Cortisol as a predictor of psychological therapy response in anxiety disorders-Systematic review and meta-analysis

The predictive value of cortisol in psychodynamic psychotherapy for social anxiety disorder: Extended results of the SOPHONET-Study

Psychotherapy is an effective treatment for anxiety disorders (AD), yet a vast majority of patients do not respond to therapy, necessitating the identification of predictors to enhance outcomes. Several studies have explored the relationship between stress response and treatment outcome, as a potential treatment mechanism. However, the latter remains under-researched in patients with social anxiety disorder (SAD). We studied N = 29 patients undergoing psychodynamic psychotherapy (PDT) within the SOPHONET-Study. Stress reactivity (i.e., area under the curve with respect to the increase; AUCi) was induced by a standardized psychosocial stressor (Trier Social Stress Test; TSST) and assessed by means of adrenocorticotropic hormone (ACTH), blood and salivary cortisol samples before (t1) treatment. Samples of these biomarkers were taken -1 min prior stress exposure and six more blood samples were collected post-TSST ( + 1, + 10, + 20, + 30, + 45, + 60 min.). The participants were diagnosed with SAD based on the Structured Clinical Interview for DSM-IV (SCID) and completed the Liebowitz Social Anxiety Scale as well as the Beck Depression Inventory before (t1) and after psychotherapy (t2). Pre-treatment stress reactivity significantly predicted changes in depression (salivary p < 0.001 and blood cortisol p = 0.001), as well as in avoidance behavior (blood cortisol p = 0.001). None of the biomarkers revealed significant results in fear or in the total LSAS-scores, except for ACTH with a trend finding (p = 0.06). Regarding therapy success, symptoms of social anxiety (p = 0.005) and depression (p < 0.001) were significantly reduced from pre (t1) to post-treatment (t2). Our study showed that stress reactivity pre-treatment may serve as a predictor of psychotherapy outcome. In this regard, alterations in stress response relate to changes in symptoms of social anxiety and depression after PDT. This implies that patients with chronic stress might benefit from a targeted interventions during psychotherapy, especially to manage fear in social contexts.

Efficacy of Vagal nerve stimulation on anxiety among elderly retired teachers during COVID-19 pandemic

BACKGROUND

Excessive fear, worry and behavioral disturbances define anxiety, with particular significance attributed to vagal nerve, a crucial transmitter of information to the brain regions governing anxiety. Highlighting the importance of vagal nerve, transcutaneous auricular vagal nerve stimulation (TaVNS) emerges as a tolerable and safe technique. The success of non-invasive vagal nerve stimulation in alleviating anxiety underscores the pivotal role of the vagal nerve.

OBJECTIVES

The purpose of this study was to assess the effectiveness of physiotherapy interventions in mitigating anxiety among retired teachers during the COVID-19 pandemic, emphasizing the relevance of targeting the vagal nerve for improved mental well-being.

METHODS

60 retired teachers diagnosed with anxiety were chosen through random allocation. Participants were divided into two groups: Group A (Experimental group) received transcutaneous auricular vagal nerve stimulation (TaVNS), and Group B (Control group) underwent the Jacobson relaxation technique. Intervention period spanned 4 weeks, with four sessions per week, lasting 30 minutes. The outcome measures included Generalized Anxiety Disorder-7 (GAD-7) questionnaire and salivary cortisol levels.

RESULTS

Following the 4-week intervention, both groups exhibited a significant reduction in Generalized Anxiety Disorder-7 (GAD-7) scores and salivary cortisol levels (P <  0.001). Notably, Group A demonstrated a significantly higher effectiveness rate compared to Group B.

CONCLUSION

The study concludes that transcutaneous auricular vagal nerve stimulation (TaVNS) is effective in reducing anxiety among retired teachers. Transcutaneous auricular vagal nerve stimulation (TaVNS) proves to be a powerful and effective intervention in alleviating anxiety among retired teachers, emphasizing its potential significance in enhancing mental well-being.

Associations of serum cortisol and inflammatory marker features with depression and anxiety in young women with gynecologic cancer

PURPOSE

Serum cortisol and inflammatory markers may play a role in depression and anxiety, but little is known about whether various features of serum cortisol and inflammatory markers have different associations with depression and anxiety. This study examines the associations of serum cortisol and inflammatory marker features with depression and anxiety in young women with gynecologic cancer.

METHODS

Sixty-four young women with gynecologic cancer, aged 15-39 years, were recruited in a tertiary general hospital and a tertiary hospital specializing in oncology in China from May to December 2021. The Hospital Anxiety and Depression Scale was used to evaluate depression and anxiety. Blood samples were taken at 8 am, 4 pm, and 10 pm on the same day to examine the various features (average, variability, and diurnal patterns) of serum cortisol and inflammatory markers, namely C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α).

RESULTS

Young women with gynecologic cancer who reported depression/anxiety had significantly higher average levels of serum cortisol, IL-6 and TNF-α than those who did not. The dysregulations in the diurnal patterns of serum cortisol and IL-6 were associated with depression and anxiety. Serum cortisol levels were significantly higher in the depression/anxiety group at 10 pm. Depression and anxiety were associated with elevated levels of IL-6 and TNF-α at each time point.

CONCLUSION

This study revealed various associations of serum cortisol and inflammatory marker features with depression and anxiety in young women with gynecologic cancer. Further research is needed to understand the role of serum cortisol and inflammatory marker features in the progression of depression and anxiety.

Diet's Impact on Post-Traumatic Brain Injury Depression: Exploring Neurodegeneration, Chronic Blood-Brain Barrier Destruction, and Glutamate Neurotoxicity Mechanisms

Traumatic brain injury (TBI) has a profound impact on cognitive and mental functioning, leading to lifelong impairment and significantly diminishing the quality of life for affected individuals. A healthy blood-brain barrier (BBB) plays a crucial role in guarding the brain against elevated levels of blood glutamate, making its permeability a vital aspect of glutamate regulation within the brain. Studies have shown the efficacy of reducing excess glutamate in the brain as a treatment for post-TBI depression, anxiety, and aggression. The purpose of this article is to evaluate the involvement of dietary glutamate in the development of depression after TBI. We performed a literature search to examine the effects of diets abundant in glutamate, which are common in Asian populations, when compared to diets low in glutamate, which are prevalent in Europe and America. We specifically explored these effects in the context of chronic BBB damage after TBI, which may initiate neurodegeneration and subsequently have an impact on depression through the mechanism of chronic glutamate neurotoxicity. A glutamate-rich diet leads to increased blood glutamate levels when contrasted with a glutamate-poor diet. Within the context of chronic BBB disruption, elevated blood glutamate levels translate to heightened brain glutamate concentrations, thereby intensifying neurodegeneration due to glutamate neurotoxicity.

