The role of stress in the pathogenesis and maintenance of obsessive-compulsive disorder

Stress Influences the Effect of Obsessive-Compulsive Symptoms on Emotion Regulation

Obsessive-compulsive disorder (OCD) is associated with emotion regulation impairments, namely the frequent use of maladaptive strategies such as suppression and the decreased use of reappraisal strategies. Additionally, these patients exhibit elevated stress levels. Since stress exposure affects emotion regulation abilities, stress might influence the relationship between obsessive-compulsive symptoms and emotion regulation. In this study, we explored the effects of stress and obsessive-compulsive symptoms on emotion regulation in a sample of healthy and OCD individuals. We used self-reported psychometric scales to measure stress levels, obsessive-compulsive symptoms, and emotion reappraisal and suppression skills. We applied multiple regression and mediation analyses. Our results demonstrated that increased reappraisal scores were associated with higher suppression scores. Additionally, elevated stress values predicted increased scores for suppression and decreased scores for reappraisal. Furthermore, the reappraisal abilities resulted from a combination of a direct effect of obsessive-compulsive symptoms and an indirect effect of obsessive-compulsive symptoms mediated by stress. The reliance on suppression strategies and the difficulty in using reappraisal approaches are explained by stress levels and are not directly explained by obsessive-compulsive symptoms. This study highlights the necessity of targeting stress in current therapy-based treatments for OCD.

Eating Disorders: An Evolutionary Psychoneuroimmunological Approach

Eating disorders are evolutionarily novel conditions. They lead to some of the highest mortality rates of all psychiatric disorders. Several evolutionary hypotheses have been proposed for eating disorders, but only the intrasexual competition hypothesis is extensively supported by evidence. We present the mismatch hypothesis as a necessary extension to the current theoretical framework of eating disorders. This hypothesis explains the evolutionarily novel adaptive metaproblem that has arisen when mating motives conflict with the large-scale and easy availability of hyper-rewarding but obesogenic foods. This situation is exacerbated particularly in those contemporary environments that are characterized by sedentary lifestyles, ever-present junk foods, caloric surplus and the ubiquity of social comparisons that take place via social media. Our psychoneuroimmunological model connects ultimate-level causation with proximate mechanisms by showing how the adaptive metaproblem between mating motives and food rewards leads to chronic stress and, further, to disordered eating. Chronic stress causes neuroinflammation, which increases susceptibility to OCD-like behaviors that typically co-occur with eating disorders. Chronic stress upregulates the serotonergic system and causes dysphoric mood in anorexia nervosa patients. Dieting, however, reduces serotonin levels and dysphoric mood, leading to a vicious serotonergic-homeostatic stress/starvation cycle whereby cortisol and neuroinflammation increase through stringent dieting. Our psychoneuroimmunological model indicates that between-individual and within-individual variation in eating disorders partially arises from (co)variation in gut microbiota and stress responsivity, which influence neuroinflammation and the serotonergic system. We review the advances that have been made in recent years in understanding how to best treat eating disorders, outlining directions for future clinical research. Current evidence indicates that eating disorder treatments should aim to reduce the chronic stress, neuroinflammation, stress responsivity and gut dysbiosis that fuel the disorders. Connecting ultimate causes with proximate mechanisms and treating biopsychosocial causes rather than manifest symptoms is expected to bring more effective and sophisticated long-term interventions for the millions of people who suffer from eating disorders.

