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Publications (291)
Background
Multiple genetic and environmental risk factors play a role in the development of both schizophrenia-spectrum disorders and affective psychoses. How they act in combination is yet to be clarified.
Methods
We analyzed 573 first episode psychosis cases and 1005 controls, of European ancestry. Firstly, we tested whether the association of...
Background
The association between cannabis and psychosis is established, but the role of underlying genetics is unclear. We used data from the EU-GEI case-control study and UK Biobank to examine the independent and combined effect of heavy cannabis use and schizophrenia polygenic risk score (PRS) on risk for psychosis.
Methods
Genome-wide associa...
Background
Cannabis use and familial vulnerability to psychosis have been associated with social cognition deficits. This study examined the potential relationship between cannabis use and cognitive biases underlying social cognition and functioning in patients with first episode psychosis (FEP), their siblings, and controls.
Methods
We analyzed a...
Background
Urbanicity is a well‐established risk factor for psychosis. Our recent multi‐national study found an association between urbanicity and clinical psychosis in Northern Europe but not in Southern Europe. In this study, we hypothesized that the effect of current urbanicity on variation of schizotypy would be greater in North‐western Europe...
Childhood adversity is associated with various clinical dimensions in psychosis; however, how genetic vulnerability shapes the adversity-associated psychopathological signature is yet to be studied. We studied data of 583 First Episode Psychosis (FEP) cases from the EU-GEI FEP case-control study, including Polygenic risk scores for major depressive...
The rising prevalence and legalisation of cannabis worldwide have underscored the need for a comprehensive understanding of its biological impact, particularly on mental health. Epigenetic mechanisms, specifically DNA methylation, have gained increasing recognition as vital factors in the interplay between risk factors and mental health. This study...
Several studies have highlighted increased psychosis risk in migrant and minority ethnic populations. Migration before age 18 appears to increase risk, but further evidence is required. We investigated this issue in a European case-control study. We hypothesized that migration during two key socio-developmental periods, childhood and adolescence, w...
The social defeat hypothesis posits that low status and repeated humiliation increase the risk for psychotic disorders (PDs) and psychotic experiences (PEs). The purpose of this paper was to provide a systematic review of studies on risk of PDs and PEs among lesbian, gay, or bisexual (LGB) people and a quantitative synthesis of any difference in ri...
Background
Several studies have observed that mentalization-based treatment (MBT) is an effective treatment for borderline personality disorder (BPD), but its effectiveness for other personality disorders (PDs) has hardly been examined. Additionally, the evidence supporting the claim that MBT improves mentalizing capacity is scarce. The present stu...
Background and Hypothesis
Recent findings suggest the incidence of first-episode psychotic disorders (FEP) varies according to setting-level deprivation and cannabis use, but these factors have not been investigated together. We hypothesized deprivation would be more strongly associated with variation in FEP incidence than the prevalence of daily o...
The dopamine hypothesis of schizophrenia posits that elevated striatal dopamine functioning underlies the development of psychotic symptoms. Chronic exposure to social stressors increases psychosis risk, possibly by upregulating striatal dopamine functioning. Here we systematically review single photon emission computed tomography (SPECT) and posit...
Background
We examined whether cannabis use contributes to the increased risk of psychotic disorder for non-western minorities in Europe.
Methods
We used data from the EU-GEI study (collected at sites in Spain, Italy, France, the United Kingdom, and the Netherlands) on 825 first-episode patients and 1026 controls. We estimated the odds ratio (OR)...
Background Childhood adversity is associated with various clinical dimensions in psychosis; however, how genetic vulnerability shapes the adversity associated psychopathological signature is yet to be clarified.
Methods Using data from the EU-GEI study, in 376 First Episode Psychosis (FEP) cases, we evaluated the interaction between polygenic risk...
Background
Interactions between the endocannabinoid system (ECS) and neurotransmitter systems might mediate the risk of developing a schizophrenia spectrum disorder (SSD). Consequently, we investigated in patients with SSD and healthy controls (HC) the relations between (1) plasma concentrations of two prototypical endocannabinoids (N-arachidonoyle...
