Childhood schizotypy and positive symptoms in schizophrenic patients predict schizotypy in relatives

Familial aggregation of schizotypy in schizophrenia-spectrum disorders and its relation to clinical and neurodevelopmental characteristics

INTRODUCTION

This study explored schizotypy as a familial liability marker for schizophrenia-spectrum disorders (SSD) by examining: 1) the aggregation of schizotypy in families with a SSD patient, 2) whether familial resemblance of schizotypy is associated with ridge dissociations (RD), another SSD liability marker, 3) whether schizotypy aggregation patterns influence patients' psychopathology.

METHODS

The sample comprised 30 SSD patients and 82 healthy first-degree relatives. Schizotypy was assessed using the Structured Interview for Schizotypy-Revised (SIS-R). Patients' psychopathology was evaluated using the Comprehensive Assessment of Symptoms and History (CASH). RD were identified as anomalies of the dermal ridge junction. Familiality of SIS-R was investigated using a linear mixed model (LMM) and its strength was assessed using an intraclass correlation coefficient (ICC). Another LMM using the absolute differences in SIS-R scores between all possible pairs of relatives as the dependent variable was fitted to obtain an intra-family resemblance score, a family-specific indicator of resemblance of SIS-R scores within each family.

RESULTS

1) Schizotypy was familial (ICC = 0.30); families with high resemblance displayed low schizotypy, whereas families with low resemblance included at least one healthy relative with high schizotypy (p < 0.001). 2) Relatives with RD had higher SIS-R scores (p = 0.018) and belonged to families with discordant schizotypy scores among members (p < 0.001). 3) Patients from high schizotypy families showed more severe disorganized symptoms at the psychotic episode (p = 0.035) and 1 year later (p = 0.011).

CONCLUSIONS

Schizotypy is a marker of vulnerability for SSD that runs within a subgroup of families. The schizotypy familial aggregation pattern correlates with RD in relatives and with patients' psychopathology.

Genetic Consideration of Schizotypal Traits: A Review

Schizotypal traits are of interest and importance in their own right and also have theoretical and clinical associations with schizophrenia. These traits comprise attenuated psychotic symptoms, social withdrawal, reduced cognitive capacity, and affective dysregulation. The link between schizotypal traits and psychotic disorders has long since been debated. The status of knowledge at this point is such schizotypal traits are a risk for psychotic disorders, but in and of themselves only confer liability, with other risk factors needing to be present before a transition to psychosis occurs. Investigation of schizotypal traits also has the possibility to inform clinical and research pursuits concerning those who do not make a transition to psychotic disorders. A growing body of literature has investigated the genetic underpinnings of schizotypal traits. Here, we review association, family studies and describe genetic disorders where the expression of schizotypal traits has been investigated. We conducted a thorough review of the existing literature, with multiple search engines, references, and linked articles being searched for relevance to the current review. All articles and book chapters in English were sourced and reviewed for inclusion. Family studies demonstrate that schizotypal traits are elevated with increasing genetic proximity to schizophrenia and some chromosomal regions have been associated with schizotypy. Genes associated with schizophrenia have provided the initial start point for the investigation of candidate genes for schizotypal traits; neurobiological pathways of significance have guided selection of genes of interest. Given the chromosomal regions associated with schizophrenia, some genetic disorders have also considered the expression of schizotypal traits. Genetic disorders considered all comprise a profile of cognitive deficits and over representation of psychotic disorders compared to the general population. We conclude that genetic variations associated with schizotypal traits require further investigation, perhaps with targeted phenotypes narrowed to assist in refining the clinical end point of significance.

