Family history of psychiatric disorders and age at first contact in schizophrenia: An epidemiological study

Predictors of treatment resistant schizophrenia: a systematic review of prospective observational studies

Treatment-resistant schizophrenia, affecting approximately 20-30% of patients with schizophrenia, has a high burden both for patients and healthcare services. There is a need to identify treatment resistance earlier in the course of the illness, in order that effective treatment, such as clozapine, can be offered promptly. We conducted a systemic literature review of prospective longitudinal studies with the aim of identifying predictors of treatment-resistant schizophrenia from the first episode. From the 545 results screened, we identified 12 published studies where data at the first episode was used to predict treatment resistance. Younger age of onset was the most consistent predictor of treatment resistance. We discuss the gaps in the literature and how future prediction models can identify predictors of treatment response more robustly.

Age of onset group characteristics in forensic patients with schizophrenia

This study aims to empirically identify age of onset groups and their clinical and background characteristics in forensic patients with schizophrenia. Hospital charts were reviewed of all 138 forensic patients with schizophrenia admitted to Geha Psychiatric Hospital that serves a catchment area of approximately 500,000 people, from 2000 to 2009 inclusive. Admixture analysis empirically identified early- (M = 19.99, SD = 3.31) and late-onset groups (M = 36.13, SD = 9.25). Early-onset was associated with more suicide attempts, violence before the age of 15, and early conduct problems, whereas late-onset was associated with a greater likelihood of violence after the age of 18 and marriage (P < 0.01). The current findings provide clinicians with a unique direction for risk assessment and indicate differences in violence between early- and late-onset schizophrenia, particularly co-occurrence of harmful behavioral phenotypes.

Schizophrenia and gut-flora related epigenetic factors

BACKGROUND

Schizophrenia (SZ) is a complex psychiatric disorder and the exact mechanisms that underpin SZ remain poorly understood despite decades of research. Genetic, epigenetic, and environmental factors are all considered to play a role. The importance of gut flora and its influence on the central nervous system has been recognized in recent years. We hypothesize that gut flora may be a converging point where environmental factors interact with epigenetic factors and contribute to SZ pathogenesis.

AIM

To summarize the current understanding of genetic and epigenetic factors and the possible involvement of gut flora in the pathogenesis of schizophrenia.

RESULTS

We searched PubMed and Medline with a combination of the key words schizophrenia, microbiome, epigenetic factors to identify studies of genetic and epigenetic factors in the pathogenesis of schizophrenia. Numerous genes that encode key proteins in neuronal signaling pathways have been linked to SZ. Epigenetic modifications, particularly, methylation and acetylation profiles, have been found to differ in individuals that present with SZ from those that don't. Gut flora may affect epigenetic modifications by regulation of key metabolic pathway molecules, including methionine, florate, biotin, and metabolites that are acetyl group donors. Despite a lack of direct studies on the subject, it is possible that gut flora may influence genetic and epigenetic expression and thereby contribute to the pathogenesis of SZ.

CONCLUSION

Gut flora is sensitive to both internal and environmental stimuli and the synthesis of some key molecules that participate in the epigenetic modulation of gene expression. Therefore, it is possible that gut flora is a converging point where environmental factors interact with genetic and epigenetic factors in the pathogenesis of SZ.

Sensory Gating Deficits and their Clinical Correlates in Drug-Free/Drug-Naive Patients with Schizophrenia

BACKGROUND

Sensory gating refers to "filtering" of irrelevant sensory input in the brain. Auditory sensory gating deficit has been considered as a marker of schizophrenia (SCZ) and assessed using P50 paired-click paradigm. We explore sensory gating deficits and their clinical correlates in SCZ.

MATERIALS AND METHODS

Twenty-five drug-free/drug-naïve patients with SCZ, whose psychopathology was assessed using Positive and Negative Syndrome Scale (PANSS), and 25 age-matched normal controls (NC) were recruited. ERP recordings were done using 40-channel event-related potential measuring system.

RESULTS

S2-S1 P50 amplitude difference, an index of sensory gating, was significantly lower in SCZ at F3 and F4 sites when compared to NC, indicating impaired gating. SCZ had significantly lower S1 amplitude compared to NC at these sites; S2 amplitudes were comparable. The sensory gating index also showed significant correlations with PANSS scores.

CONCLUSIONS

Our study reiterates sensory gating abnormalities in SCZ and confers a frontal specificity, implying specific deficits in early preattentive processes to them. Further, we suggest that gating deficits in SCZ are driven predominantly by abnormally small S1 rather than an inability to suppress S2. A correlation between sensory gating parameters and measures of psychopathology strengthens the hypothesis that abnormal response to sensory input may contribute to the psychopathology in SCZ.

Risk of hospitalization for psychiatric disorders among siblings and parents of probands with psychotic or affective disorders: A population-based study

Relatives of people diagnosed with psychotic and affective disorders have a higher risk of developing psychiatric disorders compared to the general population. This study examined the risk of hospitalization for psychiatric disorders among siblings and parents of patients affected with major psychiatric disorders. In this large population-based case-control study, 17,895 siblings and parents of 7671 hospitalized subjects with a diagnosis of narrowly defined schizophrenia (SZ), broadly defined SZ, schizoaffective disorder (SAD), bipolar disorder (BD) or unipolar depression (UD) were identified from the Israeli Psychiatric Hospitalization Registry and compared to 71,580 age and gender-matched controls from the Israeli Population Registry. Results indicated that siblings of people diagnosed with broadly defined SZ had a significantly higher risk of hospitalization for broadly (OR=11.06, 95% CI=7.93-15.41) and narrowly defined SZ (OR=10.59, 95% CI=6.8-16.33), SAD (OR=9.69, 95% CI=4.76-19.73), BD (OR=7.46, 95% CI=21.8-25.52), UD (OR=2.84, 95% CI=1.01-8.00), and other psychiatric disorders (OR=1.85, 95% CI=1.16-2.93), compared to controls. Siblings of patients with BD had a significantly higher risk of hospitalization for broadly defined SZ (OR=2.92, 95% CI=1.11-7.71) and for other psychiatric disorders (OR=6.67, 95% CI=2.17-20.50), compared to controls. Parents of probands with SZ were at significantly increased risk for all disorders examined, except for UD and ¨other psychiatric disorders¨, which was not significant in parents of probands with BD. This large, population-based study provides evidence for common genetic risk across different psychiatric disorders.