Acupressure can reduce preoperative anxiety in adults with elective surgery: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Preoperative anxiety is prevalent amongst adults with elective surgery and is associated with multiple detrimental perioperative physiological effects. Increasing studies support the effectiveness of acupressure in managing preoperative anxiety. However, the magnitude of acupressure's positive association with preoperative anxiety is still unclear due to a lack of rigorous evidence synthesis.

OBJECTIVE

To estimate the efficacy of acupressure on preoperative anxiety and physiological parameters amongst adults scheduled for elective surgery.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Search terms were combined for acupressure and preoperative anxiety in PubMed, Cochrane Library, EMBASE, CINAHL, China National Knowledge Infrastructure, and WanFang Data Knowledge Service Platform to search for eligible randomised controlled trials from the inception of each database through September 2022.

METHODS

Pairs of researchers independently screened and extracted data from included studies. The risk of bias was assessed using the Cochrane risk of bias tool Version 2.0. Meanwhile, random-effects meta-analysis of overall effects and prespecified subgroup (i.e., surgery types, intervention providers, and acupressure stimulation tools) was conducted using Review Manager Software 5.4.1. Meta-regression was performed to explore study-level variables that may contribute to heterogeneity using STATA 16.

RESULTS

Of 24 eligible randomised controlled trials, there were a total of 2537 participants from 5 countries contributed to this synthesis. When comparing acupressure with usual care or placebo, acupressure showed a large effect size for preoperative anxiety (SMD = -1.30; 95%CI = -1.54 to -1.06; p < 0.001; I2 = 86%). The significant mean reduction of heart rate, and systolic and diastolic blood pressure was -4.58 BPM (95%CI = -6.70 to -2.46; I2 = 89%), -6.05 mmHg (95%CI = -8.73 to -3.37; p < 0.001; I2 = 88%), and -3.18 mmHg (95%CI = -5.09 to -1.27; p = 0.001; I2 = 78%), respectively. Exploratory subgroup analyses showed significant differences in surgery types and acupressure stimulation tools, whilst the intervention providers (i.e., healthcare professionals and self-administered) showed no statistically significant difference for acupressure therapy. None of the predefined participants and study-level characteristics moderated preoperative anxiety through meta-regression.

CONCLUSION

Acupressure appears efficacious as a therapy for improving preoperative anxiety and physiological parameters amongst adults with elective surgery. Self-administered acupressure, which is effective with a large effect, may be considered as an evidence-based approach to managing preoperative anxiety. Hence, this review aids in the development of acupressure in different types of elective surgeries and the improvement of the rigour of acupressure therapy.

Cortisol dysregulation in anxiety infertile women and the influence on IVF treatment outcome

Introduction

Dysregulation of the stress-regulatory hormone cortisol is associated with anxiety, but its potential impact on infertile women and in vitro fertilization (IVF) treatment remains unclear. This prospective cross-sectional study aimed at evaluating the dysregulation of cortisol and its correlation to anxiety in infertile women. The influence of stress on IVF outcomes was also investigated.

Methods

A point-of-care test was used for the measurement of morning serum cortisol in 110 infertile women and 112 age-matching healthy individuals. A Self-Rating Anxiety Scale (SAS) was used for the anxiety assessment of infertile women, and 109 of them underwent IVF treatment starting with the GnRH-antagonist protocol. If clinical pregnancy was not achieved, more IVF cycles were conducted with adjusted protocols until the patients got pregnant or gave up.

Results

Higher morning serum cortisol level was identified for infertile patients, especially for the elder. Women with no anxiety showed significant differences in cortisol levels, monthly income, and BMI compared with those with severe anxiety. A strong correlation was found between the morning cortisol level and the SAS score. When the cutoff value is 22.25 μg/dL, cortisol concentration could predict the onset of anxiety with high accuracy (95.45%) among infertile women. After IVF treatments, women with high SAS scores (>50) or cortisol levels (>22.25 μg/dL) demonstrated a lower rate of pregnancy (8.0%-10.3%) and more IVF cycles, although the impact of anxiety was not affirmative.

Conclusion

Hypersecretion of cortisol related to anxiety was prevalent among infertile women, but the influence of anxiety on multi-cycle IVF treatment was not affirmative due to the complicated treatment procedures. This study suggested that the assessment of psychological disorders and stress hormone dysregulation should not be overlooked. An anxiety questionnaire and rapid cortisol test might be included in the treatment protocol to provide better medical care.

Complementary and Integrative Medicine for Anxiety in Children, Adolescents, and Young Adults

An integrative approach to treating anxiety in children and adolescents takes a biopsychosocial-spiritual approach. Early life stress may translate into anxiety via epigenetic mechanisms, the adoption of maladaptive coping tendencies (poor eating, sedentary lifestyle, substance use), and dysregulation of central autonomic nervous system function. Each of these mechanisms may increase inflammatory markers. This article will explore the efficacy of CIM interventions that work on these mechanisms through mind-body-medicine, acupuncture, nutrition, and supplements.

The impact of hormonal contraceptives on anxiety treatments: From preclinical models to clinical settings

Exposure therapy is a central component of the first-line treatment for anxiety disorders, a common mental health condition that is twice as prevalent in women relative to men. A key underlying mechanism of exposure therapy is fear extinction, which is an active learning process supported by a neural circuitry that is highly regulated by ovarian hormones. This review synthesises research examining the impact of hormonal contraceptives on laboratory fear extinction tasks in female rats and women, and on exposure therapy in women with anxiety disorders. The evidence indicates that hormonal contraceptives have a detrimental impact on fear extinction and exposure therapy that is consistent across species, and from laboratory to clinical settings. Candidate pathways by which hormonal contraceptives impede fear extinction and exposure therapy include suppression of endogenous ovarian hormones and glucocorticoids, and downregulation of signalling pathways that support extinction learning. Key areas of focus for future research are discussed.

