Risk of schizophrenia in adults born after obstetric complications and their association with early onset of illness: a controlled study

Gender differences in the association between environment and psychosis

Various environmental exposures have been associated with psychosis spectrum disorder. However, the role of gender in this association has received little attention. Therefore, we conducted a systematic review to evaluate gender-related differences and identified 47 research articles investigating the associations of psychosis with childhood adversity, substance use, urbanicity, migration, season of birth, and obstetric complication in the PubMed database. The findings suggest that childhood abuse may be more strongly associated with a risk to develop psychosis and an earlier age at onset of illness in women than in men. Furthermore, childhood adversity has been associated with the severity of different symptom dimensions in men and women. Growing up in an urban environment and immigration are more strongly associated with psychosis risk in men than in women. Despite a higher prevalence of substance abuse comorbidity in men diagnosed with psychotic disorders, it appears that the association between substance use and psychosis risk may be stronger in women. These findings should be evaluated with caution considering several methodological limitations, limited number of studies, and lack of consistency across results. Overall, although further investigation is needed, our review shows that gender-related differences in the associations of environmental exposures with psychosis expression may exist.

Obstetric Complications and Polygenic Risk Score: Which Role in Predicting a Severe Short-Term Outcome in Psychosis?

Understanding and improving the outcomes of psychosis remains a major challenge for clinical research. Obstetric complications (OCs) as a risk factor for schizophrenia (SZ) have been investigated as a potential predictor of outcomes in relation to illness severity and poorer treatment outcome, but there are less reports on first episode psychosis (FEP) patients. We test whether OCs, collected in a cohort of FEP patients, can predict illness course and psychopathology severity after 2 years from the onset. Moreover, we explore whether the SZ-polygenic risk score (PRS) would predict the illness course and whether the interaction between OCS and PRS shows a significant effect. A cohort of 264 FEP patients were assessed with standardized instruments. OCs were recorded using the Lewis-Murray scale in interviews with the patients' mothers: 30% of them reported at least one OC. Patients with at least one OC were more likely to have a non-remitting course of illness compared to those without OCs (35.3% vs. 16.3%, p = 0.014). No association between SZ-PRS and course of illness nor evidence for a gene-environment interaction was found. In our sample, poor short-term outcomes were associated with OCs, while SZ-PRS was not a prognostic indicator of poor outcomes.

Association of family history of schizophrenia and history of obstetric complications at birth: relationship with age at onset and psychopathology dimensions in a Nigerian cohort

Background

The nature of the association between obstetric complications (OCs) at birth and the genetic aetiology of schizophrenia remains unclear, as some authors suggest that it is an independent risk factor while others support either interactionism or an epiphenomenon perspective.

Objective

To examine the association of family history of schizophrenia (FHS) with history of OCs, with a view to assessing whether this relationship moderates clinical phenotypes such as symptom dimensions and age at onset of illness.

Methods

This study examined OCs among schizophrenia probands using the Obstetric Complications Scale. An inquiry into family history was performed using the Family history method. Psychopathological symptom dimensions were assessed using standard scales. Data were analyzed to examine the interaction of FHS and history of OCs with age at onset and symptom dimensions, using ANCOVA.

Results

FHS was significantly associated with the disorganized symptoms dimension (p=0.03). History of OCs was significantly associated with earlier age at onset (p=0.007). However, in ANCOVA, the effect of the interaction between FHS and history of OCs was not significant for age at onset and symptom dimensions (P = 0.059).

Conclusion

FHS was significantly associated with disorganization syndrome, and OCs was significantly associated with age at onset.

Obstetric complications in patients with schizophrenia and their unaffected siblings

Objective

We sought to explore whether obstetric complications (OCs) are more likely to occur in the presence of familial/genetic susceptibility for schizophrenia or whether they themselves represent an independent environmental risk factor for schizophrenia.

Methods

The presence of OCs was assessed through maternal interview on 216 subjects, comprising 36 patients with schizophrenia from multiply affected families, 38 of their unaffected siblings, 31 schizophrenic patients with no family history of psychosis, 51 of their unaffected siblings and 60 normal comparison subjects. We examined the familiality of OCs and whether OCs were commoner in the patient and sibling groups than in the control group.

Results

OCs tended to cluster within families, especially in multiply affected families. Patients with schizophrenia, especially those from multiply affected families, had a significantly higher rate of OCs compared to normal comparison subjects, but there was no evidence for an elevated rate of OCs in unaffected siblings.

Conclusion

Our data provides little evidence for a link between OCs and genetic susceptibility to schizophrenia. If high rates of OCs are related to schizophrenia genes, this relationship is weak and will only be detected by very large sample sizes.

Pharmacological intervention in the initial prodromal phase of psychosis

Early identification and treatment of schizophrenia may alleviate the symptoms, delay the onset and improve the outcome of psychosis. Thus, detection of individuals at risk during the prodromal phase is an important task. Universal approaches to screen the general population or healthy subjects at risk have not proven possible to-date. However, clinical criteria for detecting ultra-high risk individuals have been developed for specialized settings, with their implementation in interventional studies. This article examines the rationale for early detection and intervention of psychosis, along with a review of some of the current studies. These target prevention using psychological and/or pharmacological intervention strategies have demonstrated promising results in high risk individuals. The German Research Network on Schizophrenia (GRNS) is conducting two multicenter early intervention studies; one with early psychological intervention in subjects who manifest early prodromal symptoms; with the second trial applying clinical management and pharmacological early intervention in subjects experiencing late prodromal symptoms (high risk subjects). Despite the promising results, many of the current studies have small sample sizes with study durations of a short period. The full benefits of early detection and intervention should be revealed once larger and longer studies are conducted.

Schizophrenia spectrum and other psychotic disorders

Since its earliest conceptualization, schizophrenia has been considered a disorder of "young men." Contemporary research suggests that there are sex differences in schizophrenia that are both transdiagnostic and representative of general sex/gender differences across the psychopathology spectrum. This chapter selectively summarizes representative sex/gender differences in clinical expression, epidemiology, risk factors, treatment, as well as course and outcome in schizophrenia. The consistent sex differences found, such as onset age, generic brain anomalies, and hormonal involvement, are not specific to schizophrenia or necessarily to psychopathology. It is suggested that in working with those diagnosed as meeting the current criteria for schizophrenia, clinicians adopt a transdiagnostic framework informed by sex and gender role processes.

Use of Machine Learning to Determine Deviance in Neuroanatomical Maturity Associated With Future Psychosis in Youths at Clinically High Risk

IMPORTANCE

Altered neurodevelopmental trajectories are thought to reflect heterogeneity in the pathophysiologic characteristics of schizophrenia, but whether neural indicators of these trajectories are associated with future psychosis is unclear.

OBJECTIVE

To investigate distinct neuroanatomical markers that can differentiate aberrant neurodevelopmental trajectories among clinically high-risk (CHR) individuals.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective longitudinal multicenter study, a neuroanatomical-based age prediction model was developed using a supervised machine learning technique with T1-weighted magnetic resonance imaging scans of 953 healthy controls 3 to 21 years of age from the Pediatric Imaging, Neurocognition, and Genetics (PING) study and then applied to scans of 275 CHR individuals (including 39 who developed psychosis) and 109 healthy controls 12 to 21 years of age from the North American Prodrome Longitudinal Study 2 (NAPLS 2) for external validation and clinical application. Scans from NAPLS 2 were collected from January 15, 2010, to April 30, 2012.

