Maternal exposure to respiratory infections and adult schizophrenia spectrum disorders: a prospective birth cohort study

Perinatal inflammation and adult psychopathology: From preclinical models to humans

Perinatal environment plays a crucial role in brain development and determines its function through life. Epidemiological studies and clinical reports link perinatal exposure to infection and/or immune activation to various psychiatric disorders. In addition, accumulating evidence from animal models shows that perinatal inflammation can affect various behaviors relevant to psychiatric disorders such as schizophrenia, autism, anxiety and depression. Remarkably, the effects on behavior and brain function do not always depend on the type of inflammatory stimulus or the perinatal age targeted, so diverse inflammatory events can have similar consequences on the brain. Moreover, other perinatal environmental factors that affect behavior (e.g. diet and stress) also elicit inflammatory responses. Understanding the interplay between perinatal environment and inflammation on brain development is required to identify the mechanisms through which perinatal inflammation affect brain function in the adult animal. Evidence for the role of the peripheral immune system and glia on perinatal programming of behavior is discussed in this review, along with recent evidence for the role of epigenetic mechanisms affecting gene expression in the brain.

Gestational length affects neurocognition in early-onset schizophrenia

Obstetric complications (OC) have been linked to an increased risk for schizophrenia in offspring, especially in early-onset schizophrenia (EOS). Extensive cognitive deficits occur in EOS, although no study has yet to investigate the relationship between OC and cognition in EOS. This study aims to examine the frequency of OC in EOS compared to controls, and also investigates the relationship between OC and neurocognitive dysfunction in the two groups. Nineteen EOS patients and 53 healthy controls were tested with the MATRICS Consensus Cognitive Battery (MCCB), and the cognitive measures were combined with OC data from the Norwegian Birth Registry. The results indicated no group differences in OC in EOS and healthy controls, but a shorter gestational length in the EOS group led to significant decreases in the overall neurocognitive composite score, and in processing speed. This suggests that the poorer neuropsychological performances commonly found in EOS may be partly attributable to the length of gestation. The worsened neurocognitive functioning did not appear among controls, so gestational length had a different impact on the two groups. Our findings indicated that a shorter gestational length did not increase the risk for developing EOS, but did significantly affect the cognitive difficulties in this group.

Modeling neurodevelopmental cognitive deficits in tasks with cross-species translational validity

Numerous psychiatric disorders whose cognitive dysfunction links to functional outcome have neurodevelopmental origins including schizophrenia, autism and bipolar disorder. Treatments are needed for these cognitive deficits, which require development using animal models. Models of neurodevelopmental disorders are as varied and diverse as the disorders themselves, recreating some but not all aspects of the disorder. This variety may in part underlie why purported procognitive treatments translated from these models have failed to restore functioning in the targeted patient populations. Further complications arise from environmental factors used in these models that can contribute to numerous disorders, perhaps only impacting specific domains, while diagnostic boundaries define individual disorders, limiting translational efficacy. The Research Domain Criteria project seeks to 'develop new ways to classify mental disorders based on behavioral dimensions and neurobiological measures' in hopes of facilitating translational research by remaining agnostic toward diagnostic borders derived from clinical presentation in humans. Models could therefore recreate biosignatures of cognitive dysfunction irrespective of disease state. This review highlights work within the field of neurodevelopmental models of psychiatric disorders tested in cross-species translational cognitive paradigms that directly inform this newly developing research strategy. By expounding on this approach, the hopes are that a fuller understanding of each model may be attainable in terms of the cognitive profile elicited by each manipulation. Hence, conclusions may begin to be drawn on the nature of cognitive neuropathology on neurodevelopmental and other disorders, increasing the chances of procognitive treatment development for individuals affected in specific cognitive domains.

N-acetylcysteine attenuates lipopolysaccharide-induced impairment in lamination of Ctip2-and Tbr1- expressing cortical neurons in the developing rat fetal brain

Oxidative stress and inflammatory insults are the major instigating events of bacterial intrauterine infection that lead to fetal brain injury. The purpose of this study is to investigate the remedial effects of N-acetyl-cysteine (NAC) for inflammation-caused deficits in brain development. We found that lipopolysaccharide (LPS) induced reactive oxygen species (ROS) production by RAW264.7 cells. Macrophage-conditioned medium caused noticeable cortical cell damage, specifically in cortical neurons. LPS at 25 μg/kg caused more than 75% fetal loss in rats. An increase in fetal cortical thickness was noted in the LPS-treated group. In the enlarged fetal cortex, laminar positioning of the early born cortical cells expressing Tbr1 and Ctip2 was disrupted, with a scattered distribution. The effect was similar, but minor, in later born Satb2-expressing cortical cells. NAC protected against LPS-induced neuron toxicity in vitro and counteracted pregnancy loss and alterations in thickness and lamination of the neocortex in vivo. Fetal loss and abnormal fetal brain development were due to LPS-induced ROS production. NAC is an effective protective agent against LPS-induced damage. This finding highlights the key therapeutic impact of NAC in LPS-caused abnormal neuronal laminar distribution during brain development.

Upper respiratory infection during pregnancy and neurodevelopmental outcomes among offspring

Objective

Maternal infection during pregnancy is associated with psychiatric disorders among offspring. The aim of this study was to investigate associations between upper respiratory infection (URI) in pregnancy and measures of cognitive and behavioral outcomes in child offspring.

Materials and methods

A longitudinal study of 534 mother-child pairs with information regarding prenatal exposures collected through an interview conducted on average one year after delivery and subsequent participation in a childhood cognitive and psychosocial assessment between the ages 5–12 years. Childhood cognition was measured using the Peabody Picture Vocabulary Test (PPVT-III) and the Beery-Buktenica Test of Visual Motor Integration-Fifth Edition (VMI-5) and behavioral function measured using the Child Behavior Checklist (CBCL) and teacher-report using the Teacher Report Form (TRF). Adjusted mean differences (adjMD) in outcome measures were calculated between mothers reporting the presence or absence of a URI during pregnancy.

Results

URI during pregnancy was not associated with the two measures of cognition given to offspring, but was associated with modest increases in total behavioral problems reported by mothers (adjMD: 3.72; CI: 1.91–5.54) and teachers (adjMD: 2.74; CI: 0.97–4.50). We observed differences in CBCL and TRF scores based on timing of URI: infections in mid-pregnancy (lunar months 4–5) were associated with poorer scores than were infections in early pregnancy (lunar months 2–3).

Conclusions

In general, URI in pregnancy was not associated with decrements in childhood cognition, but may be associated with behavior problems.

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URI in early pregnancy was not associated with childhood cognitive outcomes.

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URI in pregnancy was associated with increases in behavior problems among offspring.

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Associations with behavior were varied by the timing and duration of reported URI.

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Both treated and untreated URI were associated with increases in behavior problems.

Labor market effects of intrauterine exposure to nutritional deficiency: Evidence from administrative data on Muslim immigrants in Denmark

This paper examines whether nutritional disruptions experienced during the stage of fetal development impair an individual's labor market productivity later in life. We consider intrauterine exposure to the month of Ramadan as a natural experiment that might cause shocks to the inflow of nutrients essential for fetal development. Specifically, we use administrative data from Denmark to investigate the impact of exposure to Ramadan in utero on labor market outcomes of adult Muslim males, including employment status, annual salary, hourly wage rate, and hours of work. Our findings indicate that potential exposure to nutritional disruptions during a critical stage of fetal development is likely to have scarring effects on the fetus expressed as poor labor market outcomes later in life. Specifically, exposure to Ramadan around the 7th month of gestation results in a lower likelihood of employment and, to a lesser extent, a lower salary, and reduced labor supply. For example, the 7th month intrauterine exposure to Ramadan is associated with a 2.6 percentage points reduction in the likelihood of employment among Muslim males. We do not find an impact on the wage rate. Finally, we also document suggestive evidence that these results may partially be driven by increased disability and to a lesser extent by poor educational attainment among those who were exposed to Ramadan during this particular period in utero.