Ten-year stability of self-reported schizotypal personality features in patients with psychosis and their healthy siblings

Schizotypal personality disorder (SPD) symptoms or features are common in patients with psychosis and their healthy relatives. However, the long-term stability of these SPD features and therefore their constituting enduring traits underlying vulnerability to psychosis remain to be clarified. Thirty-two patients with psychotic disorders and 29 of their healthy siblings were included from the long-term follow-up study of 89 nuclear families. Participants were clinically assessed by means of a semi-structured diagnostic interview, whereas the Schizotypal Personality Questionnaire-Brief (SPQ-B) was applied for the self-assessment of SPD symptoms. The assessments were carried out upon admission to the study and at follow-up, about 10 years later. The patients had higher scores than their siblings on the SPQ-B both at baseline and follow-up. In addition, self-reported SPD symptoms remained stable over time in total scores and in all the SPQ-B subscores, except for the SPQ-B Disorganization subscale. Self-reported SPD symptoms were stable over the long term among patients with psychotic disorders and their healthy siblings. This finding provides new support for including the SPD construct as a trait measure for studies addressing both vulnerability to psychosis in first-degree relatives of patients with psychosis and long-term persistence of symptoms in patients suffering from psychosis.

Effect of illness expression and liability on familial associations of clinical and subclinical psychosis phenotypes

OBJECTIVE

Given the familial influences on schizophrenia, it may be hypothesized that specific symptom domains also cluster within families, and that this applies to both clinical and subclinical levels of expression. This hypothesis was put to the test in a group of patients with a DSM-IV diagnosis of psychotic disorder together with their unaffected siblings, and a group of healthy sib-pairs.

METHOD

Subclinical positive, negative and depressive symptoms in relatives and healthy controls were assessed with the Community Assessment of Psychic Experiences (CAPE). Positive and negative schizotypy in relatives and controls was measured with the Structured Interview for Schizotypy-Revised. Multilevel linear regression analyses were conducted to investigate clustering of symptom dimensions within patient-relative sib-pairs (N = 811 pairs), healthy sib-pairs of affected families (N = 136 pairs) and healthy control sib-pairs (N = 58 pairs).

RESULTS

Familial clustering of symptoms was found in all three groups. Effect sizes were largest in healthy control sib-pairs, smallest in patient-relative sib-pairs and intermediate in healthy sib-pairs of affected families.

CONCLUSION

Studies of sibling associations in genetic studies of psychometric expression of psychosis liability need to take into account the fact that the higher levels of background genetic risk and presence of diagnosed illness are inversely associated with sibling associations.

Revisiting the relationship between autism and schizophrenia: toward an integrated neurobiology

Schizophrenia and autism have been linked since their earliest descriptions. Both are disorders of cerebral specialization originating in the embryonic period. Genetic, molecular, and cytologic research highlights a variety of shared contributory mechanisms that may lead to patterns of abnormal connectivity arising from altered development and topology. Overt behavioral pathology likely emerges during or after neurosensitive periods in which resource demands overwhelm system resources and the individual's ability to compensate using interregional activation fails. We are at the threshold of being able to chart autism and schizophrenia from the inside out. In so doing, the door is opened to the consideration of new therapeutics that are developed based upon molecular, synaptic, and systems targets common to both disorders.

A comprehensive review of auditory verbal hallucinations: lifetime prevalence, correlates and mechanisms in healthy and clinical individuals

Over the years, the prevalence of auditory verbal hallucinations (AVHs) have been documented across the lifespan in varied contexts, and with a range of potential long-term outcomes. Initially the emphasis focused on whether AVHs conferred risk for psychosis. However, recent research has identified significant differences in the presentation and outcomes of AVH in patients compared to those in non-clinical populations. For this reason, it has been suggested that auditory hallucinations are an entity by themselves and not necessarily indicative of transition along the psychosis continuum. This review will examine the presentation of auditory hallucinations across the life span, as well as in various clinical groups. The stages described include childhood, adolescence, adult non-clinical populations, hypnagogic/hypnopompic experiences, high schizotypal traits, schizophrenia, substance induced AVH, AVH in epilepsy, and AVH in the elderly. In children, need for care depends upon whether the child associates the voice with negative beliefs, appraisals and other symptoms of psychosis. This theme appears to carry right through to healthy voice hearers in adulthood, in which a negative impact of the voice usually only exists if the individual has negative experiences as a result of their voice(s). This includes features of the voices such as the negative content, frequency, and emotional valence as well as anxiety and depression, independently or caused by voices presence. It seems possible that the mechanisms which maintain AVH in non-clinical populations are different from those which are behind AVH presentations in psychotic illness. For example, the existence of maladaptive coping strategies in patient populations is one significant difference between clinical and non-clinical groups which is associated with a need for care. Whether or not these mechanisms start out the same and have differential trajectories is not yet evidenced. Future research needs to focus on the comparison of underlying factors and mechanisms that lead to the onset of AVH in both patient and non-clinical populations.