MAIN OUTCOMES AND MEASURES

Discrepancy between neuroanatomical-based predicted age (hereafter referred to as brain age) and chronological age.

RESULTS

The PING-derived model (460 females and 493 males; age range, 3-21 years) accurately estimated the chronological ages of the 109 healthy controls in the NAPLS 2 (43 females and 66 males; age range, 12-21 years), providing evidence of independent external validation. The 275 CHR individuals in the NAPLS 2 (111 females and 164 males; age range, 12-21 years) showed a significantly greater mean (SD) gap between model-predicted age and chronological age (0.64 [2.16] years) compared with healthy controls (P = .008). This outcome was significantly moderated by chronological age, with brain age systematically overestimating the ages of CHR individuals who developed psychosis at ages 12 to 17 years but not the brain ages of those aged 18 to 21 years. Greater brain age deviation was associated with a higher risk for developing psychosis (F = 3.70; P = .01) and a pattern of stably poor functioning over time, but only among younger CHR adolescents. Previously reported evidence of accelerated reduction in cortical thickness among CHR individuals who developed psychosis was found to apply only to those who were 18 years of age or older.

CONCLUSIONS AND RELEVANCE

These results are consistent with the view that neuroanatomical markers of schizophrenia may help to explain some of the heterogeneity of this disorder, particularly with respect to early vs later age of onset of psychosis, with younger and older individuals having differing intercepts and trajectories in structural brain parameters as a function of age. The results also suggest that baseline neuroanatomical measures are likely to be useful in estimating onset of psychosis, especially (or only) among CHR individuals with an earlier age of onset of prodromal symptoms.

Psychiatric services for women

The need for specific psychiatric services for women has been debated by many practitioners involved in care delivery and management of women with differing degrees of mental health problems.

Differential expression of the inflammation marker IL12p40 in the at-risk mental state for psychosis: a predictor of transition to psychotic disorder?

BACKGROUND

The identification of biomarkers of transition from the at-risk mental state (ARMS) to psychotic disorder is important because early treatment of psychosis is associated with improved outcome. Increasing evidence points to an inflammatory contribution to psychosis. We questioned whether raised levels of plasma inflammatory markers predict transition from ARMS to psychotic disorder and whether any such predictors could be reduced by omega-3 (ω-3) polyunsaturated fatty acids (PUFAs).

METHODS

We measured the levels of 40 neuroinflammation biomarkers using a commercially available immunoassay kit. Firstly, we compared inflammatory markers in subjects in the ARMS who transitioned to psychotic disorder (n = 11) compared to subjects who did not (n = 28). Then we compared inflammatory markers in all subjects before and after ω-3 PUFA treatment (n = 40).

RESULTS

Our data provides preliminary evidence that elevations in the baseline plasma levels of the inflammatory marker IL12/IL23p40 are associated with transition from ARMS to psychotic disorder. IL12/IL23p40 levels did not change following 12 weeks administration of ω-3 PUFAs. These findings provide evidence that elevated plasma IL12/IL23p40 is a potential biomarker of increased risk for transition to psychotic disorder.

CONCLUSION

Further studies are required to confirm and extend this finding. Our results do not provide support for the possibility that administration of ω-3 PUFAs act to reduced transition to psychotic disorder by reducing blood levels of IL12/IL23p40.

TRIAL REGISTRATION

ClinicalTrials.gov, a service of the U.S. National Institutes of Health, Identifier: NCT00396643 , last updated December 20, 2007. Retrospectively registered.

A new developmental epidemiology of schizophrenia: the HRB Schizophrenia Research Unit, 1991-92, and contemporary perspectives of the disease

General aspects of research funding in the biomedical sciences are briefly discussed and some specific issues of policy considered, as they relate particularly to the Health Research Board's Unit strategy. The origins, objectives and workings of the Board's Schizophrenia Research Unit are elaborated, in relation to contemporary perspectives of this illness as a neuro-developmental disorder, and the extent of progress made over it's first year of operation is outlined. It is argued that the ‘neurodevelopmental hypothesis’ now has substantial foundations; it provides an important conceptual focus, both for the field in general and for the Health Research Board's Schizophrenia Research Unit in particular.

Body size at birth and psychiatric disorders among adolescents: a clinical study of 310 under-age inpatient adolescents in Northern Finland

BACKGROUND

Deviant birth measure is a risk factor for later somatic illness but also for later psychiatric disorders of the offspring. Only a few studies have examined the association of birth measures to later psychiatric disorders among adolescents. Studies on sex differences in these associations are scarce as well.

METHODS

The cases consisted of 508 adolescents (208 boys and 300 girls) aged 12-17 years, who were admitted to inpatient psychiatric hospitalization between 2001 and 2006. In addition, 478 healthy controls were derived from the Northern Finnish Birth Cohort 1986, born in approximately the same period and same area as the cases. Data of birth measures were collected from the National Birth Register for cases and from antenatal clinics for controls. Both cases and controls were interviewed using the Schedule for Affective Disorder and Schizophrenia for School-Age Children-Present and Lifetime (K-SADS-PL) to assess psychiatric disorders.

RESULTS

The adolescent patients were statistically significantly shorter and had higher ponderal index at birth compared to healthy controls. In addition, the age of the mothers at adolescent's birth was significantly younger in the patients than the controls. After controlling for various covariates, a 2.4-fold increased likelihood for internalizing disorders was seen among male adolescents with high ponderal index.

CONCLUSIONS

The association of birth measures to psychiatric disorders was confirmed in our study, particularly among male adolescents suffering from internalizing disorders. Further studies in larger adolescent samples are needed to confirm our findings and clear up the association of high ponderal index to specific psychiatric disorders.

Gender difference in age at onset of schizophrenia: a meta-analysis

BACKGROUND

Most studies reporting the gender difference in age at onset of schizophrenia show an earlier onset in males, but vary considerably in their estimates of the difference. This may be due to variations in study design, setting and diagnostic criteria. In particular, several studies conducted in developing countries have found no difference or a reversed effect whereby females have an earlier onset. The aim of the study was to investigate gender differences in age of onset, and the impact of study design and setting on estimates thereof.

METHOD

Study methods were a systematic literature search, meta-analysis and meta-regression.

RESULTS

A total of 46 studies with 29,218 males and 19,402 females fulfilled the inclusion criteria and were entered into a meta-analysis. A random-effects model gave a pooled estimate of the gender difference of 1.07 years (95% confidence interval 0.21-1.93) for age at first admission of schizophrenia, with males having earlier onset. The gender difference in age at onset was not significantly different between developed and developing countries. Studies using diagnostic and statistical manual of mental disorders (DSM) criteria showed a significantly greater gender difference in age at onset than studies using International Classification Of Diseases (ICD) criteria, the latter showing no difference.

CONCLUSIONS

The gender difference in age of onset in schizophrenia is smaller than previously thought, and appears absent in studies using ICD. There is no evidence that the gender difference differs between developed and developing countries.

