritable affective temperaments [F = 88.955, R² = 0.710, p < 0.001] and lower MEQ scores [F = 75.456, R² = 0.405, p < 0.001] statistically significantly predicted higher hsCRP.

CONCLUSION

Eveningness chronotype and a depressive affective temperament appeared to be associated with higher hsCRP levels during moderate-to-severe unipolar and bipolar depression. Further longitudinal and larger studies should better characterise patients with mood disorders by investigating the influence of chronotype and temperament.

An inflamed subtype of difficult-to-treat depression

BACKGROUND

Chronic low-grade inflammation may play a role in the pathophysiology of depression, at least in a subset of patients. High-sensitivity C-reactive protein (hs-CRP) has been used to define an inflamed subgroup of depression with specific clinical characteristics and symptoms. In this study we investigated biochemical and clinical characteristics in patients with difficult-to-treat depression with and without chronic low-grade inflammation.

METHOD

We assayed plasma levels of interferon-gamma, tumor necrosis factor-alpha, Interleukin (IL)-10, IL-6, IL-8, and vitamin D in a clinically well-characterized sample of patients with difficult-to-treat depression (n = 263) and healthy controls (n = 46). Serum hs-CRP levels were available in the patient group and were used to define "inflamed depression" (hs-CRP > 3 mg/L). Based on previous studies correlating specific depressive symptoms to inflammatory markers, we calculated a composite score of inflammatory depressive symptoms (Infl-Dep score). A principal component analysis (PCA) was performed to identify patterns of variance in cytokines and vitamin D among patients.

RESULTS

Mean levels of IL-6 and IL-8 were significantly higher in depressed patients compared to controls, also after adjusting for sex, smoking, BMI, and age. None of the other inflammatory markers differed significantly between depressed patients and controls. Two components were extracted using PCA; one showed general cytokine elevations and one represented a pattern where IL-6 and IL-8 were inversely related to vitamin D (IL6-IL8-VitD component). The inflamed subgroup (hs-CRP > 3, n = 51) exhibited significantly higher BMI, higher Infl-Dep scores and higher IL6-IL8-VitD component scores than uninflamed patients (hs-CRP ≤ 3, n = 212). There were no significant differences in overall depression severity or suicidality between the inflamed and uninflamed groups.

CONCLUSION

Our results support the hypothesis of an inflamed subgroup of depression as a meaningful construct. This subgroup may have certain biological and clinical characteristics and more studies are needed to determine potential clinical implications.

Lipopolysaccharide-induced changes in the kynurenine pathway and symptoms of sickness behavior in humans

Metabolites of the kynurenine pathway are hypothesized to be implicated in inflammation-associated depression, but there is a lack of experimental studies in humans assessing the kinetics of kynurenine metabolites in relation to experimentally-induced sickness. The aim of the present study was to assess changes in the kynurenine pathway and to explore its relation to symptoms of sickness behavior during an acute experimental immune challenge. This double-blind placebo-controlled randomized cross-over study included 22 healthy human participants (n = 21 both sessions, M_age = 23.4, SD = 3.6, nine women) who received an intravenous injection of 2.0 ng/kg lipopolysaccharide (LPS) and saline (placebo) on two different occasions in a randomized order. Blood samples (0 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 5 h, 7 h post-injection) were analyzed for kynurenine metabolites and inflammatory cytokines. The intensity of symptoms of sickness behavior was assessed using the 10-item Sickness Questionnaire at 0 h, 1.5 h, 3 h, 5 h, and 7 h post-injection. LPS induced significantly lower concentrations of plasma tryptophan (at 2 h, 4 h, 5 h, and 7 h post-injection), kynurenine (at 2 h, 3 h, 4 h, and 5 h post-injection), nicotinamide (at 4 h, 5 h, and 7 h post-injection), and higher levels for quinolinic acid at 5 h post-injection as compared to placebo. LPS did not affect kynurenic acid, 3-hydroxykynurenine, and picolinic acid. The development of the sickness symptoms was largely similar across items, with the highest levels around 1.5-3 h post-injection. Changes in plasma levels of kynurenine metabolites seem to coincide rather than precede or follow changes in subjective sickness. Exploratory analyses indicate that higher Sickness Questionnaire total scores at 1.5-5 h post-injection were correlated with lower kynurenic acid and nicotinamide levels. These results lend further support for LPS-induced changes in the kynurenine pathway, but may not, as interpreted from blood levels, causally link to LPS-induced acute symptoms of sickness behavior. Future research may consider a larger sample to further scrutinize the role of the kynurenine pathway in the sickness response.

Nutritional counselling in adults promoting adherence to the Mediterranean diet as adjuvant in the treatment of major depressive disorder (INDEPT): a randomized open controlled trial study protocol

BACKGROUND

Major Depressive Disorder (MDD) is a leading cause of disability worldwide. Approximately one-third of patients with MDD do not respond to treatment, and often exhibit elevated inflammation biomarkers, which are associated with worse prognosis. Previous research has linked healthier dietary patterns, such as the Mediterranean Diet (MedDiet), with a lower risk of MDD and symptoms of depression, potentially due to their anti-inflammatory properties. The aim of this study is to evaluate the effectiveness of a nutritional counselling intervention promoting MedDiet to alleviate symptoms of depression in adults recently diagnosed with MDD and presenting with elevated inflammation biomarkers.

