Evidence for chronic low-grade systemic inflammation in individuals with agoraphobia from a population-based prospective study

Sampaio TP, Marçal L, Burdmann EA, Neto FL, Bernik MA. Inflammatory markers changes following acceptance-based behavioral psychotherapy in generalized anxiety disorder patients: Evidence from a randomized controlled trial

Introduction

Generalized anxiety disorder (GAD) has been associated with elevated levels of C-reactive protein (CRP) and proinflammatory cytokines. Despite robust evidence as an effective treatment for GAD, research on the effects of cognitive-behavioral therapies (CBT) in the inflammatory profile of patients with clinical anxiety has presented mixed results.

Objective

The present study aimed to investigate the effect of an acceptance-based behavior therapy (ABBT) on inflammatory biomarkers and their association with anxiety levels in GAD patients in comparison to supportive therapy as an active control.

Methods

Peripheral inflammatory biomarkers (CRP, IL-1β, IL-4, IL-6, IL-10, TNF-α) were measured in 77 GAD patients who participated in a 14-week 10-session randomized clinical trial of group ABBT (experimental, n = 37) or supportive group therapy (ST: active control group, n = 40).

Results

The concentrations of IL-1β decreased in the control group and the concentrations of IL-6 increased in the experimental group from baseline to post-treatment, whereas no difference was identified in IL-4, IL-10, TNF, or CRP. Although anxiety and depression levels decreased in both treatment conditions, no correlation with inflammation markers was found for most clinical and biological variables. A negative correlation between changes in IL-6 and IL-10 and anxiety symptom score changes was identified.

Conclusions

The present study results found that a short trial of acceptance-based behavior therapy did not change the proinflammatory profile which may be associated with GAD. Additional research is needed to evaluate the influence of other inflammation-related variables, longer periods of follow-up as well as the effect of supportive therapy on peripheral inflammatory biomarkers in GAD patients.

Alterations in heart rate variability and pro-inflammatory cytokine TNF-alpha in individuals with panic disorder

Based on the autonomic flexibility-neurovisceral integration model, panic disorder (PD) has been associated with a generalized proinflammatory state and lower cardiac vagal tone. The heart rate variability (HRV) provides an index of cardiac autonomic function and reflects the parasympathetic innervation to the heart regulated by the vagus nerve. The aim of this study was to explore the heart rate variability, pro-inflammatory cytokines and their associations in individuals with PD. Short-term HRV with time and frequency domain indices as well as pro-inflammatory cytokines Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-alpha) were assessed in seventy individuals with PD (mean age: 35.64 ± 14.21 years) and thirty-three healthy controls (mean age: 38.33 ± 14.14 years). Individuals with PD showed significantly lower HRV in the time and frequency domain parameters during a short-term resting condition. A lower TNF-alpha concentration could be observed in individuals with PD in comparison to healthy controls, but no differences in IL-6. Furthermore, the HRV parameter absolute power in the low-frequency band 0.04-0.15 Hz (LF) predicted TNF-alpha concentrations. In conclusion, a lower cardiac vagal tone, decreased adaptive autonomic nervous system (ANS), and higher pro-inflammatory cytokine state could be observed in individuals with PD compared to healthy controls.

Effect of a slow-paced breathing with heart rate variability biofeedback intervention on pro-inflammatory cytokines in individuals with panic disorder - A randomized controlled trial

A generalized proinflammatory state has been observed in individuals with panic disorder (PD). There is evidence that slow-paced breathing (SPB) with heart rate variability-biofeedback (HRV-BF) strengthens the nervus vagus with its anti-inflammatory pathway. Therefore, with this randomized controlled trial we aimed to investigate the effect of a four-week SPB with HRV-BF intervention on pro-inflammatory cytokines in people with PD. Fifty-five individuals with PD (mean age: 37.22 ± 15.13 years) were randomly allocated either to SPB-HRV-BF (intervention group) or to HRV-Sham-BF (active control group). SPB-HRV-BF was performed over four weeks while cytokine concentration and HRV during a short-term resting condition were measured before and after intervention. SPB-HRV-BF decreased concentration of Tumor Necrosis Factor alpha (TNF-alpha) (F_{(1, 53)} = 4.396, p ≤ .05, η2 = 0.077) in individuals with PD. In addition, SPB-HRV-BF demonstrated an increase in the HRV-time and frequency domain parameters SDNN, Total Power and LF during short-term resting condition. There was no intervention effect in HRV-Sham-BF group. In conclusion, SBP-HRV-BF as a non-pharmacological treatment may reduce pro-inflammatory cytokine TNF-alpha via the cholinergic anti-inflammatory pathway in individuals with PD. Based on the generalized proinflammatory state in PD, decreasing TNF-alpha is highly beneficial to reduce risk of cardiovascular diseases and metabolic syndrome.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

C-reactive protein as a potential biomarker in psychiatric practice: Are we there yet?