Comparison of children with autism spectrum disorder with and without schizophrenia spectrum traits: gender, season of birth, and mental health risk factors

Children with autism spectrum disorder (ASD) with and without co-occurring schizophrenia spectrum traits (SST) were examined for differences in co-occurring psychiatric symptoms, background characteristics, and mental health risk factors. Participating mothers and teachers completed a DSM-IV-referenced rating scale and a background questionnaire (mothers only) describing 147 children (6-12 years) with ASD. There was a clear pattern of group differences in co-occurring psychiatric symptom severity (+SST > SST-) and background characteristics. Children with impairing SST had more mental health risk factors. Girls were more likely to be classified SST according to mothers' ratings. Children born in spring-summer were more likely to be classified non-SST by teachers' ratings. Findings provide tentative evidence that SST may be a useful marker of behavioral heterogeneity within the ASD clinical phenotype.

Exploring the relationships between tobacco smoking and schizophrenia in first-degree relatives

Up to 90% of individuals with schizophrenia suffer from nicotine dependence. Both schizophrenia and nicotine consumption have strong genetic components, which may overlap. The relationship between schizophrenia and nicotine dependence remains unclear, due in part to confounding factors. Studies of the relationship between nicotine consumption and milder schizophrenia-related phenotypes, such as schizotypy, in first-degree relatives of individuals with schizophrenia could help to better understand the relationship between smoking and schizophrenia while avoiding such confounders. We assessed the proportion of smokers, their level of nicotine dependence and their level of schizotypy in a sample of 98 first-degree relatives of schizophrenic subjects and 110 healthy controls. Partial correlation analysis was used to assess the relationship between schizotypal dimensions and smoking dependence. The prevalence of smoking and nicotine dependence levels were higher in the relatives than in the healthy control group. We found no relationship between nicotine dependence and the magnitude of schizotypal features in either group. Our results support the hypothesis that the relationship between schizophrenia and smoking is largely mediated by common familial factors, which may be genetic.

Symptoms of autism and schizophrenia spectrum disorders in clinically referred youth with oppositional defiant disorder

Examined autism spectrum disorder (ASD) and schizophrenia spectrum disorder (SSD) symptoms in a clinically referred, non-ASD sample (N=1160; ages 6-18) with and without oppositional defiant disorder (ODD). Mothers and teachers completed DSM-IV-referenced symptom checklists. Youth with ODD were subdivided into angry/irritable symptom (AIS) or noncompliant symptom (NS) subtypes. Two different classification strategies were used: within-informant (source-specific) and between-informant (source-exclusive). For the source-specific strategy, youth were classified AIS, NS, or Control (C) according to mothers' and teachers' ratings separately. A second set of analyses focused on youth classified AIS according to mother or teacher report but not both (source-exclusive) versus both mother and teacher (cross-informant) AIS. Results indicated the mother-defined source-specific AIS groups generally evidenced the most severe ASD and SSD symptoms (AIS>NS>C), but this was more pronounced among younger youth. Teacher-defined source-specific ODD groups exhibited comparable levels of symptom severity (AIS, NS>C) with the exception of SSD (AIS>NS>C; younger youth). Source-exclusive AIS groups were clearly differentiated from each other, but there was little evidence of differential symptom severity in cross-informant versus source-exclusive AIS. These findings were largely dependent on the informant used to define the source-exclusive groups. AIS and NS groups differed in their associations with ASD and SSD symptoms. Informant discrepancy provides valuable information that can inform nosological and clinical concerns and has important implications for studies that use different strategies to configure clinical phenotypes.