METHODS

This study is a randomized controlled trial (RCT) that will recruit adults from outpatient clinics, between the ages of 18 and 70 years who have been diagnosed with MDD and are currently receiving treatment with the first prescribed antidepressant, and who exhibit elevated inflammation biomarkers (interleukin-6 and/or C-reactive protein). The control group will receive treatment-as-usual (TAU) only. The primary outcome of the study will be the change in symptoms of depression, as measured by the Beck Depression Inventory 2 (BDI-II), after 12 weeks of intervention. Data analysis will follow an intention-to-treat approach. Secondary outcomes will include changes in inflammation biomarkers, quality of life, adherence to the MedDiet, and cost-effectiveness of nutritional counselling. All outcomes will be assessed at baseline, after the 12-week intervention, and at 6- and 12-months post-baseline.

DISCUSSION

This study will be the first RCT to evaluate the effect of a nutritional intervention with anti-inflammatory properties, as an adjuvant in the treatment of MDD, in individuals diagnosed with MDD and elevated inflammation biomarkers. The results of this study may contribute to the development of more effective and personalized interventions for MDD patients with elevated inflammation biomarkers.

Inflammation, stress and depression: An exploration of ketamine's therapeutic profile

Well-established animal models of depression have described a proximal relationship between stress and central nervous system (CNS) inflammation - a relationship mirrored in the peripheral inflammatory biomarkers of individuals with depression. Evidence also suggests that stress-induced proinflammatory states can contribute to the neurobiology of treatment-resistant depression. Interestingly, ketamine, a rapid-acting antidepressant, can partially exert its therapeutic effects via anti-inflammatory actions on the hypothalamic-pituitary adrenal (HPA) axis, the kynurenine pathway or by cytokine suppression. Further investigations into the relationship between ketamine, inflammation and stress could provide insight into ketamine's unique therapeutic mechanisms and stimulate efforts to develop rapid-acting, anti-inflammatory-based antidepressants.

Impact of data extraction errors in meta-analyses on the association between depression and peripheral inflammatory biomarkers: an umbrella review

BACKGROUND

Accumulating evidence suggests that alterations in inflammatory biomarkers are important in depression. However, previous meta-analyses disagree on these associations, and errors in data extraction may account for these discrepancies.

METHODS

PubMed/MEDLINE, Embase, PsycINFO, and the Cochrane Library were searched from database inception to 14 January 2020. Meta-analyses of observational studies examining the association between depression and levels of tumor necrosis factor-α (TNF-α), interleukin 1-β (IL-1β), interleukin-6 (IL-6), and C-reactive protein (CRP) were eligible. Errors were classified as follows: incorrect sample sizes, incorrectly used standard deviation, incorrect participant inclusion, calculation error, or analysis with insufficient data. We determined their impact on the results after correction thereof.

RESULTS

Errors were noted in 14 of the 15 meta-analyses included. Across 521 primary studies, 118 (22.6%) showed the following errors: incorrect sample sizes (20 studies, 16.9%), incorrect use of standard deviation (35 studies, 29.7%), incorrect participant inclusion (7 studies, 5.9%), calculation errors (33 studies, 28.0%), and analysis with insufficient data (23 studies, 19.5%). After correcting these errors, 11 (29.7%) out of 37 pooled effect sizes changed by a magnitude of more than 0.1, ranging from 0.11 to 1.15. The updated meta-analyses showed that elevated levels of TNF- α, IL-6, CRP, but not IL-1β, are associated with depression.

CONCLUSIONS

These findings show that data extraction errors in meta-analyses can impact findings. Efforts to reduce such errors are important in studies of the association between depression and peripheral inflammatory biomarkers, for which high heterogeneity and conflicting results have been continuously reported.

Combined effects of inflammation and coronavirus disease 2019 (COVID-19) on the risks of anxiety and depression: A cross-sectional study based on UK Biobank

Infection-induced perturbation of immune homeostasis could promote psychopathology. Psychiatric sequelae have been observed after previous coronavirus outbreaks. However, limited studies were conducted to explore the potential interaction effects of inflammation and coronavirus disease 2019 (COVID-19) on the risks of anxiety and depression. In this study, first, polygenic risk scores (PRS) were calculated for eight COVID-19 clinical phenotypes using individual-level genotype data from the UK Biobank. Then, linear regression models were developed to assess the effects of COVID-19 PRS, C-reactive protein (CRP), systemic immune inflammation index (SII), and their interaction effects on the Generalized Anxiety Disorder-7 (GAD-7, 104 783 individuals) score and the Patient Health Questionnaire-9 (PHQ-9, 104 346 individuals) score. Several suggestive interactions between inflammation factors and COVID-19 clinical phenotypes were detected for PHQ-9 score, such as CRP/SII × Hospitalized/Not_Hospitalized in women group and CRP × Hospitalized/Unscreened in age >65 years group. For GAD-7 score, we also found several suggestive interactions, such as CRP × Positive/Unscreened in the age ≤65 years group. Our results suggest that not only COVID-19 and inflammation have important effects on anxiety and depression but also the interactions of COVID-19 and inflammation have serious risks for anxiety and depression.