OBJECTIVES

Serum or plasma levels of C-reactive protein (CRP) and high-sensitivity CRP (hsCRP) are widely used clinical markers of inflammation in other branches of medicine, whereas its clinical use in psychiatry has been limited to research studies. We aimed to assess the possibility of using CRP/hsCRP in psychiatric practice. This is a review and evaluation of various lines of evidence supporting the concept of CRP as a biomarker for psychiatric disorders in certain conditions.

METHODS

We searched the literature for studies which assessed CRP/hsCRP levels in various psychiatric disorders.

RESULTS

The accumulating evidence from large studies and meta-analyses allows us to understand the role of CRP in major psychiatric disorders and increase our understanding of specific symptoms and subtypes of disorders. CRP may be considered a 'psychiatric biomarker' which can alert clinicians about neuroinflammation, adverse effects of medications, cardiometabolic status, co-morbidities, and may also predict clinical outcomes and guide optimal treatment.selection.

CONCLUSION

Although the underlying pathophysiological role of CRP and hsCRP is still elusive and the association between CRP and psychiatric disorders is inconsistent, CRP holds promise to become a psychiatric biomarker.

Basal and LPS-stimulated inflammatory markers and the course of anxiety symptoms

A cross-sectional relationship between low-grade inflammation -characterized by increased blood levels of C-reactive protein (CRP) and pro-inflammatory cytokines- and anxiety has been reported, but the potential longitudinal relationship has been less well studied. We aimed to examine whether basal and lipopolysaccharide (LPS-)induced levels of inflammatory markers are associated with anxiety symptom severity over the course of nine years. We tested the association between basal and LPS-induced inflammatory markers with anxiety symptoms (measured with the Beck's Anxiety Inventory; BAI, Fear Questionnaire; FQ and Penn's State Worry Questionnaire; PSWQ) at 5 assessment waves over a period up nine years. We used multivariate-adjusted mixed models in up to 2867 participants of the Netherlands Study of Depression and Anxiety (NESDA). At baseline, 43.6% of the participants had a current anxiety disorder, of which social phobia (18.5%) was most prevalent. Our results demonstrated that baseline inflammatory markers were significantly associated with several outcomes of anxiety at baseline over nine subsequent years. BAI subscale of somatic (arousal) symptoms of anxiety, and FQ subscale of agoraphobia demonstrated the strongest effects with standardized beta-coefficients of up to 0.14. The associations were attenuated by 25%-30% after adjusting for the presence of (comorbid) major depressive disorder (MDD), but remained statistically significant. In conclusion, we found that participants with high levels of inflammatory markers have on average high levels of anxiety consisting of physical arousal and agoraphobia, which tended to persist over a period of nine years, albeit with small effect sizes. These associations were partly driven by co-morbid depression.

Effects of celecoxib augmentation of antidepressant or anxiolytic treatment on affective symptoms and inflammatory markers in patients with anxiety disorders: exploratory study

Prolonged stress has been associated with elevated levels of circulating proinflammatory cytokines. Cyclo-oxygenase-2 inhibitors such as celecoxib exert anti-inflammatory effects and may enhance the response to antidepressant drug treatment in patients with depressive disorders, but their effect on anxiety symptoms in patients with anxiety disorders is uncertain. Patients with a primary diagnosis of an anxiety disorder, with stabilised symptoms, underwent either 6 weeks of celecoxib augmentation of continued treatment (n = 18) or continued 'treatment as usual' (n = 9). Assessments included the Warwick-Edinburgh mental well-being Scale (WEMWEBS), Hospital Anxiety and Depression Scale (HADS), Oxford questionnaire of emotional side effects of antidepressants (OQUESA) and Clinical Global Impression of Illness Severity (CGI-S). Venous blood samples were collected for assays of inflammatory cytokines. Patients who underwent celecoxib augmentation showed significant reductions in anxiety (HADS-A -3.17) and depressive (HADS-D -2.11) symptoms and in overall illness severity (CGI-S -1.11), and improvements in mental well-being (WEMWBS 7.5) and positive changes in emotional responsiveness (OQUESA-RP -3.56; OQUESA-AC -4.22): these were not seen with 'treatment as usual'. There were no significant changes in blood levels of inflammatory cytokines in either group. Celecoxib augmentation appeared associated with beneficial effects on anxiety and depressive symptoms and mental well-being. The findings from this pilot study merit further exploration within a double-blind, randomised placebo-controlled study.