Obstetric complications in early psychosis: relation with family history of psychosis

The people classified as being at ultra-high risk (UHR) of developing psychosis are expected to share many risk factors for psychosis with the patients diagnosed with schizophrenia, including an enhanced incidence of obstetric complications (OCs). This study set out to investigate the incidence and correlates of OCs in a sample of patients accessing an early intervention center. Patients' mothers were asked whether they had suffered from any somatic complication during pregnancy from a list of OCs with potential direct relevance to the physical wellbeing of the offspring. Out of 86 patients diagnosed with first-episode psychosis, 20 (23%) cases were positive for the occurrence of severe OCs, as reported by their mothers during an interview; out of 83 UHR patients, 21 (25%) cases were positive for OCs. OCs were more common in individuals with a family history of psychosis than in those without such a history. OCs might interact with genetic vulnerability to increase the risk of psychosis. Lack of comparison to healthy controls is a limitation that decreases the value of these findings.

Obstetric complications and neurological soft signs in male patients with schizophrenia

Bersani G, Clemente R, Gherardelli S, Bersani FS, Manuali G. Obstetric complications and neurological soft signs in male patients with schizophrenia.

Objective: The study investigated the relationship between neurological soft signs (NSS) and obstetric complications (OCs) in patients with schizophrenia.

Methods: Sixty-three male patients with schizophrenia were divided into two subgroups, based on the OCs presence or absence, which were compared in relation to NSS prevalence. After that, a Person's correlation test was performed to explore the correlation between NSS and OCs severity.

Results: The subgroup with OCs showed more NSS, but there were not significant correlations between NSS and OCs severity.

Conclusions: It seems that any OC, without distinction in typology and severity, could unspecifically impair the neurodevelopment and inducing NSS expression. Our findings confirm the hypothesis that neurodevelopment alterations, such as those probably induced by OCs, can contribute to a premorbid brain dysfunctional state expressed by NSS.

Family history and obstetric complications in deficit and non-deficit schizophrenia: preliminary results

The aim of this study was to test that deficit (D) schizophrenic patients as defined by Carpenter et al had a higher prevalence of family history of schizophrenia but less obstetric complications than non-deficit (ND) patients. A lower rate of obstetric complications but an excess of schizophrenic and a higher rate of alcoholism family antecedents in 18 D patients compared to 23 ND patients were found. These results could suggest that there is a different weight of genetic and early environmental factors in D and ND patients.

Early risk factors in schizophrenia: place and season of birth

First admission psychiatric patients born in England and Wales between 1938 and 1963, and discharged from hospitals in England and Wales between 1976 and 1986, were examined. Using logistic regression, we tested the hypothesis that the risk of shizophrenia varies by place, and season of birth. Persons born in city areas showed a 12% greater risk of schizophrenia (odds ratio 1.12; 95% confidence interval 1.06 to 1.19) than those born in non-city areas, when compared with other psychiatric patients. The increase in risk was particularly high for individuals born in city areas in winter (21%, ie odds ratio 1.21 and confidence interval 1.08 to 1.36). These findings suggest that the factor(s) responsible for the season-of-birth effect preferentially affects city born schizophrenics.

A plausible model of schizophrenia must incorporate psychological and social, as well as neuro developmental, risk factors

Subtle alterations in brain development caused by genes or early environmental hazards, such as obstetric complications, play a role in projecting some individuals on a trajectory toward schizophrenia. High-risk and cohort studies demonstrate that children destined to develop schizophrenia tend to have delayed milestones and subtle neuromotor and cognitive impairments (particularly in coordination and language). These neurocognitive problems lead to difficulties in interpersonal relations, and their progressive alienation makes these at-risk children more likely to harbor odd or paranoid ideas. This cascade of increasingly deviant development may then be compounded by brain maturational changes during adolescence with a resultant lability of the dopaminergic response to stress. As a result, the individual is more susceptible to the effects of the abuse of dopamine-releasing drugs, and to other risk factors such as migration or stressful life events; social isolation may be a common pathway underlying several of the social risk factors.

Environmental risk factors and their impact on the age of onset of schizophrenia: Comparing familial to non-familial schizophrenia

BACKGROUND AND AIMS

Several risk factors for schizophrenia have yet been identified. The aim of our study was to investigate how certain childhood and adolescent risk factors predict the age of onset of psychosis in patients with and without a familial component (i.e. a relative with schizophrenia or schizoaffective disorder).

METHODS

Aside from the age of onset of psychosis, we examined the risk factors for schizophrenia including obstetric complications, birth during winter or spring, behavioral deviances or delayed motor and speech development, exposure to adverse life events and exposure to substance use within a group of 100 patients (45 female, 55 male) with a mean age (± standard deviation) of 35.15 ± 13.21.

RESULTS

Birth complications and cannabis abuse are predictors for an earlier onset of schizophrenia in patients with non-familial schizophrenia. No environmental risk factors for an earlier age of onset in familial schizophrenia have been identified.

CONCLUSIONS

Certain environmental risk factors for schizophrenia seem to have an impact on the age of onset of psychosis in non-familial schizophrenia, they do not seem to have an impact on familial schizophrenia.

Exposure to obstetric complications in relation to subsequent psychiatric disorders of adolescent inpatients: specific focus on gender differences

BACKGROUND

Exposure to obstetric complications is known to be associated with subsequent development of psychiatric disorders. However, earlier findings are mainly based on adult populations having a long follow-up time for onset of psychiatric illness. We examined whether the association of obstetric complications with severe mental disorders is already seen in a population of underage adolescents admitted to psychiatric inpatient care.

METHOD

The study population was a clinical sample of adolescents (n = 508) aged 12-17 years admitted to psychiatric hospital. DSM-IV diagnoses of the psychiatric disorders of the adolescents as well as information on obstetric (i.e., pregnancy, delivery and perinatal) complications and substance use during pregnancy reported by the mothers of the adolescents were based on the semi-structured Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime.

RESULTS

A total of 96 (19%) adolescents had been exposed to obstetric complications. The prevalence of pregnancy, delivery or perinatal complications reported by the mothers of the offspring was 55 (57%), 57 (59%) and 13 (14%), respectively. Among adolescents with conduct disorder, exposure to delivery complications was more common among males compared to females (16 vs. 5%, p = 0.006); this was particularly true for section delivery (7 vs. 1%, p = 0.023). A trend towards a significant gender difference was also found among adolescents with anxiety disorder (21 vs. 8%, p = 0.085).

CONCLUSIONS

Boys seem to be more vulnerable to the exposure of delivery complications than girls. Exposure to obstetric complication may be associated with development of subsequent psychiatric disorder; particularly conduct disorder of adolescent boys.

The epidemiology of schizophrenia: replacing dogma with knowledge

Major advances have been made in our understanding of the epidemiology of schizophrenia. We now know that the disorder is more common and severe in young men, and that the incidence varies geographically and temporally. Risk factors have been elucidated; biological risks include a family history of the disorder, advanced paternal age, obstetric complications, and abuse of drugs such as stimulants and cannabis. In addition, recent research has also identified social risk factors such as being born and brought up in a city, migration, and certain types of childhood adversity such as physical abuse and bullying, as well as social isolation and adverse events in adult life. Current research is focussing on the significance of minor psychotic symptoms in the general population, gene-environmental interaction, and how risk factors impact on pathogenesis; perhaps all risk factors ultimately impact on striatal dopamine as the final common pathway.