Cortisol response under low intensity exercise during cognitive-behavioral therapy is associated with therapeutic outcome in panic disorder–an exploratory study

Objectives

Patients with Panic Disorder (PD) show an abnormal stress-induced functioning of the Hypothalamic-Pituitary-adrenal (HPA)-axis. Different protocols for stress induction are of rather low relevance for the psychotherapeutic treatment. In practice, interoceptive exposure is often realized as Low Intensity Exercise (LIE), as compared to an incremental cycle exercise test to exhaustion. Currently, it is not known, whether LIE displays an effective interoceptive stressor 1.) leading to a significant anxiety induction; 2.) a comparable HPA- and Sympathetic-Adreno-Medullar (SAM)-axis response in both patients and healthy controls; 3.) stress responses under LIE are associated with treatment outcomes.

Patients and methods

N = 20 patients with PD and n = 20 healthy controls were exposed to ten minutes of LIE on an exercise bike. LIE was applied as part of the interoceptive exposure, during an intensive Cognitive-Behavioral Therapy (CBT) in a day clinic. Heart rate was monitored and salivary cortisol samples collected. Before and after the LIE, state anxiety/ arousal were assessed. In order to evaluate psychopathology, the Panic and Agoraphobia Scale, Mobility Inventory, Agoraphobic Cognitions Questionnaire and Body Sensations Questionnaire were applied, before (T1) and after five weeks (T2) of an intensive CBT.

Results

LIE led to a significant and similar heart rate increase in both groups. Cortisol decreased over time in both groups, especially in male patients. A higher psychopathology before, and after CBT, was associated with a significantly lower cortisol response under LIE.

Conclusions

In the present study, LIE led to a divergent stress response: while there was a significant heart rate increase, cortisol decreased over time, particularly in male patients. A lower reactivity of the HPA-axis seems to be associated with a lower treatment outcome, which may affect extinction based learning. The findings suggest, that interoceptive stimuli should be designed carefully in order to be potent stressors.

Heart rate variability predicts outcome of short-term psychotherapy at the workplace

The bio-psycho-social model highlights intra-individual and inter-individual interactions, including psychotherapy. The processing of these interactions within a person takes place, among others, in the central autonomic network (CAN). The CAN's autonomic output to the periphery can be indexed by heart rate variability (HRV), representing individual adaptive capacity. Further, the CAN influences the hypothalamus-pituitary-adrenal axis with its product cortisol. The aim consisted in investigating HRV and cortisol as well as their relation to symptom course in response to short-term psychotherapy. A single-arm, uncontrolled, explorative study was conducted at an outpatient psychotherapeutic consultation in the workplace offered to employees with mental or psychosomatic complaints. Questionnaires included symptoms of depression, irritation and functional impairment. Circadian profile of HRV and salivary cortisol concentrations collected pre and post short-term psychotherapeutic intervention (4-12 sessions) were assessed. Multilevel-linear mixed regressions were calculated. Out of 29 participants (mean age 42; 72% female), 24% were on sick leave from work. Cortisol concentrations were neither affected by intervention nor by symptom course. The proportion of individuals showing a vagally mediated HRV in the range of the lowest quartile assessed for age- and sex-matched healthy controls was reduced at follow-up (pre 34%, post 22%; p = .017). Higher vagally mediated HRV at baseline predicted lower symptom burden at follow-up. Thus, the results support the assumption that HRV reflects the capability of an organism to adapt and recover. Patients with reduced HRV might need additional psychotherapeutic sessions to achieve the same symptom improvements than patients with retained HRV.

Why Does Psychotherapy Work and for Whom? Hormonal Answers

The questions of for whom and why psychotherapy is effective have been the focus of five decades of research. Most of this knowledge is based on self-report measures. Following the biopsychosocial model of mental disorders, this article explores the potential of hormones in answering these questions. The literature on cortisol, oxytocin, and oestradiol in psychotherapy was systematically searched, focusing on (a) baseline hormonal predictors of who may benefit from psychotherapy and (b) hormonal changes as indicators of therapeutic change. The search was limited to depression and anxiety disorders. In sum, the findings show that, of all three hormones, the role of cortisol is most established and that both cortisol and oxytocin are implicated in psychotherapy, although a causal role is still waiting to be demonstrated. Moreover, there is a differential role of hormones in the psychotherapy of depression versus anxiety. The directions of research mapped in this article may elucidate how psychotherapy can be selected to match patients’ endocrine states and how hormonal levels can be manipulated to improve outcomes.

Efficacy of manual acupuncture versus placebo acupuncture for generalized anxiety disorder (GAD) in perimenopause women: study protocol for a randomized controlled trial

BACKGROUND

Generalized anxiety disorder (GAD) is common among perimenopausal women. Acupuncture may be an effective treatment for GAD, but evidence is limited. The pathogenesis of GAD is not yet clear, but it is related to the hypothalamic-pituitary-adrenal axis and its excretion, cortisol (CORT), and adrenocorticotropic hormone (ACTH). The object of this study is to evaluate the efficacy of manual acupuncture (MA) versus placebo acupuncture (PA) for perimenopausal women with GAD.

METHODS

This study is a single-center, randomized, single-blind clinical trial that will be conducted in the First Affiliated Hospital of Guangzhou University of Chinese Medicine. A total of 112 eligible GAD patients will be randomly assigned (1:1) to receive MA (n=56) or PA (n=56) three times per week for 4 weeks. The primary outcome measure will be the HAMA score. The secondary outcome measures will be the GAD-7 and PSQI scores and the levels of CORT and ACTH. The evaluation will be executed at baseline, 2 weeks, the end of the treatment, and a follow-up 3-month period. All main analyses will be carried out based on the intention-to-treat (ITT) principle.

DISCUSSION

This study intends to compare the efficacy between MA and PA in the treatment of perimenopausal women with GAD and to further study the mechanisms underlying the effect.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100046604 . Registered on 22 May 2021.

Genes and hormones of the hypothalamic-pituitary-adrenal axis in post-traumatic stress disorder. What is their role in symptom expression and treatment response?

BACKGROUND

Less than half of all individuals with post-traumatic stress disorder (PTSD) remit spontaneously and a large proportion of those seeking treatment do not respond sufficiently. This suggests that there may be subgroups of individuals who are in need of augmentative or alternative treatments. One of the most frequent pathophysiological findings in PTSD is alterations in the hypothalamic-pituitary-adrenal (HPA) axis, including enhanced negative feedback sensitivity and attenuated peripheral cortisol. Given the role of the HPA axis in cognition, this pattern may contribute to PTSD symptoms and interfere with key processes of standard first-line treatments, such as trauma-focused cognitive behavioural therapy (TF-CBT).

