Incidence of first-episode psychosis (FEP) varies substantially across geographic regions. Phenotypes of subclinical psychosis (SP), such as psychotic-like experiences (PLEs) and schizotypy, present several similarities with psychosis. We aimed to examine whether SP measures varied across different sites and whether this variation was comparable with FEP incidence within the same areas. We further examined contribution of environmental and genetic factors to SP.

We used data from 1497 controls recruited in 16 different sites across 6 countries. Factor scores for several psychopathological dimensions of schizotypy and PLEs were obtained using multidimensional item response theory models. Variation of these scores was assessed using multi-level regression analysis to estimate individual and between-sites variance adjusting for age, sex, education, migrant, employment and relational status, childhood adversity, and cannabis use. In the final model we added local FEP incidence as a second-level variable. Association with genetic liability was examined separately.

Schizotypy showed a large between-sites variation with up to 15% of variance attributable to site-level characteristics. Adding local FEP incidence to the model considerably reduced the between-sites unexplained schizotypy variance. PLEs did not show as much variation. Overall, SP was associated with younger age, migrant, unmarried, unemployed and less educated individuals, cannabis use, and childhood adversity. Both phenotypes were associated with genetic liability to schizophrenia.

Schizotypy showed substantial between-sites variation, being more represented in areas where FEP incidence is higher. This supports the hypothesis that shared contextual factors shape the between-sites variation of psychosis across the spectrum.

Childhood adversity and cannabis use are considered independent risk factors for psychosis, but whether different patterns of cannabis use may be acting as mediator between adversity and psychotic disorders has not yet been explored. The aim of this study is to examine whether cannabis use mediates the relationship between childhood adversity and psychosis.

Data were utilised on 881 first-episode psychosis patients and 1231 controls from the European network of national schizophrenia networks studying Gene–Environment Interactions (EU-GEI) study. Detailed history of cannabis use was collected with the Cannabis Experience Questionnaire. The Childhood Experience of Care and Abuse Questionnaire was used to assess exposure to household discord, sexual, physical or emotional abuse and bullying in two periods: early (0–11 years), and late (12–17 years). A path decomposition method was used to analyse whether the association between childhood adversity and psychosis was mediated by (1) lifetime cannabis use, (2) cannabis potency and (3) frequency of use.

The association between household discord and psychosis was partially mediated by lifetime use of cannabis (indirect effect coef. 0.078, s.e. 0.022, 17%), its potency (indirect effect coef. 0.059, s.e. 0.018, 14%) and by frequency (indirect effect coef. 0.117, s.e. 0.038, 29%). Similar findings were obtained when analyses were restricted to early exposure to household discord.

Harmful patterns of cannabis use mediated the association between specific childhood adversities, like household discord, with later psychosis. Children exposed to particularly challenging environments in their household could benefit from psychosocial interventions aimed at preventing cannabis misuse.

While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis.

We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case–control study. 558 first-episode psychosis patients (FEPp) and 567 population controls who had used cannabis and reported their RFUC.

We ran logistic regressions to examine whether RFUC were associated with first-episode psychosis (FEP) case–control status. Path analysis then examined the relationship between RFUC, subsequent patterns of cannabis use, and case–control status.

Controls (86.1%) and FEPp (75.63%) were most likely to report ‘because of friends’ as their most common RFUC. However, 20.1% of FEPp compared to 5.8% of controls reported: ‘to feel better’ as their RFUC (χ2 = 50.97; p < 0.001). RFUC ‘to feel better’ was associated with being a FEPp (OR 1.74; 95% CI 1.03–2.95) while RFUC ‘with friends’ was associated with being a control (OR 0.56; 95% CI 0.37–0.83). The path model indicated an association between RFUC ‘to feel better’ with heavy cannabis use and with FEPp-control status.

Both FEPp and controls usually started using cannabis with their friends, but more patients than controls had begun to use ‘to feel better’. People who reported their reason for first using cannabis to ‘feel better’ were more likely to progress to heavy use and develop a psychotic disorder than those reporting ‘because of friends’.

Child maltreatment (CM) and migrant status are independently associated with psychosis. We examined prevalence of CM by migrant status and tested whether migrant status moderated the association between CM and first-episode psychosis (FEP). We further explored whether differences in CM exposure contributed to variations in the incidence rates of FEP by migrant status.