Effectiveness of Repetitive Transcranial Magnetic Stimulation (rTMS) Add-On Therapy to a Standard Treatment in Individuals with Multiple Sclerosis and Concomitant Symptoms of Depression—Results from a Randomized Clinical Trial and Pilot Study

Background: Compared to the general population, persons with multiple sclerosis (MS) are at increased risk of suffering from major depressive disorder (MDD). Repetitive Transcranial Magnetic Stimulation (rTMS) was used successfully to treat individuals with MDD. Here, we conducted a randomized clinical trial and pilot study, and tested the effectiveness of rTMS adjuvant to a standard pharmacological treatment among persons with MS, compared to a sham condition. Materials and Methods: A total of 40 persons with MS (mean age: 32 years; 42.5% females; median EDSS score: 4) and with moderate to severe symptoms of depression were randomly assigned to the rTMS or to the rTMS sham condition, always as adjuvant intervention to the standard treatment with sertraline, a selective serotonin reuptake inhibitor (SSRI). rTMS consisted of 10 sessions each of 37.5 min; the sham condition was identical to the active condition except for the absence of rTMS stimuli. At the beginning and two weeks after the end of the study, participants reported on their fatigue, while experts rated the severity of participants’ depressive symptoms (Montgomery–Asberg Depression Rating Scale; MADRS), cognitive performance (Montreal Cognitive Assessment; MoCA), and degree of disability (Expanded Disability Status Scale; EDSS). Results: Data were analyzed per intent-to-treat. Scores for depression, fatigue, and EDSS declined significantly over time (large effect sizes), but more so in the rTMS condition than in the sham condition (large effect sizes for the time by group-interactions). Compared to the sham condition, scores for depression were significantly lower in the rTMS condition. Scores for cognition improved over time in both study conditions (large effect size). Conclusion: Compared to a sham condition, adjuvant rTMS to a standard pharmacological treatment ameliorated typical MS-related symptoms (depression; fatigue; EDSS scores). Results from this pilot study suggested that rTMS might be routinely applied in persons with MS displaying symptoms of depression and fatigue.

α7 Nicotinic acetylcholine receptor: a key receptor in the cholinergic anti-inflammatory pathway exerting an antidepressant effect

Depression is a common mental illness, which is related to monoamine neurotransmitters and the dysfunction of the cholinergic, immune, glutamatergic, and neuroendocrine systems. The hypothesis of monoamine neurotransmitters is one of the commonly recognized pathogenic mechanisms of depression; however, the drugs designed based on this hypothesis have not achieved good clinical results. A recent study demonstrated that depression and inflammation were strongly correlated, and the activation of alpha7 nicotinic acetylcholine receptor (α7 nAChR)-mediated cholinergic anti-inflammatory pathway (CAP) in the cholinergic system exhibited good therapeutic effects against depression. Therefore, anti-inflammation might be a potential direction for the treatment of depression. Moreover, it is also necessary to further reveal the key role of inflammation and α7 nAChR in the pathogenesis of depression. This review focused on the correlations between inflammation and depression as well-discussed the crucial role of α7 nAChR in the CAP.

Inflammation and severity of depressive symptoms in physically active individuals after COVID-19 – An exploratory immunopsychological study investigating the effect of inflammation on depressive symptom severity

Background

SARS-CoV-2 infection is a risk factor for the development of depressive symptoms such as lack of energy, loss of interest, and depressed mood. Inflammatory processes might underline this association. The aim of this study was to investigate the association between inflammatory markers and the severity of depression after SARS-CoV-2 infection, and the predictive effect of inflammatory markers on the severity of depressive symptoms. Lifestyle factors and lifestyle-related diseases can influence inflammation and depressive symptoms. As these lifestyle factors and lifestyle-related diseases are less common in physically active individuals, they are a suitable population for investigating this research question.

Methods

We investigated 61 at least moderate physically active individuals on average ∼6 months (SD = 4.22, range = 0.5–19 months) after SARS-CoV-2 infection (t₀) and performed a follow-up after 3 months (t₁). Depressive symptoms and biomarkers of inflammation (interleukin [IL]-1β, IL-8, IL-10, Ferritin, Lipopolysaccharide-binding-protein [LBP], neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], lymphocyte-to-monocyte ratio [LMR]) and kynurenine [KYN] were measured at both time points. Concentrations of inflammatory markers at t₀ were used to predict the severity of depressive symptoms at t₀ and t₁.

Results

Concentrations of KYN were negatively related to the severity of depressive symptoms at t_0. Concentrations of LMR predicted higher depressive symptoms at t₀ as well as at t₁. Furthermore, individuals with lower concentrations of LBP at t₀ showed a higher severity of depressive symptoms at t₁. No correlation was found between severity of depressive symptoms and IL1β, IL-8, IL-10, ferritin, NLR, and PLR at both time points.