Investigation of shared genetic effects for psychotic and obsessive symptoms in young adult twins

Genetic and environmental architecture of psychotic and obsessive symptoms are not completely elucidated. This study estimated for these symptoms (i) the genetic and environmental components, (ii) the within-individual association, and (iii) the extent to which this association originates from common genetic and environmental factors. Young adult twins (N=701) from the population-based Italian Twin Register were assessed for psychotic and obsessive-compulsive symptoms by using the Symptom Check List (SCL-90). Multivariate Cholesky models were fitted by the Mx statistical program. No previous study used this design to examine the same dimensions. The best-fitting model included additive genetic and nonshared environmental components, each accounting for about half of total variance in the symptoms. Genetic influences on the different symptoms overlapped considerably (r(g)=0.81 to 0.99). Phenotypic correlations of psychotic symptoms and of psychotic with obsessive symptoms were high (r=0.61 to 0.76), with 53% to 69% explained by shared genetic effects. This study shows substantial genetic influence on psychotic and obsessive symptoms, and indicates that their co-occurrence may be due to genetic factors to a greater extent than to environmental effects. These results encourage the search for genetic and environmental factors underlying the covariance between different psychotic traits as well as between psychotic and obsessive traits.

Heritability and longitudinal stability of schizotypal traits during adolescence

The study investigated the genetic and environmental etiology of schizotypal personality traits in a non-selected sample of adolescent twins, measured on two occasions between the ages of 11 and 16 years old. The 22-item Schizotypal Personality Questionnaire- Child version (SPQ-C) was found to be factorially similar to the adult version of this instrument, with three underlying factors (Cognitive-Perceptual, Interpersonal-Affective, and Disorganization). Each factor was heritable at age 11-13 years (h (2) = 42-53%) and 14-16 years old (h (2) = 38-57%). Additive genetic and unique environmental influences for these three dimensions of schizotypal personality acted in part through a single common latent factor, with additional genetic effects specific to both Interpersonal-Affective and Disorganization subscales at each occasion. The longitudinal correlation between the latent schizotypy factor was r = 0.58, and genetic influences explained most of the stability in this latent factor over time (81%). These longitudinal data demonstrate significant genetic variance in schizotypal traits, with moderate stability between early to middle adolescence. In addition to common influences between the two assessments, there were new genetic and non-shared environmental effects that played a role at the later assessment, indicating significant change in schizotypal traits and their etiologies throughout adolescence.

Overlap of autistic and schizotypal traits in adolescents with Autism Spectrum Disorders

This study addresses the unraveling of the relationship between autism spectrum and schizophrenia spectrum traits in a population of adolescents with Autism Spectrum Disorders (ASD). Recent studies comparing isolated symptoms of both spectrum disorders as well as diagnostic criteria for each (DSM-IV-TR) suggest resemblances in the clinical phenotype. A group of 27 adolescents with ASD (11 to 18 years) and 30 typically developing adolescents, matched for age and gender, participated in this study. Within the ASD group 11 adolescents satisfied DSM-IV-TR criteria for schizotypal personality disorders. Autistic and schizotypal traits were identified by means of well validated questionnaires (Autism Questionnaire, AQ and Schizotypal Personality Questionnaire-Revised, SPQ). Significantly more schizotypal traits in adolescents with ASD were found than in typically developing controls. Besides high levels of negative symptoms, adolescents with ASD also displayed high levels of positive and disorganized symptoms. There appeared to be a relationship between the mean level of autistic symptoms and schizotypal traits, as well as specific associations between autistic symptoms and negative, disorganized and positive schizotypal symptoms within individuals. Schizotypal symptomatology in all sub dimensions that are reflected by the SPQ scores, was most prominently associated with attention switching problems of the autism symptoms from the AQ. These findings indicate that patients diagnosed with an ASD show schizophrenia spectrum traits in adolescence. Although other studies have provided empirical support for this overlap in diagnostic criteria between both spectrum disorders, the present findings add to the literature that behavioral overlap is not limited to negative schizotypal symptoms, but extends to disorganized and positive symptoms as well.