Investigation of the COMT Val158Met variant association with age of onset of psychosis, adjusting for cannabis use

OBJECTIVE

COMT rs4680 (Val158Met) genotype moderates the effect of cannabis on the age of onset of psychosis (AoP). We investigated the association between rs4680 and AoP, after adjusting for relevant covariates, in a Canadian Caucasian sample.

METHODS

One hundred and sixty-nine subjects with psychosis were recruited. AoP, defined as age of DSM-IV diagnosis was established using the Structured Clinical Interview for DSM-IV. Cannabis use data were collected using a self-report computerized questionnaire. DNA was extracted from saliva and genotyping of the COMT Val158Met polymorphism was done by SNaPshot and TaqMan assays. Kaplan-Meier analysis results are reported.

RESULTS

In those who had used cannabis before 20 years of age, rs4680 had a trend level effect on AoP (median AoP: Val/Val < Val/Met < Met/Met 19.37, 20.95, 21.24 years, respectively; log-rank test p = .051).

CONCLUSION

Our data are indicative of the need to further investigate the association between the COMT rs4680 variant and AoP in the context of adolescent cannabis use.

Is an Early Age at Illness Onset in Schizophrenia Associated With Increased Genetic Susceptibility? Analysis of Data From the Nationwide Danish Twin Register

Background

Early age at illness onset has been viewed as an important liability marker for schizophrenia, which may be associated with an increased genetic vulnerability. A twin approach can be valuable, because it allows for the investigation of specific illness markers in individuals with a shared genetic background.

Methods

We linked nationwide registers to identify a cohort of twin pairs born in Denmark from 1951 to 2000 (N = 31,524 pairs), where one or both twins had a diagnosis in the schizophrenia spectrum. We defined two groups consisting of; N = 788 twin pairs (affected with schizophrenia spectrum) and a subsample of N = 448 (affected with schizophrenia). Survival analysis was applied to investigate the effect of age at illness onset.

Findings

We found that early age at illness onset compared to later onset in the first diagnosed twin can be considered a major risk factor for developing schizophrenia in the second twin. Additionally, we found that the stronger genetic component in MZ twins compared to DZ twins is manifested in the proximity of assigned diagnosis within pairs.

Discussion

Early onset schizophrenia could be linked to a more severe genetic predisposition, indicating that age might be perceived as a clinical marker for genetic vulnerability for the illness.

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Early age at schizophrenia onset in one twin increases risk of illness in the second twin 4.7 times compared to a later onset.

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A stronger genetic predisposition may be needed to affect early schizophrenia onset in females compared to males.

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Genetic factors seem to play an important role in the proximity of assigned diagnosis within twin pairs.

The main aim of this study is to examine if early age at schizophrenia onset can be viewed as a clinical marker for increased genetic vulnerability in the illness. By linking the Danish Twin Register to other nationwide health registers we obtain accurate data regarding psychiatric diagnostic outcome in a complete twin population (> 31,000 twin pairs). Our study shows how an early age at illness onset in the first diagnosed twin in a pair is a major risk factor for developing schizophrenia in the second twin, underlining the importance of genetic factors in illness vulnerability.

Cannabis use, COMT, BDNF and age at first-episode psychosis

Although an interaction between COMT Val158Met and BDNF Val66Met polymorphisms with cannabis use has been proposed with respect to the risk of psychosis emergence, findings remain inconclusive. The aim of the present study was to evaluate the different possible associations between these polymorphisms and early cannabis use and the age at the first episode of psychosis. The relationship between age at psychosis onset and COMT Val158Met and BDNF Val66Met polymorphisms with early cannabis use as well as those factors associated with early cannabis use were investigated. Among 260 Caucasian first-episode psychosis patients, early cannabis use and the presence of the met-allele from the BDNF Val66Met polymorphism were significantly associated with age at psychosis onset. Furthermore, early cannabis use was significantly associated with male gender in the logistic regression analysis. These findings provide evidence of the important role of early cannabis use and the Val66Met BDNF polymorphism on age at psychosis onset and they point out to sex-specific differences in cannabis use patterns.

Genetic Association of TCF4 and AKT1 Gene Variants with the Age at Onset of Schizophrenia

BACKGROUND

Age at onset (AAO) is a known prognostic indicator for schizophrenia and is hypothesized to correlate with cognition and symptom severity. TCF4 and AKT1 are schizophrenia risk genes involved in cognitive functions. The current study examined the interactive effects of TCF4 and AKT1 variants with gender, family history of psychiatric disorders and ethnicity on the AAO of schizophrenia.

METHODS

This study consisted of 322 patients with schizophrenia meeting the DSM-IV criteria. Six single nucleotide polymorphisms (SNPs) of TCF4 (rs12966547, rs8766, rs2958182, rs9960767, rs10401120 and rs17512836) and seven AKT1 SNPs (rs2498804, rs3803304, rs2494732, rs3730358, rs1130214, rs2498784 and rs3803300) were genotyped using the TaqMan® SNP genotyping-based assays method. The relationship of AAO with each variant was investigated using analyses of covariance.