Depression and worry symptoms predict future executive functioning impairment via inflammation

BACKGROUND

Scar models posit that heightened anxiety and depression can increase the risk for subsequent reduced executive function (EF) through increased inflammation across months. However, the majority of past research on this subject used cross-sectional designs. We therefore examined if elevated generalized anxiety disorder (GAD), major depressive disorder (MDD), and panic disorder (PD) symptoms forecasted lower EF after 20 months through heightened inflammation.

METHODS

Community-dwelling adults partook in this study (n = 614; MAGE = 51.80 years, 50% females). Time 1 (T1) symptom severity (Composite International Diagnostic Interview - Short Form), T2 (2 months after T1) inflammation serum levels (C-reactive protein, fibrinogen, interleukin-6), and T3 (20 months after T1) EF (Brief Test of Adult Cognition by Telephone) were assessed. Structural equation mediation modeling was performed.

RESULTS

Greater T1 MDD and GAD (but not PD) severity predicted increased T2 inflammation (Cohen's d = 0.21-1.92). Moreover, heightened T2 inflammation forecasted lower T3 EF (d = -1.98 to -1.87). T2 inflammation explained 25-32% of the negative relations between T1 MDD or GAD and T3 EF. T1 GAD severity predicting T3 EF via T2 inflammation path was stronger among younger (v. older) adults. Direct effects of T1 MDD, GAD, and PD forecasting decreased T3 EF were found (d = -2.02 to -1.92). Results remained when controlling for socio-demographic, physical health, and lifestyle factors.

CONCLUSIONS

Inflammation can function as a mechanism of the T1 MDD or GAD-T3 EF associations. Interventions that successfully treat depression, anxiety, and inflammation-linked disorders may avert EF decrements.

Anxiety Is Associated With DPPIV Alterations in Children With Selective Mutism and Social Anxiety Disorder: A Pilot Study

Background: Both selective mutism (SM) and social anxiety disorder (SAD) are severe pediatric anxiety disorders with the common trait of behavioral inhibition (BI). The underlying pathophysiology of these disorders remains poorly understood, however converging evidence suggests that alterations in several peripheral molecular pathways might be involved. In a pilot study, we investigated alterations in plasma molecular markers (dipeptidyl peptidase-4 [DPPIV], interleukin-6 [IL-6], tumor necrosis factor-β [TNF-β] and neuropeptide-Y [NPY]) in children with SM, SAD, and healthy controls, as well as the correlation of these markers to symptom severity. Methods: We included 51 children and adolescents (aged 5-18 years; n = 29 girls): n = 20 children in the SM-, n = 16 in the SAD- and n = 15 in the control-group (CG). Peripheral blood samples were analyzed for DPPIV, IL-6, TNF-β, and NPY concentrations. Diverse psychometric measures were used for BI, anxiety, and mutism symptoms. Results: Lower DPPIV-levels were correlated with more anxiety symptoms. However, we could not find a difference in any molecular marker between the patients with SAD and SM in comparison to the CG. Conclusion: DPPIV is proposed as relevant marker for child and adolescent anxiety. Investigating the pathophysiology of SM and SAD focusing on state and trait variables as anxiety or BI might help better understanding the underlying mechanisms of these disorders. Further studies with especially larger cohorts are needed to validate the current pilot-findings.

Neuroinflammation-Associated Alterations of the Brain as Potential Neural Biomarkers in Anxiety Disorders

Stress-induced changes in the immune system, which lead to neuroinflammation and consequent brain alterations, have been suggested as possible neurobiological substrates of anxiety disorders, with previous literature predominantly focusing on panic disorder, agoraphobia, and generalized anxiety disorder, among the anxiety disorders. Anxiety disorders have frequently been associated with chronic stress, with chronically stressful situations being reported to precipitate the onset of anxiety disorders. Also, chronic stress has been reported to lead to hypothalamic–pituitary–adrenal axis and autonomic nervous system disruption, which may in turn induce systemic proinflammatory conditions. Preliminary evidence suggests anxiety disorders are also associated with increased inflammation. Systemic inflammation can access the brain, and enhance pro-inflammatory cytokine levels that have been shown to precipitate direct and indirect neurotoxic effects. Prefrontal and limbic structures are widely reported to be influenced by neuroinflammatory conditions. In concordance with these findings, various imaging studies on panic disorder, agoraphobia, and generalized anxiety disorder have reported alterations in structure, function, and connectivity of prefrontal and limbic structures. Further research is needed on the use of inflammatory markers and brain imaging in the early diagnosis of anxiety disorders, along with the possible efficacy of anti-inflammatory interventions on the prevention and treatment of anxiety disorders.

