Prevention of psychosis: moving on from the at-risk mental state to universal primary prevention

Why we need to pursue both universal and targeted prevention to reduce the incidence of affective and psychotic disorders: Systematic review and meta-analysis

The effectiveness of universal preventive approaches in reducing the incidence of affective/psychotic disorders is unclear. We therefore aimed to synthesise the available evidence from randomised controlled trials. For studies reporting change in prevalence, we simulated all possible scenarios for the proportion of individuals with the disorder at baseline and at follow-up to exclude them. We then combined these data with studies directly measuring incidence and conducted random effects meta-analysis with relative risk (RR) to estimate the incidence in the intervention group compared to the control group. Eighteen studies (k=21 samples) were included investigating the universal prevention of depression in 66,625 individuals. No studies were available investigating universal prevention on the incidence of bipolar/psychotic disorders. 63 % of simulated scenarios showed a significant preventive effect on reducing the incidence of depression (k=9 - 19, RR=0.75-0.94, 95 %CIs=0.55-0.87,0.93-1.15, p=0.007-0.246) but did not survive sensitivity analyses. There is some limited evidence for the effectiveness of universal interventions for reducing the incidence of depression but not for bipolar/psychotic disorders.

Development and initial validation of the cannabis-related psychosis risk literacy scale (CPRL): a multinational psychometric study

BACKGROUND

Public education efforts to address and reduce potential harms from cannabis use in Arab countries are either slow or inexistent, and do not follow the steadily increasing trends of cannabis use in Arab youth. Several decades of research on substance use, it can be suggested that being aware of, and knowing about, psychosis risk related to cannabis can at least limit the consumption of the substance. Motivated by a lack of measures specifically designed to measure literacy about cannabis-related psychosis risk in younger populations, and based on an extensive literature review, we aimed to create and validate a new self-report scale to assess the construct, the Cannabis-related Psychosis Risk Literacy Scale (CPRL), in the Arabic language.

METHOD

A cross-sectional study was carried-out during the period from September 2022 to June 2023, enrolling 1855 university students (mean age of 23.26 ± 4.96, 75.6% females) from three Arab countries (Egypt, Kuwait and Tunisia).

RESULTS

Starting from an initial pool of 20 items, both Exploratory Factor Analysis and Confirmatory Factor Analysis suggested that the remaining 8 items loaded into a single factor. The scale demonstrated good internal consistency, with both McDonald omega and Cronbach's alpha values exceeding 0.7 (omega = 0.85 / alpha = 0.85). The CPRL showed measurement invariance across gender and country at the configural, metric, and scalar levels. Concurrent validity of the CPRL was established by correlations with less favourable attitudes towards cannabis (r = -.14; p <.001). In addition, higher literacy levels were found in students who never used cannabis compared to lifetime users (4.18 ± 1.55 vs. 3.44 ± 1.20, t(1853) = 8.152, p <.001).

CONCLUSION

The newly developed CPRL scale offers a valid and reliable instrument for assessing and better understanding literacy about cannabis-related psychosis risk among Arabic-speaking young adults. We believe that this new scale is suitable as a screening tool of literacy, as an instrument for measuring the effect of public education interventions aimed at promoting cannabis-related psychosis risk literacy among young people, and as a research tool to facilitate future studies on the topic with a wider application.

Duration of the psychosis prodrome and its relationship to duration of untreated psychosis across all 12 DSM-IV psychotic diagnoses: Evidence for a trans-diagnostic process associated with resilience