Developmental history of the subplate zone, subplate neurons and interstitial white matter neurons: relevance for schizophrenia

The subplate zone is a transient cytoarchitectonic compartment of the fetal telencephalic wall and contains a population of subplate neurons which are the main neurons of the fetal neocortex and play a key role in normal development of cerebral cortical structure and connectivity. While the subplate zone disappears during the perinatal and early postnatal period, numerous subplate neurons survive and remain embedded in the superficial (gyral) white matter of adolescent and adult brain as so-called interstitial neurons. In both fetal and adult brain, subplate/interstitial neurons belong to two major classes of cortical cells: (a) projection (glutamatergic) neurons and (b) local circuit (GABAergic) interneurons. As interstitial neurons remain strategically positioned at the cortical/white matter interface through which various cortical afferent systems enter the deep cortical layers, they probably serve as auxiliary interneurons involved in differential "gating" of cortical input systems. It is widely accepted that prenatal lesions which alter the number of surviving subplate neurons (i.e., the number of interstitial neurons) and/or the nature of their involvement in cortical circuitry represent an important causal factor in pathogenesis of at least some types of schizophrenia--e.g., in the subgroup of patients with cognitive impairment and deficits of frontal lobe functions. The abnormal functioning of cortical circuitry in schizophrenia becomes manifest during the adolescence, when there is an increased demand for proper functioning of the prefrontal cortex. In this review, we describe developmental history of subplate zone, subplate neurons and surviving interstitial neurons, as well as presumed consequences of the increased number of GABAergic interstitial neurons in the prefrontal cortex. We propose that the increased number of GABAergic interstitial neurons leads to the increased inhibition of prefrontal cortical neurons. This inhibitory action of GABAergic interstitial neurons is facilitated by their strategic position at the cortical/white matter interface where limbic and modulatory afferent pathways enter the prefrontal cortex. Thus, enlarged population of inhibitory interstitial neurons (even if they represent a minor fraction of total neuron number, as in the cerebral cortex itself) may alter the differential "gating" of limbic and modulatory inputs (as well as other cortical and subcortical inputs) and cause a functional disconnectivity between the prefrontal and limbic cortex in the adolescent brain. In conclusion, fetal subplate neurons and surviving postnatal interstitial neurons are important modulators of cortical functions in both normal and schizophrenic cerebral cortex.

The epidemiology of schizophrenia: replacing dogma with knowledge

Major advances have been made in our understanding of the epidemiology of schizophrenia. We now know that the disorder is more common and severe in young men, and that the incidence varies geographically and temporally. Risk factors have been elucidated; biological risks include a family history of the disorder, advanced paternal age, obstetric complications, and abuse of drugs such as stimulants and cannabis. In addition, recent research has also identified social risk factors such as being born and brought up in a city, migration, and certain types of childhood adversity such as physical abuse and bullying, as well as social isolation and adverse events in adult life. Current research is focussing on the significance of minor psychotic symptoms in the general population, gene-environmental interaction, and how risk factors impact on pathogenesis; perhaps all risk factors ultimately impact on striatal dopamine as the final common pathway.

AKT1 Gene Polymorphisms and Obstetric Complications in the Patients with Schizophrenia

OBJECTIVE

We performed a genetic association study with schizophrenic patients to investigate whether the V-akt murine thymoma viral oncogene homolog 1 (AKT1) gene plays a role in obstetric complications.

METHODS

One-hundred-eighty patients with schizophrenia (male, 113; female, 67) were included. All patients fulfilled DSM-IV criteria for schizophrenia. Obstetric complications were measured by the Lewis scale. Prenatal and perinatal information was retrospectively collected from the patients' mothers. We selected six single nucleotide polymorphisms (SNPs) for the AKT1 gene: SNP1 (rs3803300), SNP2 (rs1130214), SNP3 (rs3730358), SNP4 (rs 1130233), SNP5 (rs2494732), and SNPA (rs2498804). The genotype data were analyzed for an association with the Lewis total score in terms of allele, genotype, and haplotype distribution.

RESULTS

The mean total Lewis scores were 1.30+/-1.61 for males and 1.54+/-1.87 for females. Higher total score tended to be correlated with an earlier age of onset of schizophrenia in females. In the total sample, no SNP was associated with obstetric complications. However, the additional analyses for male and female subgroups found a significant association between SNPA and SNP4 and Lewis score in females (p=0.02 for SNPA, p=0.04 for SNP4). The SNP5-SNPA haplotype showed a positive association with obstetric complications (p=0.03) in the female patient group.

CONCLUSION

We found an association between SNPs in the AKT1 gene and total Lewis score measuring obstetric complications in female patients with schizophrenia. Because these findings did not survive a correction for multiple testing, the significance should be interpreted carefully and replication studies are required.

Gene-environment interactions in schizophrenia: review of epidemiological findings and future directions

Concern is building about high rates of schizophrenia in large cities, and among immigrants, cannabis users, and traumatized individuals, some of which likely reflects the causal influence of environmental exposures. This, in combination with very slow progress in the area of molecular genetics, has generated interest in more complicated models of schizophrenia etiology that explicitly posit gene-environment interactions (EU-GEI. European Network of Schizophrenia Networks for the Study of Gene Environment Interactions. Schizophrenia aetiology: do gene-environment interactions hold the key? [published online ahead of print April 25, 2008] Schizophr Res; S0920-9964(08) 00170-9). Although findings of epidemiological gene-environment interaction (G x E) studies are suggestive of widespread gene-environment interactions in the etiology of schizophrenia, numerous challenges remain. For example, attempts to identify gene-environment interactions cannot be equated with molecular genetic studies with a few putative environmental variables "thrown in": G x E is a multidisciplinary exercise involving epidemiology, psychology, psychiatry, neuroscience, neuroimaging, pharmacology, biostatistics, and genetics. Epidemiological G x E studies using indirect measures of genetic risk in genetically sensitive designs have the advantage that they are able to model the net, albeit nonspecific, genetic load. In studies using direct molecular measures of genetic variation, a hypothesis-driven approach postulating synergistic effects between genes and environment impacting on a final common pathway, such as "sensitization" of mesolimbic dopamine neurotransmission, while simplistic, may provide initial focus and protection against the numerous false-positive and false-negative results that these investigations engender. Experimental ecogenetic approaches with randomized assignment may help to overcome some of the limitations of observational studies and allow for the additional elucidation of underlying mechanisms using a combination of functional enviromics and functional genomics.

Common behavioral influences of the ErbB1 ligands transforming growth factor alpha and epiregulin administered to mouse neonates

Ligands for epidermal growth factor (EGF) receptor (ErbB1), such as EGF, transforming growth factor alpha (TGFalpha), and epiregulin, are enriched in body fluids and blood and regulate development of various peripheral organs. It remains however how such circulating polypeptide growth factors influence brain development and function. Here, we performed peripheral injections of TGFalpha and epiregulin to mouse neonates and evaluated immediate physical and neurochemical development and later behavioral consequences. Subcutaneous administration of TGFalpha and epiregulin increased phosphorylation of brain ErbB1, suggesting their effects on brain development. Repeated their injections similarly enhanced physical development of eyelid opening and tooth eruption during early postnatal stage and resulted in abnormal behavioral traits in the adult stage. Acoustic startle responses of mice treated with these growth factors as neonates were enhanced and prepulse inhibition was decreased without an apparent correlation between prepulse inhibition level and startle intensity. Locomotor activity and fear-learning performance with tone and context cues were not altered, however. These results suggest that circulating ErbB1 ligands in the periphery of neonates have some common influences on later behavioral traits. Abnormal ErbB1 ligand production at neonatal and potentially prenatal stages might therefore associate with neurodevelopmental disorders such as schizophrenia.