Conclusions

KYN, LBP and LMR might be useful as a predictive factor of depressive symptoms in physically active individuals after SARS-CoV-2 infection. While the results for KYN confirm the current scientific evidence, our results highlight the importance of the innovative inflammatory markers LMR and LBP. LMR and LBP might be interesting targets for predicting the development of depressive symptoms in SARS-CoV-2 infected populations and should be further investigated in future studies.

Prospective study on Maresin-1 and cytokine levels in medication-naïve adolescents with first-episode major depressive disorder

Background

Inflammation and immune activation may play a role in the pathological mechanism of Major Depressive Disorder (MDD). Evidence from cross-sectional and longitudinal studies of adolescents and adults has shown that MDD is associated with increased plasma pro-inflammatory cytokines (e.g., IL-1β, IL-6). It has been reported that Specialized Pro-resolving Mediators (SPMs) mediate inflammation resolution, and Maresin-1 can activate the process of inflammation and promote inflammation resolution by promoting macrophage phagocytosis. However, no clinical studies have been conducted to evaluate the relationship between the levels of Maresin-1 and cytokine and the severity of MDD symptomatology in adolescents.

Methods

40 untreated adolescent patients with primary and moderate to severe MDD and 30 healthy participants as the healthy control (HC) group aged between 13 and 18 years old were enrolled. They received clinical and Hamilton Depression Rating Scale (HDRS-17) evaluation and then, blood samples were collected. Patients in the MDD group were re-evaluated for HDRS-17, and blood samples were taken after a six to eight-week fluoxetine treatment.

Results

The adolescent patients with MDD had lower serum levels of Maresin-1 and higher serum levels of interleukin 6 (IL-6) compared with the HC group. Fluoxetine treatment alleviated depressive symptoms in MDD adolescent patients, which was reflected by higher serum levels of Maresin-1 and IL-4 and lower HDRS-17 scores, serum levels of IL-6, and IL-1β. Moreover, the serum level of Maresin-1 was negatively correlated with the depression severity scores on the HDRS-17.

Conclusion

Adolescent patients with primary MDD had lower levels of Maresin-1 and higher levels of IL-6 compared with the HC group, implying that the peripheral level of pro-inflammatory cytokines may be elevated in MDD, resulting in the insufficiency of inflammation resolution. The Maresin-1 and IL-4 levels increased after anti-depressant treatment, whereas IL-6 and IL-1β levels decreased significantly. Moreover, Maresin-1 level negatively correlated with depression severity, suggesting that reduced levels of Maresin-1 promoted the progression of MDD.

Importance of immunometabolic markers for the classification of patients with major depressive disorder using machine learning

BACKGROUND

Although there is scientific evidence of the presence of immunometabolic alterations in major depression, not all patients present them. Recent studies point to the association between an inflammatory phenotype and certain clinical symptoms in patients with depression. The objective of our study was to classify major depression disorder patients using supervised learning algorithms or machine learning, based on immunometabolic and oxidative stress biomarkers and lifestyle habits.

METHODS

Taking into account a series of inflammatory and oxidative stress biomarkers (C-reactive protein (CRP), tumor necrosis factor (TNF), 4-hydroxynonenal (HNE) and glutathione), metabolic risk markers (blood pressure, waist circumference and glucose, triglyceride and cholesterol levels) and lifestyle habits of the participants (physical activity, smoking and alcohol consumption), a study was carried out using machine learning in a sample of 171 participants, 91 patients with depression (71.42% women, mean age = 50.64) and 80 healthy subjects (67.50% women, mean age = 49.12). The algorithm used was the support vector machine, performing cross validation, by which the subdivision of the sample in training (70%) and test (30%) was carried out in order to estimate the precision of the model. The prediction of belonging to the patient group (MDD patients versus control subjects), melancholic type (melancholic versus non-melancholic patients) or resistant depression group (treatment-resistant versus non-treatment-resistant) was based on the importance of each of the immunometabolic and lifestyle variables.

RESULTS

With the application of the algorithm, controls versus patients, such as patients with melancholic symptoms versus non-melancholic symptoms, and resistant versus non-resistant symptoms in the test phase were optimally classified. The variables that showed greater importance, according to the results of the area under the ROC curve, for the discrimination between healthy subjects and patients with depression were current alcohol consumption (AUC = 0.62), TNF-α levels (AUC = 0.61), glutathione redox status (AUC = 0.60) and the performance of both moderate (AUC = 0.59) and vigorous physical exercise (AUC = 0.58). On the other hand, the most important variables for classifying melancholic patients in relation to lifestyle habits were past (AUC = 0.65) and current (AUC = 0.60) tobacco habit, as well as walking routinely (AUC = 0.59) and in relation to immunometabolic markers were the levels of CRP (AUC = 0.62) and glucose (AUC = 0.58). In the analysis of the importance of the variables for the classification of treatment-resistant patients versus non-resistant patients, the systolic blood pressure (SBP) variable was shown to be the most relevant (AUC = 0.67). Other immunometabolic variables were also among the most important such as TNF-α (AUC = 0.65) and waist circumference (AUC = 0.64). In this case, sex (AUC = 0.59) was also relevant along with alcohol (AUC = 0.58) and tobacco (AUC = 0.56) consumption.