Predicting the course of anxiety disorders: The role of biological parameters

OBJECTIVE

Clinical characteristics appear limited in their ability to predict course of anxiety disorders, therefore we explored the predictive value of biological parameters on course of anxiety disorders.

METHODS

907 persons with an anxiety (panic, social phobia, generalised anxiety) disorder with a baseline and two-year follow-up measure were selected from the Netherlands Study of Depression and Anxiety (NESDA). Previously, three course trajectories were distinguished which vary in terms of symptom severity and chronicity. Baseline clinical parameters like anxiety severity, anxiety duration, and disability were limited in their ability to predict the two-year course. This study explored whether metabolic syndrome, hypothalamic-pituitary-adrenal-axis functioning, inflammation markers, and neuroplasticity were indicators of two-year course and whether these parameters improved the model containing the most predictive clinical parameters only.

RESULTS

Baseline diastolic blood pressure of persons with chronic moderate symptoms was significantly higher than of persons with non-chronic mild symptoms (odds ratio [OR] = 1.18, 95% confidence interval [CI95%] 1.01 to 1.38). Baseline high-density lipid cholesterol of persons with severe chronic symptoms was significantly lower than of persons with non-chronic mild symptoms (OR = 0.77, CI95% 0.62 to 0.96). The predictive ability of both parameters was however low with concordance statistics of 0.55 and 0.57 respectively. Addition of biological parameters did not improve the predictive ability of the model containing the clinical parameters.

CONCLUSIONS

In addition to clinical characteristics, biological parameters did not improve the predictive ability of the model for course trajectory of anxiety disorders. Prediction of course trajectory in anxiety disorders remains difficult and warrants further research.

Neuroimmune Mechanisms and Sex/Gender-Dependent Effects in the Pathophysiology of Mental Disorders

Innate and adaptive immune mechanisms have emerged as critical regulators of CNS homeostasis and mental health. A plethora of immunologic factors have been reported to interact with emotion- and behavior-related neuronal circuits, modulating susceptibility and resilience to mental disorders. However, it remains unclear whether immune dysregulation is a cardinal causal factor or an outcome of the pathologies associated with mental disorders. Emerging variations in immune regulatory pathways based on sex differences provide an additional framework for discussion in these psychiatric disorders. In this review, we present the current literature pertaining to the effects that disrupted immune pathways have in mental disorder pathophysiology, including immune dysregulation in CNS and periphery, microglial activation, and disturbances of the blood-brain barrier. In addition, we present the suggested origins of such immune dysregulation and discuss the gender and sex influence of the neuroimmune substrates that contribute to mental disorders. The findings challenge the conventional view of these disorders and open the window to a diverse spectrum of innovative therapeutic targets that focus on the immune-specific pathophenotypes in neuronal circuits and behavior. SIGNIFICANCE STATEMENT: The involvement of gender-dependent inflammatory mechanisms on the development of mental pathologies is gaining momentum. This review addresses these novel factors and presents the accumulating evidence introducing microglia and proinflammatory elements as critical components and potential targets for the treatment of mental disorders.

Association between Leukocyte Counts and Physical Fitness in Male Military Members: The CHIEF Study

Low-grade inflammation, which is related to obesity and toxic substance use in young adults, may be associated with poor physical fitness. We investigated the association between total leukocyte count and physical fitness in a military cohort of 3,453 healthy young Taiwanese males aged 20-50 years in a cross-sectional study in 2014. Low-grade inflammation was defined according to equally sized quartiles of total leukocyte counts within the suggested normal limits (4.00-9.99 × 10³/mm³). Aerobic fitness was assessed by the time for a 3-kilometer run test, and anaerobic fitness was evaluated by the numbers of sit-ups and push-ups performed in 2 minutes. Automatic monitoring systems were used to verify the scores for all procedures. Multiple linear regression was utilized to identify the associations among variables. When compared with the lowest counts (4.00-5.49 × 10³/mm³), the second highest (6.50-7.49 × 10³/mm³) and highest normal leukocyte counts (7.50-9.99 × 10³/mm³) were correlated with longer times for a 3-kilometer run (β and 95% confidence intervals =4.93 (1.61, 8.25) and 4.65 (2.20, 7.10), respectively) and fewer numbers of push-ups performed in 2 minutes (β = -0.59 (-1.15, -0.03) and -0.56 (-0.96, -0.17), respectively), after adjustments for age, service specialty, waist circumference, body mass index, alcohol consumption, tobacco smoking, and physical activity. However, the association with 2-minute sit-ups was null. Our study suggested an inverse association between total leukocyte count and not only aerobic fitness but also parts of anaerobic fitness in young males. The temporal association needs confirmation in longitudinal studies.

