Study protocol for a single-blind, parallel-group, randomised, controlled non-inferiority trial of 4-day intensive versus standard cognitive behavioural therapy for adults with obsessive-compulsive disorder.

INTRODUCTION: Individual cognitive behavioural therapy (CBT) with exposure and response prevention is an effective treatment for obsessive-compulsive disorder (OCD). However, individual CBT is costly and time-consuming, requiring weekly therapy sessions for 3-4 months. A 4-day intensive version of CBT for OCD delivered in group format has been recently developed in Norway (Bergen 4-day treatment, B4DT). B4DT has shown promising results in several uncontrolled and one small, randomised trial, but its non-inferiority to the gold standard treatment has not been established. METHODS AND ANALYSIS: This single-blind, randomised controlled trial including 120 patients (60 per arm) will compare B4DT to individual CBT. The primary outcome is the blind assessor-rated Yale-Brown Obsessive Compulsive Scale (Y-BOCS). We hypothesise that B4DT will be non-inferior to gold standard CBT 15 weeks after treatment start. The non-inferiority margin is set at four points on the Y-BOCS. Secondary outcomes include time to treatment response, cost-effectiveness, response and remission rates, drop-out rates and adverse events. ETHICS AND DISSEMINATION: This study has been approved by the Swedish Ethical Review Authority. Hypotheses were specified and analysis code published before data collection started. Results from all analyses will be reported in accordance with the Consolidated Standards of Reporting Trials statement for non-pharmacological trials and Consolidated Health Economic Evaluation Reporting Standards irrespective of outcome. TRIAL REGISTRATION NUMBER: NCT05608278.

Exhaustion disorder: scoping review of research on a recently introduced stress-related diagnosis.

BACKGROUND: Symptoms related to chronic stress are prevalent and entail high societal costs, yet there is a lack of international consensus regarding diagnostics and treatment. A new stress-related diagnosis, exhaustion disorder, was introduced into the Swedish version of ICD-10 in 2005. Since then, use of the diagnosis has increased rapidly. AIMS: To create the first comprehensive synthesis of research on exhaustion disorder to report on the current state of knowledge. Preregistration: Open Science Framework (http://www.w3.org/1999/xlink">osf.io), doi 10.17605/OSF.IO/VFDKW. METHOD: A PRISMA-guided scoping review of all empirical studies of exhaustion disorder was conducted. Searches were run in the MEDLINE, PsycInfo and Web of Science databases. Data were systematically charted and thematically categorised based on primary area of investigation. RESULTS: Eighty-nine included studies were sorted into six themes relating to lived experience of exhaustion disorder (n = 9), symptom presentation and course (n = 13), cognitive functioning (n = 10), biological measures (n = 24), symptom measurement scales (n = 4) and treatment (n = 29). Several studies indicated that individuals with exhaustion disorder experience a range of psychiatric and somatic symptoms beyond fatigue, but robust findings within most thematic categories were scarce. The limited number of studies, lack of replication of findings and methodological limitations (e.g. small samples and scarcity of specified primary outcomes) preclude firm conclusions about the diagnostic construct. CONCLUSIONS: More research is needed to build a solid knowledge base for exhaustion disorder. International collaboration regarding the conceptualisation of chronic stress and fatigue is warranted to accelerate the growth of evidence.

Augmented pain inhibition and higher integration of pain modulatory brain networks in women with self-injury behavior.

Individuals who engage in nonsuicidal self-injury (NSSI) have demonstrated insensitivity to pain compared with individuals without NSSI. Yet, the neural mechanisms behind this difference are unknown. The objective of the present study was to determine which aspects of the pain regulatory system that account for this decreased sensitivity to pain. In a case-control design, 81 women, aged 18-35 (mean [SD] age, 23.4 [3.9]), were included (41 with NSSI and 40 healthy controls). A quantitative sensory testing protocol, including heat pain thresholds, heat pain tolerance, pressure pain thresholds, conditioned pain modulation (assessing central down-regulation of pain), and temporal summation (assessing facilitation of pain signals) was used. Pain-evoked brain responses were assessed by means of fMRI scanning during thermal pain. NSSI participants showed a more effective central down-regulation of pain, compared to controls, assessed with conditioned pain modulation. The neural responses to painful stimulation revealed a stronger relation between nociceptive and pain modulatory brain regions in NSSI compared to controls. In line with previous studies, pressure and heat pain thresholds were higher in participants with NSSI, however, there were no correlations between pain outcomes and NSSI clinical characteristics. The augmented pain inhibition and higher involvement of pain modulatory brain networks in NSSI may represent a pain insensitive endophenotype associated with a greater risk for developing self-injurious behavior.

Odor-Taste Interactions in Food Perception: Exposure Protocol Shows No Effects of Associative Learning.

Repeated exposure can change the perceptual and hedonic features of flavor. Associative learning during which a flavor's odor component is affected by co-exposure with taste is thought to be central in this process. However, changes can also arise due to exposure to the odor in itself. The aim of this study was to dissociate effects of associative learning from effects of exposure without taste by repeatedly presenting one odor together with sucrose and a second odor alone. Sixty individuals attended two testing sessions separated by a 5-day Exposure Phase during which the stimuli were presented as flavorants in chewing gums that were chewed three times daily. Ratings of odor sweetness, odor pleasantness, odor intensity enhancement by taste, and odor referral to the mouth were collected at both sessions. Consistent with the notion that food preferences are modulated by exposure, odor pleasantness increased between the sessions independently of whether the odor (basil or orange flower) had been presented with or without sucrose. However, we found no evidence of associative learning in any of the tasks. In addition, exploratory equivalence tests suggested that these effects were either absent or insignificant in magnitude. Taken together, our results suggest that the hypothesized effects of associative learning are either smaller than previously thought or highly dependent on the experimental setting. Future studies are needed to evaluate the relative support for these explanations and, if experimental conditions can be identified that reliably produce such effects, to identify factors that regulate the formation of new odor-taste associations.

Multisensory flavor perception: The relationship between congruency, pleasantness, and odor referral to the mouth.

Our hedonic response to a food is determined by its flavor, an inherently multisensory experience that extends beyond the mere addition of its odor and taste. While congruency is known to be important for multisensory processes in general, little is known about its specific role in flavor processing. The aim of the present study was to delineate the effects of odor-taste congruency on two central aspects of flavor: odor referral (or mislocalization) to the mouth, and pleasantness. We further aimed to test whether an eventual effect on pleasantness was mediated by odor referral. Aqueous solutions containing odors and tastes were prepared to create food-like stimuli with varying degrees of congruency, ranging from maximally incongruent to maximally congruent in nine steps. Thirty participants reported where they perceived the odors, and how much they liked the solutions. Congruency had a positive linear effect both on odor referral to the oral cavity and on pleasantness. However, the effect of congruency on pleasantness was not mediated by odor referral. These results indicate that as an odor-taste mixture approximates a mental representation of a familiar food, its components are increasingly merged into one perceptual object sensed in the mouth. In parallel, the mixture is evaluated as increasingly pleasant, which promotes consumption of familiar foods that have been determined through experience to be non-toxic. While the modulatory role of congruency on pleasantness and odor referral was confirmed, our results also indicate that these effects arise through distinct perceptual mechanisms.