CONCLUSIONS

The results obtained in our study show that it is possible to predict the diagnosis of depression and its clinical typology from immunometabolic markers and lifestyle habits, using machine learning techniques. The use of this type of methodology could facilitate the identification of patients at risk of presenting depression and could be very useful for managing clinical heterogeneity.

Depressive symptoms, anxiety and social stress are associated with diminished cardiovascular reactivity in a psychological treatment-naive population

BACKGROUND

There is now an increasing appreciation of how psychological health can contribute to cardiovascular disease, called the mind-heart connection. A blunted cardiovascular reactivity to depression and anxiety may be responsible for the potential mechanism, however, with inconsistent results. Anti-psychological drugs have an effect on the cardiovascular system and, thus, may disturb their relationship. However, in treatment-naive individuals with psychological symptoms, no research has specifically evaluated the relationship between psychological state and cardiovascular reactivity.

METHODS

We included 883 treatment-naive individuals who came from a longitudinal cohort study of Midlife in the United States. Symptoms of depression, anxiety, and stress were assessed by the Center for Epidemiologic Studies Depression Scale (CES-D), Spielberger Trait Anxiety Inventory (STAI), the Liebowitz Social Anxiety scale (LSAS) and the Perceived Stress Scale (PSS), respectively. Cardiovascular reactivity was measured using standardized, laboratory-based stressful tasks.

RESULTS

Treatment-naive individuals with depressive symptoms (CES-D ≥ 16), anxiety symptoms (STAI ≥ 54), and higher stress levels (PSS ≥ 27) had lower cardiovascular reactivity as assessed by systolic blood pressure (SBP) reactivity, diastolic blood pressure (DBP) reactivity and heart rate (HR) reactivity (P < 0.05). Pearson analyses showed that psychological symptoms were correlated with lower SBP reactivity, DBP reactivity, and heart rate reactivity (P < 0.05). Multivariate linear regression showed that depression and anxiety were negatively related to lower cardiovascular reactivity (SBP, DBP and HR reactivity) after full adjustments (P < 0.05). Stress was associated with reduced SBP and DBP reactivity but with a nonsignificant association with HR reactivity (P = 0.056).

CONCLUSION

Depression, anxiety, and stress symptoms are associated with blunted cardiovascular reactivity in treatment-naive adult Americans. These findings suggest that blunted cardiovascular reactivity is an underlying mechanism linking psychological health and cardiovascular diseases.

Dose-response association of handgrip strength and risk of depression: a longitudinal study of 115 601 older adults from 24 countries

BACKGROUND

Prior research has solely focused on the association between handgrip strength and risk of depression in single countries or general populations, but more knowledge is required from wider-spread cohorts and target populations.

AIMS

This study aimed to investigate the association between handgrip strength and risk of depression using repeated measures in adults aged 50 years and over.

METHOD

Data on handgrip strength and risk of depression were retrieved from the Survey of Health, Ageing and Retirement in Europe (SHARE) waves 1, 2, 4, 5, 6 and 7, using a hand dynamometer (Smedley, S Dynamometer, TTM) and the EURO-D 12-item scale, respectively. Time-varying exposure and covariates were modelled using both Cox regression and restricted cubic splines.

RESULTS

A total of 115 601 participants (mean age 64.3 years (s.d. = 9.9), 54.3% women) were followed-up for a median of 7.3 years (interquartile range: 3.9-11.8) and 792 459 person-years. During this period, 30 208 (26.1%) participants experienced a risk of depression. When modelled as a continuous variable, we observed an inverse significant association for each kg increase of handgrip strength and depression up to 40 kg in men and up to 27 kg in women.

CONCLUSIONS

Being physically strong may serve as a preventive factor for depression in older adults, but this is limited up to a maximum specific threshold for men and women.

White matter integrity and pro-inflammatory cytokines as predictors of antidepressant response in MDD

Major depressive disorder (MDD) is a multifactorial, serious and heterogeneous mental disorder that can lead to chronic recurrent symptoms, treatment resistance and suicidal behavior. MDD often involves immune dysregulation with high peripheral levels of inflammatory cytokines that might have an influence on the clinical course and treatment response. Moreover, patients with MDD show brain volume changes as well as white matter (WM) alterations that are already existing in the early stage of illness. Mounting evidence suggests that both neuroimaging markers, such as WM integrity and blood markers, such as inflammatory cytokines might serve as predictors of treatment response in MDD. However, the relationship between peripheral inflammation, WM structure and antidepressant response is not yet clearly understood. The aim of the present review is to elucidate the association between inflammation and WM integrity and its impact on the pathophysiology and progression of MDD as well as the role of possible novel biomarkers of treatment response to improve MDD prevention and treatment strategies.