Cognitive mediators of the relationship between adverse childhood experiences and adult psychopathology: A systematic review

This is the first review to rigorously examine the mediating role of cognitive factors in the relationship between childhood trauma and subsequent adult psychopathology, and highlight areas for future research. A database search (Child Development & Adolescent Studies, ERIC, Global Health, PsycARTICLES, and PsycINFO) was conducted to identify empirical studies on cognitive factors, explaining the relationship between different types of adverse childhood experiences and adult psychopathology across clinical and nonclinical populations. A narrative synthesis and appraisal of the methodological quality of the studies was conducted. Ninety-eight mediation studies were identified, comprising 4,137 clinical and 28,228 nonclinical participants. Despite great variation in methodological quality of the studies, our narrative synthesis suggests that cognitive factors mediate the relationship between early trauma and later psychopathology. This finding is consistent across different measures of traumatic experiences, psychopathology, and cognitive mediators. Cognitive mediators represent potentially valuable intervention targets for (non)clinical patients who have experienced childhood adversity. Future studies are needed to (a) establish longitudinal causal connections, and (b) assess the effect of interventions that specifically target cognitive change in patients with different levels and types of pathology.

Animal models of OCD-relevant processes: an RDoC perspective

Animal models have been invaluable tools in deciphering pathophysiology in many branches of medicine. Their application in the study of complex neuropsychiatric conditions such as obsessive-compulsive disorder (OCD), however, raises vexing interpretative challenges. The Research Domain Criteria (RDoC) approach of identifying dimensions of function and dysfunction that cut across syndromic diagnoses provides one potential path forward. We review some of the domains in the current RDoC matrix that may inform our understanding of patients with obsessions and compulsions, and how work in animal model systems is helping us to understand them. We focus on three specific RDoC constructs that may be particularly informative for our understanding of OCD: potential threat, habit, and cognitive control. In each case we review selected recent studies in animal models and their potential contribution to our understanding of OCD, and suggest directions for future research, informed by the animal studies. Such mechanistic work in animal models, in parallel with clinical studies refining our understanding of the relationship between these dimensional constructs and the symptomatology of particular groups of patients, may over time help us to generate a more comprehensive understanding of the pathogenesis and complexity of obsessions and compulsions.

The Neurobiology and Pharmacotherapy of Posttraumatic Stress Disorder

New approaches to the neurobiology of posttraumatic stress disorder (PTSD) are needed to address the reported crisis in PTSD drug development. These new approaches may require the field to move beyond a narrow fear-based perspective, as fear-based medications have not yet demonstrated compelling efficacy. Antidepressants, particularly recent rapid-acting antidepressants, exert complex effects on brain function and structure that build on novel aspects of the biology of PTSD, including a role for stress-related synaptic dysconnectivity in the neurobiology and treatment of PTSD. Here, we integrate this perspective within a broader framework-in other words, a dual pathology model of ( a) stress-related synaptic loss arising from amino acid-based pathology and ( b) stress-related synaptic gain related to monoamine-based pathology. Then, we summarize the standard and experimental (e.g., ketamine) pharmacotherapeutic options for PTSD and discuss their putative mechanism of action and clinical efficacy.

The neurobiology of depression, ketamine and rapid-acting antidepressants: Is it glutamate inhibition or activation?

The discovery of the antidepressant effects of ketamine has opened a breakthrough opportunity to develop a truly novel class of safe, effective, and rapid-acting antidepressants (RAADs). In addition, the rapid and robust biological and behavioral effects of ketamine offered a unique opportunity to utilize the drug as a tool to thoroughly investigate the neurobiology of stress and depression in animals, and to develop sensitive and reproducible biomarkers in humans. The ketamine literature over the past two decades has considerably enriched our understanding of the mechanisms underlying chronic stress, depression, and RAADs. However, considering the complexity of the pharmacokinetics and in vivo pharmacodynamics of ketamine, several questions remain unanswered and, at times, even answered questions continue to be considered controversial or at least not fully understood. The current perspective paper summarizes our understanding of the neurobiology of depression, and the mechanisms of action of ketamine and other RAADs. The review focuses on the role of glutamate neurotransmission - reviewing the history of the "glutamate inhibition" and "glutamate activation" hypotheses, proposing a synaptic connectivity model of chronic stress pathology, and describing the mechanism of action of ketamine. It will also summarize the clinical efficacy findings of putative RAADs, present relevant human biomarker findings, and discuss current challenges and future directions.