METHODS

This review provides a comprehensive summary of the current state of research regarding the role of HPA axis functioning in PTSD symptoms and treatment.

RESULTS

Overall, there is preliminary evidence that hypocortisolaemia contributes to symptom manifestation in PTSD; that it predicts non-responses to TF-CBT; and that it is subject to change in parallel with positive treatment trajectories. Moreover, there is evidence that genetic and epigenetic alterations within the genes NR3C1 and FKBP5 are associated with this hypocortisolaemic pattern and that some of these alterations change as symptoms improve over the course of treatment.

CONCLUSIONS

Future research priorities include investigations into the role of the HPA axis in day-to-day symptom variation, the time scale in which biological changes in response to treatment occur, and the effects of sex. Furthermore, before conceiving augmentative or alternative treatments that target the described mechanisms, multilevel studies are warranted.

Additive effects of acupuncture in alleviating anxiety: A double-blind, three-arm, randomized clinical trial

BACKGROUND

In this trial, additive effects of acupuncture to selective serotonin reuptake inhibitors (SSRIs) treatment for reducing anxiety, were investigated.

METHODS

112 patients with anxiety disorder were randomly divided into three groups including SSRIs alone (drug group), SSRIs with sham acupuncture (control group) and SSRI with acupuncture (acupuncture group), and treated for 4 weeks. At the beginning of the study and on day 28, Spielberger State-Trait Anxiety Inventory (STAI) questionnaire was completed and serum levels of cortisol were measured.

RESULTS

105 patients completed the treatment period. STAI score showed significant differences among the three groups at the end of the study; importantly, changes in STAI score in the acupuncture group were significantly larger than the other groups. A decrease in cortisol levels was observed in all groups; though statistically non-significant, this decrease in the acupuncture group was larger.

CONCLUSION

Acupuncture combined with SSRIs can significantly improve anxiety state compared to anti-anxiety therapy using SSRIs alone.

Hydrocortisone as an adjunct to brief cognitive-behavioural therapy for specific fear: Endocrine and cognitive biomarkers as predictors of symptom improvement

BACKGROUND

Glucocorticoid (GC) administration prior to exposure-based cognitive-behavioural therapy (CBT) has emerged as a promising approach to facilitate treatment outcome in anxiety disorders. Further components relevant for improved CBT efficacy include raised endogenous GCs and reductions in information-processing biases to threat.

AIMS

To investigate hydrocortisone as an adjunct to CBT for spider fear and the modulating role of threat bias change and endogenous short-term and long-term GCs for treatment response.

METHODS

Spider-fearful individuals were randomized to receiving either 20 mg of hydrocortisone (n = 17) or placebo (n = 16) one hour prior to single-session predominantly computerised exposure-based CBT. Spider fear was assessed using self-report and behavioural approach measures at baseline, 1-day and 1-month follow-up. Threat processing was assessed at baseline and 1-day follow-up. Cortisol and cortisone were analysed from hair and saliva samples at baseline.

RESULTS/OUTCOMES

Self-report, behavioural and threat processing indices improved following CBT. Hydrocortisone augmentation resulted in greater improvement of self-report spider fear and stronger increase in speed when approaching a spider, but not on threat bias. Neither threat bias nor endogenous GCs predicted symptom change, and no interactive effects with hydrocortisone emerged. Preliminary evidence indicated higher hair cortisone as predictor of a stronger threat bias reduction.

CONCLUSIONS/INTERPRETATION

Our data extend earlier findings by suggesting that GC administration boosts the success of exposure therapy for specific fear even with a low-level therapist involvement. Future studies corroborating our result of a predictive hair GC relationship with threat bias change in larger clinical samples are needed.

Associations between baseline cortisol and trajectory of symptom improvement in depressed adolescents receiving psychological therapy

BACKGROUND

Cortisol hypersecretion in depressed adolescents and adults is associated with more persistent illness and may signal a lower response to psychological therapies. A meta-analysis of small and heterogenous studies demonstrated that higher pre-treatment basal cortisol levels were associated with poorer response specifically to psychological therapy for depression. The objective of this study was to investigate the relationship between both morning and evening salivary cortisol levels and response to psychological therapy in depressed adolescents participating in one large randomised controlled trial.

METHODS

We tested the association between morning and evening salivary cortisol levels at baseline and improvement in depressive symptoms in response to psychological therapies in depressed adolescents at 6 time points: baseline, 6, 12, 36, 52- and 86-weeks post-randomisation, using the self-reported Mood and Feelings Questionnaire (MFQ).

RESULTS

High evening cortisol was associated with a slower initial decline in depressive symptoms (cortisol x quadratic time p = .022); however it was not associated with total change in depressive symtoms over the whole course of the study. Morning cortisol was not associated with change in depressive symptoms. These effects were not significantly different across the three psychological therapies.

LIMITATIONS

Results may not generalize to adolescents receiving other treatments (medication) or no treatment, and may not generalize to adults. Only a minority of eligible participants collected valid cortisol samples.

CONCLUSIONS

Higher pretreatment evening cortisol may impair a depressed adolescent's ability to use psychological therapy.

Biological Markers in Anxiety Disorders

Anxiety disorders are one of the most commonly reported disorders in psychiatry, causing a high medical and socio-economic burden. Recently, there has been a soaring interest in the biological basis of anxiety disorders, which is reflected in an increasing number of articles related to the topic. Due to the ambiguity of the diagnosis and a large number of underdiagnosed patients, researchers are looking for laboratory tests that could facilitate the diagnosis of anxiety disorders in clinical practice and would allow for the earliest possible implementation of appropriate treatment. Such potential biomarkers may also be useable in monitoring the efficacy of pharmacological therapy for anxiety disorders. Therefore this article reviews the literature of potential biomarkers such as components of saliva, peripheral blood, cerebrospinal fluid (CSF), and neuroimaging studies. There are promising publications in the literature that can be useful. The most valuable and promising markers of saliva are cortisol, lysozyme, and α-amylase (sAA). In the blood, in turn, we can distinguish serotonin, brain-derived serum neurotrophic factor (BDNF), cortisol, and microRNA. Structural changes in the amygdala and hippocampus are promising neuroimaging markers, while in CSF, potential markers include oxytocin and 5-Hydroxyindoleacetic acid (5-HIAA). Unfortunately, research in the field of biomarkers is hampered by insufficient knowledge about the etiopathogenesis of anxiety disorders, the significant heterogeneity of anxiety disorders, frequent comorbidities, and low specificity of biomarkers. The development of appropriate biomarker panels and their assessment using new approaches may have the prospective to overcome the above-mentioned obstacles.