Association of sugar intake from different sources with incident depression in the prospective cohort of UK Biobank participants

PURPOSE

To elucidate the association of different sources of free sugars (FS) and intrinsic sugars with depression risk in the prospective population-based UK Biobank cohort.

METHODS

Sugar consumption was assessed in 188,426 participants (age range: 39-72 years, 54.4% female) with at least one web-based dietary questionnaire (Oxford WebQ). The hazard ratios (HR) for incident depression were assessed with Cox proportional hazard regression models including sugar intake from different sources as penalized cubic splines to allow non-linear predictor effects. Over a mean follow-up of 12.3 (standard deviation 1.8) years, 5410 incident depression cases occurred.

RESULTS

FS intake was significantly associated with depression risk in an ascending approximately linear way with the lowest HR observed at 9% total energy (%E). In contrast, consumption of intrinsic sugars was not significantly related with incident depression. FS in beverages were significantly associated with depression risk in an ascending approximately linear way with the lowest HR at 4%E whereas no association was found for FS in solids. Concerning beverage types, FS in soda/fruit drinks, milk-based drinks, and tea/coffee were significantly and positively related to depression risk whereas the association was U-shaped for juice. Major findings were robust in sensitivity analyses.

CONCLUSION

Only some sources of FS are positively associated with incident depression. Public health initiatives targeting FS subtypes might be most effective concerning depression risk if focused on the reduction of sugary beverages and more specifically soda/fruit drinks, milk-based drinks, and tea/coffee.

Sex differences in the mediating role of chronic inflammation on the association between social isolation and cognitive functioning among older adults in the United States

BACKGROUND

Previous research has reported the association between social isolation and cognitive impairment. However, biological mechanisms underlying this association are understudied. It is also unclear whether there are sex differences in these biological mechanisms.

OBJECTIVES

To examine whether chronic inflammation biomarkers are potential mediators of the association between social isolation and cognitive functioning among older men and women.

METHODS

Data were the National Health and Nutrition Examination Survey 1999-2002. A total of 2535 older adults aged 60 and older were included. Chronic inflammation was measured by C-reactive protein (CRP), plasma fibrinogen, and serum albumin. Cognitive functioning was assessed by the Digit Symbol Substitution Test (DSST). Social isolation was defined using a 4-point composite index of items pertaining to the strength of social network and support. Linear regression models and formal mediation analysis were applied.

RESULTS

Social isolation was associated with lower DSST scores [β (SE) = -2.445 (1.180), p < 0.01 for men; β (SE) = -5.478 (1.167), p < 0.001 for women]. For older men, social isolation was associated with higher levels of CRP (β [SE] = 0.226 (0.110), p < 0.05) and fibrinogen (β [SE] = 0.058 (0.026), p < 0.05). In mediation analyses, among older men, CRP mediated 6.1% and fibrinogen mediated 12.0% of the association of social isolation with DSST.

CONCLUSION

Social isolation was associated with poorer cognitive functioning partially via heightened inflammatory responses in older men. Defining these associations' mechanisms in sex-specific contexts could inform preventive and therapeutic strategies for cognitive impairment in older adults.

Peripheral blood cellular immunophenotype in depression: a systematic review and meta-analysis

INTRODUCTION

Meta-analyses implicate immune dysfunction in depression confirming increased levels of circulating immune proteins (e.g., cytokines) in depression cases compared to controls. White blood cells (WBC) both produce and are influenced by cytokines, and play key roles in orchestrating innate and adaptive immune responses, but their role in depression remains unclear. Therefore, a systematic review of studies of various WBC subsets in depression is required for a greater understanding of the nature of immune dysfunction in this illness.

METHODS

We searched PubMed and PsycINFO databases (inception to 5th April 2022) and conducted a systematic review and meta-analysis of identified studies comparing absolute count and/or relative percentage of flow cytometry-derived WBC subsets between depression cases and controls. Selected studies were quality assessed. Random-effect meta-analysis was performed.

RESULTS

Thirty-three studies were included and 27 studies (n = 2277) were meta-analysed. We report an increase in mean absolute counts of WBC (seven studies; standardised mean difference [SMD] = 1.07; 95% CI, 0.61-1.53; P < 0.01; I2 = 64%), granulocytes (two studies; SMD = 2.07; 95% CI, 1.45-2.68; P < 0.01; I2 = 0%), neutrophils (four studies; SMD = 0.91; 95% CI, 0.23-1.58; P < 0.01; I2 = 82%), monocytes (seven studies; SMD = 0.60; 95% CI, 0.19-1.01; P < 0.01; I2 = 66%), CD4+ helper T cells (11 studies; SMD = 0.30; 95% CI, 0.15-0.45; P < 0.01; I2 = 0%), natural killer cells (11 studies; SMD = 1.23; 95% CI, 0.38-2.08; P < 0.01; I2 = 95%), B cells (10 studies; SMD = 0.30; 95% CI, 0.03-0.57; P = 0.03; I2 = 56%), and activated T cells (eight studies; SMD = 0.45; 95% CI, 0.24-0.66; P < 0.01; I2 = 0%) in depression, compared to controls. Fewer studies reported relative percentage, indicating increased neutrophils and decreased total lymphocytes, Th1, and Th2 cells in depression.

