A neurodevelopmental approach to the classification of schizophrenia

Early developmental disturbances of cortical inhibitory neurons: contribution to cognitive deficits in schizophrenia

Cognitive dysfunction is a disabling and core feature of schizophrenia. Cognitive impairments have been linked to disturbances in inhibitory (gamma-aminobutyric acid [GABA]) neurons in the prefrontal cortex. Cognitive deficits are present well before the onset of psychotic symptoms and have been detected in early childhood with developmental delays reported during the first year of life. These data suggest that the pathogenetic process that produces dysfunction of prefrontal GABA neurons in schizophrenia may be related to altered prenatal development. Interestingly, adult postmortem schizophrenia brain tissue studies have provided evidence consistent with a disease process that affects different stages of prenatal development of specific subpopulations of prefrontal GABA neurons. Prenatal ontogeny (ie, birth, proliferation, migration, and phenotypic specification) of distinct subpopulations of cortical GABA neurons is differentially regulated by a host of transcription factors, chemokine receptors, and other molecular markers. In this review article, we propose a strategy to investigate how alterations in the expression of these developmental regulators of subpopulations of cortical GABA neurons may contribute to the pathogenesis of cortical GABA neuron dysfunction and consequently cognitive impairments in schizophrenia.

Transcription factor 4 (TCF4) and schizophrenia: integrating the animal and the human perspective

Schizophrenia is a genetically complex disease considered to have a neurodevelopmental pathogenesis and defined by a broad spectrum of positive and negative symptoms as well as cognitive deficits. Recently, large genome-wide association studies have identified common alleles slightly increasing the risk for schizophrenia. Among the few schizophrenia-risk genes that have been consistently replicated is the basic Helix-Loop-Helix (bHLH) transcription factor 4 (TCF4). Haploinsufficiency of the TCF4 (formatting follows IUPAC nomenclature: TCF4 protein/protein function, Tcf4 rodent gene cDNA mRNA, TCF4 human gene cDNA mRNA) gene causes the Pitt-Hopkins syndrome-a neurodevelopmental disease characterized by severe mental retardation. Accordingly, Tcf4 null-mutant mice display developmental brain defects. TCF4-associated risk alleles are located in putative coding and non-coding regions of the gene. Hence, subtle changes at the level of gene expression might be relevant for the etiopathology of schizophrenia. Behavioural phenotypes obtained with a mouse model of slightly increased gene dosage and electrophysiological investigations with human risk-allele carriers revealed an overlapping spectrum of schizophrenia-relevant endophenotypes. Most prominently, early information processing and higher cognitive functions appear to be associated with TCF4 risk genotypes. Moreover, a recent human study unravelled gene × environment interactions between TCF4 risk alleles and smoking behaviour that were specifically associated with disrupted early information processing. Taken together, TCF4 is considered as an integrator ('hub') of several bHLH networks controlling critical steps of various developmental, and, possibly, plasticity-related transcriptional programs in the CNS and changes of TCF4 expression also appear to affect brain networks important for information processing. Consequently, these findings support the neurodevelopmental hypothesis of schizophrenia and provide a basis for identifying the underlying molecular mechanisms.

Cognitive functioning associated with stimulant use in patients with non-affective psychosis, their unaffected siblings and healthy controls

BACKGROUND

Little is known about the effect of stimulant use (amphetamines, cocaine, ecstasy) on cognitive functioning in schizophrenia patients. The current study examined (1) whether recency and frequency of stimulant use is associated with cognitive functioning and (2) whether these associations differ between psychotic patients, their unaffected siblings and controls.

METHOD

Participants completed a comprehensive cognitive test battery. Stimulant use was assessed by urinalysis and by the Composite International Diagnostic Interview (CIDI). Using random effects regression models, the main effects of Stimulant Use and the interaction with Diagnostic Status on cognitive functioning were assessed.

RESULTS

The interaction term between Stimulant Use and Diagnostic Status was not significant for any of the cognitive outcome variables, indicating similar effects of stimulant use in all three groups. Recent stimulant users showed more errors deficit in verbal learning in comparison to never users (Cohen's d = -0.60, p < 0.005). Lifetime frequent stimulant use was significantly associated with worse immediate and delayed verbal recall, working memory and acquired knowledge (Cohen's d = -0.22 to -0.29, p < 0.005). Lifetime infrequent stimulant use was not associated with significant cognitive alterations in comparison to never use.

CONCLUSIONS

The presence of cognitive deficits associated with lifetime stimulant use is dependent on the frequency of use, with no observed deficits in infrequent users and modest negative effects in frequent users.