RESULTS

Among the TCF4 variants, rs12966547 (p = 0.024) and rs8766 (p = 0.021) were significantly associated with earlier AAO. We found a lower average AAO in patients with the AA genotype of rs12966547, while the CT genotype of rs8766 was demonstrated to have a protective effect on AAO. For rs8766, there was significant gene × gender interaction (p = 0.012) in influencing AAO. However, these results were not significant after false discovery rate correction. Significant gene × ethnicity interactions were observed to influence AAO (p < 0.05). The Kaplan-Meier curve of the minor AA genotype of rs12966547 displayed a significant trend (p = 0.008) for onset after 19 years of age. Similarly, the minor CC genotype of rs8766 showed a significantly (p = 0.034) lower AAO compared to the TT genotype.

CONCLUSION

Our analyses suggest that individual risk genotypes may influence the risk of schizophrenia in an age-specific manner.

Association of age-of-onset groups with GWAS significant schizophrenia and bipolar disorder loci in Romanian bipolar I patients

We investigated the influence of the age-of-onset (AO) on the association of 45 loci conferring risk for bipolar disorder (BP) and schizophrenia with BP-type-I in a Romanian sample (461 patients, 436 controls). The AO-analysis implicated the EGFR gene, as well as loci in other genes, in the AO variation of BP-type-I and revealed for the first time the link between BP-type-I and risk variants considered specific to schizophrenia (polymorphisms in MMP16/RIPK2 and CNNM2 genes).

Age at onset mixture analysis and systematic comparison in schizophrenia spectrum disorders: Is the onset heterogeneity dependent on heterogeneous diagnosis?

A major obstacle to the identification of the neurobiological correlates of schizophrenia is the substantial diagnostic heterogeneity of this disorder. Dividing schizophrenia into "early" and "late" subtypes may reduce heterogeneity and facilitate identification of biomarkers related to this disease. Our objective was to assess the presence of different sub-groups in schizophrenia by age at onset analysis. The participants in this study were 612 unrelated patients with schizophrenia. Admixture analysis was applied in order to identify a model of separate normal distributions of age at onset characterized by different means, variances and population proportions to evaluate the effect of winter birth and ethnicity on early onset schizophrenia. The best-fitting model suggested three subgroups with means and standard deviations of 17.11 ± 2.09, 21.96 ± 3.43 and 30.02 ± 7.1 years, comprising 34.6%, 42.6% and 22.8% of the sample respectively. We considered as predictors of early onset schizophrenia: male gender, winter birth, white ethnicity and positive family history for psychiatric disorders. Earlier onset was significantly associated with male gender. We also compared our age at onset distribution with those published in other studies and we found significant differences with several studies suggesting heterogeneity in age at onset that is likely influenced by diagnostic heterogeneity in applying the DSM-IV criteria. Overall, our study showed that a typical early onset schizophrenia patient is more likely to be a white male with cannabis abuse and positive family history of psychiatric disorders. The heterogeneity in reporting age at onset across different studies suggests the application of more stringent criteria in diagnosing schizophrenia.

Family patterns of psychopathology in psychiatric disorders

OBJECTIVE

Familial loading and crucial outcomes of family history of psychopathology in psychiatric disorders have long been recognized. There has been ample literature providing convincing evidence for the importance of family psychopathology in development of emotional disturbances in children as well as worse outcomes in the course of psychiatric disorders. More often, maternal psychopathology seems to have been an issue of interest rather than paternal psychopathology while effects of second-degree familiality have received almost no attention. In this study, we addressed the relations between affected first- and second-degree relatives of probands and categories of psychiatric disorders.

METHOD

Subjects were 350 hospitalized psychiatric inpatients, consecutively admitted to psychiatry clinics in Van, Turkey. Mean age was 34.16 (SD±12) and 51.4% of the sample consisted of male patients. Assessment of psychopathology in psychiatric probands was conducted based on DSM-IV TR. Familial loading of psychiatric disorders amongst first- and second-degree relatives of patients were initially noted primarily relying on patients' retrospective reports, and confirmed by both phone call and following official health records via the Medical Knowledge System. We analyzed the data using latent class analysis approach.

RESULTS

We found four patterns of familial psychopathology. Latent homogeneous subsets of patients due to familial characteristics were as paternal kinship psychopathology with schizophrenia, paternal kinship psychopathology with mood disorders, maternal kinship psychopathology and core family psychopathology.

CONCLUSION

Family patterns were critical to exerting variation in psychiatric disorders of probands and affected relatives. Probands with a core family pattern of psychopathology exhibited the most colorful clinical presentations in terms of variation in psychopathology. We observed a specificity of intergenerational transmission of psychiatric disorders when family patterns of psychopathology were taken into consideration, even second-degree relatives of psychiatric probands.

Commingling analysis of age-of-onset in bipolar I disorder and the morbid risk for major psychoses in first degree relatives of bipolar I probands

BACKGROUND

Age-of-onset (AO) is increasingly used in molecular genetics of bipolar I disorder (BP-I) as a phenotypic specifier with the goal of reducing genetic heterogeneity. However, questions regarding the cut-off age for defining early onset (EO), as well as the number of onset groups characterizing BP-I have emerged over the last decade with no definite conclusion. The aims of this paper are: 1) to see whether a mixture of three distributions better describes the AO of BP-I than a mixture of two distributions in different independent samples; 2) to compare the morbid risk (MR) for BP-I and for major affective disorders and schizophrenia in first degree relatives of BP-I probands by proband onset group derived from commingling analysis, since the MR to relatives is a trait with strong genetic background.

