Obsessive–compulsive disorder (OCD) is a debilitating mental disorder commonly treated with selective serotonin reuptake inhibitors, atypical antipsychotic augmentation and cognitive–behavioural therapy. However, up to 60% of people with OCD do not respond to these treatments. Therefore, a novel intervention, psilocybin-assisted psychotherapy (PAP), is an option of interest. Moreover, there is a need to better understand the mechanisms underpinning PAP’s effect on OCD symptoms.

We aimed to (a) establish the feasibility, tolerability and safety of administering PAP to adults with treatment-resistant OCD; (b) provide preliminary data on the clinical effects of PAP for treatment-resistant OCD, to inform the design of larger clinical trials; and (c) compare neuroimaging and neurophysiological markers pre- and post-PAP in treatment-resistant OCD.

In this 12-week open-label trial, ten adults with treatment-resistant OCD will receive one 25 mg dose of psilocybin combined with psychological support. Feasibility, tolerability and safety will be assessed throughout. Clinical outcomes will be measured with the Yale–Brown Obsessive–Compulsive Scale. Exploratory measures will include brain imaging examining changes in dynamic connectivity from pre to post treatment, electroencephalogram to investigate changes in brain dynamics associated with psilocybin under acute conditions, and transcranial magnetic stimulation-electroencephalogram measures between baseline, provocation of OCD symptoms and up to 1-week post-dose.

The study will provide important preliminary data on the feasibility and efficacy of PAP in adults with treatment-resistant OCD, as well as inform our understanding of neurobiological mechanisms.

The findings of the study will inform the design of larger randomised controlled trials and advance the field of psychedelic-assisted therapies.

Substantial experimental research has explored mental contamination – feelings of internal pollution proposed to result from misinterpreting perceived violations. The Mental Contamination Report (MCR) was developed to measure in-the-moment experiences of mental contamination, and has been used in seminal experiments in this domain. However, the MCR has yet to be psychometrically evaluated. The aim of the current study was to evaluate the psychometric properties of the MCR, and if warranted, propose a revised version with improved research utility.

Data for this study were collected as part of a larger experiment examining the impact of moral self-violation on mental contamination. A sample of 150 undergraduate students completed the MCR, Vancouver Obsessional-Compulsive Inventory-Mental Contamination Subscale, and the Vancouver Obsessional-Compulsive Inventory.

The original Emotions Subscale of the MCR demonstrated excellent internal consistency (${\rm{\alpha }}$=0.92) but contained emotions non-specific to mental contamination. We conducted an exploratory factor analysis (EFA) of the emotion items to identify which items load more heavily onto a mental contamination-specific factor. The EFA revealed a two-factor solution, with five items items loading strongly on the mental contamination-specific factor. For the 5-item mental contamination-specific Emotions Subscale, we found excellent internal consistency (${\rm{\alpha }}$=0.90), strong known groups validity, F2,147=63.17, p<.001, ηp2=.46, good convergent validity and mixed results for divergent validity. For the Behavioural Urges Subscale, we found overall mixed psychometric properties.

Based on the results of the psychometric analysis, a revised version of the MCR is proposed.

Perinatal obsessive-compulsive disorder (PNOCD) can impact up to one in five individuals in the perinatal period. Whilst effective treatment for PNOCD is available, parents experience barriers accessing this evidence-based psychological therapy. Healthcare professionals’ perspectives on barriers to accessing support are valuable to develop targeted interventions to increase access to support for PNOCD.

This study aimed to prioritise a list of barriers to accessing therapy for PNOCD, in terms of importance and amenability to change, from the perspective of healthcare professionals.

203 healthcare professionals from across primary, community and secondary care services completed a survey where they ranked barriers in terms of importance and amenability to change. Barriers were ranked within clusters and across cluster names; 47 barriers were organised into seven clusters. Rankings were analysed using descriptive statistics and the non-parametric Friedman’s test.