Background
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 co...
Successful leaders are at risk of developing exaggerated pride, contempt for others, and a diminished sense of reality. The ancient Greeks feared this syndrome and called it hubris. Although certain contemporaneous leaders show signs of hubris and pose a great danger, the hubris syndrome does not yet figure in our classification systems. The purpos...
The rising prevalence and legalization of cannabis worldwide have underscored the need for a comprehensive understanding of its biological impact, particularly on mental health. Epigenetic mechanisms, specifically DNA methylation, have gained increasing recognition as vital factors in the interplay between risk factors and mental health. This study...
Background:
The stressful minority position of transgender persons may result in a high risk of psychosis. Conflicting data suggest that the observed risk depends on setting of recruitment. We assessed the relative risk of non-affective psychotic disorder (NAPD) in a large, representative cohort of transgender persons.
Methods:
This cohort was c...
Background:
Use of illegal stimulants is associated with an increased risk of psychotic disorder. However, the impact of stimulant use on odds of first-episode psychosis (FEP) remains unclear. Here, we aimed to describe the patterns of stimulant use and examine their impact on odds of FEP.
Methods:
We included patients with FEP aged 18-64 years...
This study investigated if the association between childhood maltreatment and cognition among psychosis patients and community controls was partially accounted for by genetic liability for psychosis. Patients with first-episode psychosis (N = 755) and unaffected controls (N = 1219) from the EU-GEI study were assessed for childhood maltreatment, int...
Background
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 adve...
Background:
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.
Methods:
We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case-control study. 558 first-...
Abtract
Studies conducted in psychotic disorders have shown that DNA-methylation (DNAm) is sensitive to the impact of Childhood Adversity (CA). However, whether it mediates the association between CA and psychosis is yet to be explored. Epigenome wide association studies (EWAS) using the Illumina Infinium-Methylation EPIC array in peripheral blood...
Background and Hypothesis
It is argued that availability of diagnostic models will facilitate a more rapid identification of individuals who are at a higher risk of first episode psychosis (FEP). Therefore, we developed, evaluated, and validated a diagnostic risk estimation model to classify individual with FEP and controls across six countries.
S...
Background
Little is known on whether associations between childhood autistic traits and psychotic experiences persist into adulthood and whether genetic confounding and childhood trauma influence them. Here we investigate the associations between childhood autistic traits and psychotic experiences until young adulthood and assess the influence of...
Background: Several studies have observed that mentalization-based treatment (MBT) is an effective treatment for borderline personality disorder (BPD), but its effectiveness for other personality disorders (PDs) has hardly been examined. Additionally, the evidence supporting the claim that MBT improves mentalizing capacity is scarce. The present st...
Background:
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 incidenc...
Studies conducted in psychotic disorders have shown that DNA-methylation (DNAm) is sensitive to the impact of Childhood Adversity (CA). However, whether it mediates the association between CA and psychosis is yet to be explored. Epigenome-wide association studies (EWAS) using the Illumina Infinium-Methylation EPIC array in peripheral blood tissue f...
Introduction
The social defeat hypothesis of psychosis posits that an outsider status or subordinate position is a common denominator of several psychosis risk factors, leads to elevated striatal dopamine function and thereby to an increased risk for the disorder. The purpose of this paper is to examine whether this hypothesis offers a good explana...
Cluster studies identified a subgroup of patients with psychosis whose premorbid adjustment deteriorates before the onset, which may reflect variation in genetic influence. However, other studies reported a complex relationship between distinctive patterns of cannabis use and cognitive and premorbid impairment that is worthy of consideration. We ex...
Background
The high risk of psychosis among migrants is often attributed to social stressors in the host country. We examined whether the relative risk of psychosis among migrants is low on arrival and increases thereafter.
Methods
In this cohort study, first-generation immigrants to the Netherlands, aged 10 years and older ( N = 1 281 678), were...
Gene x environment (GxE) interactions have not been reliably established regarding etiology of psychotic disorders, while genes-environment (G-E) associations have been displayed. We studied the role of GxE interaction between psychosocial stressors (childhood trauma, stressful life-events, self-reported discrimination experiences and low social ca...