METHODS

We applied commingling (admixture) analysis to the AO of three BP-I samples from Romania (n=621), Germany (n=882), and Poland (n=354). Subsequently, the morbid risk (MR) for BP-I and for major psychoses (BP-I, BP-II, Mdd-UP, schizoaffective disorders, schizophrenia) was estimated in first degree relatives by proband AO-group derived from admixture analysis in the Romanian sample.

RESULTS

In the three independent samples and in the combined sample two- and three-AO-group distributions fitted the empirical data equally well. The upper EO limit varied between 21 and 25 years from sample to sample. The MR for both BP-I and for all major psychoses was similar in first degree relatives of EO probands (AO≤21) and in relatives of intermediate-onset probands (AO=22-34). Significant MR differences appeared only when comparing the EO group to the late-onset (LO) group (AO>34). Similar to Mdd-UP and schizophrenia, a significant MR decrease in proband first degree relatives was visible after proband AO of 34 years. Under the three-AO-group classification the MR for both BP-I and all major psychoses in first degree relatives did not differ by relative sex in any proband AO-group. Under the two-AO-group classification female relatives of LO probands (AO>24) had a significantly higher MR for all major psychoses than male relatives, while there was no sex difference for the relatives of EO probands.

LIMITATIONS

MR was not computed in the German and Polish samples because family data were not available and 34% of the relatives of the Romanian probands were not available for direct interview.

CONCLUSION

Similar to other clinical traits, the MR for major psychoses to relatives failed to support a three-AO-group classification in BP-I suggesting that this is not more useful for the molecular analysis than a two-AO-group classification.

Central registry in psychiatry: A structured review

BACKGROUND

Central registry in psychiatry is being practiced in few countries and has been found useful in research and clinical management. Role of central registry has also expanded over the years.

MATERIALS AND METHODS

All accessible internet database Medline, Scopus, Embase were accessed from 1990 till date. Available data were systematically reviewed in structured manner and analyzed.

RESULTS

Central registry was found useful in epidemiological analysis, association studies, outcome studies, comorbidity studies, forensic issue, effective of medication, qualitative analysis etc..

CONCLUSION

Central registry proves to be effective tool in quantitative and qualitative understanding of psychiatry practice. Findings of studies from central registry can be useful in modifying best practice and evidence based treatment in psychiatry.

The Longitudinal Youth at Risk Study (LYRIKS)--an Asian UHR perspective

Numerous studies have been published on the psychosis prodrome and have explored a wide array of its many aspects. However, the set of risk factors identified by these various efforts is not homogenous across studies. This could be due to unique population factors or relatively small sample sizes. Only few studies were conducted on Asian populations, whose socio-cultural characteristics differ - in some cases remarkably - from those in western populations. Singapore is a highly dense city-state in South-east Asia, with low rates of substance abuse. The Longitudinal Youth at Risk Study (LYRIKS) commenced in Singapore in 2008, designed to comprehensively assess a group of ultra high risk (UHR) individuals and identify clinical, social, neuropsychological and biological risk factors unique to the local population. 173 UHR individuals were recruited from this single-site study over 4 years. Here, we detail aspects of the study methodology and report on the baseline social and clinical characteristics of the sample population. 78% of the UHR sample suffered from a psychiatric disorder, with Major Depressive Disorder present in more than half of the sample. The mean Global Assessment of Functioning (GAF) score was 57.4, which indicated a moderate level of impairment. Although the recruited sample did not differ significantly by social and clinical characteristics when compared to previously published reports, the conversion rate to psychosis was 3.5% (n=6) at 6 months. Follow-up measures are currently underway to assess longitudinal incidence of psychosis and impact of risk factors on cognition, functioning and remission.

Inefficient cerebral recruitment as a vulnerability marker for schizophrenia

BACKGROUND

Patients with schizophrenia and their first-degree relatives exhibit both abnormally diminished and increased neural activation during cognitive tasks. In particular, excessive task-related activity is often observed when tasks are easy, suggesting that inefficient cerebral recruitment may be a marker of vulnerability for schizophrenia. This hypothesis might best be tested using a very easy task, thus avoiding confounding by individual differences in task difficulty.

METHOD

Eighteen people with schizophrenia, 18 unaffected full siblings of patients with schizophrenia and 26 healthy controls performed an easy auditory target-detection task in a 3-T magnetic resonance imaging (MRI) scanner. Groups were matched for accuracy on the task. Blood oxygen level-dependent (BOLD) responses to non-target stimuli in participants with vulnerability for schizophrenia (siblings and patients) were compared with those of healthy controls, and those of patients with those of unaffected siblings. BOLD responses to targets were compared with baseline, across groups.

RESULTS

Subjects with vulnerability for schizophrenia showed significant hyperactivation to non-targets in brain areas activated by targets in all groups, in addition to reduced deactivation to non-targets in areas suppressed by targets in all groups. Siblings showed greater activation than patients to non-targets in the medial frontal cortex. Patients exhibited significantly longer reaction times (RTs) than unaffected siblings and healthy controls.

CONCLUSIONS

Inefficient cerebral recruitment is a vulnerability marker for schizophrenia, marked by reduced suppression of brain areas normally deactivated in response to task stimuli, and increased activation of areas normally activated in response to task stimuli. Moreover, siblings show additional activation in the medial frontal cortex that may be protective.

Modelling the contribution of family history and variation in single nucleotide polymorphisms to risk of schizophrenia: a Danish national birth cohort-based study

BACKGROUND

Epidemiological studies indicate that having any family member with schizophrenia increases the risk of schizophrenia in the probands. However, genome-wide association studies (GWAS) have accounted for little of this variation. The aim of this study was to use a population-based sample to explore the influence of single-nucleotide polymorphisms (SNPs) on the excess schizophrenia risk in offspring of parents with a psychotic, bipolar affective or other psychiatric disorder.