Hydrocortisone administration for reducing post-traumatic stress symptoms: A systematic review and meta-analysis

BACKGROUND

Post-traumatic stress disorder (PTSD) is a debilitating disorder that is often accompanied by alterations in the hypothalamic-pituitary (HPA) axis. While there is abundant evidence for the efficacy of psychological therapies in reducing post-traumatic stress symptoms, barely anything is known about pharmacological interventions. Given the role of the HPA axis in the pathophysiology of PTSD, the aim of this study was to provide the first meta-analysis of Hydrocortisone as a potential treatment for this condition.

METHOD

A systematic review of randomized-controlled trials (RCTs) was conducted to investigate the efficacy of hydrocortisone in the prevention and curative treatment of post-traumatic stress symptoms. This study was pre-registered with the OSF (doi:10.17605/OSF.IO/GJAZF).

FINDINGS

Eight studies (9 effect sizes) covering 362 participants met our inclusion criteria. We found that Hydrocortisone as compared to placebo significantly reduced PTSD symptoms (d = 0.96, 95% Cl 0.22-1.69 p = 0.011) and PTSD incidence (logRR = 0.85, 95% CI 1.12-1.59, p = 0.023). Subgroup analyses revealed a significant effect of Hydrocortisone when it was administered in a preventative context (d = 1.50; 95%CI 0.30-2.69, p = 0.014), but not when it was administered in a curative context (d = 0.28; 95%CI -0.11 to 0.66, p = 0.161).

CONCLUSION

Hydrocortisone appears to be a promising and efficient low-cost medication for the prevention of PTSD. However, the small number of included studies and their limited methodological quality emphasize the need for further rigorous studies in this field.

The hypothalamus in anxiety disorders

Of all mental disorders, anxiety disorders are currently the strongest contributors to the global burden of disease, with 7.3% of the general population affected worldwide. The hypothalamus is crucial hub of a network of neural structures modulating fear conditioning and extinction and, as such, highly relevant to the pathophysiology of these conditions. Three hypothalamic systems have emerged as particularly relevant in this context. First, the oxytocin system is highly likely to be involved anxiety disorders and in particular in the cognitive and behavioral deficits pertaining to social anxiety disorder. Second, peripheral markers of the hypothalamic-pituitary-adrenal axis appear altered in patients with panic disorder and generalized anxiety disorder, which may denote aberrant functioning of their central corticotropin-releasing hormone system. Furthermore, cortisol seems to augment the effects of exposure therapy in patients with specific phobia. Third, the integrity of the hypothalamic-pituitary-thyroid axis is likely compromised in panic disorder. Further, cross-disciplinary research efforts are required to shed more light on how, exactly, these hypothalamic systems interact with the neural structures involved in fear conditioning and extinction, which should ultimately open up new avenues for the prevention and treatment of anxiety disorders.

Role of PPARs in Progression of Anxiety: Literature Analysis and Signaling Pathways Reconstruction

Peroxisome proliferator-activated receptor (PPAR) group includes three isoforms encoded by PPARG, PPARA, and PPARD genes. High concentrations of PPARs are found in parts of the brain linked to anxiety development, including hippocampus and amygdala. Among three PPAR isoforms, PPARG demonstrates the highest expression in CNS, where it can be found in neurons, astrocytes, and glial cells. Herein, the highest PPARG expression occurs in amygdala. However, little is known considering possible connections between PPARs and anxiety behavior. We reviewed possible connections between PPARs and anxiety. We used the Pathway Studio software (Elsevier). Signal pathways were created according to previously developed algorithms. SNEA was performed in Pathway Studio. Current study revealed 14 PPAR-regulated proteins linked to anxiety. Possible mechanism of PPAR involvement in neuroinflammation protection is proposed. Signal pathway reconstruction and reviewing aimed to reveal possible connection between PPARG and CCK-ergic system was conducted. Said analysis revealed that PPARG-dependent regulation of MME and ACE peptidase expression may affect levels of nonhydrolysed, i.e., active CCK-4. Impairments in PPARG regulation and following MME and ACE peptidase expression impairments in amygdala may be the possible mechanism leading to pathological anxiety development, with brain CCK-4 accumulation being a key link. Literature data analysis and signal pathway reconstruction and reviewing revealed two possible mechanisms of peroxisome proliferator-activated receptors involvement in pathological anxiety: (1) cytokine expression and neuroinflammation mechanism and (2) regulation of peptidases targeted to anxiety-associated neuropeptides, primarily CCK-4, mechanism.

Treatment Response Biomarkers in Anxiety Disorders: From Neuroimaging to Neuronally-Derived Extracellular Vesicles and Beyond

Multiple and diverse psychotherapeutic or psychopharmacologic treatments effectively reduce symptoms for many patients with anxiety disorders, but the trajectory and magnitude of response vary considerably. This heterogeneity of treatment response has invigorated the search for biomarkers of treatment response in anxiety disorders, across the lifespan. In this review, we summarize evidence for biomarkers of treatment response in children, adolescents and adults with generalized, separation and social anxiety disorders as well as panic disorder. We then discuss the relationship between these biomarkers of treatment response and the pathophysiology of anxiety disorders. Finally, we provide context for treatment response biomarkers of the future, including neuronally-derived extracellular vesicles in anxiety disorders and discuss challenges that must be overcome prior to the debut of treatment response biomarkers in the clinic. A number of promising treatment response biomarkers have been identified, although there is an urgent need to replicate findings and to identify which biomarkers might guide clinicians in selecting from available treatments rather than just simply identifying patients who may be less likely to respond to a given intervention.