We included FEP patients aged 18–64 years in 14 European sites and recruited controls representative of the local populations. Migrant status was operationalized according to generation (first/further) and region of origin (Western/non-Western countries). The reference population was composed by individuals of host country's ethnicity. CM was assessed with Childhood Trauma Questionnaire. Prevalence ratios of CM were estimated using Poisson regression. We examined the moderation effect of migrant status on the odds of FEP by CM fitting adjusted logistic regressions with interaction terms. Finally, we calculated the population attributable fractions (PAFs) for CM by migrant status.

We examined 849 FEP cases and 1142 controls. CM prevalence was higher among migrants, their descendants and migrants of non-Western heritage. Migrant status, classified by generation (likelihood test ratio:χ2 = 11.3, p = 0.004) or by region of origin (likelihood test ratio:χ2 = 11.4, p = 0.003), attenuated the association between CM and FEP. PAFs for CM were higher among all migrant groups compared with the reference populations.

The higher exposure to CM, despite a smaller effect on the odds of FEP, accounted for a greater proportion of incident FEP cases among migrants. Policies aimed at reducing CM should consider the increased vulnerability of specific subpopulations.

Gene x environment (G×E) interactions, i.e. genetic modulation of the sensitivity to environmental factors and/or environmental control of the gene expression, have not been reliably established regarding aetiology of psychotic disorders. Moreover, recent studies have shown associations between the polygenic risk scores for schizophrenia (PRS-SZ) and some risk factors of psychotic disorders, challenging the traditional gene v. environment dichotomy. In the present article, we studied the role of GxE interaction between psychosocial stressors (childhood trauma, stressful life-events, self-reported discrimination experiences and low social capital) and the PRS-SZ on subclinical psychosis in a population-based sample.

Data were drawn from the EUropean network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) study, in which subjects without psychotic disorders were included in six countries. The sample was restricted to European descendant subjects (n = 706). Subclinical dimensions of psychosis (positive, negative, and depressive) were measured by the Community Assessment of Psychic Experiences (CAPE) scale. Associations between the PRS-SZ and the psychosocial stressors were tested. For each dimension, the interactions between genes and environment were assessed using linear models and comparing explained variances of ‘Genetic’ models (solely fitted with PRS-SZ), ‘Environmental’ models (solely fitted with each environmental stressor), ‘Independent’ models (with PRS-SZ and each environmental factor), and ‘Interaction’ models (Independent models plus an interaction term between the PRS-SZ and each environmental factor). Likelihood ration tests (LRT) compared the fit of the different models.

There were no genes-environment associations. PRS-SZ was associated with positive dimensions (β = 0.092, R2 = 7.50%), and most psychosocial stressors were associated with all three subclinical psychotic dimensions (except social capital and positive dimension). Concerning the positive dimension, Independent models fitted better than Environmental and Genetic models. No significant GxE interaction was observed for any dimension.

This study in subjects without psychotic disorders suggests that (i) the aetiological continuum hypothesis could concern particularly the positive dimension of subclinical psychosis, (ii) genetic and environmental factors have independent effects on the level of this positive dimension, (iii) and that interactions between genetic and individual environmental factors could not be identified in this sample.

A history of childhood adversity is associated with psychotic disorder, with an increase in risk according to the number of exposures. However, it is not known why only some exposed individuals go on to develop psychosis. One possibility is pre-existing polygenic vulnerability. Here, we investigated, in the largest sample of first-episode psychosis (FEP) cases to date, whether childhood adversity and high polygenic risk scores for schizophrenia (SZ-PRS) combine synergistically to increase the risk of psychosis, over and above the effect of each alone.

We assigned a schizophrenia-polygenic risk score (SZ-PRS), calculated from the Psychiatric Genomics Consortium (PGC2), to all participants in a sample of 384 FEP patients and 690 controls from the case–control component of the EU-GEI study. Only participants of European ancestry were included in the study. A history of childhood adversity was collected using the Childhood Trauma Questionnaire (CTQ). Synergistic effects were estimated using the interaction contrast ratio (ICR) [odds ratio (OR)exposure and PRS − ORexposure − ORPRS + 1] with adjustment for potential confounders.

There was some evidence that the combined effect of childhood adversities and polygenic risk was greater than the sum of each alone, as indicated by an ICR greater than zero [i.e. ICR 1.28, 95% confidence interval (CI) −1.29 to 3.85]. Examining subtypes of childhood adversities, the strongest synergetic effect was observed for physical abuse (ICR 6.25, 95% CI −6.25 to 20.88).

Our findings suggest possible synergistic effects of genetic liability and childhood adversity experiences in the onset of FEP, but larger samples are needed to increase precision of estimates.