METHOD

A nested case-control study with 739 cases with schizophrenia and 800 controls. Their parents and siblings. Information from national health registers and GWAS data from the national neonatal biobank.

RESULTS

Offspring schizophrenia risk was elevated in those whose mother, father or siblings had been diagnosed with schizophrenia or related psychosis, bipolar affective disorder or any other psychiatric disorder. The rate ratio was 9.31 (3.85; 22.44) in offspring whose 1st degree relative was diagnosed with schizophrenia. This rate ranged between 8.31 and 11.34 when adjusted for each SNP individually and shrank to 8.23 (3.13; 21.64) when adjusted for 25% of the SNP-variation in candidate genes. The percentage of the excess risk associated with a family history of schizophrenia mediated through genome-wide SNP-variation ranged between -6.1%(-17.0%;2.6%) and 4.1%(-3.9%;15.2%). Analogous results were seen for each parent and for histories of bipolar affective and other psychiatric diagnoses.

CONCLUSIONS

The excess risk of schizophrenia in offspring of parents who have a psychotic, bipolar affective or other psychiatric disorder is not currently explained by the SNP variation included in this study in accordance with findings from published genetic studies.

Familial aggregation of schizophrenia: the moderating effect of age at onset, parental immigration, paternal age and season of birth

AIMS

An abundance of evidence has firmly established the familial aggregation of schizophrenia. The aim of this study was to examine how age at onset, parental characteristics and season of birth modify the familiality in schizophrenia.

METHODS

A population-based cohort was created by linking the Swedish Multi-Generation and Hospital Discharge Registers. Among 5,075,998 full siblings born between 1932 through to 1990, 16,346 cases of schizophrenia were identified. Familial aggregation was measured by the sibling recurrence-risk ratio, defined as the risk of schizophrenia among full siblings of schizophrenia patients compared with the risk among siblings of unaffected people.

RESULTS

We found a statistically significantly lower recurrence-risk ratio in siblings of later onset cases (7.2; 95% confidence interval (95% CI) 6.7-7.9) than of early onset cases (10.8; 95% CI 9.4-12.2). A lower recurrence-risk ratio was observed among offspring to fathers above 40 years (6.3; 95% CI 5.3-7.3) as compared with offspring of younger fathers (8.6; 95% CI 8.0-9.3). Further, among offspring to parents born outside Sweden the recurrence-risk ratio was statistically significantly lower (maternal immigrants 4.8; 95% CI 4.0-5.7, paternal immigrants 5.7; 95% CI 4.6-6.9) than among offspring to parents born in Sweden.

CONCLUSIONS

The familial aggregation of schizophrenia was reduced by higher age at onset, advancing paternal age and immigrant status of parents.

Effects of cannabis use on age at onset in schizophrenia and bipolar disorder

BACKGROUND

Cannabis use may decrease age at onset in both schizophrenia and bipolar disorder, given the evidence for substantial phenotypic and genetic overlap between both disorders.

METHODS

766 patients, aged 16 to 65 years, were assessed with the Composite International Diagnostic Interview (CIDI) for substance abuse/use. 676 subjects were diagnosed with schizophrenia and 90 subjects with bipolar disorder. The influence of cannabis use on age at onset in both schizophrenia and bipolar disorder was examined using regression analysis.

RESULTS

Cannabis and other substance use was more frequent in patients with schizophrenia compared to the bipolar group. Both cannabis use and a schizophrenia diagnosis predicted earlier age at onset. There was a significant interaction between cannabis use and diagnosis, cannabis having a greater effect in bipolar patients. Age at onset in users of cannabis was comparable in both diagnostic groups whereas bipolar non-users were significantly older than schizophrenia non-users at onset.

CONCLUSION

Cannabis use may decrease age at onset in both schizophrenia and bipolar patients and reduce the effect of diagnosis. This is consistent with the view that cannabis use may unmask a pre-existing genetic liability that is partly shared between patients with schizophrenia and bipolar disorder.

The METEOR study of diabetes and other metabolic disorders in patients with schizophrenia treated with antipsychotic drugs. I. Methodology

Patients with schizophrenia present a two- to three-fold higher prevalence of diabetes, of metabolic syndrome and of cardiovascular morbidity. The reason for this increased prevalence may involve intrinsic vulnerability, lifestyle factors and iatrogenic effects of antipsychotic drugs. The objective of this multinational, cross-sectional, pharmacoepidemiological study was to determine the prevalence of diabetes, lipid disorders, obesity, hypertension and the metabolic syndrome in patients with schizophrenia treated with antipsychotic drugs. Particular attention was taken to acquire data on a wide a range as possible of demographic, clinical and lifestyle variables that may influence the risk of metabolic disorders, which were taken into account in the calculation of prevalence data by propensity scoring. The study included 2270 subjects from 16 European countries, predominantly from Central and Eastern Europe. The proportion of subjects presenting the pathologies of interest was relatively high, ranging from 28% for glycaemic disorders to 70% for lipid disorders.