Serious obstetric complications interact with hypoxia-regulated/vascular-expression genes to influence schizophrenia risk

The etiology of schizophrenia is thought to include both epistasis and gene-environment interactions. We sought to test whether a set of schizophrenia candidate genes regulated by hypoxia or involved in vascular function in the brain (AKT1, BDNF, CAPON, CHRNA7, COMT, DTNBP1, GAD1, GRM3, NOTCH4, NRG1, PRODH, RGS4, TNF-alpha) interacted with serious obstetric complications to influence risk for schizophrenia. A family-based study of transmission disequilibrium was conducted in 116 trios. Twenty-nine probands had at least one serious obstetric complication (OC) using the McNeil-Sjostrom Scale, and many of the OCs reported were associated with the potential for fetal hypoxia. Analyses were conducted using conditional logistic regression and a likelihood ratio test (LRT) between nested models was performed to assess significance. Of the 13 genes examined, four (AKT1 (three SNPs), BDNF (two SNPs), DTNBP1 (one SNP) and GRM3 (one SNP)) showed significant evidence for gene-by-environment interaction (LRT P-values ranged from 0.011 to 0.037). Although our sample size was modest and the power to detect interactions was limited, we report significant evidence for genes involved in neurovascular function or regulated by hypoxia interacting with the presence of serious obstetric complications to increase risk for schizophrenia.

Effect of Rhesus D incompatibility on schizophrenia depends on offspring sex

Rhesus D incompatibility increases risk for schizophrenia, with some evidence that risk is limited to male offspring. The purpose of this study is to determine whether risk for schizophrenia due to Rhesus D incompatibility differs by offspring sex using a nuclear family-based candidate gene approach and a meta-analysis approach. The genetic study is based on a sample of 277 nuclear families with RHD genotype data on at least one parent and at least one child diagnosed with schizophrenia or related disorder. Meta-analysis inclusion criteria were (1) well-defined sample of schizophrenia patients with majority born before 1970, (2) Rhesus D incompatibility phenotype or genotype data available on mother and offspring, and by offspring sex. Two of ten studies, plus the current genetic study sample, fulfilled these criteria, for a total of 358 affected males and 226 affected females. The genetic study found that schizophrenia risk for incompatible males was significantly greater than for compatible offspring (p=0.03), while risk for incompatible and compatible females was not significantly different (p=.32). Relative risks for incompatible males and females were not significantly different from each other. Meta-analysis using a larger number of affected males and females supports their difference. Taken together, these results provide further support that risk of schizophrenia due to Rhesus D incompatibility is limited to incompatible males, although a weak female incompatibility effect cannot be excluded. Sex differences during fetal neurodevelopment should be investigated to fully elucidate the etiology of schizophrenia.

Are obstetric complications related to adult schizophrenia? A case-control study

BACKGROUND

Early environmental events may be relevant to the etiology of schizophrenia. Among such events, interest has focused especially on obstetric complications (OCs).

OBJECTIVE

Aims of the study were to compare the incidence of OCs in patients, siblings and normal controls and to examine the relationship between OCs and later schizophrenia.

METHOD

One hundred and thirteen patients with schizophrenia were recruited, as were 140 patients' siblings and 113 controls without schizophrenia. The OCs history of patients, their sibs and controls was obtained through interviews with patients' and controls' mothers.

RESULTS

The results highlighted that more patients than sibs had at least one definite OC and a higher mean number of OCs; more patients had premature rupture of membranes, threatened abortion and a labor of more than 36 h.

CONCLUSIONS

Our data provide some evidence for a link between OCs and later schizophrenia. Furthermore, this study highlights how OCs, which may cause fetal distress through a hypoxic-ischemic mechanism, could increase the risk of schizophrenia interacting with genetic susceptibility.

The cellular and behavioral consequences of interleukin-1 alpha penetration through the blood-brain barrier of neonatal rats: a critical period for efficacy

Proinflammatory cytokines circulating in the periphery of early postnatal animals exert marked influences on their subsequent cognitive and behavioral traits and are therefore implicated in developmental psychiatric diseases such as schizophrenia. Here we examined the relationship between the permeability of the blood-brain barrier to interleukin-1 alpha (IL-1 alpha) in neonatal and juvenile rats and their later behavioral performance. Following s.c. injection of IL-1 alpha into rat neonates, IL-1 alpha immunoreactivity was first detected in the choroid plexus, brain microvessels, and olfactory cortex, and later diffused to many brain regions such as neocortex and hippocampus. In agreement, IL-1 alpha administration to the periphery resulted in a marked increase in brain IL-1 alpha content of neonates. Repeatedly injecting IL-1 alpha to neonates triggered astrocyte proliferation and microglial activation, followed by behavioral abnormalities in startle response and putative prepulse inhibition at the adult stage. Analysis of covariance with a covariate of startle amplitude suggested that IL-1 alpha administration may influence prepulse inhibition. However, adult rats treated with IL-1 alpha as neonates exhibited normal learning ability as measured by contextual fear conditioning, two-way passive shock avoidance, and a radial maze task and had no apparent sign of structural abnormality in the brain. In comparison, when IL-1 alpha was administered to juveniles, the blood-brain barrier permeation was limited. The increases in brain IL-1 alpha content and immunoreactivity were less pronounced following IL-1 alpha administration and behavioral abnormalities were not manifested at the adult stage. During early development, therefore, circulating IL-1 alpha efficiently crosses the blood-brain barrier to induce inflammatory reactions in the brain and influences later behavioral traits.

A public health genetic approach for schizophrenia

BACKGROUND

Schizophrenia is a complex disease resulting from the interplay of genetic and environmental factors. However, psychiatric genetics and epidemiology have often worked as independent research fields.

AIMS

To review the evidence about the gene-environment interplay involved in the development of schizophrenia.

METHODS

Systematic review of medical and psychological databases.

RESULTS

On one hand, quantitative and molecular genetics showed high heritability for schizophrenia and identified genes likely to be involved in its pathophysiology. The strength of the association between candidate genes and schizophrenia is however modest, and the need for a more appropriate conceptualization of the genetic risk has been claimed. On the other hand, psychiatric epidemiology described several environmental factors liked with the onset or the course of schizophrenia. The observational nature of epidemiology, however, may hamper inference on causation. Gene-environment correlations and interactions influence the exposure and the vulnerability to the environment, respectively. Current findings suggest that gene-environment correlations and interactions may be common phenomena in the pathophysiology of schizophrenia. The consideration of gene-environment interplay may help to overcome many limitations of genetic and epidemiological studies in psychiatry and suggest innovative preventive and therapeutic strategies.

CONCLUSIONS

Taking into account the complexity of schizophrenia pathophysiology, mental health genetics may provide a comprehensive and heuristic model of disease.