Perceived discrimination is associated with worse mental health. Few studies have assessed whether perceived discrimination (i) is associated with the risk of psychotic disorders and (ii) contributes to an increased risk among minority ethnic groups relative to the ethnic majority.

We used data from the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions Work Package 2, a population-based case−control study of incident psychotic disorders in 17 catchment sites across six countries. We calculated odds ratios (OR) and 95% confidence intervals (95% CI) for the associations between perceived discrimination and psychosis using mixed-effects logistic regression models. We used stratified and mediation analyses to explore differences for minority ethnic groups.

Reporting any perceived experience of major discrimination (e.g. unfair treatment by police, not getting hired) was higher in cases than controls (41.8% v. 34.2%). Pervasive experiences of discrimination (≥3 types) were also higher in cases than controls (11.3% v. 5.5%). In fully adjusted models, the odds of psychosis were 1.20 (95% CI 0.91–1.59) for any discrimination and 1.79 (95% CI 1.19–1.59) for pervasive discrimination compared with no discrimination. In stratified analyses, the magnitude of association for pervasive experiences of discrimination appeared stronger for minority ethnic groups (OR = 1.73, 95% CI 1.12–2.68) than the ethnic majority (OR = 1.42, 95% CI 0.65–3.10). In exploratory mediation analysis, pervasive discrimination minimally explained excess risk among minority ethnic groups (5.1%).

Pervasive experiences of discrimination are associated with slightly increased odds of psychotic disorders and may minimally help explain excess risk for minority ethnic groups.

Psychosis rates are higher among some migrant groups. We hypothesized that psychosis in migrants is associated with cumulative social disadvantage during different phases of migration.

We used data from the EUropean Network of National Schizophrenia Networks studying Gene-Environment Interactions (EU-GEI) case–control study. We defined a set of three indicators of social disadvantage for each phase: pre-migration, migration and post-migration. We examined whether social disadvantage in the pre- and post-migration phases, migration adversities, and mismatch between achievements and expectations differed between first-generation migrants with first-episode psychosis and healthy first-generation migrants, and tested whether this accounted for differences in odds of psychosis in multivariable logistic regression models.

In total, 249 cases and 219 controls were assessed. Pre-migration (OR 1.61, 95% CI 1.06–2.44, p = 0.027) and post-migration social disadvantages (OR 1.89, 95% CI 1.02–3.51, p = 0.044), along with expectations/achievements mismatch (OR 1.14, 95% CI 1.03–1.26, p = 0.014) were all significantly associated with psychosis. Migration adversities (OR 1.18, 95% CI 0.672–2.06, p = 0.568) were not significantly related to the outcome. Finally, we found a dose–response effect between the number of adversities across all phases and odds of psychosis (⩾6: OR 14.09, 95% CI 2.06–96.47, p = 0.007).

The cumulative effect of social disadvantages before, during and after migration was associated with increased odds of psychosis in migrants, independently of ethnicity or length of stay in the country of arrival. Public health initiatives that address the social disadvantages that many migrants face during the whole migration process and post-migration psychological support may reduce the excess of psychosis in migrants.

First episode psychosis (FEP) patients who use cannabis experience more frequent psychotic and euphoric intoxication experiences compared to controls. It is not clear whether this is consequent to patients being more vulnerable to the effects of cannabis use or to their heavier pattern of use. We aimed to determine whether extent of use predicted psychotic-like and euphoric intoxication experiences in patients and controls and whether this differs between groups.

We analysed data on patients who had ever used cannabis (n = 655) and controls who had ever used cannabis (n = 654) across 15 sites from six countries in the EU-GEI study (2010–2015). We used multiple regression to model predictors of cannabis-induced experiences and to determine if there was an interaction between caseness and extent of use.

Caseness, frequency of cannabis use and money spent on cannabis predicted psychotic-like and euphoric experiences (p ⩽ 0.001). For psychotic-like experiences (PEs) there was a significant interaction for caseness × frequency of use (p < 0.001) and caseness × money spent on cannabis (p = 0.001) such that FEP patients had increased experiences at increased levels of use compared to controls. There was no significant interaction for euphoric experiences (p > 0.5).

FEP patients are particularly sensitive to increased psychotic-like, but not euphoric experiences, at higher levels of cannabis use compared to controls. This suggests a specific psychotomimetic response in FEP patients related to heavy cannabis use. Clinicians should enquire regarding cannabis related PEs and advise that lower levels of cannabis use are associated with less frequent PEs.