While duration of the psychosis prodrome (DPP) attracts attention in relation to the developmental trajectory of psychotic illness and service models, fundamental issues endure in the context of dimensional-spectrum models of psychosis. Among 205 epidemiologically representative subjects in the Cavan-Monaghan First Episode Psychosis Study, DPP was systematically quantified and compared, for the first time, across all 12 DSM-IV psychotic diagnoses. DPP was also compared with duration of untreated psychosis (DUP) and each was then analysed in relation to premorbid features across three age ranges: <12, 12-15 and 16-18 years. For each diagnosis, medians for both DPP and DUP were shorter than means, indicating common right-skewed distributions. Rank orders for both DPP and DUP were longest for schizophrenia, intermediate for other schizophrenia-spectrum psychoses, psychotic depression and psychotic disorder not otherwise specified, and shortest for brief psychotic disorder, bipolar disorder and substance-induced psychotic disorder, though with overlapping right-skewed distributions. DPP was longer than DUP for all diagnoses except substance-induced psychotic disorder. Across functional psychotic diagnoses, longer DPP was predicted by higher premorbid intelligence and better premorbid adjustment during age 16-18 years. These findings indicate that, trans-diagnostically, DPP and DUP share right-skewed continuities, in accordance with a dimensional-spectrum model of psychotic illness, and may reflect a unitary process that has been dichotomized at a subjective threshold along its trajectory. Better premorbid functioning during age 16-18 years appears to confer resilience by delaying progression to overt psychotic symptoms and may constitute a particular target period for psychosocial interventions.

Bridging the gap: improving correspondence between low-field and high-field magnetic resonance images in young people

Background

Portable low-field-strength magnetic resonance imaging (MRI) systems represent a promising alternative to traditional high-field-strength systems with the potential to make MR technology available at scale in low-resource settings. However, lower image quality and resolution may limit the research and clinical potential of these devices. We tested two super-resolution methods to enhance image quality in a low-field MR system and compared their correspondence with images acquired from a high-field system in a sample of young people.

Methods

T1- and T2-weighted structural MR images were obtained from a low-field (64mT) Hyperfine and high-field (3T) Siemens system in N = 70 individuals (mean age = 20.39 years, range 9-26 years). We tested two super-resolution approaches to improve image correspondence between images acquired at high- and low-field: (1) processing via a convolutional neural network ('SynthSR'), and (2) multi-orientation image averaging. We extracted brain region volumes, cortical thickness, and cortical surface area estimates. We used Pearson correlations to test the correspondence between these measures, and Steiger Z tests to compare the difference in correspondence between standard imaging and super-resolution approaches.

Results

Single pairs of T1- and T2-weighted images acquired at low field showed high correspondence to high-field-strength images for estimates of total intracranial volume, surface area cortical volume, subcortical volume, and total brain volume (r range = 0.60-0.88). Correspondence was lower for cerebral white matter volume (r = 0.32, p = 0.007, q = 0.009) and non-significant for mean cortical thickness (r = -0.05, p = 0.664, q = 0.664). Processing images with SynthSR yielded significant improvements in correspondence for total brain volume, white matter volume, total surface area, subcortical volume, cortical volume, and total intracranial volume (r range = 0.85-0.97), with the exception of global mean cortical thickness (r = 0.14). An alternative multi-orientation image averaging approach improved correspondence for cerebral white matter and total brain volume. Processing with SynthSR also significantly improved correspondence across widespread regions for estimates of cortical volume, surface area and subcortical volume, as well as within isolated prefrontal and temporal regions for estimates of cortical thickness.

Conclusion

Applying super-resolution approaches to low-field imaging improves regional brain volume and surface area accuracy in young people. Finer-scale brain measurements, such as cortical thickness, remain challenging with the limited resolution of low-field systems.

Risk-thresholds for the association between frequency of cannabis use and the development of psychosis: a systematic review and meta-analysis

BACKGROUND

Epidemiological studies show a dose-response association between cannabis use and the risk of psychosis. This review aimed to determine whether there are identifiable risk-thresholds between the frequency of cannabis use and psychosis development.

