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BackgroundPoor educational achievement is associated with a range of psychiatric disorders. Several studies suggest that this underperformance is due to cognitive deficits that commence before disease onset and reflect a genetic risk for this disorder. However, the specificity and the familial contribution of this cognitive deficit are not clear. We analysed lifetime educational achievement of psychiatric patients diagnosed with schizophrenia, bipolar or depressive disorder and their unaffected siblings.MethodIn a register-based case-control study, 1561 patients with schizophrenia, 813 patients with bipolar disorder, 8112 patients with depression, and their siblings were each matched with eight population controls. Patients, siblings and controls were compared on the highest educational stream they completed.ResultsLower educational achievement was present in schizophrenia patients from primary school onwards [completing primary school: odds ratio (OR) 0.69; completing secondary school: OR 0.69; completing academic education: OR 0.46], compared to patients with bipolar disorder or depression. Siblings of schizophrenia, bipolar or depressed patients showed no underachievement at primary or secondary school, but siblings of schizophrenia patients as well as siblings of depressed patients were less successful in their educational achievement after secondary school (completing academic education, schizophrenia siblings: OR 0.90; depressive disorder siblings: OR 0.91).ConclusionsEducational underachievement from primary school onwards is specifically related to schizophrenia and not to bipolar disorder or depression. Moreover, it appears to be a harbinger of the illness, since it is not found in their siblings. These results add to evidence that early cognitive deficits are a distinct feature of the schizophrenia phenotype. [ABSTRACT FROM PUBLISHER]

BackgroundThe association between childhood trauma and psychotic and depressive symptomatology is well established. However, less is known about the specificity and course of these symptoms in relation to childhood trauma.MethodIn a large sample (n = 2765) of patients with psychosis (n = 1119), their siblings (n = 1057) and controls (n = 589), multivariate (mixed-effects) regression analyses with multiple outcomes were performed to examine the association between childhood trauma and psychotic and depressive symptomatology over a 3-year period.ResultsA dose–response relationship was found between childhood trauma and psychosis. Abuse was more strongly associated with positive symptoms than with negative symptoms whereas the strength of the associations between neglect and positive and negative symptoms was comparable. In patients, similar associations between childhood trauma and psychotic or depressive symptoms were found, and in siblings and controls, stronger associations were found between trauma and depressive symptomatology. Childhood trauma was not related to a differential course of symptoms over a 3-year time period.ConclusionsIn congruence with earlier work, our findings suggest that childhood trauma, and abuse in particular, is associated with (subthreshold) psychosis. However, childhood trauma does not seem to be associated with a differential course of symptoms, nor does it uniquely heighten the chance of developing (subthreshold) psychotic symptomatology. Our results indicate that trauma may instead contribute to a shared vulnerability for psychotic and depressive symptoms. [ABSTRACT FROM PUBLISHER]

BackgroundPost-traumatic stress disorder (PTSD) is thought to be characterized by general heightened amygdala activation. However, this hypothesis is mainly based on specific studies presenting fear or trauma-related stimuli, hence, a thorough investigation of trauma-unrelated emotional processing in PTSD is needed.MethodsIn this study, 31 male medication-naive veterans with PTSD, 28 male control veterans (combat controls; CC) and 25 non-military men (healthy controls; HC) were included. Participants underwent functional MRI while trauma-unrelated neutral, negative and positive emotional pictures were presented. In addition to the group analyses, PTSD patients with and without major depressive disorder (MDD) were compared.ResultsAll groups showed an increased amygdala response to negative and positive contrasts, but amygdala activation did not differ between groups. However, a heightened dorsal anterior cingulate cortex (dACC) response for negative contrasts was observed in PTSD patients compared to HC. The medial superior frontal gyrus was deactivated in the negative contrast in HC, but not in veterans. PTSD+MDD patients showed decreased subgenual ACC (sgACC) activation to all pictures compared to PTSD–MDD.ConclusionOur findings do not support the hypothesis that increased amygdala activation in PTSD generalizes to trauma-unrelated emotional processing. Instead, the increased dACC response found in PTSD patients implicates an attentional bias that extends to trauma-unrelated negative stimuli. Only HC showed decreased medial superior frontal gyrus activation. Finally, decreased sgACC activation was related to MDD status within the PTSD group. [ABSTRACT FROM PUBLISHER]