Cortisol, DHEA and DHEA-S during exposure therapy in patients with obsessive-compulsive disorder - secretion patterns and prediction of treatment response

The cortisol response in patients with obsessive-compulsive disorder (OCD) during exposure with response prevention (ERP), a stressful but very effective psychotherapeutic treatment, has shown contradictory findings in three prior studies with low sample sizes. In a larger cohort of 51 patients with OCD we repeatedly measured subjective units of distress (SUD) and the adrenocortical stress hormones cortisol, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) in saliva during the very first session of ERP and on the day before. Expectedly, SUD were increased on the ERP day before the session and further rose during ERP, but salivary cortisol and DHEA were statistically indistinguishable from the comparison condition. Interestingly, DHEA-S was significantly elevated throughout the ERP versus the comparison day, but did not further increase in acute response to ERP. According to an explorative analysis in a subsample, hormone levels on the comparison or the ERP day did not predict anti-OCD treatment response one month later. These results corroborate our prior findings of cortisol non-response despite considerable subjective stress in ERP. The role of DHEA-S in anticipatory anxiety and the effects of augmentative cortisol therapy in ERP need further study.

Endogenous in-session cortisol during exposure therapy predicts symptom improvement: Preliminary results from a scopolamine-augmentation trial

The purpose of this study was to explore whether individual differences in glucocorticoid concentrations were associated with symptom improvement following exposure therapy for patients with social anxiety disorder. To do this, 60 participants with social anxiety disorder completed a randomized-controlled trial of exposure therapy, where participants were randomized to receive scopolamine-augmentation or placebo during their 7 exposure sessions. Scopolamine is an antimuscarinic which blocks the effects of acetylcholine and reduces autonomic arousal. During sessions 1, 4, 7, and during the post-treatment extinction assessment, participants provided up to 16 saliva samples (4 in each session). Pre-treatment, post-treatment, and at 1-month follow-up, participants completed the Liebowitz Social Anxiety Scale to monitor change in fear and avoidance symptoms. Elevated endogenous in-session cortisol during exposure sessions was associated with less symptom improvement from pre- to post-treatment and at 1-month follow-up. The association between elevated endogenous in-session cortisol and attenuated symptom change was not moderated by scopolamine treatment condition. Individuals with social anxiety disorder who have elevated neuroendocrine signaling may under-benefit from exposure therapy. This is the first study, to our knowledge, to examine whether endogenous in-session cortisol concentrations predict symptom changes following exposure therapy for the treatment of social anxiety disorder. More investigation of non-invasive and reliable biological markers that explain variability in responses to effective treatments are needed.

Stress-induced cortisol reactivity as a predictor of success in treatment for affective dimensions

BACKGROUND

Response rates to first-line treatments for depression and anxiety remain unsatisfactory. Identification of predictors or moderators that can optimize treatment matching is of scientific and clinical interest. This study examined the role of prolonged laboratory-induced stress cortisol reactivity as a predictor of outcome for a treatment of affective dimensions (TAD). Patients received 15-sessions of a treatment targeting reductions in negative affect or increases in positive affect (Craske et al., 2019). A second aim was to examine whether treatment type would moderate the association between cortisol reactivity and treatment outcome.

METHODS

Thirty-five participants underwent a 36-minute intermittent stress induction task composed of a mental arithmetic task and a fear-potentiated startle task one week before treatment initiation. Cortisol was collected at five-time points with reactivity being quantified as peak during the task minus basal level of cortisol the evening before the assessment. Using multilevel modeling, we examined the associations between cortisol reactivity and slopes of symptom improvement.

RESULTS

Cortisol reactivity was related to treatment outcome, with average and higher levels of stress-induced cortisol response predicting greater decreases in symptoms throughout treatment and 6-month follow-up. Treatment condition differences (moderation) were not observed in the effect of cortisol reactivity on symptoms.

CONCLUSION

Our findings demonstrate the impact of greater cortisol stress reactivity on treatment outcome. Future studies should investigate how to enhance this therapeutic benefit through capitalizing on endogenous diurnal fluctuations or exogenous cortisol manipulation.

Sleep duration and timing in obsessive-compulsive disorder (OCD): evidence for circadian phase delay

OBJECTIVES

To investigate potential delays in endogenous melatonin in individuals with obsessive-compulsive disorder (OCD).

METHODS

First, data are presented for 15 individuals with OCD and matched healthy controls. Next, nine additional participants with OCD who did not have matched controls were added, resulting in a sample of 24 individuals with OCD. All participants were assessed for sleep and circadian rhythm disturbance. Dim light melatonin onset (DLMO) was derived from salivary melatonin and was used in conjunction with sleep diaries, interview measures, and questionnaires. A subset of the OCD group (n = 16) also used actigraphy.

RESULTS

In sum, 42% percent (10/24) of the patients with OCD met the criteria for delayed sleep-wake phase disorder (DSWPD) in comparison to 0% in the control sample. DLMO was significantly later in individuals with OCD compared to controls. DLMO and bedtime were not significantly associated with the severity of obsessive-compulsive symptoms or negative affect.

CONCLUSIONS

Replication of the findings presented herein, particularly the DLMO results, is warranted. Further, there are now three studies showing that nearly ½ of individuals with OCD meet criteria for a DSWPD. Future studies can explore the mechanisms underlying these connections and the implications of this comorbidity. These findings may increase our understanding of OCD and inform future interventions.

Animal models of post-traumatic stress disorder and novel treatment targets

Understanding the neurobiological basis of post-traumatic stress disorder (PTSD) is fundamental to accurately diagnose this neuropathology and offer appropriate treatment options to patients. The lack of pharmacological effects, too often observed with the most currently used drugs, the selective serotonin reuptake inhibitors (SSRIs), makes even more urgent the discovery of new pharmacological approaches. Reliable animal models of PTSD are difficult to establish because of the present limited understanding of the PTSD heterogeneity and of the influence of various environmental factors that trigger the disorder in humans. We summarize knowledge on the most frequently investigated animal models of PTSD, focusing on both their behavioral and neurobiological features. Most of them can reproduce not only behavioral endophenotypes, including anxiety-like behaviors or fear-related avoidance, but also neurobiological alterations, such as glucocorticoid receptor hypersensitivity or amygdala hyperactivity. Among the various models analyzed, we focus on the social isolation mouse model, which reproduces some deficits observed in humans with PTSD, such as abnormal neurosteroid biosynthesis, changes in GABAA receptor subunit expression and lack of pharmacological response to benzodiazepines. Neurosteroid biosynthesis and its interaction with the endocannabinoid system are altered in PTSD and are promising neuronal targets to discover novel PTSD agents. In this regard, we discuss pharmacological interventions and we highlight exciting new developments in the fields of research for novel reliable PTSD biomarkers that may enable precise diagnosis of the disorder and more successful pharmacological treatments for PTSD patients.