Background and hypothesis
Evidence suggests that childhood maltreatment (ie, childhood abuse and childhood neglect) affects educational attainment and cognition. However, the association between childhood maltreatment and Intelligence Quotient (IQ) seems stronger among controls compared to people with psychosis. We hypothesised that: the associatio...
Background:
Schizophrenia (SZ), bipolar disorder (BD) and depression (D) run in families. This susceptibility is partly due to hundreds or thousands of common genetic variants, each conferring a fractional risk. The cumulative effects of the associated variants can be summarised as a polygenic risk score (PRS). Using data from the EUropean Network...
Dopaminergic signaling is believed to be related to autistic traits. We conducted an exploratory 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine positron emission tomography/computed tomography ([18F]-FDOPA PET/CT) study, to examine cerebral [18F]-FDOPA influx constant (kicer min−1), reflecting predominantly striatal dopamine synthesis capacity and a...
Premorbid functioning and cognitive measures may reflect gradients of developmental impairment across diagnostic categories in psychosis. In this study, we sought to examine the associations of current cognition and premorbid adjustment with symptom dimensions in a large first episode psychosis (FEP) sample.
We used data from the international EU-G...
Background
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-episod...
Important questions remain about the profile of cognitive impairment in psychotic disorders across adulthood and illness stages. The age-associated profile of familial impairments also remains unclear, as well as the effect of factors, such as symptoms, functioning, and medication. Using cross-sectional data from the EU-GEI and GROUP studies, compr...
Objective:
To compare the incidence of psychosis among migrants with the incidence among the native Dutch in Amsterdam, Gouda and Voorhout.
Design:
We identified patients with a first treated episode of psychosis (ICD-10 codes F20-F33) in 2010-2013 as part of the European Network of National Schizophrenia Networks Studying Gene-Environment Inter...
Introduction: There is increasing evidence that autistic traits are associated with psychotic experiences. However, the mechanisms underlying such associations are still unknown. In this longitudinal birth cohort study, we examine the relationship between childhood autistic traits and psychotic experiences in adolescence and young adulthood, and th...
The influence of psychosocial stressors on psychosis risk has usually been studied in isolation and after the onset of the disorder, potentially ignoring important confounding relationships or the fact that some stressors that may be the consequence of the disorder rather than preexisting. The study of subclinical psychosis could help to address so...
Duration of untreated psychosis (DUP) is associated with clinical outcomes in people with a diagnosis of first-episode psychosis (FEP), but factors associated with length of DUP are still poorly understood. Aiming to obtain insights into the possible biological impact on DUP, we report genetic analyses of a large multi-center phenotypically well-de...
Schizophrenia (SZ), Bipolar Disorder (BD) and Depression (D) run in families. This susceptibility is partly due to hundreds or thousands of common genetic variants, each conferring a fractional risk. The cumulative effects of the associated variants can be summarised as a polygenic risk score (PRS). Using data from the EUGEI case-control study, we...
Background:
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.
Methods:
We used data from the European Network of N...
Background
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.
Methods
We used data from the EUropean Network of National Schizophrenia Networks studying Gene-Environment Interactions (EU-GEI) case–control study. We...
Alterations in dopamine signalling have been implied in autism spectrum disorder (ASD), and these could be associated with the risk of developing a psychotic disorder in ASD adults. Negative social experiences and feelings of social defeat might result in an increase in dopamine functioning. However, few studies examined dopamine functioning in viv...
Objective
To compare the mortality in people using clozapine to that of people using other antipsychotics.
Methods
Danish incidence cohort of 22 110 patients with a first diagnosis of non‐affective psychotic disorder (1995‐2013) and a prevalence cohort of 50 881 patients ever diagnosed with such a disorder (1969‐2013). Hazard ratios (HR) were calc...
It is likely that the chronic stress of social defeat or exclusion contributes to the increased psychosis risk among members of ethnic minorities. Is this idea compatible with the dopamine or neurodevelopmental hypothesis, two dominant hypotheses with regard to pathogenesis? Defeated animals show clear evidence of dopamine sensitization. As for hum...