Inflammation and Trauma-Related Psychopathology in Syrian and Iraqi Refugees

Refugees experience high rates of post-traumatic stress disorder (PTSD), anxiety, and depression due to exposure to civilian war trauma and forced migration. Inflammatory products may offer viable biological indicators of trauma-related psychopathology in this cohort, promoting rapid and objective assessment of psychopathology. Incoming Syrian and Iraqi refugees (n = 36) ages 18-65 completed self-report measures of PTSD, anxiety, and depression and provided saliva samples during an assessment at a primary care clinic within the first month of resettlement in the United States. Interleukin 1β (IL-1β) and C-reactive protein (CRP) differentially correlated with symptom severity by domain, and there was a non-significant trend for sex moderating the relation between inflammation and PTSD symptoms. Our findings show unique relations between trauma-related psychopathology and inflammation. There is a need for further research in diverse ethnic cohorts with differential trauma exposures for inflammation to be considered a biological indicator of psychopathology.

Peripheral adiponectin levels in anxiety, mood, trauma- and stressor-related disorders: A systematic review and meta-analysis

BACKGROUND

Anxiety, mood, trauma- and stressor-related disorders confer increased risk for metabolic disease. Adiponectin, a cytokine released by adipose tissue is associated with these disorders and obesity via inflammatory processes. Available data describing associations with mental disorders remain limited and conflicted.

METHODS

A systematic search was conducted for English, peer-reviewed articles from inception until February 2019 that assessed for serum or plasma adiponectin levels in adults with an anxiety, mood or trauma-related disorder. Diagnoses were determined by psychiatric interview, based on DSM-IV, DSM-5 or ICD-10 criteria. Analyses were performed using STATA 15 and Standardized mean difference (SMD) with 95% confidence interval was applied to pool the effect size of meta-analysis studies.

RESULTS

In total 65 eligible studies were included in the systematic review and 30 studies in this meta-analysis. 19,178 participants (11,262 females and 7916 males), comprising healthy adults and adults with anxiety, mood and trauma-related disorders, were included. Overall results indicated an inverse association between adiponectin levels and examined mental disorders. Specifically, patients with an anxiety disorder (SMD  = -1.18 µg/mL, 95% CI, -2.34; -0.01, p  = 0.047); trauma or stressor-related disorder (SMD  =  -0.34 µg/mL, 95% CI, -0.52; -0.17, p  = 0.0000) or bipolar disorder (SMD  =  -0.638 µg/mL, 95% CI, -1.16, -0.12, p  = 0.017) had significant lower adiponectin levels compared to healthy adults.

LIMITATIONS

Heterogeneity, potential publication bias, and lack of control for important potential confounders were significant limitations.

CONCLUSION

Peripheral adiponectin levels appear to be inversely associated with anxiety, mood, trauma- and stressor related disorders and may be a promising biomarker for diagnosis and disease monitoring.

The neutrophil-lymphocyte ratio and platelet-lymphocyte ratio in adolescent obsessive-compulsive disorder: Does comorbid anxiety disorder affect inflammatory response?

Recent adult etiologic studies indicated evidence linking increased inflammatory parameters with psychiatric disorders. The neutrophil-lymphocyte ratio and platelet-lymphocyte ratio are easily obtainable clinical markers of inflammation and have been found to be increased in various medical and mental disorders. In this study, we aimed to investigate the neutrophil-lymphocyte ratio and platelet-lymphocyte ratio in adolescents with obsessive-compulsive disorder (OCD). Secondarily, the effect of comorbid anxiety disorder with OCD on the inflammatory response was investigated. Sixty drug-naïve adolescents with OCD aged 12 to 18 years were enrolled in the patient group. Twenty-three of the OCD group had comorbid anxiety disorder (AD) and 37 had no comorbidities. One hundred twenty-eight adolescents in the same age range with no psychiatric disorders were recruited as the healthy control group. The severity of OCD symptoms was evaluated using the Children's Yale-Brown Obsessive Compulsive Scale. There were statistically significant differences in the neutrophil-lymphocyte ratio, white blood cell, neutrophil, and platelet counts among the three groups, even after adjusting for age and sex. The adolescents with OCD and AD had the highest neutrophil-lymphocyte ratio and white blood cell counts. A comorbid anxiety disorder diagnosis in addition to obsessive-compulsive disorder may increase the inflammatory response.