METHODS

Systematic search of Embase, MEDLINE, PsycINFO, CINAHL, and Web of Science for relevant studies (1 January 2010-26 April 2021). Case-control or cohort studies that investigated the relationship between cannabis use and the risk of psychosis development that reported effect estimates [odds ratios (OR), hazard ratios (HR), risk ratios (RR)] or the raw data to calculate them, with information on the frequency of cannabis consumption were included. Effect estimates were extracted from individual studies and converted to RR. Two-stage dose-response multivariable meta-analytic models were utilized and sensitivity analyses conducted. The Newcastle Ottawa Scale was used to assess the risk of bias of included studies.

RESULTS

Ten original (three cohorts, seven case-control) studies were included, including 7390 participants with an age range of 12-65 years. Random-effect model meta-analyses showed a significant log-linear dose-response association between cannabis use frequency and psychosis development. A restricted cubic-splines model provided the best fit for the data, with the risk of psychosis significantly increasing for weekly or more frequent cannabis use [RR = 1.01, 95% confidence interval (CI) 0.93-1.11 yearly; RR = 1.10, 95% CI 0.97-1.25 monthly; RR = 1.35, 95% CI 1.19-1.52 weekly; RR = 1.76, 95% CI 1.47-2.12 daily].

CONCLUSION

Individuals using cannabis frequently are at increased risk of psychosis, with no significant risk associated with less frequent use. Public health prevention messages should convey these risk-thresholds, which should be refined through further work.

Identifying individuals at risk of developing psychosis: A systematic review of the literature in primary care services

AIM

Psychosis and related disorders are a major public health issue. Early identification and prevention for those at high risk (at-risk-mental-state, ARMS) is important. General practitioners (GPs) are often the first point of contact for health services. In this review we aim to identify (1) the most common methods for identifying individuals with an ARMS in primary care, (2) the methods for improving identification of individuals with an ARMS in primary care, and (3) the most common barriers that prevent GPs from screening for individuals with an ARMS.

METHODS

We conducted a systematic review (PROSPERO 42021245095) of quantitative and qualitative studies with no date restriction. Searches were performed in September 2021. Studies' quality was appraised using Mixed Methods Appraisal tool (MMAT).

RESULTS

We identified 16 eligible studies, and all but one provided quantitative data. Nearly two-thirds of studies were classified as 'medium' quality. Employing narrative synthesis, we identified three themes relating to (1) improving GP knowledge and confidence in identifying individuals with an ARMS, (2) balancing the over- and under-identification of individuals with an ARMS in primary care, and (3) supporting GPs as significant stakeholders in early diagnosis and treatment of individuals with an ARMS.

CONCLUSIONS

Improved identification of individuals with an ARMS is needed. We identified various strategies, including development and implementation of identification methods (e.g., screening measures), educational interventions for GPs (e.g., workshops), and systemic interventions (e.g., simplifying referrals to secondary care, developing integrated services). When implemented successfully, these interventions may help facilitate the access to appropriate care for individuals with an ARMS.

Neighbourhood-level social capital, marginalisation, and the incidence of schizophrenia and schizoaffective disorder in Toronto, Canada: a retrospective population-based cohort study

BACKGROUND

Studies have shown mixed results regarding social capital and the risk of developing a psychotic disorder, and this has yet to be studied in North America. We sought to examine the relationship between neighbourhood-level marginalisation, social capital, and the incidence of schizophrenia and schizoaffective disorder in Toronto, Canada.

METHODS

We used a retrospective population-based cohort to identify incident cases of schizophrenia and schizoaffective disorder over a 10 year period and accounted for neighbourhood-level marginalisation and a proxy indicator of neighbourhood social capital. Mixed Poisson regression models were used to estimate adjusted incidence rate ratios (aIRRs).

RESULTS

In the cohort (n = 649 020) we identified 4841 incident cases of schizophrenia and schizoaffective disorder. A 27% variation in incidence was observed between neighbourhoods. All marginalisation dimensions, other than ethnic concentration, were associated with incidence. Compared to areas with low social capital, areas with intermediate social capital in the second [aIRR = 1.17, 95% confidence interval (CI) 1.03-1.33] and third (aIRR = 1.23, 95% CI 1.08-1.40) quintiles had elevated incidence rates after accounting for marginalisation. There was a higher risk associated with the intermediate levels of social capital (aIRR = 1.18, 95% CI 1.00-1.39) when analysed in only the females in the cohort, but the CI includes the possibility of a null effect.