Psychotic Disorders: Comprehensive Conceptualization and Treatments emphasizes a dimensional approach to psychosis that cuts across a broad array of psychiatric diagnoses from schizophrenia to affective psychosis and organic disorders like epilepsy and dementias. Written by an international roster of over seventy leading experts in the field, this...
Background:
In Europe, the incidence of psychotic disorder is high in certain migrant and minority ethnic groups (hence: 'minorities'). However, it is unknown how the incidence pattern for these groups varies within this continent. Our objective was to compare, across sites in France, Italy, Spain, the UK and the Netherlands, the incidence rates f...
To test whether: (1) psychiatrists will prescribe clozapine more often if they can delegate the monitoring tasks to an advanced nurse practitioner (ANP), (2) clozapine monitoring by an ANP is at least as safe as monitoring by a psychiatrist. Patients from 23 Dutch outpatient teams were assessed for an indication for clozapine. ANPs affiliated to th...
Background
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...
Background
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.
Methods
A total of 817 first episode psychosis patients and 1294 pop...
Background
To provide an overview of epidemiological studies of dementia among migrant groups in Europe and to estimate their pooled odds ratio (OR) v. the reference population.
Methods
Search for articles reporting on incidence or prevalence of dementia among ethnic minorities and migrants in Europe, published before 21 December 2018. We performe...
Purpose
The EUropean Network of National Schizophrenia Networks Studying Gene–Environment Interactions (EU-GEI) study contains an unparalleled wealth of comprehensive data that allows for testing hypotheses about (1) variations in incidence within and between countries, including by urbanicity and minority ethnic groups; and (2) the role of multipl...
Background: Some recent studies have challenged the direction of causality for the association between cannabis use and psychotic disorder, suggesting that cannabis use initiation is explained by common genetic variants associated with risk of schizophrenia. We used data from the European Union Gene-Environment Interaction consortium (EUGEI) case-c...
Reports of decreased mortality among patients with schizophrenia who use clozapine may be biased if clozapine is prescribed to relatively healthy patients and if intensive monitoring during its use prevents (under-treatment of) somatic disorder. We aimed to assess whether there is a difference in: (1) somatic comorbidity between patients who start...
Psychotic patients with a lifetime history of cannabis use generally show better cognitive functioning than other psychotic patients. Some authors suggest that cannabis-using patients may have been less cognitively impaired and less socially withdrawn in their premorbid life. Using a dataset comprising 948 patients with first-episode psychosis (FEP...
Psychotic patients with a lifetime history of cannabis use generally show better cognitive functioning than other psychotic patients. Some authors suggest that cannabis-using patients may have been less cognitively impaired and less socially withdrawn in their premorbid life. Using a dataset comprising 948 patients with first-episode psychosis (FEP...
Evidence for early parental death as a risk factor for psychosis in offspring is inconclusive. We analyzed data from a six-country, case-control study to examine the associations of early parental death, type of death (maternal, paternal, both), and child’s age at death with psychosis, both overall and by ethnic group. In fully adjusted multivariab...
Background
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.
Methods
817 FEP patients and 1294 population-based controls complete...
Background
The incidence of psychotic disorder is increased among various migrant and ethnic minority populations in Europe. Consistent evidence shows that risk estimates are moderated by ethnic background, but there may also be moderation by host country (1,2). We therefore aimed to study the risk of psychotic disorder in first- and second-generat...
Background:
Cannabis use is associated with increased risk of later psychotic disorder but whether it affects incidence of the disorder remains unclear. We aimed to identify patterns of cannabis use with the strongest effect on odds of psychotic disorder across Europe and explore whether differences in such patterns contribute to variations in the...
Background:
This study tested the hypotheses that (i) the relationship between a history of childhood abuse and severity of psychosis is mediated by loneliness; (ii) the relationship between loneliness and psychosis is mediated by within-person fluctuations in depressive and anxious feelings.
Methods:
Fifty-nine individuals with non-affective ps...