Professionals ranked healthcare professionals’ knowledge and training on PNOCD as the barrier which was most important and amenable to change. Parents’ knowledge and awareness of PNOCD and services, their attitudes to mental health problems, and their attitudes towards healthcare professionals and services were ranked as the second most important and amenable to change.

Professionals view their colleagues’ knowledge and training on PNOCD as the most important barrier impacting parents access to evidence-based therapy for PNOCD. Training for professionals could be targeted to increase access. Parents’ awareness and attitudes surrounding PNOCD, mental health and services were also identified by professionals as an important barrier and is recommended to be targeted to increase access.

Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder characterized by recurrent intrusive thoughts and ritualized behaviors, often aimed at reducing distress. OCD is heterogeneous in its presentation and many patients with OCD experience a variety of different symptoms throughout their course of illness. Efforts to understand symptom domains in OCD have typically identified three to five symptom domains, such as the domains of doubt/checking, contamination, superstitions/rituals, symmetry/hoarding, and taboo thoughts. Recent studies in the genetics of OCD have suggested a common OCD dimension may provide additional information above and beyond the previously identified symptom domains. Thus, we sought to test a hierarchical model of lifetime OCD symptoms and evaluate the utility of the inclusion of a common OCD dimension.

Participants included 999 individuals participating in the OCD Collaborative Genetics Study (OCGS) and an additional 2363 individuals participating in the OCD Genetic Association Study (OCGAS). We evaluated unidimensional, 5-factor, and hierarchical models of lifetime OCD symptom presentation using confirmatory factor analysis.

Results suggested that the hierarchical model best fit the data. Further evaluation of these models using a Bayesian testlet response model showed that lifetime presence of specific OCD symptoms was differentially associated with lifetime OCD severity. Moreover, symptoms associated with greater lifetime severity were generally reported less frequently than symptoms present at lower levels of lifetime severity. Implications of these findings and future directions are discussed.

Obsessive-compulsive symptoms (OCS) emerge in a significant proportion of clozapine-treated schizophrenia patients, affecting social functioning and increasing depressive symptoms. This study investigates the underexplored cognitive mechanisms of clozapine-induced OCS, particularly focusing on dysfunctional checking behavior.

Clinical and cognitive profiles of OCS and their relationship to dysfunctional checking were investigated using a novel checking paradigm (image verification task or IVT) in four groups: clozapine-treated schizophrenia patients with clozapine-induced OCS (SCZ-OCS, n = 21) and without (SCZ-only, n = 15), patients with obsessive-compulsive disorder (OCD, n = 32) and IQ-matched healthy volunteers (HV, n = 30).

Only SCZ-OCS patients showed a distinctive pattern of dysfunctional checking on the IVT. Compared with SCZ-OCS, SCZ-only patients exhibited functional checking while having equivalent deficits in executive cognition, clozapine dose, and treatment duration, though with less severe positive and depressive symptoms. In SCZ-OCS, dysfunctional checking was positively correlated with clozapine dose and working memory performance. By contrast, OCD patients’ checking was positively related to intolerance of uncertainty. Checking in the OCD and SCZ-OCS groups was positively correlated with YBOCS-compulsion.

This study is the first to compare the distinct cognitive and clinical profiles of SCZ-OCS, SCZ-only, and OCD, with a focus on checking behavior, a major symptom in clozapine-treated patients. We introduced a novel and sensitive measure for checking, which showed dysfunctional checking only in SCZ-OCS patients treated with clozapine. These findings indicate that a subset of patients with schizophrenia with more severe positive symptoms and cognitive deficits are especially susceptible to OCD symptoms when treated with clozapine.

Hoarding disorder studies are primarily based on persons who seek treatment and demonstrate good insight. The aim of the present study is to evaluate whether there are differences between community and treatment-seeking samples of individuals with hoarding disorder (HD).

Fourteen people with HD from the community and twenty treatment-seeking people with HD were assessed by a battery of instruments to evaluate HD features and other associated characteristics.