Environmental exposure to metals, neurodevelopment, and psychosis

PURPOSE OF REVIEW

This article presents a new hypothesis about the possible relation between early life exposure to metals and psychosis. We review limitations of available research, and discuss novel approaches to overcome previous methodological barriers.

RECENT FINDINGS

Mechanistic studies suggest a possible association between excess lead, manganese, cadmium, arsenic, or copper, and zinc deficiency, and several biochemical disturbances related to psychosis, such as altered neurotransmitters levels, excitotoxicity, and inflammation. Furthermore, studies suggest that some metals (lead, manganese, cadmium excess, and zinc deficiency) are associated with schizophrenia or psychosis-related phenotype. However, previous studies had multiple methodological limitations. Importantly, metal exposure was often measured after disease development and seldom determined during critical developmental periods. Most studies fell short of depicting the exact timing of exposure and the change in exposure over time. Here, we propose several methods to overcome these methodological limitations.

SUMMARY

There is a plausible role of early life exposure to metals in the cause of psychosis. Owing to methodological limitations in exposure measurement, this has not been well characterized. Considering the wide exposure to metals and the high cost of psychosis to society, this hypothesis should be rigorously examined.

Clinical chorioamnionitis at term V: umbilical cord plasma cytokine profile in the context of a systemic maternal inflammatory response

OBJECTIVE

Microbial invasion of the fetus due to intra-amniotic infection can lead to a systemic inflammatory response characterized by elevated concentrations of cytokines in the umbilical cord plasma/serum. Clinical chorioamnionitis represents the maternal syndrome often associated with intra-amniotic infection, although other causes of this syndrome have been recently described. The objective of this study was to characterize the umbilical cord plasma cytokine profile in neonates born to mothers with clinical chorioamnionitis at term, according to the presence or absence of bacteria and/or intra-amniotic inflammation.

MATERIALS AND METHODS

A cross-sectional study was conducted, including patients with clinical chorioamnionitis at term (n=38; cases) and those with spontaneous term labor without clinical chorioamnionitis (n=77; controls). Women with clinical chorioamnionitis were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) and amniotic fluid interleukin (IL)-6 concentration into three groups: 1) no intra-amniotic inflammation; 2) intra-amniotic inflammation without detectable microorganisms; or 3) microbial-associated intra-amniotic inflammation. A fetal inflammatory response syndrome (FIRS) was defined as an umbilical cord plasma IL-6 concentration >11 pg/mL. The umbilical cord plasma concentrations of 29 cytokines were determined with sensitive and specific V-PLEX immunoassays. Nonparametric statistical methods were used for analysis, adjusting for a false discovery rate of 5%.

RESULTS

1) Neonates born to mothers with clinical chorioamnionitis at term (considered in toto) had significantly higher median umbilical cord plasma concentrations of IL-6, IL-12p70, IL-16, IL-13, IL-4, IL-10 and IL-8, but significantly lower interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF)-α concentrations than neonates born to mothers with spontaneous term labor without clinical chorioamnionitis; 2) neonates born to mothers with clinical chorioamnionitis at term but without intra-amniotic inflammation had higher concentrations of IL-6, IL-12p70, IL-13, IL-4, IL-5, and IL-8, but lower IFN-γ, than neonates not exposed to clinical chorioamnionitis, suggesting that maternal fever in the absence of intra-amniotic inflammation leads to a change in the fetal cytokine network; 3) there were significant, positive correlations between maternal and umbilical cord plasma IL-6 and IL-8 concentrations (IL-6: Spearman correlation=0.53; P<0.001; IL-8: Spearman correlation=0.42; P<0.001), consistent with placental transfer of cytokines; 4) an elevated fetal plasma IL-6 (>11 pg/mL), the diagnostic criterion for FIRS, was present in 21% of cases (8/38), and all these neonates were born to mothers with proven intra-amniotic infection; and 5) FIRS was associated with a high concentration of umbilical cord plasma IL-8, IL-10 and monocyte chemoattractant protein (MCP)-1.

CONCLUSIONS

Neonates born to mothers with clinical chorioamnionitis at term had higher concentrations of umbilical cord plasma cytokines than those born to mothers without clinical chorioamnionitis. Even neonates exposed to clinical chorioamnionitis but not to intra-amniotic inflammation had elevated concentrations of multiple cytokines, suggesting that intrapartum fever alters the fetal immune response.

Prenatal Inflammation, Infections and Mental Disorders

BACKGROUND

The objective of this descriptive review is to summarize the current scientific evidence on the effect of prenatal exposure to maternal infection and immune response on the offspring's risk for mental disorders (schizophrenia spectrum disorders, autism spectrum disorders, attention-deficit hyperactivity disorder, anorexia nervosa, and mood disorders).

SAMPLING AND METHODS

Studies were searched from PubMed and Ovid MEDLINE (R) databases with the following keywords: 'prenatal exposure delayed effects' and 'infection', and 'inflammation' and 'mental disorders'. A comprehensive manual search, including a search from the reference list of included articles, was also performed.

RESULTS

Prenatal exposure to maternal influenza appears to increase the offspring's risk for schizophrenia spectrum disorders, although studies are not fully consistent. Prenatal exposure to maternal fever and elevated cytokine levels seems to be related to the elevated risk for autism spectrum disorders in the offspring. No replicated findings of an association between prenatal infectious exposure and other mental disorders exist.

CONCLUSIONS

Evidence for the effect of prenatal exposure to maternal infection on risk for mental disorders exists for several different infections, suggesting that common factors occurring in infections (e.g. elevated cytokine levels and fever), rather than the infectious agent itself, might be the underlying factor in increasing the risk for mental disorders. Additionally, it is likely that genetic liability to these disorders operates in conjunction with the exposure. Therefore, genetically sensitive study designs are needed in future studies.

Schizophrenia-Like Phenotype Inherited by the F2 Generation of a Gestational Disruption Model of Schizophrenia

Both environmental and genetic factors contribute to schizophrenia; however, the exact etiology of this disorder is not known. Animal models are utilized to better understand the mechanisms associated with neuropsychiatric diseases, including schizophrenia. One of these involves gestational administration of methylazoxymethanol acetate (MAM) to induce a developmental disruption, which in turn produces a schizophrenia-like phenotype in post-pubertal rats. The mechanisms by which MAM produces this phenotype are not clear; however, we now demonstrate that MAM induces differential DNA methylation, which may be heritable. Here we demonstrate that a subset of both second (F2) and third (F3) filial generations of MAM-treated rats displays a schizophrenia-like phenotype and hypermethylation of the transcription factor, Sp5. Specifically, ventral tegmental area of dopamine neuron activity was examined using electrophysiology as a correlate for the dopamine hyperfunction thought to underlie psychosis in patients. Interestingly, only a subset of F2 and F3 MAM rats exhibited increases in dopamine neuron population activity, indicating that this may be a unique model with a susceptibility to develop a schizophrenia-like phenotype. An increase in dopamine system function in rodent models has been previously associated with decreases in hippocampal GABAergic transmission. In line with these observations, we found a significant correlation between hippocampal parvalbumin expression and dopamine neuron activity in F2 rats. These data therefore provide evidence that offspring born from MAM-treated rats possess a susceptibility to develop aspects of a schizophrenia-like phenotype and may provide a useful tool to investigate gene-environment interactions.

Synaptic activity: An emerging player in schizophrenia

Schizophrenia is a polygenic disorder with a complex etiology. While the genetic and molecular underpinnings of the disease are poorly understood, variations in genes encoding synaptic pathways are consistently implicated. Although its impact is still an open question, a deficit in synaptic activity provides an attractive model to explain the cognitive etiology of schizophrenia. Recent advances in high-throughput imaging and functional studies bring new hope for the application of in vitro disease modeling with patient-derived neurons to empirically ascertain the extent to which these synaptic pathways are involved in the disease. In addition, the emergent avenue of research targeted to probe neuronal connections is revealing critical insight into circuitry and may influence how we think about psychiatric disorders in the near future. This article is part of a Special Issue entitled SI: Exploiting human neurons.