BackgroundSchizophrenia is associated with lower pre-morbid intelligence (IQ) in addition to (pre-morbid) cognitive decline. Both schizophrenia and IQ are highly heritable traits. Therefore, we hypothesized that genetic variants associated with schizophrenia, including copy number variants (CNVs) and a polygenic schizophrenia (risk) score (PSS), may influence intelligence.MethodIQ was estimated with the Wechsler Adult Intelligence Scale (WAIS). CNVs were determined from single nucleotide polymorphism (SNP) data using the QuantiSNP and PennCNV algorithms. For the PSS, odds ratios for genome-wide SNP data were calculated in a sample collected by the Psychiatric Genome-Wide Association Study (GWAS) Consortium (8690 schizophrenia patients and 11 831 controls). These were used to calculate individual PSSs in our independent sample of 350 schizophrenia patients and 322 healthy controls.ResultsAlthough significantly more genes were disrupted by deletions in schizophrenia patients compared to controls (p = 0.009), there was no effect of CNV measures on IQ. The PSS was associated with disease status (R2 = 0.055, p = 2.1 × 10−7) and with IQ in the entire sample (R2 = 0.018, p = 0.0008) but the effect on IQ disappeared after correction for disease status.ConclusionsOur data suggest that rare and common schizophrenia-associated variants do not explain the variation in IQ in healthy subjects or in schizophrenia patients. Thus, reductions in IQ in schizophrenia patients may be secondary to other processes related to schizophrenia risk. [ABSTRACT FROM PUBLISHER]

BackgroundCannabis use is associated with increased risk for psychotic-like experiences (PLEs) and psychotic disorders. It remains unclear whether this relationship is causal or due to confounding.MethodA total of 1929 young adults aged 18–30 years participated in a nationwide internet-based survey in The Netherlands and gave information on demographics, substance use and parental psychiatric illness and completed the Community Assessment of Psychic Experiences (CAPE).ResultsCigarette smoking and cannabis use were equally strongly associated with the frequency of PLEs in a fully adjusted model (β = 0.098 and 0.079 respectively, p < 0.05). Cannabis use was associated with distress from PLEs in a model adjusted for an elaborate set of confounders excluding smoking (β = 0.082, p < 0.05). However, when cigarette smoking was included in the model, cannabis use was not a significant predictor of distress from PLEs. Cigarette smoking remained associated with distress from PLEs in a fully adjusted model (β = 0.107, p < 0.001).ConclusionsSmoking is an equally strong independent predictor of frequency of PLEs as monthly cannabis use. Our results suggest that the association between moderate cannabis use and PLEs is confounded by cigarette smoking. [ABSTRACT FROM PUBLISHER]

BackgroundAlthough the association between cannabis use and a wide range of psychiatric symptoms is fairly well established, it is not clear whether cannabis use is also a risk factor for general mental health problems at secondary school.MethodA total of 10 324 secondary school children aged 11–16 years, participating in an ongoing Public Health Service School Survey, gave information on demographics, substance use, school factors and stressful life events and completed the Strengths and Difficulties Questionnaire (SDQ).ResultsCannabis use in the past month was associated with a clinically relevant score on the SDQ [unadjusted odds ratio (OR) 4.46, 95% confidence interval (CI) 3.46–5.76]. Other risk factors associated with poor psychosocial functioning were: a low level of education, alcohol use, cigarette smoking, hard drug use, frequent truancy, an unfavourable school evaluation, feeling unsafe at school, being victimized, frequent absence due to illness, a mentally ill parent, molestation by a parent, financial problems and feeling distressed by an adverse event. In a full model adjusting for these risk factors, cannabis was not significantly associated with mental health problems, although an association at trend level was apparent. Of these risk factors, regular alcohol use, cigarette smoking, hard drug use, frequent truancy, an unfavourable school evaluation and frequent absence due to illness were also associated with cannabis use.ConclusionsThe association between cannabis use and poor psychosocial functioning in adolescence is due, at least in part, to confounding by other risk factors. Thus, cannabis use can best be viewed as an indicator of risk for mental health problems in adolescence. [ABSTRACT FROM AUTHOR]