Psychopathology and personality traits in psychotic patients and their first-degree relatives

Personality dimensions have been associated with symptoms dimensions in schizophrenic patients (SP). In this paper we study the relationships between symptoms of functional psychoses and personality dimensions in SP and their first-degree relatives (SR), in other psychotic patients (PP) and their first-degree relatives (PR), and in healthy controls in order to evaluate the possible clinical dimensionality of these disorders. Twenty-nine SP, 29 SR, 18 PP, 18 PR and 188 controls were assessed using the temperament and character inventory (TCI-R). Current symptoms were evaluated with positive and negative syndrome scale (PANSS) using the five-factor model described previously (positive [PF], negative [NF], disorganized [DF], excitement [EF] and anxiety/depression [ADF]). Our TCI-R results showed that patients had different personality dimensions from the control group, but in relatives, these scores were not different from controls. With regard to symptomatology, we highlight the relations observed between harm avoidance (HA) and PANSS NF, and between self-transcendence (ST) and PANSS PF. From a personality traits-genetic factors point of view, schizophrenia and other psychosis may be initially differentiated by temperamental traits such as HA. The so-called characterial traits like ST would be associated with the appearance of psychotic symptoms.

Correlation and familial aggregation of dimensions of psychosis in affected sibling pairs from China

BACKGROUND

A number of studies with conflicting results have examined the familiality of schizophrenia syndromes in Western populations.

AIMS

The objective of this study was to determine, using clinical data from concordant sibling pairs, whether symptom dimensions and other clinical characteristics of schizophrenia show familial aggregation and are therefore potentially useful traits in genetic studies.

METHOD

We measured clinical and demographic features, and symptom dimensions of schizophrenia in 137 families from China who had two or more affected members with schizophrenia. Within-sibling pair correlation was assessed with intraclass correlation coefficient and kappa statistics.

RESULTS

Global functioning, positive, disorganisation and dysphoric symptoms, premorbid schizotypal and schizoid traits, premorbid social adjustment, type and age at illness onset all showed significant evidence of familial aggregation. DSM-IV schizophrenia subtypes were also found to be familial.

CONCLUSIONS

This is the first study in a large non-European population to confirm that schizophrenia dimensions and clinical characteristics show significant familiality, implying possible heritability. This supports their use in the delineation of homogeneous subsets for future genetic studies.

Psychosis and autism as diametrical disorders of the social brain

Autistic-spectrum conditions and psychotic-spectrum conditions (mainly schizophrenia, bipolar disorder, and major depression) represent two major suites of disorders of human cognition, affect, and behavior that involve altered development and function of the social brain. We describe evidence that a large set of phenotypic traits exhibit diametrically opposite phenotypes in autistic-spectrum versus psychotic-spectrum conditions, with a focus on schizophrenia. This suite of traits is inter-correlated, in that autism involves a general pattern of constrained overgrowth, whereas schizophrenia involves undergrowth. These disorders also exhibit diametric patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language, and behavior. Social cognition is thus underdeveloped in autistic-spectrum conditions and hyper-developed on the psychotic spectrum.;>We propose and evaluate a novel hypothesis that may help to explain these diametric phenotypes: that the development of these two sets of conditions is mediated in part by alterations of genomic imprinting. Evidence regarding the genetic, physiological, neurological, and psychological underpinnings of psychotic-spectrum conditions supports the hypothesis that the etiologies of these conditions involve biases towards increased relative effects from imprinted genes with maternal expression, which engender a general pattern of undergrowth. By contrast, autistic-spectrum conditions appear to involve increased relative bias towards effects of paternally expressed genes, which mediate overgrowth. This hypothesis provides a simple yet comprehensive theory, grounded in evolutionary biology and genetics, for understanding the causes and phenotypes of autistic-spectrum and psychotic-spectrum conditions.