Catechol-O-Methyltransferase (COMT) Val158Met variations and cannabis use in first-episode non-affective psychosis: clinical-onset implications

New models of interaction between genetic and environmental factors have been proposed to explain the pathogenesis of schizophrenia. The Val158Met polymorphism of the COMT (Catechol-O-Methyltransferase) gene, involved in dopamine regulation and related to negative symptoms, has been previously thought to interact with cannabis use in the modulation of risk of psychosis. The aim of the study was to explore the existence of an interaction between COMT genotype and cannabis use in early stages of psychosis and its effects on the age of onset in a representative group of first-episode psychosis patients. Age of onset, DUP (Duration of Untreated Psychosis) and cannabis use (regular user versus sporadic or non-user) were assessed in 169 Caucasian patients with a first-episode schizophrenia spectrum disorder. COMT polymorphism was typed using PCR of the relevant region followed by digestion with NlaIII and electrophoresis. A multivariate ANCOVA was performed with DUP and age of onset as dependent variables, cannabis and the COMT genotype as fixed factors, and gender as a covariate. The MANCOVA was significant for age of onset and DUP. Cannabis users had a significant earlier age of onset. Age of onset was later in the Met homozygote group (non-significant). The cannabis-COMT interaction showed a significant effect on both DUP and age of onset. Post hoc analyses showed that differences between genotypes were only present in the non-users' group. Based on these results, the use of cannabis could exert a modulator effect on the genotype, suppressing the delay effect for the age of onset in the case of the Met allele patients.

Beyond the first episode: candidate factors for a risk prediction model of schizophrenia

Many early psychosis services are financially compromised and cannot offer a full tenure of care to all patients. To maintain viability of services it is important that those with schizophrenia are identified early to maximize long-term outcomes, as are those with better prognoses who can be discharged early. The duration of untreated psychosis remains the mainstay in determining those who will benefit from extended care, yet its ability to inform on prognosis is modest in both the short and medium term. There are a number of known or putative genetic and environmental risk factors that have the potential to improve prognostication, though a multivariate risk prediction model combining them with clinical characteristics has yet to be developed. Candidate risk factors for such a model are presented, with an emphasis on environmental risk factors. More work is needed to corroborate many putative factors and to determine which of the established factors are salient and which are merely proxy measures. Future research should help clarify how gene-environment and environment-environment interactions occur and whether risk factors are dose-dependent, or if they act additively or synergistically, or are redundant in the presence (or absence) of other factors.

Etiological and clinical features of childhood psychotic symptoms: results from a birth cohort

CONTEXT

It has been reported that childhood psychotic symptoms are common in the general population and may signal neurodevelopmental processes that lead to schizophrenia. However, it is not clear whether these symptoms are associated with the same extensive risk factors established for adult schizophrenia.

OBJECTIVE

To examine the construct validity of children's self-reported psychotic symptoms by testing whether these symptoms share the risk factors and clinical features of adult schizophrenia.

DESIGN

Prospective, longitudinal cohort study of a nationally representative birth cohort in Great Britain.

PARTICIPANTS

A total of 2232 twelve-year-old children followed up since age 5 years (retention, 96%). Main Outcome Measure Children's self-reported hallucinations and delusions.

RESULTS

Children's psychotic symptoms are familial and heritable and are associated with social risk factors (eg, urbanicity); cognitive impairments at age 5; home-rearing risk factors (eg, maternal expressed emotion); behavioral, emotional, and educational problems at age 5; and comorbid conditions, including self-harm.

CONCLUSIONS

The results provide a comprehensive picture of the construct validity of children's self-reported psychotic symptoms. For researchers, the findings indicate that children who have psychotic symptoms can be recruited for neuroscience research to determine the pathogenesis of schizophrenia. For clinicians, the findings indicate that psychotic symptoms in childhood are often a marker of an impaired developmental process and should be actively assessed.

Parental psychiatric hospitalisation and offspring schizophrenia

The risk of schizophrenia has been linked with a family history of schizophrenia and less strongly with other psychiatric disorders in family members. Using data from the Copenhagen Perinatal Cohort and from the Danish Psychiatric Case Register, we studied the relationship between offspring risk of schizophrenia and a range of psychotic and non-psychotic psychiatric diagnoses in parents. Psychiatric admission data after 1969 were available for 7047 cohort members born between 1959 and 1961, and for 7006 mothers and 6993 fathers. Univariate analysis showed that neurosis, alcohol and substance dependence in both parents were associated with elevated risk of offspring schizophrenia; in addition, maternal schizophrenia, affective disorder and personality disorder were associated with elevated risk. Controlling for parental age, parental social status, and parental psychiatric co-diagnosis, offspring risk of schizophrenia was associated with maternal schizophrenia (OR = 15.41 with 95% CI 5.96-39.81) and, independently, with paternal hospitalisation with neurosis (OR = 5.90 with 95% CI 2.23-15.62). The risk of schizophrenia associated with paternal neurosis remained significant after excluding offspring of parents with non-affective psychosis from the sample. These findings suggest that genetic and family studies should not only focus on parental history of schizophrenia since the simple distinction between positive and negative family history could not accurately describe offspring risk in this sample.

Employment status amongst those with psychosis at first presentation

INTRODUCTION

Employment is generally beneficial to health and quality of life. Despite many advances in the treatment of psychosis there are continuing reports of high levels of unemployment. In most studies of first episode psychosis (FEP) only rudimentary rates of employment are provided. We sought to establish the prevalence of employment amongst those with FEP from a geographically defined area, to compare employment categories for differences in demographical and clinical characteristics and finally, to examine factors associated with employment.

METHODS

All cases of FEP were assessed from a defined suburban area with a structured clinical interview for DSM-III-R diagnosis and a standardised assessment protocol. Employment status was divided into employed, non-labour force work and unemployed.

RESULTS

Of 162 cases of psychosis, those employed (46%) were indistinguishable from those in non-labour force work (21%). Those unemployed (33%) had significantly longer DUP, more negative symptoms and lower quality of life than those engaged in non-labour force work or those employed. Having a non-affective psychosis (chi(2) = 0.05, OR = 1.2; 95% CI 1.0, 1.4) was associated with being unemployed at presentation. Better (beta = -0.2, P = 0.00) academic premorbid adjustment was associated with being employed at presentation.