Compared to the treatment-seeking sample, the HD community sample was older, had poorer insight, and had a lower prevalence of comorbid obsessive-compulsive disorder (OCD). There were no differences in gender, education, presence of psychiatric comorbidities, quality of life, and hoarding behavior characteristics between the samples. The final logistic regression model with the Dimensional Obsessive-Compulsive Scale (DOCS) as the single predictor of treatment-seeking status was statistically significant, indicating that it was able to distinguish between the two samples. The model explained between 20.7% and 27.9% of the variance of subjects, and correctly classified 67.6% of cases.

Our results indicate that there appear to be few differences between the treatment-seeking and community samples of individuals with HD. The presence of comorbid OCD in treatment-seeking groups seems to be more frequent than in HD community samples.

Cognitive models of mental contamination (i.e. feelings of internal dirtiness without contact with a contaminant) propose that these feelings arise when individuals misappraise a violation. However, an operational definition of ‘violation’ and identification of specific violation misappraisals is limited.

This study’s aim was to elaborate on cognitive models using qualitative data from those with lived experience to fill these gaps.

Twenty participants with a diagnosis of obsessive-compulsive disorder and/or a trauma history took part in a semi-structured interview about violation. Grounded theory was used to analyse interview transcripts.

Three categories emerged, each with several themes – qualities of violation, violation-related appraisals, and violation-related behaviours. Different violation-related appraisals were associated with different emotions and urges. Specific self-focused appraisal sub-themes (i.e. permanence of consequences; self-worth; responsibility, self-blame and regret) were most closely related to emotions tied to mental contamination. These findings support and expand upon existing cognitive models of mental contamination, identifying key violation-related appraisals and differentiating between mental contamination-related appraisals and those related to other emotional sequelae. Future quantitative and experimental research can evaluate the potential of these appraisals as intervention targets.

1. (1) Delivering CBT to adolescents with OCD as a blended treatment combining individual and group-based treatment with flexible parental involvement is a promising option which merits further evaluation.

2. (2) OCD symptoms and general psychiatric symptoms were reduced during and after treatment.

3. (3) Use of a blended treatment based on a CBT model is feasible.

Problems with cognitive flexibility have been associated with multiple psychiatric disorders, but there has been little understanding of how cognitive flexibility compares across these disorders. This study examined problems of cognitive flexibility in young adults across a range of psychiatric disorders using a validated computerized trans-diagnostic flexibility paradigm. We hypothesized that obsessive-compulsive spectrum disorders (eg, obsessive-compulsive disorder, trichotillomania, and skin-picking disorder) would be associated with pronounced flexibility problems as they are most often associated with irrational or purposeless repetitive behaviors.

A total of 576 nontreatment seeking participants (aged 18-29 years) were enrolled from general community settings, provided demographic information, and underwent structured clinical assessments. Each participant undertook the intra-extra-dimensional task, a validated computerized test measuring set-shifting ability. The specific measures of interest were total errors on the task and performance on the extra-dimensional (ED) shift, which reflects the ability to inhibit and shift attention away from one stimulus dimension to another.

Participants with depression and PTSD had elevated total errors on the task with moderate effect sizes; and those with the following had deficits of small effect size: generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), antisocial personality disorder, and binge-eating disorder. For ED errors, participants with PTSD, GAD, and binge-eating disorder exhibited deficits with medium effect sizes; those with the following had small effect size deficits: depression, social anxiety disorder, OCD, substance dependence, antisocial personality disorder, and gambling disorder.

These data indicate cognitive flexibility deficits occur across a range of mental disorders. Future work should explore whether these deficits can be ameliorated with novel treatment interventions.

1. (1) To explore the literature considering explanations of the co-occurrence of OCD and PTSD symptomology.

2. (2) To consider how symptoms of two mental health conditions can maintain one another and attenuate the effectiveness of evidence-based treatment for the other mental health condition.

3. (3) Consider the use of concurrent therapeutic approaches to treat co-occurring mental health conditions.