Evidence that the COMTVal158Met Polymorphism Moderates Subclinical Psychotic and Affective Symptoms in Unaffected First-Degree Relatives of Patients With Schizophrenia

Objectives.

Psychotic patients with COMTVal158Met Met alleles were recently found to display more intense psychotic and affective responses to daily life stressors. We aimed to test the hypothesis that the Met allele is implicated in the development of affective and psychotic symptomatology in subjects genetically at risk for schizophrenia, by testing if unaffected first-degree relatives of patients with schizophrenia who share a Met allele have greater concordance of symptomatology than relatives not sharing a Met allele.

Methods.

Unaffected relatives (n = 38) were arranged in as many genetically related pairs as possible (n = 26), and Met-sharing between Index Unaffected Subject (IUS) and Related Unaffected Subject (RUS) was assessed. Symptomatology was assessed with the Brief Psychiatric Rating Scale (BPRS) total score.

Results.

Multilevel regression revealed an interaction between RUS BPRS score and Met-sharing in the model of IUS BPRS score (interaction χ2 = 3.78, p = 0.05). Stratified analyses revealed that IUS–RUS total BPRS scores were significantly associated in the case of Met-sharing (B = 0.57, 95% CI: 0.22–0.93, p = 0.002), but were not when there was no Met-sharing.

Conclusion.

These findings support the hypothesis that the Met allele may be involved in the causation of psychopathology, at least in populations with a genetic predisposition to psychosis.

Nicotine consumption and schizotypy in first-degree relatives of individuals with schizophrenia and non-psychiatric controls

Individuals with schizophrenia have very high rates of cigarette smoking, and much has been discovered about the influence of nicotine on brain functioning in schizophrenia. However, less is understood about the relationship between nicotine consumption and milder phenotypes related to schizophrenia, specifically schizotypy. This study examined the relationship between nicotine consumption and schizotypy in two unmedicated samples that included first-degree relatives and non-psychiatric controls. Forty-two first-degree relatives and 50 control participants were administered a self-report questionnaire on schizotypal features as well as a self-report questionnaire on smoking behavior. A positive relationship was found between smoking status and level of schizotypy, and higher levels of schizotypy significantly predicted the odds of being a smoker after controlling for gender and group status. Interestingly, group status was a significant moderator in the relationship between level of schizotypy and smoking status, such that the relationship between these two variables was only significant in the first-degree relatives. This is the first study to investigate the relationship between these variables in a sample of first-degree relatives of individuals with schizophrenia. Those individuals with more schizotypal features are presumably at greater risk for schizophrenia-spectrum disorders and thus may be more likely to smoke cigarettes given the known biochemical effects of nicotine on overt positive and negative symptoms of schizophrenia. Although relatives did not differ from controls in their level of self-reported schizotypy, the significant relationship between smoking status and schizotypy in the former group is likely explained by their genetic vulnerability to schizophrenia-spectrum disorders.

Psychometric properties of the Brief Version of the Schizotypal Personality Questionnaire in relatives of patients with schizophrenia-spectrum disorders and non-psychiatric controls