Psychological Treatment for Depressive Disorder

Depression is highly prevalent and causes unnecessary human suffering and economic loss. Therefore, its treatment and prevention are of utmost importance. There are several advantages of using psychotherapy either by itself or combined with pharmacological treatment methods in the treatment of depression. First, it is well known that combining biological treatment with psychosocial methods increases the chances of recovery. Second, in some individuals, psychotherapy continues to be the only solution. Third, the use of antidepressants contains some safety risks and side effects, but psychotherapy does not. Fourth, clinically, depressive patients prefer psychotherapy to drug therapy. Use of a depression-focused psychotherapy alone is recommended as an initial treatment choice for patients with mild to moderate depression, with clinical evidence supporting the use of cognitive behavioral therapy (CBT), interpersonal psychotherapy (IPT), psychodynamic psychotherapy (PDP), and problem-solving therapy (PST) in individual and group formats. Important developments took place within the past 20 years in the psychotherapy of depression. In the present chapter, we introduced several key issues, such as, Are all psychotherapies equally effective? Who benefits from psychotherapies? Is telepsychotherapy effective? Finally, we introduce the psychotherapy for special populations.

Psychoneuroendocrinology and Clinical Psychology

Hormones impact on cognition, emotions, and behaviour. Given that mental disorders are defined by abnormalities in these very same domains, clinical psychologists may benefit from learning more about alterations in endocrine systems, how they can contribute to symptoms commonly experienced by patients, and how such knowledge may be put to use in clinical practice.

The aim of the present scientific update was to provide a brief overview of endocrine research relevant to the aetiology, diagnostics, and treatment of mental disorders, including some of the latest studies in this area.

Hormones appear to be intrinsic to the development and maintenance of mental disorders. Oxytocin is involved in social cognition and behaviour and as such may be relevant to mental disorders characterised by social deficits (e.g., autism spectrum disorder and schizophrenia). Stress and sex steroids exert demonstrable effects on mood and cognition. In patients with depression and anxiety disorders, initial attempts to lower/enhance such hormones have thus been undertaken within conventional therapies in order to improve outcomes. Finally, hunger and satiety hormones may be involved in the vicious circle of dysfunctional eating behaviours and weight loss/gain in anorexia or bulimia nervosa.

Three conclusions can be drawn from this review: First, endocrine research should be considered when patients and clinicians are developing multidimensional illness models together. Second, endocrine markers can complement conventional assessments to provide a more comprehensive account of a patient’s current state. Third, endocrine testing may guide treatment choices and inform the development of novel treatments.

Hormones are intrinsic to the development and maintenance of mental disorders

Endocrine research should be incorporated into multidimensional illness models

Endocrine markers can complement conventional diagnostic assessments

Endocrine testing may guide treatment choices and inform the development of new treatments

Biological and Clinical Markers in Panic Disorder

OBJECTIVE

Classifying mental disorders on the basis of objective makers might clarify their aetiology, help in making the diagnosis, identify "at risk" individuals, determine the severity of mental illness, and predict the course of the disorder. This study aims to review biological and clinical markers of panic disorder (PD).

METHODS

A computerized search was carried out in PubMed and Science Direct using the key words: "marker/biomarker/clinical marker/neurobiology/staging" combined using Boolean AND operator with "panic." In addition, the reference lists from existing reviews and from the articles retrieved were inspected. Only English language papers published in peer-reviewed journals were included.

RESULTS

Structural changes in the amygdala, hippocampus, cerebral blood level in the left occipital cortex, serotonin 5-TH and noradrenergic systems activation, aberrant respiratory regulation, hearth rate variability, blood cells and peripheral blood stem cells, hypothalamic-pituitary-adrenal axis dysregulation were identified as potential candidate biomarkers of PD. Staging was identified as clinical marker of PD. According to the staging model, PD is described as follows: prodromal phase (stage 1); acute phase (stage 2); panic attacks (stage 3); chronic phase (stage 4).

CONCLUSION

The clinical utility, sensitivity, specificity, and the predictive value of biomarkers for PD is still questionable. The staging model of PD might be a valid susceptibility, diagnostic, prognostic, and predictive marker of PD. A possible longitudinal model of biological and clinical markers of PD is proposed.

Psychotherapeutic treatment and HPA axis regulation in posttraumatic stress disorder: A systematic review and meta-analysis

Posttraumatic stress disorder (PTSD) has been associated with dysregulation of the hypothalamic-pituitary- adrenal (HPA) axis. Research over the past years has investigated potential changes of these alterations in the context of psychotherapy. Yet, no systematic review has been conducted. To summarize the current state of research on psychotherapy and HPA hormones, namely cortisol, dehydroepiandrosterone and its sulfate form (DHEA(S)), we searched for studies investigating predictions or changes in hormones over treatment course within the databases PubMed, Scopus, Medline, PsychINFO, Pilots/ProQuest, and Web of Science, and in the grey literature up to May 2018. Controlled and uncontrolled trials investigating adult samples with a clinical status of PTSD were eligible for inclusion. Twelve studies (428 participants) were included. Study quality was overall sufficient. Hormone assessment designs differed considerably. Treatment efficacy on PTSD symptom reduction was mostly high, but predictions of pre-treatment hormone concentrations on treatment efficacy were largely non-significant. Changes from pre- to post-test in basal cortisol (g = -0.07, 95% CI = -0.36; 0.21) and in the cortisol awakening response (g = -0.07, 95% CI = -0.48; 0.35) were also non-significant. Future studies require comparable designs and need to be sufficiently powered to be able to detect potential associations with HPA regulation.

Hair cortisol and childhood trauma predict psychological therapy response in depression and anxiety disorders

OBJECTIVE

Around 30-50% of patients with depression and anxiety disorders fail to respond to standard psychological therapy. Given that cortisol affects cognition, patients with altered hypothalamic-pituitary-adrenal (HPA) axis functioning may benefit less from such treatments. To investigate this, reliable pretreatment cortisol measures are needed.