Common or distinct pathways to psychosis? A systematic review of evidence from prospective studies for developmental risk factors and antecedents of the schizophrenia spectrum disorders and affective psychoses

BACKGROUND

Identifying the unique and shared premorbid indicators of risk for the schizophrenia spectrum disorders (SSD) and affective psychoses (AP) may refine aetiological hypotheses and inform the delivery of universal versus targeted preventive interventions. This systematic review synthesises the available evidence concerning developmental risk factors and antecedents of SSD and AP to identify those with the most robust support, and to highlight remaining evidence gaps.

METHODS

A systematic search of prospective birth, population, high-risk, and case-control cohorts was conducted in Medline and supplemented by hand searching, incorporating published studies in English with full text available. Inclusion/exclusion decisions and data extraction were completed in duplicate. Exposures included three categories of risk factors and four categories of antecedents, with case and comparison groups defined by adult psychiatric diagnosis. Effect sizes and prevalence rates were extracted, where available, and the strength of evidence synthesised and evaluated qualitatively across the study designs.

RESULTS

Of 1775 studies identified by the search, 127 provided data to the review. Individuals who develop SSD experience a diversity of subtle premorbid developmental deficits and risk exposures, spanning the prenatal period through early adolescence. Those of greatest magnitude (or observed most consistently) included obstetric complications, maternal illness during pregnancy (especially infections), other maternal physical factors, negative family emotional environment, psychopathology and psychotic symptoms, and cognitive and motor dysfunctions. Relatively less evidence has accumulated to implicate this diversity of exposures in AP, and many yet remain unexamined, with the most consistent or strongest evidence to date being for obstetric complications, psychopathology, cognitive indicators and motor dysfunction. Among the few investigations affording direct comparison between SSD and AP, larger effect sizes and a greater number of significant associations are commonly reported for SSD relative to AP.

CONCLUSIONS

Shared risk factors for SSD and AP may include obstetric complications, childhood psychopathology, cognitive markers and motor dysfunction, but the capacity to distinguish common versus distinct risk factors/antecedents for SSD and AP is limited by the scant availability of prospective data for AP, and inconsistency in replication. Further studies considering both diagnoses concurrently are needed. Nonetheless, the prevalence of the risk factors/antecedents observed in cases and controls helps demarcate potential targets for preventative interventions for these disorders.

Schizophrenia: a tale of two critical periods for prefrontal cortical development

Schizophrenia is a disease of abnormal brain development. Considerable evidence now indicates that environmental factors have a causative role in schizophrenia. Elevated incidence of the disease has been linked to a wide range of disturbances in the prenatal environment and to social factors and drug intake during adolescence. Here we examine neurodevelopment of the prefrontal cortex in the first trimester of gestation and during adolescence to gain further insight into the neurodevelopmental processes that may be vulnerable in schizophrenia. Early embryonic development of the prefrontal cortex is characterized by cell proliferation, including renewal of progenitor cells, generation of early transient cell populations and neurogenesis of subcortical populations. Animal models show that curtailing early gestational cell proliferation produces schizophrenia-like pathology in the prefrontal cortex and mimics key behavioral and cognitive symptoms of the disease. At the other end of the spectrum, elimination of excitatory synapses is the fundamental process occurring during adolescent maturation in the prefrontal cortex. Adverse social situations that elevate stress increase dopamine stimulation of the mesocortical pathway and may lead to exaggerated synaptic pruning during adolescence. In a non-human primate model, dopamine hyperstimulation has been shown to decrease prefrontal pyramidal cell spine density and to be associated with profound cognitive dysfunction. Development of the prefrontal cortex in its earliest stage in gestation and in its final stage in adolescence represents two critical periods of vulnerability for schizophrenia in which cell proliferation and synaptic elimination, respectively, may be influenced by environmental factors.

Perinatal Risks and Childhood Premorbid Indicators of Later Psychosis: Next Steps for Early Psychosocial Interventions

Schizophrenia and affective psychoses are debilitating disorders that together affect 2%-3% of the adult population. Approximately 50%-70% of the offspring of parents with schizophrenia manifest a range of observable difficulties including socioemotional, cognitive, neuromotor, speech-language problems, and psychopathology, and roughly 10% will develop psychosis. Despite the voluminous work on premorbid vulnerabilities to psychosis, especially on schizophrenia, the work on premorbid intervention approaches is scarce. While later interventions during the clinical high-risk (CHR) phase of psychosis, characterized primarily by attenuated positive symptoms, are promising, the CHR period is a relatively late phase of developmental derailment. This article reviews and proposes potential targets for psychosocial interventions during the premorbid period, complementing biological interventions described by others in this Special Theme issue. Beginning with pregnancy, parents with psychoses may benefit from enhanced prenatal care, social support, parenting skills, reduction of symptoms, and programs that are family-centered. For children at risk, we propose preemptive early intervention and cognitive remediation. Empirical research is needed to evaluate these interventions for parents and determine whether interventions for parents and children positively influence the developmental course of the offspring.

Adolescent olanzapine sensitization is correlated with hippocampal stem cell proliferation in a maternal immune activation rat model of schizophrenia

Previous work established that repeated olanzapine (OLZ) administration in normal adolescent rats induces a sensitization effect (i.e. increased behavioral responsiveness to drug re-exposure) in the conditioned avoidance response (CAR) model. However, it is unclear whether the same phenomenon can be detected in animal models of schizophrenia. The present study explored the generalizability of OLZ sensitization from healthy animals to a preclinical neuroinflammatory model of schizophrenia in the CAR. Maternal immune activation (MIA) was induced via polyinosinic:polycytidylic acid (PolyI:C) administration into pregnant dams. Behavioral assessments of offspring first identified decreased maternal separation-induced pup ultrasonic vocalizations and increased amphetamine-induced hyperlocomotion in animals prenatally exposed to PolyI:C. In addition, repeated adolescent OLZ administration confirmed the generalizability of the sensitization phenomenon. Using the CAR test, adolescent MIA animals displayed a similar increase in behavioral responsiveness after repeated OLZ exposure during both the repeated drug test days as well as a subsequent challenge test. Neurobiologically, few studies examining the relationship between hippocampal cell proliferation and survival and either antipsychotic exposure or MIA have incorporated concurrent behavioral changes. Thus, the current study also sought to reveal the correlation between OLZ behavioral sensitization in the CAR and hippocampal cell proliferation and survival. 5'-bromodeoxyuridine immunohistochemistry identified a positive correlation between the magnitude of OLZ sensitization (i.e. change in avoidance suppression induced by OLZ across days) and hippocampal cell proliferation. The implications of the relationship between behavioral and neurobiological results are discussed.

Maternal immune activation in nonhuman primates alters social attention in juvenile offspring

BACKGROUND

Sickness during pregnancy is associated with an increased risk of offspring neurodevelopmental disorders. Rodent models have played a critical role in establishing causal relationships and identifying mechanisms of altered brain and behavior development in pups prenatally exposed to maternal immune activation (MIA). We recently developed a novel nonhuman primate model to bridge the gap between human epidemiological studies and rodent models of prenatal immune challenge. Our initial results demonstrated that rhesus monkeys given the viral mimic synthetic double-stranded RNA (polyinosinic:polycytidylic acid stabilized with poly-l-lysine) during pregnancy produce offspring with abnormal repetitive behaviors, altered communication, and atypical social interactions.

METHODS

We utilized noninvasive infrared eye tracking to further evaluate social processing capabilities in a subset of the first trimester MIA-exposed offspring (n = 4) and control animals (n = 4) from our previous study.

RESULTS

As juveniles, the MIA offspring differed from control animals on several measures of social attention, particularly when viewing macaque faces depicting the fear grimace facial expression. Compared with control animals, MIA offspring had a longer latency before fixating on the eyes, had fewer fixations directed at the eyes, and spent less total time fixating on the eyes of the fear grimace images.