Old Friends, immunoregulation, and stress resilience

There is a considerable body of evidence indicating that chronic adverse experience, especially chronic psychosocial stress/trauma, represents a major risk factor for the development of many somatic and affective disorders, including inflammatory bowel disease (IBD) and posttraumatic stress disorder (PTSD). However, the mechanisms underlying the development of chronic stress-associated disorders are still in large part unknown, and current treatment and prevention strategies lack efficacy and reliability. A greater understanding of mechanisms involved in the development and persistence of chronic stress-induced disorders may lead to novel approaches to prevention and treatment of these disorders. In this review, we provide evidence indicating that increases in immune (re-)activity and inflammation, potentially promoted by a reduced exposure to immunoregulatory microorganisms ("Old Friends") in today's modern society, may be causal factors in mediating the vulnerability to development and persistence of stress-related pathologies. Moreover, we discuss strategies to increase immunoregulatory processes and attenuate inflammation, as for instance contact with immunoregulatory Old Friends, which appears to be a promising strategy to promote stress resilience and to prevent/treat chronic stress-related disorders.

The association between anxiety, traumatic stress, and obsessive-compulsive disorders and chronic inflammation: A systematic review and meta-analysis

BACKGROUND

Anxiety is characterized by prolonged preparation for real or perceived threat. This may manifest both as psychological and physiological activation, ultimately leading to greater risk for poor health. Chronic inflammation may play an integral role in this relationship, given the influential role that it has in chronic illness. The aim of this meta-analysis is to examine levels of chronic inflammation, measured by inflammatory cytokines and C-reactive protein, in people with anxiety disorders, PTSD (posttraumatic stress disorder), or obsessive-compulsive disorder compared to healthy controls. Several moderating variables, including specific diagnosis and depression comorbidity, were also assessed.

METHODS

Seventy six full-text articles were screened for eligibility with 41 studies ultimately included in analysis.

RESULTS

Results demonstrated a significant overall difference between healthy controls (HCs) and people with anxiety disorders in pro-inflammatory cytokines (P = 0.013, Hedge's g = -0.39), which appears to be largely driven by interleukin-1β (IL-1β; P = 0.009, Hedge's g = -0.50), IL-6 (P < 0.001, Hedge's g = -0.93), and tumor necrosis factor-α (P = 0.030, Hedge's g = -0.56). Moderation analyses revealed a moderating effect of diagnosis (P = 0.050), as only individuals with PTSD demonstrated differences in inflammation between HCs (P = 0.004, Hedge's g = -0.68).

CONCLUSIONS

These data demonstrate the association between inflammatory dysregulation and diagnoses associated with chronic, impactful, and severe anxiety and provides insight into the way that anxiety, and in particular PTSD, is related to certain inflammatory markers. In doing so, these findings may provide an initial step in disentangling the relationship between anxiety and basic health processes.

Anxiety disorders and CRP in a population cohort study with 54,326 participants: The LifeLines study

OBJECTIVES

Growing evidence indicates that inflammatory processes may play a role in the pathogenesis of anxiety disorders. Nevertheless, much remains to be learned about the involvement of inflammation, including C-reactive protein (CRP), in specific anxiety disorders. This study examines the relation between anxiety disorders and CRP.

METHODS

Associations of serum CRP with anxiety disorders were determined in a large population study (n = 54,326 participants, mean age = 47 years; 59% female), the LifeLines cohort. Depressive and anxiety disorders (generalized anxiety disorder, social anxiety phobia, panic disorder with or without agoraphobia and agoraphobia without panic disorder) were assessed using the Mini-International Neuropsychiatric Interview.

RESULTS

Anxiety disorders, with the exception of social anxiety disorder, were significantly associated with increased CRP. After adjusting for demographics, life style factors, health factors, medication use, depression, and psychological stressors, CRP remained significantly associated with panic disorder with agoraphobia (β = 0.01, P = .013). Moreover, CRP levels were significantly higher in people with panic disorder with agoraphobia compared to other anxiety disorders, independent of all covariates (F = 3.00, df = 4, P = .021).

CONCLUSIONS

Panic disorder with agoraphobia is associated with increased CRP, although the effect size of this association is small. This indicates that neuroinflammatory mechanisms may play a potential role in its pathophysiology.

Mood disorders and circulating levels of inflammatory markers in a longitudinal population-based study

BACKGROUND

There has been increasing evidence that chronic low-grade inflammation is associated with mood disorders. However, the findings have been inconsistent because of heterogeneity across studies and methodological limitations. Our aim is to prospectively evaluate the bi-directional associations between inflammatory markers including interleukin (IL)-6, tumor necrosis factor (TNF)-α and high sensitivity C-reactive protein (hsCRP) with mood disorders.