Background. Hallucinations have consistently been associated with traumatic experiences during childhood. This association appears strongest between physical and sexual abuse and auditory verbal hallucinations (AVH). It remains unclear whether traumatic experiences mainly colour the content of AVH or whether childhood trauma triggers the vulnerability to experience hallucinations in general. In order to investigate the association between hallucinations, childhood trauma and the emotional content of hallucinations, experienced trauma and phenomenology of AVH were investigated in non-psychotic individuals and in patients with a psychotic disorder who hear voices. Method. A total of 127 non-psychotic individuals with frequent AVH, 124 healthy controls and 100 psychotic patients with AVH were assessed for childhood trauma. Prevalence of childhood trauma was compared between groups and the relation between characteristics of voices, especially emotional valence of content, and childhood trauma was investigated. Results. Both non-psychotic individuals with AVH and patients with a psychotic disorder and AVH experienced more sexual and emotional abuse compared with the healthy controls. No difference in the prevalence of traumatic experiences could be observed between the two groups experiencing AVH. In addition, no type of childhood trauma could distinguish between positive or negative emotional valence of the voices and associated distress. No correlations were found between sexual abuse and emotional abuse and other AVH characteristics. Conclusions. These results suggest that sexual and emotional trauma during childhood render a person more vulnerable to experience AVH in general, which can be either positive voices without associated distress or negative voices as part of a psychotic disorder. [ABSTRACT FROM AUTHOR]

Background. Cannabis use is associated with an earlier age at onset of psychotic illness. The aim of the present study was to examine whether this association is confounded by gender or other substance use in a large cohort of patients with a non-affective psychotic disorder. Method. In 785 patients with a non-affective psychotic disorder, regression analysis was used to investigate the independent effects of gender, cannabis use and other drug use on age at onset of first psychosis. Results. Age at onset was 1.8 years earlier in camtabis users compared to non-users, controlling for gender and other possible confounders. Use of other drugs did not have an additional effect on age at onset when cannabis use was taken into account. In 63.5 % of cannabis-using patients, age at most intense cannabis use preceded the age at onset of first psychosis. In males, the mean age at onset was 1.3 years lower than in females, controlling for cannabis use and other confounders. Conclusions, Cannabis use and gender are independently associated with an earlier onset of psychotic illness. Our findings also suggest that cannabis use may precipitate psychosis. More research is needed to clarify the neurobiological factors that make people vulnerable to this precipitating effect of cannabis. [ABSTRACT FROM AUTHOR]

BackgroundMovement disorders and schizotypy are both prevalent in unaffected siblings of patients with schizophrenia and both are associated with the risk of developing psychosis or schizophrenia. However, to date there has been no research into the association between these two vulnerability factors in persons with an increased genetic risk profile. We hypothesized that unaffected siblings of patients with non-affective psychosis have more movement disorders and schizotypy than healthy controls and that these co-occur.MethodIn a cross-sectional design we assessed the prevalence and inter-relationship of movement disorders and schizotypy in 115 unaffected siblings (mean age 27 years, 44% males) and 100 healthy controls (mean age 26 years, 51% males). Movement disorders were measured with the Abnormal Involuntary Movement Scale (AIMS), the Unified Parkinson Disease Rating Scale (UPDRS), the Barnes Akathisia Rating Scale (BARS), and one separate item for dystonia. Schizotypy was assessed with the Structured Interview for Schizotypy – Revised (SIS-R).ResultsThere were significant differences in the prevalence of movement disorders in unaffected siblings versus healthy controls (10% v. 1%, p<0.01) but not in the prevalence of schizotypy. Unaffected siblings with a movement disorder displayed significantly more positive and total schizotypy (p=0.02 and 0.03 respectively) than those without. In addition, dyskinesia correlated with positive schizotypy (r=0.51, p=0.02).ConclusionsThe association between movement disorders (dyskinesia in particular) with positive and total schizotypy in unaffected siblings suggests that certain vulnerability factors for psychosis or schizophrenia cluster in a subgroup of subjects with an increased genetic risk of developing the disease. [ABSTRACT FROM PUBLISHER]