CONCLUSIONS

In the rhesus monkey model, exposure to MIA at the end of the first trimester results in abnormal gaze patterns to salient social information. The use of noninvasive eye tracking extends the findings from rodent MIA models to more human-like behaviors resembling those in both autism spectrum disorder and schizophrenia.

Maternal viral infection during pregnancy impairs development of fetal serotonergic neurons

BACKGROUND

Maternal viral infection during pregnancy induces morphological abnormalities in the fetus and may cause emotional and psychological problems in offspring through unknown mechanisms. We have previously shown that prenatal exposure of rats to chemicals such as thalidomide causes an autistic-like phenotype in offspring, indicating that prenatal events affecting serotonergic development may cause developmental disorder.

METHODS

We investigated whether prenatal viral infection altered the expression of neurotransmitters involved in the emotional or psychological status of offspring. We here took advantage of the polyriboinosinic:polyribocytidylic acid (poly I:C) system, the synthetic double-stranded RNA, which is often used in animal models of viral infection.

RESULTS

Ten mg/kg of poly I:C was intraperitoneally injected on gestational day (GD) 9 and counted the numbers of serotonin-immunopositive cells on GD15 using flat whole-mount preparation method, resulting 11.1% of increase in the number of serotonergic neurons in poly I:C group. Furthermore, there was a significant decrease in hippocampal serotonin content in offspring by postnatal day 50 following poly I:C administration by high-performance liquid chromatography.

DISCUSSION AND CONCLUSION

Since serotonin is known to link with behavior and emotion after birth, these results suggest that maternal viral infection might cause, in addition to morphological abnormalities, serotonin-related pathogenesis such as neurodevelopmental disorders including autism spectrum disorders.

Maternal stress, nutrition and physical activity: Impact on immune function, CNS development and psychopathology

Evidence suggests that maternal and fetal immune dysfunction may impact fetal brain development and could play a role in neurodevelopmental disorders, although the definitive pathophysiological mechanisms are still not completely understood. Stress, malnutrition and physical inactivity are three maternal behavioral lifestyle factors that can influence immune and central nervous system (CNS) functions in both the mother and fetus, and may therefore, increase risk for neurodevelopmental/psychiatric disorders. First, we will briefly review some aspects of maternal-fetal immune system interactions and development of immune tolerance. Second, we will discuss the bidirectional communication between the immune system and CNS and the pathways by which immune dysfunction could contribute to neurodevelopmental disorders. Third, we will discuss the effects of prenatal stress and malnutrition (over and undernutrition) on perinatal programming of the CNS and immune system, and how this might influence neurodevelopment. Finally, we will discuss the beneficial impact of physical fitness during pregnancy on the maternal-fetal unit and infant and how regular physical activity and exercise can be an effective buffer against stress- and inflammatory-related disorders. Although regular physical activity has been shown to promote neuroplasticity and an anti-inflammatory state in the adult, there is a paucity of studies evaluating its impact on CNS and immune function during pregnancy. Implementing stress reduction, proper nutrition and ample physical activity during pregnancy and the childbearing period may be an efficient strategy to counteract the impact of maternal stress and malnutrition/obesity on the developing fetus. Such behavioral interventions could have an impact on early development of the CNS and immune system and contribute to the prevention of neurodevelopmental and psychiatric disorders. Further research is needed to elucidate this relationship and the underlying mechanisms of protection. This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.

Maternal complement C1q and increased odds for psychosis in adult offspring

The presence of maternal antibodies to food and infectious antigens may confer an increased risk of developing schizophrenia and psychosis in adult offspring. Complement factor C1q is an immune molecule with multiple functions including clearance of antigen-antibody complexes from circulation and mediation of synaptic pruning during fetal brain development. To determine if maternal C1q was associated with offspring schizophrenia and psychosis, we evaluated 55 matched case-control maternal serum pairs from the National Collaborative Perinatal Project. Sample pairs were composed of mothers whose offspring developed psychoses as adults and those whose offspring were free from psychiatric disease. Matching criteria for offspring included birth date, delivery hospital, race, and gender, with further matching based on mother's age. IgG markers of C1q, bovine milk casein, egg ovalbumin, and wheat gluten were measured with enzyme-linked immunosorbent assays. C1q levels were compared to food antigen IgG and to previously generated data for C-reactive protein, adenovirus, herpes simplex viruses, influenza viruses, measles virus, and Toxoplasma gondii. C1q was significantly elevated in case mothers with odds ratios of 2.66-6.31 (conditional logistic regressions, p ≤ 0.008-0.05). In case mothers only, C1q was significantly correlated with antibodies to both food and infectious antigens: gluten (R(2)=0.26, p ≤ 0.004), herpes simplex virus type 2 (R(2)=0.21, p ≤ 0.02), and adenovirus (R(2)=0.25, p ≤ 0.006). In conclusion, exposure to maternal C1q activity during pregnancy may be a risk factor for the development of schizophrenia and psychosis in offspring. Prenatal measurement of maternal C1q may be an important and convergent screening tool to identify potentially deleterious immune activation from multiple sources.

Preventive effect of α-lipoic acid on prepulse inhibition deficits in a juvenile two-hit model of schizophrenia

Some pathophysiological models of schizophrenia posit that prenatal inflammation sensitizes the developing brain to second insults in early life and enhances brain vulnerability, thereby increasing the risk of developing the disorder during adulthood. We previously developed a two-hit animal model, based on the well-established prenatal immune challenge with poly-inosinic/cytidylic acid (polyI:C), followed by juvenile restraint stress (RS). We observed an additive disruption of prepulse inhibition (PPI) of acoustic startle in juvenile mice submitted to both insults. Previous studies have also reported that oxidative stress is associated with pathophysiological mechanisms of psychiatric disorders, including schizophrenia. We report here that PPI disruption in our two-hit animal model of schizophrenia is associated with an increase in oxidative stress. These findings led us to assess whether α-lipoic acid, an antioxidant, can prevent both increase in oxidative status and PPI deficits in our juvenile in vivo model of schizophrenia. In the offspring submitted to prenatal injection of polyI:C and to RS, treatment with α-lipoic acid prevented the development of PPI deficits 24h after the last period of RS. α-Lipoic acid also improved PPI performance in control mice. The reversal effect of α-lipoic acid pretreatment on these behavioral alterations was further accompanied by a normalization of the associated oxidative status and dopaminergic and GABAergic abnormalities in the prefrontal cortex. Based on our double insult paradigm, these results support the hypothesis that oxidative stress plays an important role in the development of PPI deficits, a well-known behavior associated with schizophrenia. These findings form the basis of future studies aiming to unravel mechanistic insights of the putative role of antioxidants in the treatment of schizophrenia, especially during the prodromal stage.

Activation of the maternal immune system during pregnancy alters behavioral development of rhesus monkey offspring

BACKGROUND

Maternal infection during pregnancy is associated with an increased risk of schizophrenia and autism in the offspring. Supporting this correlation, experimentally activating the maternal immune system during pregnancy in rodents produces offspring with abnormal brain and behavioral development. We have developed a nonhuman primate model to bridge the gap between clinical populations and rodent models of maternal immune activation (MIA).

METHODS

A modified form of the viral mimic, synthetic double-stranded RNA (polyinosinic:polycytidylic acid stabilized with poly-L-lysine) was delivered to two separate groups of pregnant rhesus monkeys to induce MIA: 1) late first trimester MIA (n = 6), and 2) late second trimester MIA (n = 7). Control animals (n = 11) received saline injections at the same first or second trimester time points or were untreated. Sickness behavior, temperature, and cytokine profiles of the pregnant monkeys confirmed a strong inflammatory response to MIA.