METHODS

The sample consisted of 3118 participants (53.7% women; mean age: 51.0, s.d. 8.8 years), randomly selected from the general population, who underwent comprehensive somatic and psychiatric evaluations at baseline and follow-up (mean follow-up duration = 5.5 years, s.d. 0.6). Current and remitted mood disorders including bipolar and major depressive disorders (MDD) and its subtypes (atypical, melancholic, combined atypical and melancholic, and unspecified) were based on semi-structured diagnostic interviews. Inflammatory biomarkers were analyzed in fasting blood samples. Associations were tested by multiple linear and logistic regression models.

RESULTS

Current combined MDD [β = 0.29, 95% confidence interval (CI) 0.03-0.55] and current atypical MDD (β = 0.32, 95% CI 0.10-0.55) at baseline were associated with increased levels of hsCRP at follow-up. There was little evidence for inflammation markers at baseline predicting mood disorders at follow-up.

CONCLUSIONS

The prospective unidirectional association between current MDD subtype with atypical features and hsCRP levels at follow-up suggests that inflammation may be a consequence of this condition. The role of inflammation, particularly hsCRP that is critically involved in cardiovascular diseases, warrants further study. Future research that examines potential influences of medications on inflammatory processes is indicated.

The bidirectional relationship between anxiety disorders and circulating levels of inflammatory markers: Results from a large longitudinal population-based study

BACKGROUND

Although there has been abundant research on chronic low-grade inflammation as a potential mechanism underlying the link between mood disorders and cardiovascular risk, less is known about the role of inflammatory factors and anxiety disorders. The aim of this paper is to evaluate the bi-directional associations between inflammatory markers including interleukin (IL)-6, tumor necrosis factor (TNF)-α, and high sensitivity C-reactive protein (hsCRP) with anxiety disorders and its subgroups.

METHODS

The sample consisted of 3,113 participants (53.7% women; mean age: 51.0, S.D. 8.8 years), randomly selected from the general population, who underwent comprehensive somatic and psychiatric evaluations at baseline and follow-up (mean follow-up duration = 5.5 years, S.D. 0.6). Anxiety disorders were assessed with semistructured diagnostic interviews. Inflammatory biomarkers were analyzed in fasting blood samples.

RESULTS

After adjustment for potential confounders, current anxiety disorders (β = 0.09, 95% CI 0.00-0.17) and agoraphobia (β = 0.25, 95% CI: 0.07-0.43) at baseline were associated with a steeper increase of hsCRP levels over the follow-up period. Current posttraumatic stress disorder (PTSD) was associated with a lower increase of IL-6 levels over the follow-up period (β = -0.52, 95% CI: -1.00/-0.04). There was no evidence for an association between inflammation markers at baseline and anxiety disorders at follow-up.

CONCLUSIONS

The prospective association between agoraphobia at baseline and hsCRP levels over the follow-up period suggests that chronic low-grade inflammation may be a consequence of this condition. The decrease in IL-6 in PTSD also requires further investigation. No evidence was found for chronic low-grade inflammation as a predictor of future anxiety disorders.

Peripheral inflammatory cytokines and immune balance in Generalised Anxiety Disorder: Case-controlled study

INTRODUCTION

Previous investigations have demonstrated that major depression is associated with particular patterns of cytokine signalling. The primary aim of this study was to examine peripheral pro-inflammatory and anti-inflammatory cytokines and immune balance in Generalised Anxiety Disorder (GAD).

METHODS

A case-controlled cross-sectional study design was employed: 54 patients with GAD and 64 healthy controls were recruited. Participants completed self-report measures of anxiety and depression. Two pro-inflammatory and two anti-inflammatory cytokines were measured using multiplex technology.

RESULTS

Case-control logistic regression analyses revealed significant differences in serum levels of IL-10, TNF-α, and IFN-γ between GAD and control groups after adjusting for age, gender, body mass index, smoking and alcohol consumption: these group differences were independent of the presence or degree of depression. Comparison of pro-inflammatory to anti-inflammatory cytokine ratios indicated that there were significantly higher ratios of TNF-α/IL10, TNF-α/IL4, IFN-γ/IL10, and IFN-γ/IL4 in the GAD group compared to the control group.

CONCLUSIONS

This study is the first to investigate both pro- and anti-inflammatory cytokines and their balance in patients with GAD in comparison to healthy controls. The findings indicate a relatively increased pro-inflammatory response and decreased anti-inflammatory response and provide the first demonstration of an altered cytokine balance in GAD. Serum cytokine levels in GAD were independent of the presence of depression.