CONCLUSIONS

The risk of developing schizophrenia and schizoaffective disorder in Toronto varies by neighbourhood and is associated with socioenvironmental exposures. Social capital was not linearly associated with risk, and risk differs by sex and social capital quintile. Future research should examine these relationships with different forms of social capital and examine how known individual-level risk factors impact these findings.

The relative and interactive impact of multiple risk factors in schizophrenia spectrum disorders: a combined register-based and clinical twin study

BACKGROUND

Research has yielded evidence for genetic and environmental factors influencing the risk of schizophrenia. Numerous environmental factors have been identified; however, the individual effects are small. The additive and interactive effects of multiple risk factors are not well elucidated. Twin pairs discordant for schizophrenia offer a unique opportunity to identify factors that differ between patients and unaffected co-twins, who are perfectly matched for age, sex and genetic background.

METHODS

Register data were combined with clinical data for 216 twins including monozygotic (MZ) and dizygotic (DZ) proband pairs (one or both twins having a schizophrenia spectrum diagnosis) and MZ/DZ healthy control (HC) pairs. Logistic regression models were applied to predict (1) illness vulnerability (being a proband v. HC pair) and (2) illness status (being the patient v. unaffected co-twin). Risk factors included: A polygenic risk score (PRS) for schizophrenia, birth complications, birth weight, Apgar scores, paternal age, maternal smoking, season of birth, parental socioeconomic status, urbanicity, childhood trauma, estimated premorbid intelligence and cannabis.

RESULTS

The PRS [odds ratio (OR) 1.6 (1.1-2.3)], childhood trauma [OR 4.5 (2.3-8.8)], and regular cannabis use [OR 8.3 (2.1-32.7)] independently predicted illness vulnerability as did an interaction between childhood trauma and cannabis use [OR 0.17 (0.03-0.9)]. Only regular cannabis use predicted having a schizophrenia spectrum diagnosis between patients and unaffected co-twins [OR 3.3 (1.1-10.4)].

CONCLUSION

The findings suggest that several risk factors contribute to increasing schizophrenia spectrum vulnerability. Moreover, cannabis, a potentially completely avoidable environmental risk factor, seems to play a substantial role in schizophrenia pathology.

The Inflammatory Signals Associated with Psychosis: Impact of Comorbid Drug Abuse

Psychosis and substance use disorders are two diagnostic categories whose association has been studied for decades. In addition, both psychosis spectrum disorders and drug abuse have recently been linked to multiple pro-inflammatory changes in the central nervous system. We have carried out a narrative review of the literature through a holistic approach. We used PubMed as our search engine. We included in the review all relevant studies looking at pro-inflammatory changes in psychotic disorders and substance use disorders. We found that there are multiple studies that relate various pro-inflammatory lipids and proteins with psychosis and substance use disorders, with an overlap between the two. The main findings involve inflammatory mediators such as cytokines, chemokines, endocannabinoids, eicosanoids, lysophospholipds and/or bacterial products. Many of these findings are present in different phases of psychosis and in substance use disorders such as cannabis, cocaine, methamphetamines, alcohol and nicotine. Psychosis and substance use disorders may have a common origin in an abnormal neurodevelopment caused, among other factors, by a neuroinflammatory process. A possible convergent pathway is that which interrelates the transcriptional factors NFκB and PPARγ. This may have future clinical implications.