Association between the interleukin-1 receptor antagonist gene and negative symptom improvement during antipsychotic treatment

The contribution of immune system to schizophrenia has been an important area of focus in schizophrenia research. Several genetic variants in the cytokine system have been associated with the pathogenesis of schizophrenia. The purpose of this study was to determine whether a pharmacogenetic relationship exists between a variable number of tandem repeats (VNTR) polymorphism in the interleukin-1 receptor antagonist gene (IL-1RN) and clinical improvement during antipsychotic treatment in patients with a first non-affective psychotic episode. One hundred and fifty-four subjects presenting with a first non-affective psychotic episode were randomly assigned to treatment with haloperidol, risperidone, or olanzapine and rated with the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Negative Symptoms (SANS) and the Scale for the Assessment of Positive Symptoms (SAPS) both at baseline and after 6 weeks of treatment. A control sample of 336 blood bank donors was also included. No differences in genotype or allele distributions were found between patients and controls. However, after controlling for baseline SANS scores, the genotype in the VNTR polymorphism in the IL-1RN gene significantly predicted negative symptom improvement, accounting for approximately 7% of the variance (F = 5.23, df = 2, P = 0.006). The mean decrease in SANS scores was 58% for the IL-1RN* 2/2, 44% for the IL-1RN* 1/2, and 14% for the IL-1RN* 1/1 subjects, respectively. These results suggest that the VNTR polymorphism in the IL-1RN gene may be a useful predictor of negative symptom improvement in schizophrenic patients treated with antipsychotic drugs.

Exposures to environmental toxicants and attention deficit hyperactivity disorder in U.S. children

OBJECTIVE

The purpose of this study was to examine the association of exposures to tobacco smoke and environmental lead with attention deficit hyperactivity disorder (ADHD).

METHODS

Data were obtained from the National Health and Nutrition Examination Survey 1999-2002. Prenatal and postnatal tobacco exposure was based on parent report; lead exposure was measured using blood lead concentration. ADHD was defined as having current stimulant medication use and parent report of ADHD diagnosed by a doctor or health professional.

RESULTS

Of 4,704 children 4-15 years of age, 4.2% were reported to have ADHD and stimulant medication use, equivalent to 1.8 million children in the United States. In multivariable analysis, prenatal tobacco exposure [odds ratio (OR) = 2.5; 95% confidence interval (CI), 1.2-5.2] and higher blood lead concentration (first vs. fifth quintile, OR = 4.1; 95% CI, 1.2-14.0) were significantly associated with ADHD. Postnatal tobacco smoke exposure was not associated with ADHD (OR = 0.6; 95% CI, 0.3-1.3; p = 0.22). If causally linked, these data suggest that prenatal tobacco exposure accounts for 270,000 excess cases of ADHD, and lead exposure accounts for 290,000 excess cases of ADHD in U.S. children.

CONCLUSIONS

We conclude that exposure to prenatal tobacco and environmental lead are risk factors for ADHD in U.S. children.

Sex differences in digit ratio (2D:4D) are disrupted in adolescents with schizotypal personality disorder: altered prenatal gonadal hormone levels as a risk factor

The 2nd to 4th finger digit ratio (2D:4D) is a sexually dimorphic feature determined during gestation indexing prenatal androgen/estrogen levels. More 'feminized' 2D:4D phenotype has been demonstrated in schizophrenia versus same-sex controls. This study examined 2D:4D in adolescents with schizotypal personality disorder (SPD). Among normal controls, right 2D:4D was significantly greater (more feminized) in females than males. We replicated laterality effects; significant sex differences only on right. There were no significant sex differences among SPDs. Diagnostic group differences were restricted to White/Caucasian males with greater right 2D:4D in SPDs. Findings suggest disruptions in prenatal gonadal hormones in vulnerability for schizophrenia.

Recent progress in animal modeling of immune inflammatory processes in schizophrenia: implication of specific cytokines

Epidemiologic studies demonstrate significant environmental impact of maternal viral infection and obstetric complications on the risk of schizophrenia and indicate their detrimental influences on brain development in this disorder. Based on these findings, animal models for schizophrenia have been established using double stranded RNA, bacterial lipopolysaccharides, hippocampal lesion, or prenatal/perinatal ischemia. Key molecules regulating such immune/inflammatory reactions are cytokines, which are also involved in brain development, regulating dopaminergic and GABAergic differentiation, and synaptic maturation. Specific members of the cytokine family, such as interleukin-1, epidermal growth factor, and neuregulin-1, are induced after infection and brain injury; therefore, certain cytokines are postulated to have a central role in the neurodevelopmental defects of schizophrenia. Recently, to test this hypothesis, a variety of cytokines were administered to rodent pups. Cytokines administered in the periphery penetrated the immature blood-brain barrier and perturbed phenotypic neural development. Among the many cytokines examined, epidermal growth factor (or potentially other ErbB1 ligands) and interleukin-1 specifically induced the most severe and persistent behavioral and cognitive abnormalities, most of which were ameliorated by antipsychotics. These animal experiments illustrate that, during early development, these cytokine activities in the periphery perturbs normal brain development and impairs later psychobehavioral and/or cognitive traits. The neurodevelopmental and behavioral consequences of prenatal/perinatal cytokine activity are compared with those of other schizophrenia models and cytokine interactions with genes are also discussed in this review.

Cerebral metabolic consequences in the adult brain after neonatal excitotoxic lesions of the amygdala in rats

In the present study the effects of neonatal excitotoxic lesions of the amygdala or ventral hippocampus on local cerebral glucose utilisation in the adult rat were studied by means of the [14C]2-deoxyglucose autoradiographic method. Our hypothesis was that damage to the brain during early development leads to long-term functional activity changes in brain regions outside the primary lesioned area which might underlie the behavioural deficits observed in animals with neonatal brain damage. Cerebral glucose utilisation in animals with a neonatal amygdala lesion was significantly decreased in the amygdala itself and in several other brain regions. The neonatal ventral hippocampal lesion did not cause significant changes in cerebral glucose utilisation, except for a decrease in the primary damaged region (i.e. caudal ventral hippocampus). Behaviourally, animals lesioned in the amygdala displayed increased ambulatory activity both before and after puberty when exposed to a novel open field, while neonatal ventral hippocampal lesions did not affect adult exploratory behaviour as compared to sham controls. These results support our hypothesis that neonatal brain damage leads to long-term functional activity changes in brain regions outside the primary lesioned area. Moreover, they suggest that this long-term effect depends on the primary area lesioned since only damage to the amygdala, and not to the ventral hippocampus, affects the functional organisation of the brain of the animals later in life. Additionally, the findings may suggest that the functional changes in the brain may underlie the behavioural deficits observed after neonatal amygdala lesion in the rat.

Strain-dependent behavioral alterations induced by peripheral interleukin-1 challenge in neonatal mice

Interleukin-1 (IL-1) is implicated in the pathogenesis of various psychiatric diseases. Peripheral administration of IL-1alpha to neonatal rats induces cognitive and behavioral abnormalities and, therefore, the IL-1alpha-treated animals might serve as a schizophrenia model. The present study assessed genetic influences on IL-1alpha-triggered behavioral impairments, using four different strains of neonatal mice, C3H/He, DBA/2, C57BL/6, and ddY. Neonatal treatments with IL-1alpha differentially altered adult behavioral/cognitive traits in a strain-dependent manner. IL-1alpha treatment decreased prepulse inhibition in DBA/2 and C57BL/6 mice but not in C3H/He and ddY. The treatment increased locomotor activity and startle responses in DBA/2 mice and, conversely, decreased startle responses in C3H/He mice. Behavioral alterations were most remarkable in DBA/2 mice but undetectable in ddY mice. The magnitudes of IL-1alpha actions differed between the brain and periphery and were influenced by mouse genetic background. The IL-1-triggered acute signaling, Ikappa-B degradation, was significant in the frontal cortex of DBA/2 mice and in the hypothalamus of C3H/He mice. An increase in brain p38 MAP kinase phosphorylation was also most marked in the DBA/2 strain. In contrast, subchronic influences of IL-1alpha injections failed to illustrate the strain-dependent behavioral alterations. The peripheral effects of IL-1alpha did not match the strain-dependency of the behavioral alterations, either. Acceleration of tooth eruption and eyelid opening as well as attenuation of weight gain was most marked in C3H/He mice and the induction of serum amyloid protein was the largest in ddY mice. Thus, the peripheral effects of IL-1alpha in DBA/2 mice were relatively inferior to those in the other strains. The present animal study suggests that, in early postnatal development, circulating IL-1alpha trigger brain cytokine signaling and produce distinct influences on later neurobehavioral traits, both depending on genetic background.