Pharmacotherapy in Generalized Anxiety Disorder: Novel Experimental Medicine Models and Emerging Drug Targets

Many pharmacological and psychological approaches have been found efficacious in patients with generalized anxiety disorder (GAD), but many treatment-seeking patients will not respond and others will relapse despite continuing with interventions that initially had beneficial effects. Other patients will respond but then stop treatment early because of untoward effects such as sexual dysfunction, drowsiness, and weight gain. There is much scope for the development of novel approaches that could have greater overall effectiveness or acceptability than currently available interventions or that have particular effectiveness in specific clinical subgroups. 'Experimental medicine' studies in healthy volunteers model disease states and represent a proof-of-concept approach for the development of novel therapeutic interventions: they determine whether to proceed to pivotal efficacy studies and so can reduce delays in translating innovations into clinical practice. Investigations in healthy volunteers challenged with the inhalation of air 'enriched' with 7.5% carbon dioxide (CO₂) indicate this technique provides a validated and robust experimental medicine model, mirroring the subjective, autonomic, and cognitive features of GAD. The anxiety response during CO₂ challenge probably involves both central noradrenergic neurotransmission and effects on acid-base sensitive receptors and so may stimulate development of novel agents targeted at central chemosensors. Increasing awareness of the potential role of altered cytokine balance in anxiety and the interplay of cytokines with monoaminergic mechanisms may also encourage the investigation of novel agents with modulating effects on immunological profiles. Although seemingly disparate, these two approaches to treatment development may pivot on a shared mechanism in exerting anxiolytic-like effects through pharmacological effects on acid-sensing ion channels.

Inflammation in Fear- and Anxiety-Based Disorders: PTSD, GAD, and Beyond

The study of inflammation in fear- and anxiety-based disorders has gained interest as growing literature indicates that pro-inflammatory markers can directly modulate affective behavior. Indeed, heightened concentrations of inflammatory signals, including cytokines and C-reactive protein, have been described in posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), panic disorder (PD), and phobias (agoraphobia, social phobia, etc.). However, not all reports indicate a positive association between inflammation and fear- and anxiety-based symptoms, suggesting that other factors are important in future assessments of inflammation's role in the maintenance of these disorders (ie, sex, co-morbid conditions, types of trauma exposure, and behavioral sources of inflammation). The most parsimonious explanation of increased inflammation in PTSD, GAD, PD, and phobias is via the activation of the stress response and central and peripheral immune cells to release cytokines. Dysregulation of the stress axis in the face of increased sympathetic tone and decreased parasympathetic activity characteristic of anxiety disorders could further augment inflammation and contribute to increased symptoms by having direct effects on brain regions critical for the regulation of fear and anxiety (such as the prefrontal cortex, insula, amygdala, and hippocampus). Taken together, the available data suggest that targeting inflammation may serve as a potential therapeutic target for treating these fear- and anxiety-based disorders in the future. However, the field must continue to characterize the specific role pro-inflammatory signaling in the maintenance of these unique psychiatric conditions.

Pro-inflammatory cytokines and psychotherapy in depression: Results from a randomized clinical trial

Depression is a serious condition that is associated with great psychic suffering and major impairments on the patient's general health, quality of life, and social and occupational activities. In some cases, it may lead to suicide. Regardless of the innumerous research works that have already addressed depression in wide and specific facets, there is still a lot to grasp in order to effectively help preventing and treating depression. This work presents data from a randomized clinical trial that sought to evaluate the effectiveness of two brief psychotherapeutic for Depression: Cognitive Behavioral Therapy (CBT) and Supportive-Expressive Dynamic Psychotherapy (SEDP). This was a convenience sample composed of 46 individuals that were evaluated using a structured diagnostic interview and then randomly allocated to the SEDP group. We examined baseline and post-intervention serum levels of the Interleukin-6 (IL-6) and the Tumor Necrosis Factor (TNF-α) in addition to the severity of depressive symptoms according to the Outcome Questionnaire - 45.2 (OQ-45.2) and the Beck Depression Inventory (BDI). Results show that serum IL-6 and TNF-α levels, as well as the scores from the OQ-45.2 and the BDI significantly decreased after 16 sessions of SEDP (p < 0.001), except for the Interpersonal Relationship domain from the OQ-45. Despite the reduction of serum cytokines levels and OQ-45 and BDI scores, they were only significantly correlated regarding the social role domain from the OQ-45. Nonetheless, our data suggests an effective role of brief psychodynamic psychotherapy in the reduction of depressive symptoms and serum inflammatory levels that are associated with depression.