RESULTS

Behavioral development of the offspring was studied for 24 months. Following weaning at 6 months of age, MIA offspring exhibited abnormal responses to separation from their mothers. As the animals matured, MIA offspring displayed increased repetitive behaviors and decreased affiliative vocalizations. When evaluated with unfamiliar conspecifics, first trimester MIA offspring deviated from species-typical macaque social behavior by inappropriately approaching and remaining in immediate proximity of an unfamiliar animal.

CONCLUSIONS

In this rhesus monkey model, MIA yields offspring with abnormal repetitive behaviors, communication, and social interactions. These results extended the findings in rodent MIA models to more human-like behaviors resembling those in both autism and schizophrenia.

Practitioner review: maternal mood in pregnancy and child development--implications for child psychology and psychiatry

BACKGROUND

The empirical base suggesting a link between prenatal maternal anxiety, stress or depression and cognitive, behavioral, and biological outcomes in the infant and child has increased dramatically in the past 10 years.

METHODS

In this review, we consider the relevance of prenatal maternal mood for child mental health practitioners; the empirical base for a likely causal impact of the link between prenatal anxiety, depression, or stress and child outcomes; the degree to which the available evidence is sufficient for informing or altering clinical practice; and the possible role of prenatal interventions for promoting child health and development. A selective review of PubMed, Cochrane Library and other sources was undertaken.

FINDINGS

Clinically significant links between maternal prenatal distress and child behavioral and cognitive outcomes have been reported; predictions to stress physiology, immunology, and neurodevelopment have been reported but the effect sizes and clinical significance is less clear. Several candidate mechanisms have been proposed, with some supporting evidence. Many behavioral treatments for prenatal maternal distress exist, but their application to promoting child health is largely unknown.

CONCLUSIONS

Research on maternal prenatal distress is a good example of translational research and offers a strong paradigm for promoting interdisciplinary clinical research on child health and development.

Prenatal infectious and nutritional factors and risk of adult schizophrenia

Schizophrenia is a severely disabling psychiatric disorder. Despite a considerable amount of research on the underpinnings of the disorder, its etiology and pathogenesis remain unknown. In utero exposures, including infection and nutritional deficiencies, are emerging important risk factors for schizophrenia, in which neurodevelopmental influences probably play an important role. Our group and others have embarked on investigations aimed at identifying these risk factors and examining the mechanisms by which they increase vulnerability to this disorder. This work has the potential to lead to strategies aimed at preventing this disorder and to reveal new molecular targets for pharmacotherapeutic intervention.

Aberrant neural synchrony in the maternal immune activation model: using translatable measures to explore targeted interventions

Maternal exposure to infection occurring mid-gestation produces a three-fold increase in the risk of schizophrenia in the offspring. The critical initiating factor appears to be the maternal immune activation (MIA) that follows infection. This process can be induced in rodents by exposure of pregnant dams to the viral mimic Poly I:C, which triggers an immune response that results in structural, functional, behavioral, and electrophysiological phenotypes in the adult offspring that model those seen in schizophrenia. We used this model to explore the role of synchronization in brain neural networks, a process thought to be dysfunctional in schizophrenia and previously associated with positive, negative, and cognitive symptoms of schizophrenia. Exposure of pregnant dams to Poly I:C on GD15 produced an impairment in long-range neural synchrony in adult offspring between two regions implicated in schizophrenia pathology; the hippocampus and the medial prefrontal cortex (mPFC). This reduction in synchrony was ameliorated by acute doses of the antipsychotic clozapine. MIA animals have previously been shown to have impaired pre-pulse inhibition (PPI), a gold-standard measure of schizophrenia-like deficits in animal models. Our data showed that deficits in synchrony were positively correlated with the impairments in PPI. Subsequent analysis of LFP activity during the PPI response also showed that reduced coupling between the mPFC and the hippocampus following processing of the pre-pulse was associated with reduced PPI. The ability of the MIA intervention to model neurodevelopmental aspects of schizophrenia pathology provides a useful platform from which to investigate the ontogeny of aberrant synchronous processes. Further, the way in which the model expresses translatable deficits such as aberrant synchrony and reduced PPI will allow researchers to explore novel intervention strategies targeted to these changes.

Stereotypical alterations in cortical patterning are associated with maternal illness-induced placental dysfunction

We have previously shown in mice that cytokine-mediated damage to the placenta can temporarily limit the flow of nutrients and oxygen to the fetus. The placental vulnerability is pronounced before embryonic day 11, when even mild immune challenge results in fetal loss. As gestation progresses, the placenta becomes increasingly resilient to maternal inflammation, but there is a narrow window in gestation when the placenta is still vulnerable to immune challenge yet resistant enough to allow for fetal survival. This gestational window correlates with early cortical neurogenesis in the fetal brain. Here, we show that maternal illness during this period selectively alters the abundance and laminar positioning of neuronal subtypes influenced by the Tbr1, Satb2, and Ctip2/Fezf2 patterning axis. The disturbances also lead to a laminar imbalance in the proportions of projection neurons and interneurons in the adult and are sufficient to cause changes in social behavior and cognition. These data illustrate how the timing of an illness-related placental vulnerability causes developmental alterations in neuroanatomical systems and behaviors that are relevant to autism spectrum disorders.

Cytokines and the neurodevelopmental basis of mental illness

Epidemiological studies suggest that prenatal exposure to different types of viral or bacterial infections may be associated with similar outcomes; i.e., an increased risk of mental illness disorders in the offspring. Infections arising from various causes have similar debilitating effects in later life, suggesting that the exact pathogen may not be the critical factor in determining the neurological and cognitive outcome in the offspring. Instead, it is thought that response of the innate immune system, specifically the increased production of inflammatory cytokines, may be the critical mediator in altering fetal brain development pre-disposing the offspring to mental illness disorders later in life. Inflammatory cytokines are essential for normal brain development. Factors such as the site of cytokine production, a change in balance between anti- and pro- inflammatory cytokines, placental transfer of cytokines, the effects of cytokines on glial cells, and the effects of glucocorticoids are important when evaluating the impact of maternal infection on fetal brain development. Although it is clear that cytokines are altered in the fetal brain following maternal infection, further evidence is required to determine if cytokines are the critical factor that alters the trajectory of brain development, subsequently leading to postnatal behavioral and neurological abnormalities.

TLR7 negatively regulates dendrite outgrowth through the Myd88-c-Fos-IL-6 pathway

Toll-like receptors (TLRs) recognize both pathogen- and danger-associated molecular patterns and induce innate immune responses. Some TLRs are expressed in neurons and regulate neurodevelopment and neurodegeneration. However, the downstream signaling pathways and effectors for TLRs in neurons are still controversial. In this report, we provide evidence that TLR7 negatively regulates dendrite growth through the canonical myeloid differentiation primary response gene 88 (Myd88)-c-Fos-interleukin (IL)-6 pathway. Although both TLR7 and TLR8 recognize single-stranded RNA (ssRNA), the results of quantitative reverse transcription-PCR suggested that TLR7 is the major TLR recognizing ssRNA in brains. In both in vitro cultures and in utero electroporation experiments, manipulation of TLR7 expression levels was sufficient to alter neuronal morphology, indicating the presence of intrinsic TLR7 ligands. Besides, the RNase A treatment that removed ssRNA in cultures promoted dendrite growth. We also found that the addition of ssRNA and synthetic TLR7 agonists CL075 and loxoribine, but not R837 (imiquimod), to cultured neurons specifically restricted dendrite growth via TLR7. These results all suggest that TLR7 negatively regulates neuronal differentiation. In cultured neurons, TLR7 activation induced IL-6 and TNF-α expression through Myd88. Using Myd88-, IL-6-, and TNF-α-deficient neurons, we then demonstrated the essential roles of Myd88 and IL-6, but not TNF-α, in the TLR7 pathway to restrict dendrite growth. In addition to neuronal morphology, TLR7 knockout also affects mouse behaviors, because young mutant mice ∼2 weeks of age exhibited noticeably lower exploratory activity in an open field. In conclusion, our study suggests that TLR7 negatively regulates dendrite growth and influences cognition in mice.