CONCLUSIONS

Although 67% of those with FEP from a geographically defined area are engaged in purposeful work, the rate of unemployment is nine times the local rate. Longer DUP and negative symptoms are associated with unemployment at presentation. Standardised reporting of employment status would greatly assist research in this area.

A population-based examination of the role of years of education, age of onset, and sex on the course of schizophrenia

This article examines how premorbid years of education and age of onset relate to the course of schizophrenia in a population-based cohort. All first and subsequent cases who were hospitalized with schizophrenia (1988-92, followed up until 1996) and completed their formal education at least 1 year before hospitalization (n=2135) were extracted from the Israeli National Psychiatric Hospitalization Registry. Results, based on hierarchical moderated regression models showed that age of onset predicted the course with greater consistency and magnitude than years of education. Years of education predicted the age of first hospitalization among males. Years of education and age of first hospitalization significantly interacted to predict the length of first stay and average number of days hospitalized over the course for males. The interaction showed that for males less education predicted poorer hospitalization outcomes if an earlier onset occurred. Together, the results suggest that less educated, early onset males are at higher risk of a poorer course.

Dissection of phenotype reveals possible association between schizophrenia and Glutamate Receptor Delta 1 (GRID1) gene promoter

Recent linkage and association data have implicated the Glutamate Receptor Delta 1 (GRID1) locus in the etiology of schizophrenia. In this study, we sought to test whether variants in the promoter region are associated with this disorder. The distribution of CpG islands, which are known to be relevant for transcriptional regulation, was computationally determined at the GRID1 locus, and the putative transcriptional regulatory region at the 5'-terminus was systematically tagged using HapMap data. Genotype analyses were performed with 22 haplotype-tagging single nucleotide polymorphisms (htSNPs) in a German sample of 919 schizophrenia patients and 773 controls. The study also included two SNPs in intron 2 and one in intron 3 which have been found to be significantly associated with schizophrenia in previous studies. For the transcriptional regulatory region, association was obtained with rs3814614 (p=0.0193), rs10749535 (p=0.0245), and rs11201985 (p=0.0222). For all further analyses, the patient samples were divided into more homogeneous subgroups according to sex, age at onset, positive family history of schizophrenia and lifetime history of major depression. The p-value of the schizophrenia association finding for the three markers decreased by approximately one order of magnitude, despite the reduction in the total sample size. Marker rs3814614 (unadjusted p=0.0005), located approximately 2.0 kb from the transcriptional start point, also withstood a two-step correction for multiple testing (p=0.030). No support was obtained for previously reported associations with the intronic markers. Our results suggest that genetic variants in the GRID1 transcriptional regulatory region may play a role in the etiology of schizophrenia, and that future association studies of schizophrenia may require stratification to ensure more homogeneous patient subgroups.

Familial and sporadic schizophrenia: a comparison of somatic diseases and abuse in patients and their relatives

OBJECTIVE

Comparing schizophrenia patients on the basis of familial and non-familial forms of the illness provides a promising approach to the identification of genes involved in schizophrenia. The aim of this study was to search for somatic factors that discriminate between patients with and without a family history of schizophrenia and between their relatives.

METHODS

Ninety-five schizophrenia patients were structurally interviewed about mental and physical health and alcohol and substance use in themselves and their families. Besides this, complementary information was obtained from the patients' case records. Patients with (41%) and without (59%) a family history were then compared.

RESULTS

The main differences were found in the patients' relatives. Fewer patients with a family history, compared with patients without a family history, had relatives with cancer (p = 0.002). Conversely, there was a tendency towards that more patients with a family history, compared with patients without a family history, had relatives with cardiac infarction (p = 0.05).

CONCLUSION

The genetic risk associated with schizophrenia seems to cosegregate into a factor(s) that protects against cancer and possibly also increases the risk for cardiac infarction.

The validity of the family history screen for assessing family history of mental disorders

There is a need to collect psychiatric family history information quickly and economically (e.g., for genome-wide studies and primary care practice). We sought to evaluate the validity of family history reports using a brief screening instrument, the Family History Screen (FHS). We assessed the validity of parents' reports of seven psychiatric disorders in their adult children probands from the Dunedin Study (n = 959, 52% male), using the proband's diagnosis as the criterion outcome. We also investigated whether there were informant characteristics that enhanced accuracy of reporting or were associated with reporting biases. Using reports from multiple informants, we obtained sensitivities ranging from 31.7% (alcohol dependence) to 60.0% (conduct disorder) and specificities ranging from 76.0% (major depressive episode) to 97.1% (suicide attempt). There was little evidence that any informant characteristics enhanced accuracy of reporting. However, three reporting biases were found: the probability of reporting disorder in the proband was greater for informants with versus without a disorder, for female versus male informants, and for younger versus older informants. We conclude that the FHS is as valid as other family history instruments (e.g., the FH-RDC, FISC), and its brief administration time makes it a cost-effective method for collecting family history data. To avoid biasing results, researchers who aim to compare groups in terms of their family history should ensure that the informants reporting on these groups do not differ in terms of age, sex or personal history of disorder.

How should we construct psychiatric family history scores? A comparison of alternative approaches from the Dunedin Family Health History Study

BACKGROUND

There is increased interest in assessing the family history of psychiatric disorders for both genetic research and public health screening. It is unclear how best to combine family history reports into an overall score. We compare the predictive validity of different family history scores.

METHOD

Probands from the Dunedin Study (n=981, 51% male) had their family history assessed for nine different conditions. We computed four family history scores for each disorder: (1) a simple dichotomous categorization of whether or not probands had any disordered first-degree relatives; (2) the observed number of disordered first-degree relatives; (3) the proportion of first-degree relatives who are disordered; and (4) Reed's score, which expressed the observed number of disordered first-degree relatives in terms of the number expected given the age and sex of each relative. We compared the strength of association between each family history score and probands' disorder outcome.