The ‘jumping to conclusions’ (JTC) bias is associated with both psychosis and general cognition but their relationship is unclear. In this study, we set out to clarify the relationship between the JTC bias, IQ, psychosis and polygenic liability to schizophrenia and IQ.

A total of 817 first episode psychosis patients and 1294 population-based controls completed assessments of general intelligence (IQ), and JTC, and provided blood or saliva samples from which we extracted DNA and computed polygenic risk scores for IQ and schizophrenia.

The estimated proportion of the total effect of case/control differences on JTC mediated by IQ was 79%. Schizophrenia polygenic risk score was non-significantly associated with a higher number of beads drawn (B = 0.47, 95% CI −0.21 to 1.16, p = 0.17); whereas IQ PRS (B = 0.51, 95% CI 0.25–0.76, p < 0.001) significantly predicted the number of beads drawn, and was thus associated with reduced JTC bias. The JTC was more strongly associated with the higher level of psychotic-like experiences (PLEs) in controls, including after controlling for IQ (B = −1.7, 95% CI −2.8 to −0.5, p = 0.006), but did not relate to delusions in patients.

Our findings suggest that the JTC reasoning bias in psychosis might not be a specific cognitive deficit but rather a manifestation or consequence, of general cognitive impairment. Whereas, in the general population, the JTC bias is related to PLEs, independent of IQ. The work has the potential to inform interventions targeting cognitive biases in early psychosis.

The prevalence of Anxiety Disorders (ADs) among the elderly (65 plus) varies across studies, because of differences in diagnostic criteria's definition and the heterogeneity of clinical presentation. Furthermore the comorbidity of anxiety with affective disorders is controversial.

Estimate the prevalence of ADs in 65 years plus subjects in a random sampling of the general population and provide current estimates of comorbidity with affective disorders.

The sample was collected in the Great Age study, a population-based study conducted in a random sampling of the elderly residents in Castellana, South-East Italy. It includes 719 participants (56,33% males). Through the SCID-IVTR interview performed by a psychiatrist, ADs diagnosis and classification in subtypes (phobia, generalized anxiety disorder, OCD, panic disorder, post-traumatic stress disorder, adjustment disorder and AD nos) were assessed.

The 30,25% of females and 15,30% of males were positive for any DSM-VI disorder. The ADs prevalence was 10,43% (14,97% of women; 6,91% of men; mean age at interview 72 years). Rates prevalence in 65-74 age stratum was 11,78%; 8,1% in 75-84 and 10,26% in the oldest age. The ADs were classified as phobia (1,49%), GAD (2,22%), OCD (0,28%), panic disorder (0,7%), PTSD (0,55%), adjustment disorder (1,67%) and AD nos (3,75%). 21,33% of the ADs had apparently new-onset (Late OnsetADs). Affective disorders occur in 25,33% of ADs.

The prevalence rates of ADs in late life tend to decline, but remain the most common psychiatric disorders, especially in women. Anxiety co-occurs with affective disorders in similar rate to Late OnsetADs.

Founding: PRIN2009E4RM4Z

Previous studies suggested that migrants are at higher risk for psychosis [1] but that this risk is inversely correlated with the size of their ethnic group [2].

However, less is known about the influence of proportion of migrants in a population - a simple and readily available parameter - on the incidence of psychosis in the whole population - a measure of interest for mental health policies.

We prospectively collected data over 3 years in an urban area with a population of N=133000 at risk subjects. The area was divided in 80 geographical units classified in four categories (quartiles) according to the proportion of migrants in the latest census. For each of the geographic units we calculated the standardized incidence rates of affective, non-affective and total psychoses. We tested the hypothesis of unequal rates of psychosis according to migrants’ density quartiles using a Poisson model.

The proportion of migrants significantly influenced the incidence of total psychoses and affective psychoses. However, in this sample, an increase in migrant density was not linked to an increase in cases of psychosis over the entire spectrum of migrants’ density. A raise in the third quartile was followed by lower incidence rates in populations with the largest proportion of migrants (see figure)

More research is needed to confirm or contradict this result and test for different explanatory hypotheses.

Depression is a common disorder in late-life. Structured clinical interviews may be less efficient compared to self-administered questionnaires, but provide more accurate findings in terms of diagnosis. No population-based studies with both these depression assessment instruments have been ever performed.

To estimate the GDS-30 accuracy for depression assessment against the gold standard [Semi-structured Clinical Diagnostic Interview for DSM-IV-TR Axis I Disorders (SCID)] in subjects 65+ years in a random sampling of the general population.