Distinct Influences of Neonatal Epidermal Growth Factor Challenge on Adult Neurobehavioral Traits in Four Mouse Strains

Epidermal growth factor (EGF) receptor (ErbB1) signals regulate dopaminergic development and function and are implicated in schizophrenia. We evaluated genetic effects on neurobehavioral changes induced by neonatal EGF administration, using four mouse strains. Subcutaneous EGF administration increased phosphorylation of brain ErbB1 in all strains, although DBA/2 and C57BL/6 mice had lower basal phosphorylation. Neonatal EGF treatment differentially influenced physical and behavioral/cognitive development, depending on mouse strain. Prepulse inhibition was decreased in DBA/2 and C57BL/6 mice but not C3H/He and ddY mice. Locomotor activity was accelerated in DBA/2 mice, but reduced in ddY mice. EGF treatment enhanced fear-learning performance with a tone cue in DBA/2 mice, but decreased performance with tone and context cues in C3H/He and ddY mice, respectively. The strain-dependent behavioral sensitivity was correlated with basal ErbB1 phosphorylation. Genetic components regulating brain ErbB1 signaling strongly influence the direction and strength of behavioral responses stemming from the neonatal neurotrophic perturbation.

Lack of evidence for elevated obstetric complications in childhood onset schizophrenia

BACKGROUND

Pre-, peri-, and postnatal obstetric complications (OC) are reported to be more frequent in adult patients with schizophrenia and have been linked to both greater severity and to "earlier" age of onset (before either age 18 or 22) in studies of adult patients. We hypothesized that by extrapolation, patients with childhood-onset schizophrenia (COS), with very early onset and very severe illness, would have had more numerous or more salient OC compared with their healthy siblings.

METHODS

We compared the obstetric records of 60 COS children and 48 healthy siblings using the Columbia Obstetrics Complication Scale, a comprehensive measurement scale consisting of 37 variables having included a separate scale for fetal hypoxia.

RESULTS

Patients with COS did not have a higher incidence of OC than the healthy sibling control group with the exception of increased incidence of maternal vomiting.

CONCLUSIONS

Obstetric complications, with the possible exception of maternal vomiting, are unlikely to play a major role in the etiopathogenesis of childhood-onset schizophrenia.

Dermatoglyphics and Schizophrenia: a meta-analysis and investigation of the impact of obstetric complications upon a-b ridge count

BACKGROUND

Patients with schizophrenia show deviances in their dermatoglyphics, in particular reductions in palmar a-b ridge counts (ABRCs), which are evidence of an early developmental deviance. However, the severity or the origin of these ABRC changes has not been established.

METHOD

(i) We examined the published literature on the ABRC in patients with schizophrenia against controls with a random effects meta-analysis. (ii) We used linear regression to study the ABRC in our sample of families including 125 patients with schizophrenia, 107 of their unaffected relatives and 98 controls. (iii) The effect of obstetric complications on the patient's ABRC was examined using the Lewis Murray scale.

RESULTS

The pooled standardised effect size of ABRC differences between patients and controls obtained by our meta-analysis was 0.39 (95% CI: 0.05-0.73; p=0.03). In our sample, there were no significant differences in ABRCs between those with schizophrenia, their relatives and controls. Only those patients with obstetric complications had significantly reduced ABRC compared to controls (p=0.01).

CONCLUSIONS

We confirmed the presence of significant yet mild ABRC reductions in schizophrenia. These represent a subtle deviance from the norm and could be present in certain subsets of patients, possibly those who suffered early developmental insults.

Obstetric complications in siblings of Japanese schizophrenics: data from the Maternal and Child Health Handbook

Although the precise etiology of schizophrenia remains unknown, the development of schizophrenia has been associated with a history of obstetric complication (OC). Furthermore, some studies show structural and functional brain abnormalities in the unaffected siblings of schizophrenics. In this study the perinatal histories of 18 unaffected siblings of schizophrenics and 15 unrelated healthy controls, as detailed in their mothers' Maternal and Child Health Handbook records, were retrospectively analyzed. Records were scored for obstetric complication by the method developed by [Parnas, J., Schulsinger, F., Teasdale, T.W., Shulsinger, H., Feldman, P.M., Mednick, S.A., 1982. Perinatal complications and clinical outcome within the schizophrenia spectrum. Br. J. Psychiatry 140, 416-420]. The authors found the sibling group had greater pregnancy and birth complication (PBC) frequency, severity and total scores than the control population.

Fertility and pregnancy in women with psychotic disorders

The majority of women with psychotic disorders have children but their pregnancies are at an increased risk of obstetric and psychiatric complications. This paper reviews research into the fertility of women with psychosis and complications occurring during their pregnancies and in the postpartum period. Mesh terms were used to search electronic databases (Medline, Embase, Psychlit and the Cochrane database of systematic reviews). Recent studies have confirmed earlier findings of a low fertility in women with schizophrenia, though fertility is less affected by mood disorders. Psychotic relapse during pregnancy is rare but women with a history of mood disorders (affective psychoses) are at high risk of postpartum relapse. There is a high risk of obstetric complications, mixed evidence of stillbirths and neonatal deaths and there is some weaker evidence of an association with sudden infant death syndrome. A significant proportion of mothers with psychotic disorders have parenting difficulties and lose custody of their infant. Close liaison between all health professionals during pregnancy and postpartum is essential for optimal management of these high risk pregnancies.

Perinatal inflammatory cytokine challenge results in distinct neurobehavioral alterations in rats: implication in psychiatric disorders of developmental origin

Maternal stress, viral infection, and obstetric complications, which trigger cytokine signaling, are hypothesized to be involved in schizophrenia and its related disorders. The etiologic contribution of individual cytokines to such psychiatric disorders, however, remains to be evaluated. To estimate the impact of peripheral cytokine challenge on neurobehavioral development, we examined effects of four proinflammatory cytokines on rat neonates and their later behavioral performance. Sublethal doses of interleukin-1 alpha, interleukin-2, interleukin-6, or interferon-gamma were subcutaneously administered to rat pups for 9 days. These animals displayed alterations in physical development, including lower weight gain and/or accelerated eyelid opening. In addition, behavioral abnormalities related to fear/anxiety levels and sensorimotor gating emerged at different developmental stages, depending on the cytokine species administered. During juvenile stages, neonatal interleukin-2 treatment increased exploratory locomotor activity, whereas other cytokine treatments did not. At the post-puberty stage, however, the interleukin-2-induced abnormal motor activity became undetectable, whereas interleukin-1 alpha-treated rats developed abnormalities in startle response, prepulse inhibition (PPI), and social interaction. Subchronic treatment of an anti-psychotic drug, clozapine, ameliorated the impairment of prepulse inhibition without altering startle responses. These animal experiments illustrate that, during early postnatal development, inflammatory cytokine challenge in the periphery can induce future psycho-behavioral and/or cognitive impairments with various latencies, although the pathologic mechanisms underlying these abnormalities remain to be determined.