Obstetric complications as risk factors for schizophrenia spectrum psychoses in offspring of mothers with psychotic disorder

BACKGROUND

Obstetric complications have predicted future development of schizophrenia in previous studies, but they are also more common in mothers with schizophrenia. The aims of this study were to compare the occurrence of obstetric complications in children of mothers with schizophrenia spectrum psychoses and control children, and to investigate whether obstetric complications predicted children's psychiatric morbidity.

METHOD

The Helsinki High-Risk (HR) Study monitors females born between 1916 and 1948 and treated for schizophrenia spectrum disorders in Helsinki psychiatric hospitals, their offspring born between 1941 and 1977, and controls. We examined information on obstetric complications and neonatal health of 271 HR and 242 control offspring. We compared the frequency of obstetric complications and neonatal health problems in the HR group vs controls and in HR children who later developed psychotic disorders vs healthy HR children. A Cox regression model was used to assess whether problems in pregnancy or delivery predicted psychiatric morbidity within the HR group.

RESULTS

Few differences between HR and control offspring were found in obstetric complications. Within the HR group, infections (hazard rate ratio [HRR] 3.73, 95% CI 1.27-11.01), hypertension during pregnancy (HRR 4.10, 95% CI 1.15-14.58), and placental abnormalities (HRR 4.09, 95% CI 1.59-10.49) were associated with elevated risk of schizophrenia spectrum psychoses.

CONCLUSIONS

Common medical problems during pregnancy were associated with increased risk of schizophrenia spectrum psychoses in offspring of mothers with schizophrenia spectrum psychoses. These results underline the role of the prenatal period in the development of schizophrenia and the importance of careful monitoring of pregnancies of mothers with psychotic disorder.

Prenatal immune activation interacts with stress and corticosterone exposure later in life to modulate N-methyl-D-aspartate receptor synaptic function and plasticity

Prenatal infection is an environmental risk factor for schizophrenia while later in life, stressful events have been associated with the onset and severity of psychosis. Recent findings on the impact of stress on the N-methyl-d-aspartate receptor (NMDAR), of which hypofunctioning is implicated in schizophrenia, suggest changes in stress-induced regulation of the glutamatergic system may be related to the pathogenesis of schizophrenia. Our study aimed to test whether prenatal immune activation could interact with stress at adolescence to alter NMDAR function. We used offspring from rat dams administered bacterial lipopolysaccharide (LPS) during pregnancy (gestational days 15 and 16), an animal model expressing schizophrenia-related behavioural phenotypes. Using electrophysiological techniques, we investigated effects of stress and the stress hormone corticosterone (Cort) on NMDAR-mediated synaptic function and long-term depression (LTD) in hippocampal CA1 slices from these adolescent (aged 28-39 d) male offspring. In prenatal LPS offspring, NMDAR-mediated synaptic function and LTD were reduced and abolished, respectively, compared to prenatal saline controls. Notably, in vivo stress and in vitro Cort treatment facilitated LTD in slices from prenatal LPS rats but not prenatal saline controls. Finally, Cort enhanced NMDAR-mediated synaptic function in slices from prenatal LPS rats only. We conclude that prenatal immune activation results in NMDAR hypofunction in the hippocampus of adolescent rats but also increases responsiveness of NMDAR-mediated synaptic function and LTD towards stress. Prenatal infection could confer susceptibility to schizophrenia through modification of hippocampal NMDAR function, with hypofunction in resting conditions and heightened responsiveness to stress, thus impacting the development of the disorder.

Distinct abnormalities of the primate prefrontal cortex caused by ionizing radiation in early or midgestation

Prenatal exposure of the brain to environmental insult causes different neurological symptoms and behavioral outcomes depending on the time of exposure. To examine the cellular bases for these differences, we exposed rhesus macaque fetuses to x-rays during early gestation (embryonic day [E]30-E42), i.e., before the onset of corticogenesis, or in midgestation (E70-E81), when superficial cortical layers are generated. Animals were delivered at term (~E165), and the size and cellular composition of prefrontal association cortex (area 46) examined in adults using magnetic resonance imaging (MRI) and stereologic analysis. Both early and midgestational radiation exposure diminished the surface area and volume of area 46. However, early exposure spared cortical thickness and did not alter laminar composition, and due to higher cell density, neuron number was within the normal range. In contrast, exposure to x-rays at midgestation reduced cortical thickness, mainly due to elimination of neurons destined for the superficial layers. A cell-sparse gap, observed within layer III, was not filled by the later-generated neurons destined for layer II, indicating that there is no subsequent replacement of the lost neurons. The distinct areal and laminar pathology consequent to temporally segregated irradiation is consistent with basic postulates of the radial unit hypothesis of cortical development. In addition, we show that an environmental disturbance inflicted in early gestation can induce subtle cytoarchitectonic alterations without loss of neurons, such as those observed in schizophrenia, whereas midgestational exposure causes selective elimination of neurons and cortical thinning as observed in some forms of mental retardation and fetal alcohol syndrome.

Combination of prenatal immune challenge and restraint stress affects prepulse inhibition and dopaminergic/GABAergic markers

Gestational immune challenge with the viral-like antigen poly I:C is a well-established neurodevelopmental model of schizophrenia. However, exposure to inflammation during early life may sensitize the developing brain to secondary insults and enhance the central nervous system vulnerability. To gain a better understanding of the pathophysiology of schizophrenia, we thus developed a two-hit animal model based on prenatal poly I:C immune challenge followed by restraint stress in juvenile mice. C57BL/6 gestational mice were intraperitoneally injected with poly I:C or saline at gestational day 12. Pups were then submitted or not, to restraint stress for 2h, for three consecutive days, from postnatal days 33 to 35. Prepulse inhibition (PPI) of acoustic startle response is commonly used to assess sensorimotor gating, a neural process severely disrupted in patients with schizophrenia. Our results revealed that the combination of prenatal immune challenge with poly I:C followed by a restraint stress period was able to induce a PPI disruption in 36-day-old pups, as opposed to each insult applied separately. PPI deficits were accompanied by dopaminergic and GABAergic abnormalities in the prefrontal cortex and striatum. Indeed, measurements of cortical and striatal dopamine D2 receptor (D2R) mRNA and protein levels revealed that the combination of gestational exposure to poly I:C and postnatal restraint stress induced an increase in D2R protein and mRNA levels. Likewise, the combination of both insults reduced the mRNA and protein expression levels of the 67 kDa form of glutamic acid decarboxylase (GAD67), in those two brain regions. To our knowledge, this two-hit animal model is the first in vivo model reporting PPI deficits at pubertal age. This two-hit animal model may also help in studying innovative therapies dedicated to the treatment of schizophrenia, especially in its early phase.

The influence of maternal prenatal and early childhood nutrition and maternal prenatal stress on offspring immune system development and neurodevelopmental disorders

The developing immune system and central nervous system in the fetus and child are extremely sensitive to both exogenous and endogenous signals. Early immune system programming, leading to changes that can persist over the life course, has been suggested, and other evidence suggests that immune dysregulation in the early developing brain may play a role in neurodevelopmental disorders such as autism spectrum disorder and schizophrenia. The timing of immune dysregulation with respect to gestational age and neurologic development of the fetus may shape the elicited response. This creates a possible sensitive window of programming or vulnerability. This review will explore the effects of maternal prenatal and infant nutritional status (from conception until early childhood) as well as maternal prenatal stress and anxiety on early programming of immune function, and how this might influence neurodevelopment. We will describe fetal immune system development and maternal-fetal immune interactions to provide a better context for understanding the influence of nutrition and stress on the immune system. Finally, we will discuss the implications for prevention of neurodevelopmental disorders, with a focus on nutrition. Although certain micronutrient supplements have shown to both reduce the risk of neurodevelopmental disorders and enhance fetal immune development, we do not know whether their impact on immune development contributes to the preventive effect on neurodevelopmental disorders. Future studies are needed to elucidate this relationship, which may contribute to a better understanding of preventative mechanisms. Integrating studies of neurodevelopmental disorders and prenatal exposures with the simultaneous evaluation of neural and immune systems will shed light on mechanisms that underlie individual vulnerability or resilience to neurodevelopmental disorders and ultimately contribute to the development of primary preventions and early interventions.