The sample was collected in a population-based study (GreatAGE) conducted among elderly residents in Castellana, Southeast Italy. It includes 597 participants (57.62% males, mean age 73 years). Depression was assessed through the GDS-30 and the SCID, both double-blinded administered respectively by a trained neuropsychologist and psychiatrist. The GDS-30 screening performances were analyzed using ROC curves.

According to the gold standard SCID, the rate of depressive disorder was 10.22% (15.81% of women; 6.1% of men) while with GDS-30 instrument 12.06% of the residents met the depression cutoff. Only 36.1% of GDS cases were true positive. At the optimal cutoff score (> 5), GDS had 62% sensitivity and 81% specificity. Using a more conservative cutoff (> 9), the GDS-30 specificity reached 91% while sensitivity dropped to 43%.

These preliminary results from the first population-based study that compares GDS-30 and SCID showed that the GDS-30 identified adequate levels of screening accuracy (AUC 0.76) compatible with scores established in community settings.

PRIN2009E4RM4Z.

The authors have not supplied their declaration of competing interest.

Homeless people are more likely to have higher prevalence of psychotic disorders than general population. However, we know less about the prevalence of psychotic symptoms in this group.

To estimate the lifetime and current prevalence of psychotic symptoms and their correlates among homeless people living in the Paris metropolitan area.

We analysed data from 839 homeless randomly selected for the “Samenta” survey that studied mental health and addiction problems in this population. The mini-international neuropsychiatric interview was used to assess psychotic symptoms. Separate multivariate logistic regression analyses were conducted to estimate the associations of sociodemographic characteristics (age, gender, education level and migrant status), early life experiences (sexual abuse, physical and psychological violence, substance use) and psychiatric disorders.

The lifetime prevalence of psychotic symptoms was 35.4% (95% CI = 28.1–43.5) and the prevalence of current symptoms was 14,0% (95% CI = 9,8–19,6) with no significant difference between migrant and native groups, after exclusion of subjects with a diagnosis of psychotic disorder (n = 145). In multi-adjusted models, childhood sexual abuse was associated with an increased risk of lifetime or current psychotic symptoms (OR > 4, P < 0.05). Early life psychological violence was strongly associated with the risk of lifetime psychotic symptoms in natives (OR = 6.33; 95% CI = 2.10–19.0), whereas alcohol misuse in adolescence was related to lifetime or current psychotic symptoms in migrants (OR = 3.34; 95% CI = 1.20–9.37).

Homeless people are at higher risk of psychotic symptoms compared to the general population in France. Our findings are consistent with the hypothesis that childhood abuse is an important risk factor of the psychosis continuum.

The authors have not supplied their declaration of competing interest.

The validity of the 30-item Geriatric Depression Scale (GDS-30) in detecting late-life depression (LLD) requires a certain level of cognitive functioning. Further research is needed in population-based setting on other socio-demographic and cognitive variables that could potentially influence the accuracy of clinician rated depression.

To compare the diagnostic accuracy of two instruments used to assess depressive disorders [(GDS-30) and the Semi-structured Clinical Diagnostic Interview for DSM-IV-TR Axis I Disorders (SCID)] among three groups with different levels of cognitive functioning (normal, Mild Cognitive Impairment – MCI, Subjective Memory Complain – SMC) in a random sampling of the general population 65+ years.

The sample, collected in a population-based study (GreatAGE Study) among the older residents of Castellana Grotte, South-East Italy, included 844 subjects (54.50% males). A standardized neuropsychological battery was used to assess MCI, SMC and depressive symptoms (GDS-30). Depressive syndromes were diagnosed through the SCID IV-TR. Socio-demographic and cognitive variables were taken into account in influencing SCID performance.

According to the SCID, the rate of depressive disorders was 12.56%. At the optimal cut-off score (≥ 4), GDS-30 had 65.1% sensitivity and 68.4% specificity in diagnosing depressive symptoms. Using a more conservative cut-off (≥ 10), the GDS-30 specificity reached 91.1% while sensitivity dropped to 37,7%. The three cognitive subgroups did not differ in the rate of depression diagnosis. Educational level is the only variable associated to the SCID diagnostic performance (P = 0.015).

At the optimal cut-off, GDS-30 identified lower levels of screening accuracy for subjects with normal cognition rather than for SMC (AUC 0.792 vs. 0.692); educational attainment possibly may modulate diagnostic clinician performance.

The authors have not supplied their declaration of competing interest.