Neonatal impact of leukemia inhibitory factor on neurobehavioral development in rats

Cytokines have been implicated in the etiology or pathology of various psychiatric diseases of developmental origin such as autism and schizophrenia. Leukemia inhibitory factor (LIF) is induced by a variety of brain insults and known to have many influences on mature and immature nervous system. Here, we assessed the neurobehavioral and pathological consequences of peripheral administration of LIF in newborn rats. Subcutaneous LIF injection induced STAT3 phosphorylation in many brain regions and increased glial fibrillary acidic protein (GFAP) immunoreactivity in the neocortex, suggesting that LIF had direct effects in the central nervous system. The LIF-treated rats displayed decreased motor activity during juvenile stages, and developed abnormal prepulse inhibition in the acoustic startle test during and after adolescence. They displayed normal learning ability in active avoidance test, however. Brain neuronal structures and startle responses were grossly normal, except for the cortical astrogliosis during neonatal LIF administration. These results indicate that LIF induction in the periphery of the infant has a significant, but discrete impact on neurobehavioral development.

The causes of schizophrenia: neurodevelopment and other risk factors

Understanding the etiology of schizophrenia has been a considerable challenge. The neurodevelopmental hypothesis has held sway in recent years, focusing our attention on biological causes acting in early life. Much evidence supports this hypothesis and risk factors operating in early life (e.g., obstetric complications) have been shown to be associated with the later development of schizophrenia. Indicators of abnormal neurodevelopment that characterize individuals vulnerable to later developing schizophrenia have also been identified. For example, as a group, children who will later develop schizophrenia subtly differ from their peers in terms of their motor, cognitive, and social functioning. However, there is much that cannot be explained in purely neurodevelopmental terms. There is growing evidence of associations between the risk of schizophrenia and factors such as drug misuse, ethnicity/migration, life events, and urbanicity. A multifactorial model of causation that encompasses biological, social, and psychological elements is arguably both a better representation of current research findings and a more appropriate model for clinical practice.

Postmaturity in a genetic subtype of schizophrenia

OBJECTIVE

To determine whether postmaturity (gestation > 41 weeks), small for gestational age (SGA), and other pregnancy and birth complications that may elevate risk for neurodevelopmental disorders, are associated with elevated risk for schizophrenia in 22q11 Deletion Syndrome (22qDS), a genetic subtype of schizophrenia.

METHOD

Antepartum and intrapartum features were examined in 20 adults with 22qDS-schizophrenia and three comparison groups: newborn encephalopathy (n = 164) and healthy newborn controls (n = 400) from Badawi et al.'s (Br Med J 1998, 317: 1549) study, and 16 non-psychotic 22qDS adults (22qDS-NP).

RESULTS

Postmaturity (OR 13.0, 95% CI 3.95, 42.77; P < 0.001) and SGA (OR 3.59, 95% CI 1.23, 10.5; P = 0.03) were more prevalent in 22qDS-SZ than controls. Postmaturity was non-significantly more prevalent in 22qDS-SZ than in newborn encephalopathy (P = 0.06) or 22qDS-NP (P = 0.2). SGA showed similar rates in the two 22qDS groups and newborn encephalopathy, but was more prevalent in 22qDS-NP than controls (P = 0.05).

CONCLUSION

The results suggest that postmaturity may be associated with expression of schizophrenia in a 22qDS subtype of schizophrenia. SGA may be a non-specific marker of neurodevelopmental disturbance.

A decrease in interleukin-1 receptor antagonist expression in the prefrontal cortex of schizophrenic patients

Interleukin-1 (IL-1) mediates psychological stress responses by regulating monoamine metabolism and secretion of corticotropin-releasing factor, and is therefore, implicated in various psychiatric diseases. To evaluate the contribution of IL-1 signaling to the brain pathology of schizophrenia, we measured protein and/or mRNA levels for IL-1beta and endogenous IL-1 receptor antagonist (IL-1RA) in the postmortem brain tissues of prefrontal and parietal cortex, putamen, and hypothalamus. Both protein and mRNA levels of IL-1RA were specifically decreased in the prefrontal cortex of schizophrenic patients, whereas IL-1beta levels were not significantly altered in all the regions examined. The IL-1RA decrease was not correlated with the dose of antipsychotics given to patients. There was no influence of this illness on protein levels for IL-1 receptor type 1 in the prefrontal cortex, either. In contrast, IL-1RA serum levels were increased in schizophrenic patients, especially in drug-free patients, as reported previously. These findings suggest that chronic schizophrenia down-regulates IL-1RA production the prefrontal cortex, irrespective of its impact on the periphery. IL-1RA reduction might reflect an immunopathologic trait of the prefrontal region in schizophrenic patients.

Immunity and schizophrenia: autoimmunity, cytokines, and immune responses

As is evident from the present account, there is no single or persuasive argument that signals emanating from the immune system are directly involved in the etiology of schizophrenia. We do not even know if we are dealing with a single disorder with a single causality; almost certainly we are not. The precise etiology of schizophrenia, as with so many neurological disorders, remains obscure. However, there is abundant evidence in schizophrenia of mutual dysregulation of neuronal function and immune system activity. Although this evidence is not always consistent, a pattern emerges suggesting aspects of immune activity being involved in the pathology of neuronal development that characterizes schizophrenia. Exposure to infective agents, HLA associations, autoimmune associations, disturbances in lymphocyte populations, and cytokine imbalances with a skew toward Th2 activity are supportive of this view. That the evidence is not always consistent is a testament to the complexity and heterogeneity of the disorder, to confounding by antipsychotics that themselves are immunomodulatory, and to the multifaceted nature, with all its checks and balances, of the immune system itself.

Birth insult interacts with stress at adulthood to alter dopaminergic function in animal models: possible implications for schizophrenia and other disorders

Altered subcortical dopaminergic activity is thought to be involved in the pathophysiology of several disorders including schizophrenia, substance abuse and attention deficit hyperactivity disorder. Epidemiological studies have implicated perinatal insults, particularly obstetric complications involving fetal or neonatal hypoxia, as etiological risk factors for schizophrenia. This suggests the possibility that perinatal hypoxia might have lasting effects on dopaminergic function. In animal models, dopaminergic systems appears to be particularly vulnerable to a wide range of perinatal insults, resulting in persistent alterations in function of mesolimbic and mesostriatal pathways. This review summarizes recent work characterizing long-term changes in dopaminergic function and biochemistry in models of Caesarean section (C-section) birth and of C-section birth with added global anoxia in the rat and guinea pig. C-section birth and C-section with anoxia appear to be two distinct hypoxic birth insults, with somewhat differing patterns of lasting effects on dopamine systems. In addition, birth insult alters the manner in which dopaminergic function is regulated by stress at adulthood. The possible relevance of these finding to effects of human birth procedures is discussed.

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.