BackgroundCannabis use is associated with psychosis and a range of subclinical psychiatric symptoms. The strength of this association depends on dosage and age at first use. The current study investigates whether level of cannabis exposure and starting age are associated with specific profiles of subclinical symptoms.MethodWe collected cross-sectional data from a young adult population sample by administering an online version of the Community Assessment of Psychic Experiences (CAPE). Cannabis exposure was quantified as the amount of Euros spent on cannabis per week and the age of initial cannabis use. The primary outcome measure was the odds ratio (OR) to belong to the highest 10% of scores on the total CAPE and the positive-, negative- and depressive symptom dimensions.ResultsIn 17 698 adolescents (mean age 21.6, s.d.=4.2 years), cannabis use at age 12 years or younger was strongly associated with a top 10% score on psychotic experiences [OR 3.1, 95% confidence interval (CI) 2.1–4.3] and to a lesser degree with negative symptoms (OR 1.7, 95% CI 1.1–2.5). The OR of heavy users (>€25/week) for negative symptoms was 3.4 (95% CI 2.9–4.1), for psychotic experiences 3.0 (95% CI 2.4–3.6), and for depressive symptoms 2.8 (95% CI 2.3–3.3).ConclusionsEarly start of cannabis use is strongly associated with subclinical psychotic symptoms and to a lesser degree with negative symptoms, while smoking high amounts of cannabis is associated with increased levels of all three symptom dimensions: psychotic, negative and depressive. These results support the hypothesis that the impact of cannabis use is age specific. [ABSTRACT FROM PUBLISHER]

Background: The association between schizophrenia and decreased vitamin D levels is well documented. Low maternal and postnatal vitamin D levels suggest a possible etiological mechanism. Alternatively, vitamin D deficiency in patients with schizophrenia is presumably (also) the result of disease-related factors or demographic risk factors such as urbanicity., Methods: In a study population of 347 patients with psychotic disorder and 282 controls, group differences in vitamin D concentration were examined. Within the patient group, associations between vitamin D, symptom levels and clinical variables were analyzed. Group × urbanicity interactions in the model of vitamin D concentration were examined. Both current urbanicity and urbanicity at birth were assessed., Results: Vitamin D concentrations were significantly lower in patients (B = -8.05; 95% confidence interval (CI) -13.68 to -2.42; p = 0.005). In patients, higher vitamin D concentration was associated with lower positive (B = -0.02; 95% CI -0.04 to 0.00; p = 0.049) and negative symptom levels (B = -0.03; 95% CI -0.05 to -0.01; p = 0.008). Group differences were moderated by urbanicity at birth (χ2 = 6.76 and p = 0.001), but not by current urbanicity (χ2 = 1.50 and p = 0.224). Urbanicity at birth was negatively associated with vitamin D concentration in patients (B = -5.11; 95% CI -9.41 to -0.81; p = 0.020), but not in controls (B = 0.72; 95% CI -4.02 to 5.46; p = 0.765)., Conclusions: Lower vitamin D levels in patients with psychotic disorder may in part reflect the effect of psychosis risk mediated by early environmental adversity. The data also suggest that lower vitamin D and psychopathology may be related through direct or indirect mechanisms.

Background: Thyroid autoimmunity has been associated with bipolar disorder (BD). However, results from previous studies on the seroprevalence of anti-thyroid peroxidase antibodies (TPO-abs) in BD are inconsistent., Objectives: The aim of the present study is to investigate whether the seroprevalence and titer levels of TPO-abs are related to BD., Method: TPO-abs were measured in plasma samples of 760 patients with bipolar disorder, 261 first-degree relatives and 363 controls by enzyme-linked immunosorbent assay (ELISA). To address methodological limitations of previous studies, we assessed clinical characteristics with several (self-reported) questionnaires to investigate whether TPO-abs positivity is related to particular clinical subgroups of BD patients. We performed an additional meta-analysis of seroprevalences of TPO-abs in BD patients including data from present and previous studies., Results: Seroprevalence or titer levels of TPO-abs did not significantly differ between patients with BD, their first-degree relatives, and controls. In BD patients, the prevalence of TPO-abs was unrelated to specific clinical factors, including lithium use. Our meta-analysis of twelve studies showed an overall odds ratio of 1.3 (CI 95 %: 0.7-2.3; p = 0.30), reaffirming the absence of an association of BD with TPO-abs., Conclusions: In the largest study of TPO-abs in BD to date, our findings indicate that TPO-abs are not associated with (the risk for) bipolar disorder., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: To prospectively assess the relationship between cannabis use and psychotic experiences over time., Method: In a longitudinal design, young adults aged 18-27years (N=705) gave online information on cannabis use and completed the Community Assessment of Psychic Experiences (CAPE). These measures were repeated after an interval ranging from six months to five years., Results: A decrease in cannabis use was associated with a decrease in total psychotic experiences (β=-0.096, p=0.01) after adjustment for a range of potential confounders. An increase in cannabis use was associated with increased positive symptoms at follow-up (β=0.07, p=0.02), but was not significantly associated with increases in Negative and Depression symptom scores, nor with the total number of psychotic experiences., Conclusion: In the first study to the association of change in cannabis use and psychotic experiences over time in the general population, we found an association between changes in cannabis use and changes in the frequency of psychotic experiences. While this does not prove a causal relationship between cannabis use and psychosis, our findings are consistent with studies suggesting that cessation of cannabis use may be beneficial in terms of reducing psychotic experiences., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Objective: To investigate the relationship between cannabis use and mental health., Method: A cross-sectional analysis in a sample of 17 698 individuals with a mean age of 22 years (SD: 4.2). Participants provided information on the amount and initial age of cannabis use and history of psychiatric hospitalizations through a web-based questionnaire. To quantify Δ(9) -tetrahydrocannabinol exposure, we operationalized cannabis use as the amount of money spent on cannabis per week over the last month. The odds ratio of having a history of psychiatric hospitalizations was the primary outcome measure., Results: We found a dose-response relationship between the amount of cannabis use and the odds for psychiatric hospitalization. Adjusted odds ratios for hospitalization increased with the amount of cannabis consumed from 1.6 (95% CI: 1.1-2.3) in incidental users to 6.2 (95% CI: 4.3-8.9) in heavy users (>€25/week). Our data suggested that concomitant drug use was an intermediate factor. Exposure to cannabis before the age of 12 years was found to carry a 4.8 (95% CI: 2.9-7.8) times increased odds for past psychiatric hospitalizations., Conclusion: We conclude that early and heavy uses of cannabis are each and independently associated with poor mental health in its users., (© 2010 John Wiley & Sons A/S.)