Several studies have reported controversial links between swallowing disturbances (SD) and psychiatric disorders in older age. The available data on the epidemiology of SD in the general population are scarce and often conflicting, because of numerous methodological factors source of possible counfounders.

We aimed to screen the presence of psychiatric and cognitive disorders associated with SD in a random sampling of the general population ≥ 65.

A sample of 1127 elderly individuals collected in a population-based study (GreatAGE) in Castellana Grotte (53,50% males, mean age 74.1 ± 6.3 years), South-East Italy, were mailed a validated self-report questionnaire to assess SD (Eating Assessment Tool-EAT10). Psychiatric disorders and symptoms [assessed with Semi-structured Clinical Diagnostic Interview for DSM-IV-TR Axis I Disorders, Geriatric Depression Scale-30 (GDS-30) and Symptom Checklist Revised-90 (SCL-90R)], cognitive functions were assessed with a comprehensive neuropsychological battery, neurological exam, and demographics were compared in participants with and without SD using t-tests and Mann–Whitney U-test.

The prevalence rates of SD amounted at 5.97%. Psychiatric diagnosis (24.22% of the sample) was statistically significant associated with SD (EAT ≥ 3, P = 0.038), and a trend was found for major depressive disorder and generalized anxiety disorder. Among SCL-90R domains, only anxiety showed a significant association with EAT ≥ 3 (P = 0.006). GDS-30 score was found to be higher in subjects with SD (P = 0.008). Cognitive functions did not differ between the two groups except for an increasing trend for Clinical Dementia Rating Scale in EAT ≥ 3 (P = 0.058).

These preliminary results showed an association between SD in older age and late-life major depression and anxiety disorders.

The authors have not supplied their declaration of competing interest.

Daily use of high-potency cannabis has been reported to carry a high risk for developing a psychotic disorder. However, the evidence is mixed on whether any pattern of cannabis use is associated with a particular symptomatology in first-episode psychosis (FEP) patients.

We analysed data from 901 FEP patients and 1235 controls recruited across six countries, as part of the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) study. We used item response modelling to estimate two bifactor models, which included general and specific dimensions of psychotic symptoms in patients and psychotic experiences in controls. The associations between these dimensions and cannabis use were evaluated using linear mixed-effects models analyses.

In patients, there was a linear relationship between the positive symptom dimension and the extent of lifetime exposure to cannabis, with daily users of high-potency cannabis having the highest score (B = 0.35; 95% CI 0.14–0.56). Moreover, negative symptoms were more common among patients who never used cannabis compared with those with any pattern of use (B = −0.22; 95% CI −0.37 to −0.07). In controls, psychotic experiences were associated with current use of cannabis but not with the extent of lifetime use. Neither patients nor controls presented differences in depressive dimension related to cannabis use.

Our findings provide the first large-scale evidence that FEP patients with a history of daily use of high-potency cannabis present with more positive and less negative symptoms, compared with those who never used cannabis or used low-potency types.

Ethnic minority groups in Western countries face an increased risk of psychotic disorders. Causes of this long-standing public health inequality remain poorly understood. We investigated whether social disadvantage, linguistic distance and discrimination contributed to these patterns.

We used case–control data from the EUropean network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) study, carried out in 16 centres in six countries. We recruited 1130 cases and 1497 population-based controls. Our main outcome measure was first-episode ICD-10 psychotic disorder (F20–F33), and exposures were ethnicity (white majority, black, mixed, Asian, North-African, white minority and other), generational status, social disadvantage, linguistic distance and discrimination. Age, sex, paternal age, cannabis use, childhood trauma and parental history of psychosis were included as a priori confounders. Exposures and confounders were added sequentially to multivariable logistic models, following multiple imputation for missing data.

Participants from any ethnic minority background had crude excess odds of psychosis [odds ratio (OR) 2.03, 95% confidence interval (CI) 1.69–2.43], which remained after adjustment for confounders (OR 1.61, 95% CI 1.31–1.98). This was progressively attenuated following further adjustment for social disadvantage (OR 1.52, 95% CI 1.22–1.89) and linguistic distance (OR 1.22, 95% CI 0.95–1.57), a pattern mirrored in several specific ethnic groups. Linguistic distance and social disadvantage had stronger effects for first- and later-generation groups, respectively.

Social disadvantage and linguistic distance, two potential markers of sociocultural exclusion, were associated with increased odds of psychotic disorder, and adjusting for these led to equivocal risk between several ethnic minority groups and the white majority.