Inflammatory cytokines and neurological and neurocognitive alterations in the course of schizophrenia

A growing body of evidence suggests that immune alterations, especially those related to inflammation, are associated with increased risk of schizophrenia and schizophrenia-related brain alterations. Much of this work has focused on the prenatal period, because infections during pregnancy have been repeatedly (albeit inconsistently) linked to risk of schizophrenia. Given that most infections do not cross the placenta, cytokines associated with inflammation (proinflammatory cytokines) have been targeted as potential mediators of the damaging effects of infection on the fetal brain in prenatal studies. Moreover, additional evidence from both human and animal studies suggests links between increased levels of proinflammatory cytokines, immune-related genes, and schizophrenia as well as brain alterations associated with the disorder. Additional support for the role of altered immune factors in the etiology of schizophrenia comes from neuroimaging studies, which have linked proinflammatory cytokine gene polymorphisms with some of the structural and functional abnormalities repeatedly found in schizophrenia. These findings are reviewed and discussed with a life course perspective, examining the contribution of inflammation from the fetal period to disorder presentation. Unexplored areas and future directions, such as the interplay between inflammation, genes, and individual-level environmental factors (e.g., stress, sleep, and nutrition), are also discussed.

Neurodevelopment and inflammatory patterns in schizophrenia in relation to pathophysiology

As for other major psychoses, the etiology of schizophrenia still remains poorly understood, involving genetic and epigenetic mechanisms, as well as environmental contributions. In addition, immune alterations have been widely reported in schizophrenic patients, involving both the unspecific and specific pathways of the immune system, and suggesting that infectious/autoimmune processes play an important role in the etiopathogenesis of the disorder. Cytokines, in particular, are supposed to play a critical role in infectious and inflammatory processes, mediating the cross-talk between the brain and the immune system. In this perspective, even though mixed results have been reported, it seems that schizophrenia is associated with an imbalance in inflammatory cytokines. Alterations in the inflammatory and immune systems, moreover, seem to be already present in the early stages of schizophrenia and connected to the neurodevelopmental hypothesis of the disorder, identifying its roots in brain development abnormalities that do not manifest themselves until adolescence or early adulthood. At the same time, neuropathological and longitudinal studies in schizophrenia also support a neurodegenerative hypothesis and, more recently, a novel mixed hypothesis, integrating neurodevelopmental and neurodegenerative models, has been put forward. The present review aims to provide an updated overview of the connections between the immune and inflammatory alterations and the aforementioned hypotheses in schizophrenia.

Potential application as screening and drug designing tools of cytoarchitectural deficiencies present in three animal models of schizophrenia

BACKGROUND

The development of new treatment alternatives for schizophrenia has been prevented by the unknown etiology of the illness and the divergence of results in the field. However, consistent neuropathological findings are emerging from anatomical areas known to be at the core of schizophrenia. If these deficiencies are replicated in animal models then such anomalies could become the target for a new generation of drugs.

OBJECTIVE

To determine if the methylazoxymethanol acetate (MAM) model, the heterozygote reeler mouse (HRM) and NMDA-antagonists treated rats replicate neuropathological deficits encountered in patients with schizophrenia and to establish if such changes could lead the search for developing novel treatment alternatives.

METHODS

Databases including MEDLINE, Cochrane and Ovid were searched; search terms included neuropathology, schizophrenia and animal models.

RESULTS/CONCLUSIONS

NMDA-antagonist treated animals partially replicate schizophrenia anomalies in parvalbumin positive interneurons. In contrast, neuroanatomical deficiencies replicated by the MAM model and the HRM in the hippocampus and the prefrontal cortex seem promising targets for future pharmacological research in schizophrenia. Such neuroanatomical findings along with evidence from molecules and genes associated with schizophrenia suggest new drugs should aim to correct deficits in the formation of dendrites and axons that seems to be implicated in this illness pathophysiology.

Prenatal maternal infection, neurodevelopment and adult schizophrenia: a systematic review of population-based studies

BACKGROUND

Disruption of foetal development by prenatal maternal infection is consistent with a neurodevelopmental model of schizophrenia. Whether specific prenatal infections are involved, their timing and the mechanisms of any effect are all unknown. We addressed these questions through a systematic review of population-based studies.

METHOD

Electronic and manual searches and rigorous quality assessment yielded 21 studies that included an objective assessment of individual-level prenatal maternal infection and standardized psychotic diagnoses in adult offspring. Methodological differences between studies necessitated a descriptive review.

RESULTS

Results for prenatal maternal non-specific bacterial, respiratory or genital and reproductive infection differed between studies, which reported up to a two- to fivefold increased risk of schizophrenia. Evidence for herpes simplex virus type 2 (HSV-2) and Toxoplasma gondii was mixed; some studies reported up to a doubling of schizophrenia risk. Prenatal HSV-1 or cytomegalovirus (CMV) infections were not associated with increased risk. Exposure to influenza or other infections during early pregnancy may be more harmful than later exposure. Increased proinflammatory cytokines during pregnancy were also associated with risk. Prenatal infection was associated with structural and functional brain abnormalities relevant to schizophrenia.

CONCLUSIONS

Prenatal exposure to a range of infections and inflammatory responses may be associated with risk of adult schizophrenia. Larger samples, mediation and animal models should be used to investigate whether there is a 'sensitive period' during development, and the effects of prenatal infections on neurodevelopment. Inclusion of genetic and immunological information should help to elucidate to what extent genetic vulnerability to schizophrenia may be explained by vulnerability to infection.

Early childhood infections and risk of schizophrenia

The association between early childhood infections and the risk of schizophrenia is not clear, and this study aimed to investigate the association between childhood infections and the risk of schizophrenia in a population-based Australia male cohort. A population-based cohort of males born between 1980 and 1984 in Western Australia was identified using birth registry records and followed-up until December 31st, 2009 or death using linked health data available through the Western Australian Data Linkage System. The associations between hospitalized infections occurring during 0-3yr of age and risk of schizophrenia were assessed with stratified analysis and multivariate logistic regression models. Analysis was further repeated to assess the effect of hospitalized intestinal infections (gastroenteritis) and respiratory infections. It was observed that male participants with two or more hospitalizations for infections before the age of three had an 80% higher risk of schizophrenia, and these findings remained when the analysis was limited to intestinal infections and acute respiratory infections. These findings support the hypothesis that infections during early childhood may lead to the onset of schizophrenia in later life.

Behaviour and hippocampus-specific changes in spiny mouse neonates after treatment of the mother with the viral-mimetic Poly I:C at mid-pregnancy

Epidemiological studies have suggested a link between prenatal exposure to bacterial or viral infections and subsequent development of mental disorders such as schizophrenia and autism. Animal models to study the prenatal origin of such outcomes of pregnancy have largely used conventional rodents which are immature at birth compared to the human neonate, and doses of the infective agent (i.e., lipopolysaccharide, Poly I:C) have been large enough to cause sickness behaviour in the mother. In this study we have used the spiny mouse (Acomys cahirinus) whose offspring have completed organogenesis at birth, and a single subcutaneous injection of a low (0.5mg/kg) dose of polyriboinosinic-polyribocytidilic acid (Poly I:C) at mid gestation (20 days, term is 39 days). The treatment had no effect on maternal, fetal or neonatal survival, or postnatal growth of the offspring. However, offspring showed significant impairments in non-spatial memory and learning tasks, and motor activity. Brain histology examined at 1 and 100 days of age revealed significant decreases in reelin, increased GFAP expression, and increased numbers of activated microglia, specifically in the hippocampus. This study provides evidence that a prenatal subclinical infection can have profound effects on brain development that are long-lasting.