METHOD

N = 89 outpatients with depression and anxiety disorders were recruited before undergoing therapy within an Improving Access to Psychological Therapies (IAPT) service. Three-month hair cortisol was determined, and the Childhood Trauma Questionnaire was administered. Patients were classified as responders if they showed significant decreases in depression (>= 6 points on the Patient Health Questionnaire) or anxiety (>= 5 points on the Generalised Anxiety Disorder Scale).

RESULTS

Non-responders in terms of depression (57%) had lower pretreatment hair cortisol concentrations (P = 0.041) and reported more physical abuse (P = 0.024), sexual abuse (P = 0.010) and total trauma (P = 0.039) when compared to responders. Non-responders in terms of anxiety (48%) had lower pretreatment hair cortisol (P = 0.027), as well as higher levels of emotional abuse (P = 0.034), physical abuse (P = 0.042) and total trauma (P = 0.048).

CONCLUSION

If future research confirms hair cortisol to be a predictor of psychological therapy response, this may prove a useful clinical biomarker which identifies a subgroup requiring more intensive treatment.

Hypothalamic-pituitary-adrenal axis functioning in borderline personality disorder: A meta-analysis

Borderline Personality Disorder (BPD) has been associated with altered hypothalamic-pituitary-adrenal (HPA) axis functioning. However, evidence is inconsistent. Therefore, the present series of meta-analyses aimed to quantify HPA axis functioning in BPD patients based on singular and continuous cortisol assessments and measures of reactivity to pharmacological and psychosocial stress. Case-control studies comparing adult BPD patients and healthy and clinical controls were considered for inclusion. The search resulted in 804 publications, of which 37 studies (k = 81; BPD n = 803, controls n = 1092) were included. Analyses were based on random effect models using standardized mean differences. BPD patients displayed elevated continuous cortisol output and blunted cortisol following psychosocial challenges. Singular cortisol assessments and cortisol after pharmacological challenges were not significantly different. Meta-analyses were limited by inconsistent reporting in individual studies and small samples for some comparisons. Due to the debilitating nature of stress-related symptoms in BPD, more research on elevated continuous cortisol output and blunted cortisol responses to psychosocial stress is warranted.

Polymorphisms in genes related to the hypothalamic-pituitary-adrenal axis and antidepressant response - Systematic review

OBJECTIVE

Around 50% of depressed patients do not respond to antidepressants. Evidence from familial studies suggests a genetic component to this. This study investigated whether patients with polymorphisms in genes related to the hypothalamic-pituitary-adrenal (HPA) axis were less likely to respond to antidepressants.

METHOD

EMBASE, MEDLINE, PsycINFO, and the Cochrane Library were searched. Inclusionary criteria were: 1) patients with depression, 2) study of HPA axis-related candidate genes, 3) at least four weeks of antidepressants, and 4) assessment of depressive symptoms dividing patients into non-responders and responders.

RESULTS

Nineteen studies were identified. Non-responders and responders did not differ in single nucleotide polymorphisms (SNPs) in genes encoding arginine vasopressin. Findings were equivocal regarding genes encoding the FK506 binding protein 5 and glucocorticoid and mineralocorticoid receptors. Specific SNPs and haplotypes within genes related to corticotropin-releasing hormone (CRHBP, CRHR1) and melanocortins (POMC) predicted non-responder status.

CONCLUSIONS

Replication studies and additional investigations exploring gene x environment and drug x environment interactions are necessary before pharmacological treatments may be adjusted based on a patient's genetic profile.

Vantage sensitivity: a framework for individual differences in response to psychological intervention

PURPOSE

People differ significantly in their response to psychological intervention, with some benefitting more from treatment than others. According to the recently proposed theoretical framework of vantage sensitivity, some of this variability may be due to individual differences in environmental sensitivity, the inherent ability to register, and process external stimuli. In this paper, we apply the vantage sensitivity framework to the field of psychiatry and clinical psychology, proposing that some people are more responsive to the positive effects of psychological intervention due to heightened sensitivity.

METHODS

After presenting theoretical frameworks related to environmental sensitivity, we review a selection of recent studies reporting individual differences in the positive response to psychological intervention.

RESULTS

A growing number of studies report that some people benefit more from psychological intervention than others as a function of genetic, physiological, and psychological characteristics. These studies support the vantage sensitivity proposition that treatment response is influenced by factors associated with heightened sensitivity to environmental influences. More recently, studies have also shown that sensitivity can be measured with a short questionnaire which appears to predict the response to psychological intervention.

CONCLUSIONS

Vantage sensitivity is a framework with significant relevance for our understanding of widely observed heterogeneity in treatment response. It suggests that variability in response to treatment is partly influenced by people's differing capacity for environmental sensitivity, which can be measured with a short questionnaire. Application of the vantage sensitivity framework to psychiatry and clinical psychology may improve our knowledge regarding when, how, and for whom interventions work.

Hypothalamic-pituitary-thyroid (HPT) axis functioning in anxiety disorders. A systematic review

Depression has repeatedly been linked to subclinical hypothyroidism, and thyroid hormones have successfully been used to augment antidepressant treatment. By contrast, the extent of thyroid dysfunction in anxiety disorders remains less clear. This is surprising, given that anxiety-related symptoms (e.g., nervousness, palpitations, increased perspiration) are highly prevalent in hyperthyroidism. The present study was undertaken to synthesize the literature on hypothalamic-pituitary-thyroid (HPT) axis functioning in anxiety disorders. The PubMed and PsycINFO databases were systematically searched. Three types of studies were included: (1) "comorbidity studies" assessing the prevalence of thyroid disorders in individuals with anxiety disorders, (2) "case-control studies" comparing HPT parameters between patients and controls, and (3) "correlational studies" assessing self-reported anxiety levels and HPT parameters. Risk of bias was assessed via a standardized quality rating. Twenty studies were eligible. Nearly all found the comorbidity between anxiety and thyroid disorders was significant. Half of the studies additionally supported the notion of subtle thyroid dysfunction in that thyroid-stimulating hormone (TSH) responses to the administration of thyrotropin-releasing hormone (TRH) were blunted and an inverse relationship was observed between self-reported anxiety levels and TSH. Overall, HPT assessments were well conducted, but several studies failed to adjust their analyses for smoking, body mass index (BMI), and depression. The findings resonate well with clinical recommendations to routinely screen for thyroid disorders in patients with anxiety disorders, and with what is known from basic research about thyroid-brain interactions. The results of the risk of bias assessment underscore the importance of further high-quality experimental and longitudinal epidemiological research.