CONCLUSIONS

Depression is characterised by widespread alterations in circulating myeloid and lymphoid cells, consistent with dysfunction in both innate and adaptive immunity. Immune cells could be useful biomarkers for illness subtyping and patient stratification in future immunotherapy trials of depression, along with cytokines, other biomarkers, and clinical measures.

[Effect of Sertraline on Serum Cytokine Levels in Adolescents With First-Episode Major Depressive Disorder]

Objective

To investigate the changes in serum inflammatory cytokines and the predictive factors for the efficacy of sertraline following medication therapy in adolescents with first-episode major depressive disorder (MDD).

Methods

A total of 61 adolescent patients with first-episode drug-naïve MDD were enrolled for the MDD group and 55 healthy adolescents were enrolled for the healthy control (HC) group. Sertraline tablets were administered to the MDD group for 8 weeks after enrollment, while no medication was given to the HC group. In the MDD group, blood samples were collected to measure the cytokine levels and clinical data, including scores for the 17-item Hamilton Depression Scale (HAMD-17) and the Connor-Davidson Resilience Scale (CD-RISC), were assessed at baseline and at the end of the 8-week medication, whereas in the HC group, blood samples and clinical data were collected only at baseline. The correlation between the levels of serum inflammatory cytokines and depression severity in the MDD group was analyzed and stepwise linear regression of HAMD-17 in the MDD group was performed to find serologic indicators that could be used to predict the efficacy of sertraline.

Results

At baseline, the levels of interleukin (IL)-1β and IL-6 in the MDD group were significantly higher than those in the HC group (all P<0.0001), while the tumor necrosis factor (TNF)-α level in the MDD group was significantly lower than that in the HC group ( P=0.006). After 8 weeks of medication treatment, the MDD group showed decreased levels of IL-1β and IL-6 and increased level of TNF-α compared to the pre-treatment levels. In addition, the HAMD-17 score, CD-RISC total score, and scores for perceived competence, trust and tolerance, and control, three factors of CD-RISC, all improved after treatment. There was no significant difference in serum cytokine levels at baseline between the subgroup showing response to the treatment and the non-responding subgroup. There was a weak correlation between IL-6 levels before and after treatment and CD-RISC scores and the scores for the trust and tolerance factor of CD-RISC before and after treatment. The baseline IL-1β and TNF-α levels did not show significant effect on posttreatment HAMD-17 scores.

Conclusions

Serum cytokine levels of adolescents with first-episode MDD differ significantly from those of healthy adolescents. Although IL-6 was found to be correlated with depression severity, there was not enough support for it to be used as a predictor of the antidepression efficacy of sertraline.

Comorbidity and healthcare utilization in patients with treatment resistant depression: A large-scale retrospective cohort analysis using electronic health records

BACKGROUND

Medical comorbidity and healthcare utilization in patients with treatment resistant depression (TRD) is usually reported in convenience samples, making estimates unreliable. There is only limited large-scale clinical research on comorbidities and healthcare utilization in TRD patients.

METHODS

Electronic Health Record data from over 3.3 million patients from the INSIGHT Clinical Research Network in New York City was used to define TRD as initiation of a third antidepressant regimen in a 12-month period among patients diagnosed with major depressive disorder (MDD). Age and sex matched TRD and non-TRD MDD patients were compared for anxiety disorder, 27 comorbid medical conditions, and healthcare utilization.

RESULTS

Out of 30,218 individuals diagnosed with MDD, 15.2 % of patients met the criteria for TRD (n = 4605). Compared to MDD patients without TRD, the TRD patients had higher rates of anxiety disorder and physical comorbidities. They also had higher odds of ischemic heart disease (OR = 1.38), stroke/transient ischemic attack (OR = 1.57), chronic kidney diseases (OR = 1.53), arthritis (OR = 1.52), hip/pelvic fractures (OR = 2.14), and cancers (OR = 1.41). As compared to non-TRD MDD, TRD patients had higher rates of emergency room visits, and inpatient stays. In relation to patients without MDD, both TRD and non-TRD MDD patients had significantly higher levels of anxiety disorder and physical comorbidities.

LIMITATIONS

The INSIGHT-CRN data lack information on depression severity and medication adherence.

CONCLUSIONS

TRD patients compared to non-TRD MDD patients have a substantially higher prevalence of various psychiatric and medical comorbidities and higher health care utilization. These findings highlight the challenges of developing interventions and care coordination strategies to meet the complex clinical needs of TRD patients.

The Clinical Observation of Inflammation Theory for Depression: The Initiative of the Formosa Long COVID Multicenter Study (FOCuS)

There is growing evidence that the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with increased risks of psychiatric sequelae. Depression, anxiety, cognitive impairments, sleep disturbance, and fatigue during and after the acute phase of COVID-19 are prevalent, long-lasting, and exerting negative consequences on well-being and imposing a huge burden on healthcare systems and society. This current review presented timely updates of clinical research findings, particularly focusing on the pathogenetic mechanisms underlying the neuropsychiatric sequelae, and identified potential key targets for developing effective treatment strategies for long COVID. In addition, we introduced the Formosa Long COVID Multicenter Study (FOCuS), which aims to apply the inflammation theory to the pathogenesis and the psychosocial and nutrition treatments of post-COVID depression and anxiety.