Predicting risk and the emergence of schizophrenia

This article gives an overview of genetic and environmental risk factors for schizophrenia. The presence of certain molecular, biological, and psychosocial factors at certain points in the life span, has been linked to later development of schizophrenia. All need to be considered in the context of schizophrenia as a lifelong brain disorder. Research interest in schizophrenia is shifting to late childhood/early adolescence for screening and preventative measures. This article discusses those environmental risk factors for schizophrenia for which there is the largest evidence base.

Epidemiologic studies of exposure to prenatal infection and risk of schizophrenia and autism

In this review, we provide a synopsis of work on the epidemiologic evidence for prenatal infection in the etiology of schizophrenia and autism. In birth cohort studies conducted by our group and others, in utero exposure to infectious agents, prospectively obtained after biomarker assays of archived maternal sera and by obstetric records was related to an increased risk of schizophrenia. Thus far, it has been demonstrated that prenatal exposure to influenza, increased toxoplasma antibody, genital-reproductive infections, rubella, and other pathogens are associated with schizophrenia. Anomalies of the immune system, including enhanced maternal cytokine levels, are also related to schizophrenia. Some evidence also suggests that maternal infection and immune dysfunction may be associated with autism. Although replication is required, these findings suggest that public health interventions targeting infectious exposures have the potential for preventing cases of schizophrenia and autism. Moreover, this work has stimulated translational research on the neurobiological and genetic determinants of these conditions.

Infectious agents associated with schizophrenia: a meta-analysis

Schizophrenia is a highly disabling and limiting disorder for patients and the possibility that infections by some microorganisms may be associated to its development may allow prevention and recovery. In the current study we have done a meta-analysis of studies that have assessed the possible association between detection of different infectious agents and schizophrenia. We report results that support the idea that there is a statistically significant association between schizophrenia and infection by Human Herpesvirus 2 (OR=1.34; CI 95%: 1.09-1.70; p=0.05), Borna Disease Virus (OR=2.03; CI 95%: 1.35-3.06; p<0.01), Human Endogenous Retrovirus W (OR=19.31; CI 95%: 6.74-55.29; p<0.001), Chlamydophila pneumoniae (OR=6.34; CI 95%: 2.83-14.19; p<0.001), Chlamydophila psittaci (OR=29.05; CI 95%: 8.91-94.70; p<0.001) and Toxoplasma gondii (OR=2.70; CI 95%: 1.34-4.42; p=0.005). The implications of these findings are discussed and further research options are also explicated.

The nuclear factor-κB inhibitor pyrrolidine dithiocarbamate reduces polyinosinic-polycytidilic acid-induced immune response in pregnant rats and the behavioral defects of their adult offspring

Background

Epidemiological studies have indicated that maternal infection during pregnancy may lead to a higher incidence of schizophrenia in the offspring. It is assumed that the maternal infection increases the immune response, leading to neurodevelopmental disorders in the offspring. Maternal polyinosinic-polycytidilic acid (PolyI:C) treatment induces a wide range of characteristics in the offspring mimicking some schizophrenia symptoms in humans. These observations are consistent with the neurodevelopmental hypothesis of schizophrenia.

Methods

We examined whether suppression of the maternal immune response could prevent neurodevelopmental disorders in adult offspring. PolyI:C or saline was administered to early pregnant rats to mimic maternal infection, and the maternal immune response represented by tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) levels was determined by enzyme-linked immunosorbent assays (ELISA). The NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) was used to suppress the maternal immune response. Neurodevelopmental disorders in adult offspring were examined by prepulse inhibition (PPI), passive avoidance, and active avoidance tests.

Results

PolyI:C administration to early pregnant rats led to elevated serum cytokine levels as shown by massive increases in serum TNF-α and IL-10 levels. The adult offspring showed defects in prepulse inhibition, and passive avoidance and active avoidance tests. PDTC intervention in early pregnant rats suppressed cytokine increases and reduced the severity of neurodevelopmental defects in adult offspring.

Conclusions

Our findings suggest that PDTC can suppress the maternal immune response induced by PolyI:C and partially prevent neurodevelopmental disorders of adult offspring.

[Seasonality of Schizophrenia: Findings of a Descriptive Study in Santa Marta, Colombia]

Introduction

Multiple studies carried out around the globe have concluded that there is a seasonal effect on the births of patients that will go on to develop schizophrenia later on. A relationship between being exposed to certain infectious agents during the prenatal period and possible direct effects on the developing brain that will later be expressed by the classical clinical picture has been suggested.

Objective

To analyze the behavior of births in a sample of individuals with schizophrenia from Santa Marta, Colombia.

Methods

Descriptive study based on the review of clinical histories of the patients seen in a psychiatric institute.

Discussion

A larger number of births took place during the rainiest months of the year suggesting a possible seasonal effect. However, the lack of data on births in Santa Marta during the years of the study did not allow a comparison between the results of the study and the birth rates of the general population. Even so, these findings have implications for future research regarding seasonality of schizophrenia in Colombia. They do not reflect an individual risk of developing the illness but they do document the characteristics of the temporal behavior of the births in the sample studied. Further studies that overcome the limitations of the present one are needed.

Placental TNF-α signaling in illness-induced complications of pregnancy

Maternal infections are implicated in a variety of complications during pregnancy, including pregnancy loss, prematurity, and increased risk of neurodevelopmental disorders in the child. Here, we show in mice that even mild innate immune activation by low-dose lipopolysaccharide in early pregnancy causes hemorrhages in the placenta and increases the risk of pregnancy loss. Surviving fetuses exhibit hypoxia in the brain and impaired fetal neurogenesis. Maternal Toll-like receptor 4 signaling is a critical mediator of this process, and its activation is accompanied by elevated proinflammatory cytokines in the placenta. We evaluated the role of tumor necrosis factor-α (TNF-α) signaling and show that TNF receptor 1 (TNFR1) is necessary for the illness-induced placental pathology, accompanying fetal hypoxia, and neuroproliferative defects in the fetal brain. We also show that placental TNFR1 in the absence of maternal TNFR1 is sufficient for placental pathology to develop and that a clinically relevant TNF-α antagonist prevents placental pathology and fetal loss. Our observations suggest that the placenta is highly sensitive to proinflammatory signaling in early pregnancy and that TNF-α is an effective target for preventing illness-related placental defects and related risks to the fetus and fetal brain development.

Physical exercise increases adult neurogenesis and telomerase activity, and improves behavioral deficits in a mouse model of schizophrenia

Epidemiological studies indicate that among other early life challenges, maternal infection with influenza during pregnancy increased the risk of developing schizophrenia in the child. One morphological manifestation of schizophrenia is hippocampal atrophy. In the hippocampus, playing a key role in learning and memory formation, new granule cell neurons are produced throughout life from resident precursor cells. We hypothesize that individuals exposed to a maternal anti-viral immune response would presumably enter life with a challenged neural precursor cell pool and might later be susceptible to psychiatric pathologies due to reduced adult neurogenesis. We used the injection of double-stranded RNA (polyriboinosinicpolyribocytidylic acid - PolyI:C) in pregnant C57Bl/6 and nestin-GFP reporter mice to induce a maternal viral-like infection and schizophrenia-like behavior in the offspring. In the progeny we found impairments in the open field test and in sensorimotor gating as measured by pre-pulse inhibition of the startle response. The behavioral deficits were accompanied by reduced baseline adult hippocampal neurogenesis. Telomerase activity in neural precursor cells was reduced from birth on and telomere shortening was found in the same cell type in adult life. When we subjected the progeny of viral-like infected dams to voluntary exercise, a known stimulus of adult hippocampal neurogenesis, we could rescue the phenotype in behavior, adult neurogenesis, and cellular senescence. In summary, maternal viral-like immune response reduced telomerase activity and resulted in telomere shortening in neural precursor cells. Further we demonstrate that beneficial behavioral and cellular effects induced by exercise can be studied in a rodent model of schizophrenia.