The Schizotypal Personality Questionnaire-Brief Version (SPQ-B), which includes cognitive-perceptual, interpersonal, and disorganized domains, was developed as a concise, self-report measure of schizotypy. This analysis was conducted to: (1) determine the internal consistency reliability of SPQ-B total and subscale scores, (2) use confirmatory factor analysis to assess the three-factor model as well as a single-factor solution, and (3) examine a measure of concurrent criterion validity of SPQ-B scores. The study was conducted at a large, urban, university-affiliated, public-sector health system in the southeastern United States. Data were obtained from 118 participants, including 61 biological relatives of patients with schizophrenia, schizoaffective disorder, or schizophreniform disorder, and 57 non-psychiatric controls. Relatives and controls did not differ significantly on SPQ-B total or subscale scores (or on the full 74-item SPQ total or subscale scores). Internal consistency reliability was adequate for the total SPQ-B score and the interpersonal subscale but was less than ideal for the cognitive-perceptual and disorganized subscales. Regarding the confirmatory factor analysis, though the three-factor solution yielded reasonably good fit to the data, the single-factor solution provided equal fit. Correlations between the three subscales ranged from .63 to .74. With regard to criterion validity, correlations between the SPQ-B total and subscale scores and schizotypy scores derived from a semi-structured, interview-based assessment revealed correlations generally ranging from .40 to .60. The SPQ-B may be a useful brief screening measure of schizotypy, though some limitations in its psychometric properties were evident in this sample. It may be advisable to use total SPQ-B scores rather than subscale scores in some situations, or to use factor analytic techniques to study the instrument's latent structure in specific samples.

Premorbid personality in schizophrenia spectrum: a prospective study

Schizophrenia has been linked with premorbid character anomalies since it was first described. However, few prospective studies of premorbid personality characteristics in schizophrenia and related disorders have been conducted. This study evaluates premorbid personality in children who developed schizophrenia spectrum disorder in adult life. In 1972, 265 children at an average age of 12 (90 with at least one schizophrenic parent) from the Copenhagen Perinatal Cohort participated in a 1-day follow-up during which they were in contact with seven examiners who rated their personality by means of an Adjective Check List (ACL). In 1991-93, adult psychiatric status was assessed for 242 of these individuals, who were classified into three categories: schizophrenia spectrum (n=24), other psychiatric diagnoses (n=72) and healthy controls (n=145). Personality characteristics derived from the ACL were linked to these three diagnostic categories. Twelve-year-old children destined to develop a disorder in the schizophrenia spectrum deviated significantly from healthy controls on a number of personality characteristics: they were rated significantly lower than controls on intelligence, concentration, maturity, friendliness, cooperation, self-control and significantly higher on aggression. Non-significant trends indicated that this group displayed more deviant personality scores than psychiatric controls. Children who later develop schizophrenia spectrum disorder differed from normal controls with respect to a number of personality traits. The ACL may be too insensitive to discriminate between premorbid personality in the schizophrenia spectrum and other psychopathology.

Deconstructing the familiality of the emotive component of psychotic experiences in the general population

OBJECTIVE

Genetic and environmental influences on variation in distress associated with subclinical psychotic experiences were examined.

METHOD

A total of 289 twin pairs filled in the Community Assessment of Psychic Experiences, a self-report instrument assessing subclinical positive and negative psychotic experiences and associated distress (distresspos and distressneg). Using structural equation modelling, univariate and bivariate models were fitted.

RESULTS

Univariate model fitting showed genetic and non-shared environmental influences on both distresspos and distressneg. Bivariate model fitting showed that 52% of the correlation between the two phenotypes (r=0.46) was because of shared genes and that non-shared environmental factors accounted for 48% of the correlation.

CONCLUSION

Liability to psychosis not only refers to the development of psychosis per se, but also to the liability to develop dysfunctional emotional appraisals. The emotive component of psychosis liability involves genetic transmission of a general, non-symptom-specific distress factor that may be a target for molecular genetic research.

Advanced paternal age associated with an elevated risk for schizophrenia in offspring in a Japanese population

OBJECTIVE

Advanced paternal age at birth as a risk for schizophrenia in the adult offspring has been reported in previous studies exclusively conducted in Western countries and Israel. The question has arisen whether this finding could be replicated in countries with socially and culturally different attitudes toward marriage, including factors such as age at marriage. To address this question, we conducted a case-control study of a Japanese population.

METHODS

The subjects were representative inpatients with a DSM-IV diagnosis of schizophrenia. Unrelated healthy volunteers were recruited as control subjects. This study was conducted as one of a series of the projects by use of "The Mother and Child Health Handbooks (MCHHs)," from which information on parental characteristics around the time of birth, including parental ages at birth, had been extracted and recorded on computer.