RESULTS

Each score produced significant family history associations for all disorders. The scores that took account of the number of disordered relatives within families (i.e. the observed, proportion, and Reed's scores) produced significantly stronger associations than the dichotomous score for conduct disorder, alcohol dependence and smoking. Taking account of family size (i.e. using the proportion or Reed's score) produced stronger family history associations depending on the prevalence of the disorder among family members.

CONCLUSIONS

Dichotomous family history scores can be improved upon by considering the number of disordered relatives in a family and the population prevalence of the disorder.

Cognitive remediation therapy (CRT) for young early onset patients with schizophrenia: an exploratory randomized controlled trial

BACKGROUND

Schizophrenia with an onset in adolescence is known to be associated with a poorer outcome and cognitive difficulties. These impairments have an impact on quality of life and represent treatment targets. Cognitive remediation therapy (CRT) attempts to improve cognitive deficits by teaching information processing strategies through guided mental exercises. The objective of this study is to evaluate the efficacy of CRT in alleviating cognitive deficits compared to treatment as usual and explore the mediating and moderating effects of cognitive improvement.

METHOD

Single-blind randomized controlled trial with two groups, one receiving CRT (N21) and the other standard care (N19) assessed at baseline, 3 months (post therapy) and follow-up (3 months post therapy). Participants were recruited from specialist inpatient and community mental health services and were young patients with recent onset schizophrenia (average age of 18) and evidence of cognitive and social behavioural difficulties. The intervention was individual cognitive remediation therapy delivered over a period of 3 months with at least three sessions per week. The main outcome measures were cognition (memory, cognitive flexibility and planning) and secondary outcomes (symptoms, social contacts and self-esteem).

RESULTS

Compared to standard care, CRT produced significant additional improvements in cognitive flexibility as measured by the Wisconsin Card Sort Test (WCST). Therapy moderated the effects of improved planning ability on symptoms such that improvements only had a beneficial effect when they were achieved in the context of CRT. Improvements in cognition in all domains had a direct effect on social functioning and improvements in WCST had a direct effect on overall symptom improvement.

CONCLUSIONS

Cognitive remediation therapy can contribute to the improvement in WCST even in adolescents. The changes in cognitive outcomes also contributed to improvements in functioning either directly or solely in the context of CRT. Evidence of the mediator and moderator effects of cognitive changes should lead to more effective therapy development.

A population based elaboration of the role of age of onset on the course of schizophrenia

BACKGROUND

Despite suggestions that an earlier age of onset and being male confer to a poorer course of schizophrenia, evidence regarding when these effects are most salient appears to be ambiguous.

AIMS

To examine the relationship of age of first hospitalization and sex with the course of hospitalization in a population based cohort.

METHOD

All first admissions for schizophrenia in a national population based cohort in Israel from 1978 to 1992 were followed through 1996 (n=12,071) using data from the National Psychiatric Hospitalization Case Registry of the State of Israel, a complete national registry of psychiatric admissions. Recursive partitioning was conducted to empirically determine cut-off points for age groups showing the greatest difference on the variables of interest.

RESULTS

A younger age of first hospital admission was associated with a greater likelihood of having more than one hospital admission, longer first admissions, more hospital admissions and more inpatient days per year. Of patients with age of first admission below 17, 82.5% had more than one admission which decreased for subsequent age groups to 73.54% (18-28), 69.36% (29-31), 62.88% (32-45), and 50.77% (over 45). Men had an earlier first admission than women, and had slightly more cut-off values. Irrespective of sex, the relationship between age at first admission and later hospitalization conformed to a linear trend.

CONCLUSIONS

An earlier onset corresponds linearly with the severity of the course of illness and appears to have prognostic value.

Misattributed paternity. A bias in the family studies in schizophrenia?

One of the few consistent findings originating from the research in schizophrenia is the high familiality in the transmission of the disease. Data from family studies have been used in the attempt to disentangle the genetic from the environmental components of this familiality. The analysis of this body of research has led several groups to the conclusion that there is a higher heritability of schizophrenia through the female rather than the male lineage and that the concordance for the illness is higher among DZ twins than siblings. These assumptions have generated a flurry of hypotheses on the aetiology of schizophrenia. This article demonstrates that the above findings can instead be explained as the result of an artefact originating from the uncertainty in the paternity of the probands. None of the studies has in fact considered that, in some populations, up to 30% of children are not genetically related to their putative fathers. This issue is potentially important for the genetic studies in all pathologies, but has a particular relevance for schizophrenia, due to the high profile acquired by family studies in the research for the aetiology in this illness. The conclusions reached in most family studies in schizophrenia should therefore be reappraised.

Foetal origins of schizophrenia: testable hypotheses of genetic and environmental influences

Although four-fifths of the variance in schizophrenia is attributable to genes, the locus of genetic defect remains elusive. Moreover, genetic investigation provides little detail, beyond suggesting that the contribution of genes is complex, probably polygenic and unlikely to be sufficient in most cases to allow expression of the syndrome (Vincente & Kennedy, 1997). Some apparently genetic effects also need explanation in a more complex model. Population studies show that schizophrenia is more likely to be inherited from an affected mother than from an affected father (Byrne et al, 2002), and increasing paternal age confers increased risk (Malaspina et al, 2001). Other effects are difficult to explain in conventional genetic terms: season of birth, urbanicity and migration are consistently reported to affect rates of schizophrenia in adulthood (Mortensen et al, 1999; Cantor-Graae et al, 2003), as is prenatal exposure to famine (Susser & Lin, 1992). Hypotheses of schizophrenia must be able to account for this interplay of genetic and environmental risk factors.