Background: Several studies have reported increased incidence rates of psychotic disorders among immigrant groups. Surprisingly, the cross-cultural validity of the diagnostic instruments that were used was never tested., Aims: To examine whether the incidence rates of psychotic disorders including schizophrenia among Moroccan immigrants to the Netherlands remain increased when a cultural sensitive diagnostic interview is used., Method: We compared first contact incidence with a standard and a cultural sensitive version of a diagnostic interview., Results: Age and gender adjusted relative risk for psychotic disorders and schizophrenia among Moroccans compared to native Dutch was 7.9 (95% CI 4.7-13.5) and 7.8 (95% CI 4.0-15.2) respectively based on the standard diagnostic interview and 4.2 (95% CI 2.3-7.9) and 1.5 (0.5-4.3) respectively based on the cultural sensitive version the diagnostic interview., Conclusion: First contact incidence of schizophrenia among Moroccans was no longer significantly higher than among ethnic Dutch people when a cultural sensitive diagnostic procedure was applied., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

Purpose: To determine whether the use of relapse prevention plans (RPPs) in nursing practice is an effective intervention in reducing relapse rates among patients with schizophrenia., Design and Methods: Experimental design. Patients with schizophrenia (or a related psychotic disorder) and nurses from three mental health organizations were randomly assigned to either an experimental (RPP) or control condition (care as usual). The primary outcome measure was the psychotic relapses in the research groups., Results: The relapse rates in the experimental and control groups after 1-year follow-up were 12.5% and 26.2%, respectively (p=. 12, ns). The relative risk of a relapse in the experimental versus the control group was 0.48 (ns)., Conclusions: In this study no statistically significant effects of the intervention were found. Effectiveness research in this area should be continued with larger sample sizes and longer follow-up periods.

In this article we describe the findings of an exploratory study into the application of early recognition and early intervention methods aimed at prevention of psychotic relapses in patients with schizophrenia. Following the results we described in part 1, we now focus specifically on factors which favourably or adversely affect the use of early recognition and early intervention methods. The following issues will be addressed: (i) information and education; (ii) attitude of health care professionals; (iii) the patient's insight; (iv) acceptance of illness; (v) motivation; (vi) other relevant patient characteristics; and (vii) continuity of care. Finally, the implications of the findings for the development of a nursing intervention protocol will be discussed.

In this article we describe the findings of an exploratory study into the application of early recognition and early intervention methods aimed at prevention of psychotic relapses in patients with schizophrenia. We addressed several models of symptom recognition plans and indicated how patients, healthcare professionals and other persons involved may be able to list and evaluate early warning signs systematically. We also paid attention to the role of the patient's family and to the potential effects of using early recognition and early intervention methods. In a follow-up article (part 2), we will focus more specifically on factors which favourably or adversely affect the use of early recognition and early intervention methods. The results of this exploratory study will be used to design an intervention protocol for nursing staff to serve as a tool for preparing symptoms recognition plans with the individual patient and his/her social network.