RESULTS

Ninety-nine subjects with schizophrenia and 381 healthy control subjects enrolled for the study. Advanced paternal, but not maternal, age was associated with an elevated risk for schizophrenia. Reproducibility of the association across different cultures is suggestive of a causal link.

Schizophrenia: update on genetics, cognitive behavioural therapy and early intervention

There have been considerable advances in the understanding of schizophrenia in recent years. This educational review paper focuses on three areas of interest and relevance to trainees preparing for the membership examination of the Royal College of Psychiatrists (MRCPsych): (a) recent advances in the genetics of schizophrenia; (b) advances in cognitive behavioural therapy in schizophrenia; and (c) advances in early intervention strategies for schizophrenia. Relevant papers and systematic reviews are discussed, and recommendations for further reading are provided.

The negative symptoms of schizophrenia: a cognitive perspective

Recent reports of improvement in the negative symptoms of schizophrenia following targeted cognitive interventions have prompted interest in the cognitive underpinnings of these symptoms. This review integrates current experimental research with the phenomenological accounts of patients participating in cognitive therapy for these specific symptoms. We propose that, in addition to the well-established role of neurobiological factors in their development and maintenance, specific cognitive appraisals and beliefs play a role in the expression and persistence of negative symptoms. This cognitive model of negative symptoms is based on a diathesis-stress formulation: a continuum of predispositional traits from the premorbid personality to the full-blown negative symptomatology, the incorporation of negative social and performance attitudes within these traits, and low expectancies for pleasure or success in goal-oriented activities. We suggest that negative symptoms represent, in part, a compensatory pattern of disengagement in response to threatening delusional beliefs, perceived social threat, and anticipated failure in tasks and social activities. A psychological aspect of this motivational and behavioural inertia appears to be the patient's perception of limited psychological resources--a perception that motivates patients to conserve energy by minimizing investment in activities requiring effort.

Early maternal stress and health behaviours and offspring expression of psychosis in adolescence

OBJECTIVE

It has been suggested that influences operating early in life may affect the risk of postpubertal psychosis outcomes. This hypothesis was tested using a broad outcome of psychotic symptoms expressed in adolescence (prevalence: 15.6%).

METHOD

Findings are based on a longitudinal, population-based cohort study of 963 adolescents aged 15-20 years and their parents in the area of Munich, Germany. Trained psychologists assessed adolescents with the Munich-Composite International Diagnostic Interview. Independently, direct diagnostic interviews were conducted with the parents.

RESULTS

A range of medical complications of pregnancy and delivery, including lower birth weight, were not associated with the psychosis outcome. However, a number of maternal health behaviours and experiences did show associations, independent of confounders.

CONCLUSION

Not maternally reported medical complications of pregnancy and delivery, but maternal prenatal health behaviours predicted expression of psychosis along a continuum in adolescence. This effect may either be direct or constitute a proxy for later postnatal maternal behaviours associated with psychosis risk in the offspring.

Schizophrenia: solving the puzzle

BACKGROUND

Schizophrenia is a common mental illness with an incidence of 15 new cases per 100,000 population per year.

AIM

To review evidence for current neurodevelopmental models of the aetiology of schizophrenia.

METHODS

We performed a literature search using Medline and PsychINFO. We evaluated the relevance of each article and tracked other relevant articles through references.

RESULTS

There is considerable evidence to support neurodevelopmental models of the aetiology of schizophrenia. One or more aetiological events occur between conception and birth that disturb central nervous system (CNS) development, leading to persisting alterations in brain structure and function. These early events, acting in concert with genetic loading and later influences or insults, predispose to the development of schizophrenia in early adulthood.

CONCLUSIONS

There have been considerable advances in schizophrenia research over the past 20 years. Future study of Indices of neural development will help advance our understanding of this common, disabling mental illness.