Public health primary prevention implemented by clinical high-risk services for psychosis

Clinical High Risk for Psychosis (CHR-P) services have been primarily developed to support young people with attenuated symptoms (indicated prevention). No evidence-based appraisal has systematically investigated to what extent these clinics may implement other preventive approaches. PRISMA 2020-compliant systematic review of Web of Science, Cochrane Central Register of Reviews, and Ovid/PsychINFO, from inception until 14th June 2021, identifying original studies describing public health strategies: (a) service characteristics (configuration of mental health service, outreach, pathways to care); (b) universal interventions (general population); (c) selective interventions targeting CHR-P service-users or family/carers. Public health preventive initiatives were systematically stratified according to core social determinants of mental disorders associated with the 2030 Sustainable Development Goals promoted by the United Nations Member States (UN 2030 SDG) and good mental health outcomes. A total of 66 publications were included, providing data on 13 standalone, 40 integrated, three networks, and six regional or international surveys of CHR-P services across Europe, Asia, Oceania, Africa, North and South America, providing care to >28 M people. CHR-P services implement numerous public health initiatives targeting social and cultural (16 initiatives), economic (seven initiatives), demographic (six initiatives), environmental events (four initiatives) and neighbourhood (three initiatives) UN 2030 SGD determinants of mental disorders. There is additional evidence for CHR-P services promoting good mental health. The main barriers were the lack of resources for expanding public health prevention at a large scale. CHR-P services implement numerous public health prevention initiatives and promotion of good mental health beyond indicated prevention of psychosis.

Childhood trauma, social cognition and schizophrenia: Specific association between physical neglect and cognitive theory of mind in homicide offenders

Schizophrenia is associated with a small, but increased risk of violent behavior, including homicide. Violent individuals with schizophrenia have elevated rates of childhood trauma and substantial social cognitive impairments. The aim of this study was to examine if childhood trauma is related to social cognition in homicide offenders with schizophrenia. We recruited 26 individuals with schizophrenia sentenced to compulsory mental care for homicide/attempted homicide and 28 non-violent schizophrenia controls. They filled out the Childhood Trauma Questionnaire (CTQ), providing scores for physical abuse, sexual abuse, emotional abuse, physical neglect and emotional neglect. Social cognition was assessed with two measures of emotion processing (Emotion in Biological Motion, Pictures of Facial Affect) and two theory of mind (ToM) tests (Hinting Task, Movie for the Assessment of Social Cognition: MASC). Spearman's rho correlation coefficients were computed, and significant results followed up with partial correlation analyses controlling for IQ. Three associations were statistically significant, all in the homicide group; between CTQ physical neglect and cognitive ToM assessed with Hinting Task and with MASC, and between CTQ emotional neglect and Hinting Task. Only the first remained significant after controlling for IQ, indicating a specific association between physical neglect and cognitive ToM in homicide offenders with schizophrenia.

Predicting onset of early- and late-treatment resistance in first-episode schizophrenia patients using advanced shrinkage statistical methods in a small sample

Evidence suggests there are two treatment-resistant schizophrenia subtypes (i.e. early treatment resistant (E-TR) and late-treatment resistant (L-TR)). We aimed to develop prediction models for estimating individual risk for these outcomes by employing advanced statistical shrinkage methods. 239 first-episode schizophrenia (FES) patients were followed-up for approximately 5 years after first presentation to psychiatric services; of these, n=56 (25.2%) were defined as E-TR and n=24 (12.6%) were defined as L-TR. Using known risk factors for poor schizophrenia outcomes, we developed prediction models for E-TR and L-TR using LASSO and RIDGE logistic regression models. Models' internal validation was performed employing Harrell's optimism-correction with repeated cross-validation; their predictive accuracy was assessed through discrimination and calibration. Both LASSO and RIDGE models had high discrimination, good calibration. While LASSO had moderate sensitivity for estimating an individual risk for E-TR and L-TR, sensitivity estimated for RIDGE model for these outcomes was extremely low, which was due to having a very large estimated optimism. Although it was possible to discriminate with sufficient accuracy who would meet criteria for E-TR and L-TR during the 5-year follow-up after first contact with mental health services for schizophrenia, further work is necessary to improve sensitivity for these models.