Objective: The authors assessed the effects of nutritional deficiency during the first trimester of pregnancy on brain morphology in patients with schizophrenia., Method: Nine schizophrenic patients and nine healthy comparison subjects exposed during the first trimester of gestation to the Dutch Hunger Winter were evaluated with magnetic resonance brain imaging, as were nine schizophrenic patients and nine healthy subjects who were not prenatally exposed to the famine., Results: Prenatal famine exposure in patients with schizophrenia was associated with decreased intracranial volume. Prenatal Hunger Winter exposure alone was related to an increase in brain abnormalities, predominantly white matter hyperintensities., Conclusions: Nutritional deficiency during the first trimester of gestation resulted in an increase in clinical brain abnormalities and was associated with aberrant early brain development in patients with schizophrenia. Stunted brain development secondary to factors that affect brain growth during the first trimester of gestation may thus be a potential risk factor for developing schizophrenia.

Second-trimester exposure to the 1957 A2 influenza pandemic is a controversial risk factor for schizophrenia. Two earlier studies of the Dutch psychiatric registry failed to find an increased risk for exposed subjects, but diagnostic misclassification within the spectrum of non-affective psychoses has not yet been ruled out as an explanation for the negative findings. Using an enlarged data-set we examined not only whether second-trimester exposure to the epidemic is associated with an increased risk of schizophrenia (ICD:295), but also whether it is associated with an increased risk of paranoid states (ICD:297) or other non-organic psychoses (ICD:298). In this retrospective cohort study the risks of the above-mentioned disorders were compared for those exposed and unexposed to A2 influenza during the second trimester of fetal life. The risks for the exposed subjects were not significantly higher than the risks for the unexposed. The power of the study to detect a significant increase in the risk of schizophrenia was sufficient. If the relative risk of a lifetime hospitalization for schizophrenia for second-trimester exposed subjects (born January-April 1958) is assumed to be 1.3, the power of the study would be 0.97 (alpha=0.05; one-tailed testing). If the relative risk for subjects born five months after the peak of the epidemic (mid-February to mid-March 1958) is assumed to be 1.88, as reported for England and Wales, the power of the study would be close to 1.00. This was the largest study of its kind in Europe: 275 subjects were born in the period January-April 1958 and had a lifetime hospitalization for schizophrenia. This study indicates that there is no relation between second-trimester exposure to the 1957 influenza pandemic and risk of non-affective psychosis in the Dutch population. It adds to a growing body of work which does not support an association between maternal influenza and schizophrenia.

We tested the hypothesis that maternal stress during pregnancy increases the risk of non-affective psychosis for the child. The concept of non-affective psychosis includes the ICD categories schizophrenic disorder, paranoid state and other non-organic psychosis. Data from the Dutch Psychiatric Registry were examined for an effect of the Flood Disaster of 1 February 1953. On this day, a gale caused a flood in the South-west of The Netherlands and 1835 people perished. Our study concerned the 19 villages where mortality exceeded 0.25%. The risk of non-affective psychosis for the cohort born in the period February-October 1953 was compared to the risks for the cohorts born in the corresponding periods of the previous and subsequent 2 years. The relative risk of non-affective psychosis for those exposed during gestation was 1.8 [95% Confidence Interval (CI): 0.9-3.5]. Thus, our study failed to demonstrate a significant association between prenatal exposure to maternal stress and risk of non-affective psychosis. The possible explanations for this finding are discussed.

Background: Reports of an increased incidence of schizophrenia in Afro-Caribbean immigrants to the UK are a matter of much debate. It is of interest, therefore, that in the 1970s and 1980s many immigrants from Surinam and The Netherlands Antilles have settled in The Netherlands. The purpose of our study was to compare the risk of a first admission for schizophrenia for Surinamese- and Antillean-born persons aged 15-39 years to that for their Dutch-born peers in the period 1983-1992., Methods: We used data from the Dutch psychiatric registry. Age-adjusted relative risks were calculated using Poisson regression analysis., Results: The risk for the immigrants was found to be three to four times higher than that for the Dutch-born. Age-adjusted relative risks were significantly higher for male than for female immigrants., Conclusions: The results provide evidence of an increased incidence in these immigrant groups and support similar findings on Afro-Caribbeans in the UK. Migration from Surinam was on such a large scale that selective migration of persons at risk for the disorder is unlikely to account entirely for these findings.