Racial Differences in C-Reactive Protein, Depression Symptoms, and Social Relationships in Older Adults: A Moderated Network Analysis

INTRODUCTION

We introduce moderated network analysis as an integrative approach to assess the moderation effects of race on the relationship between C-reactive protein (CRP) and depression symptoms in older adults. This study further explores how the observed relationships differ adjusting for social relationships.

METHODS

This secondary analysis of cross-sectional data from the National Social Life, Health, and Aging Project (2010-2011) includes 2,880 older adults. We used different depression symptom domains (depressed affect, low positive affect, somatic symptoms, and interpersonal problems) from the Center for Epidemiologic Studies-Depression Scale. Social relationships were assessed with measures of social integration, social support, and social strain. The moderated networks were constructed using the R-package mgm. The racial moderator was coded as White/African American racial groups.

RESULTS

In the moderated networks of CRP and depression symptoms, CRP-"interpersonal problems" edge was present only among African Americans. CRP-"somatic symptoms" edge was present in both racial groups with equal edge weights. After adjusting for social relationships, the aforementioned patterns remained the same, but the edge weights were attenuated. We additionally observed CRP-social strain and social integration-"depressed affect" edges only in African Americans.

DISCUSSION

Race may moderate the relationship between the CRP and depression symptoms in older adults and social relationships might be important covariates to consider while analyzing them. This study as an initiation point; future network investigations would benefit from leveraging more contemporary cohorts of older adults, gaining a large sample size with diverse racial/ethnic backgrounds, and important covariates. Several important methodological issues of the current study are addressed.

Exploring Associations between C-Reactive Protein and Self-Reported Interoception in Major Depressive Disorder: A Bayesian Analysis

Major depressive disorder (MDD) is associated with dysfunctional self-reported interoception (i.e., abnormal perception of the body's physiological state) and systemic inflammation, both of which adversely affect treatment response. In this study, we explored associations between C-reactive protein (CRP) and self-reported interoception, to gain more insight into the pathophysiology of interoceptive impairments in MDD. We also aimed to replicate previous findings on the associations of depression and fatigue severity with CRP. The study included 97 depressed individuals, who completed self-administered questionnaires (Multidimensional Assessment of Interoceptive Awareness (MAIA-2); Beck Depression Inventory-II, Multidimensional Fatigue Inventory). CRP concentrations were analyzed in the serum using a particle-enhanced turbidimetric immunoassay. We applied Bayesian inference to estimate robust effect parameters from posterior distributions based on MCMC sampling, and computed Bayes factors (BF₁₀) as indices of relative evidence. The bivariate analysis supported evidence against associations between CRP and self-reported interoception (BF₁₀ ≤ 0.32), except for one dimension (Not-Distracting: r = 0.11, BF₁₀ > 0.43, absence of evidence). Positive correlations with overall depression (r = 0.21, BF₁₀ = 3.19), physical fatigue (r = 0.28, BF₁₀ = 20.64), and reduced activity (r = 0.22, BF₁₀ = 4.67) were found. The multivariate analysis showed moderate evidence that low-grade inflammation predicted higher scores on the MAIA-2 Not-Worrying scale (β = 0.28, BF₁₀ = 3.97), after controlling for relevant confounders. Inflammatory responses, as measured by CRP, may not be involved in the pathophysiology of dysfunctional self-reported interoception. However, systemic low-grade inflammation could potentially exert a protective effect against worries about pain or discomfort sensations. An immunological involvement in interoceptive impairments cannot be ruled out until future studies considering additional biomarkers of inflammation replicate our findings.

The effects of ketamine and classic hallucinogens on neurotrophic and inflammatory markers in unipolar treatment-resistant depression: a systematic review of clinical trials

Although results are still preliminary, ketamine and classical hallucinogens have shown promise in recent years as novel, fast-acting antidepressants, especially for the treatment of unipolar treatment-resistant depression (TRD). Depression also seems to be related to abnormal levels of peripheral inflammatory and neurotrophic biomarkers, which may one day help to diagnose of this disorder. In this context, this systematic review of clinical trials evaluated the current evidence that relates the antidepressant effects of ketamine and classical hallucinogens on TRD with changes in inflammatory and neurotrophic biomarkers. Twelve studies were found (n = 587), 2 with oral ayahuasca (1 mL/kg) and 10 with ketamine (mostly intravenous 0.5 mg/kg) administration. Results for all biomarkers assessed were contradictory and thus inconclusive. Randomized controlled trials with bigger samples and higher statistical power are warranted to clarify if peripheral biomarkers can confidently be used to indicate and measure ketamine's and classical hallucinogens' antidepressant effect. The PROSPERO ID for this study is CRD42021249089.