Neurodevelopmental and neurodegenerative models of schizophrenia: white matter at the center stage

Schizophrenia is a disorder of cerebral disconnectivity whose lifetime course is modeled as both neurodevelopmental and neurodegenerative. The neurodevelopmental models attribute schizophrenia to alterations in the prenatal-to-early adolescent development. The neurodegenerative models identify progressive neurodegeneration as its core attribute. Historically, the physiology, pharmacology, and treatment targets in schizophrenia were conceptualized in terms of neurons, neurotransmitter levels, and synaptic receptors. Much of the evidence for both models was derived from studies of cortical and subcortical gray matter. We argue that the dynamics of the lifetime trajectory of white matter, and the consistency of connectivity deficits in schizophrenia, support white matter integrity as a promising phenotype to evaluate the competing evidence for and against neurodevelopmental and neurodegenerative heuristics. We develop this perspective by reviewing normal lifetime trajectories of white and gray matter changes. We highlighted the overlap between the age of peak of white matter development and the age of onset of schizophrenia and reviewed findings of white matter abnormalities prior to, at the onset, and at chronic stages of schizophrenia. We emphasized the findings of reduced white matter integrity at the onset and findings of accelerated decline in chronic stages, but the developmental trajectory that precedes the onset is largely unknown. We propose 4 probable lifetime white matter trajectory models that can be used as the basis for separation between the neurodevelopmental and neurodegenerative etiologies. We argue that a combination of the cross-sectional and longitudinal studies of white matter integrity in patients may be used to bridge the neurodevelopment and degeneration heuristics to advance schizophrenia research.

Toxicity, Deficiency and Dysmetabolism of Trace Elements in Ghanaian Clinically Stable Schizophrenics

AIM: The purpose of the study was to determine the levels of Copper (Cu), selenium (Se), Zinc (Zn), Lead (Pb) and Lithium (Li) in patients in Accra and Pantang Psychiatric Hospitals in Ghana since no data exist.SUBJECTS AND METHODS: Simple random sampling of age-matched subjects was used to recruit 81 schizophrenics and 25 mentally healthy controls in 2012. Serum levels of Cu, Se, Zn, Pb and Li were determined by flame atomic absorption spectroscopy (FAAS). RESULTS: Mean levels were as follows: Cut 766 ± 250 µg/L and Cuc 855 ± 270 µg/L (p = 0.168). Set 149 ± 72 µg/L and Sec 108 ± 61 µg/L (p=0.009). Znt 702 ± 438 µg/L and Znc 1007 ± 593 µg/L (p = 0.028). Pbt 1.38 ± 0.05 µg/L and Pbc 0.10 ± 0.05 µg/L (p = 0.000). Li levels for the test group (Lit) was 4077 ± 2567 µg/L, whiles that of the controls was undetectable < 0.02 µg/L. Se, Pb and Li levels were significantly higher in schizophrenic patients compared to controls. While Zn and Cu levels were lower in the same group.CONCLUSION: Trace elements dysmetabolism exist among Ghanaian schizophrenics and monitoring is essential to avoid the adverse effects of metal overload or deficiency.

A meta-analysis of mentalizing impairments in adults with schizophrenia and autism spectrum disorder

Mentalizing has been examined both in autism spectrum disorder (ASD) and schizophrenia (SCZ) primarily by either cognitive-linguistic (referred to as verbal) or emotion recognition from eyes (referred to as visual) mentalizing tasks. Each type of task is thought to measure different aspects of mentalizing. Differences in clinical features and developmental courses of each disorder may predict distinct patterns of mentalizing performance across dis orders on each type of task. To test this, a meta-analysis was conducted using 37 studies that assessed mentalizing either verbally or visually in adults with SCZ or ASD. We found that the estimated effect sizes of impairments in verbal and visual mentalizing tasks for both clinical groups were statistically large and at a similar level (overall Hedges' g = 0.73-1.05). For each disorder, adults with SCZ showed a trend towards larger impairments on verbal (overall Hedges' g = 0.99) than on visual mentalizing task (overall Hedges' g = 0.73; Qbet = 3.45, p =.06, df =1). Adults with ASD did not show different levels of impairment on the verbal versus visual tasks (Qbet = 0.08, p =.78, df =1). These results suggest that both clinical groups share, at least in part, some common cognitive processing deficits associated with mentalizing impairments.

Antibodies directed to the gram-negative bacterium Neisseria gonorrhoeae cross-react with the 60 kDa heat shock protein and lead to impaired neurite outgrowth in NTera2/D1 cells

Children of mothers with prenatal gonococcal infections are of increased risk to develop schizophrenic psychosis in later life. The present study hypothesizes an autoimmune mechanism for this, investigating interactions of a commercial rabbit antiserum directed to Neisseria gonorrhoeae (α-NG) with human NTera2/D1 cells, an established in vitro model for human neuronal differentiation. Immunocytochemistry demonstrated α-NG to label antigens on an intracellular organelle, which by Western blot analysis showed a molecular weight shortly below 72 kDa. An antiserum directed to Neisseria meningitidis (α-NM) reacts with an antigen shortly below 95 kDa, confirming antibody specificity of these interactions. Two-dimensional gel electrophoresis and partial Western transfer, allowed to localize an α-NG reactive protein spot which was identified by LC-Q-TOF MS/MS analysis as mitochondrial heat shock protein Hsp60. This was confirmed by Western blot analysis of α-NG immunoreactivity with a commercial Hsp60 protein sample, with which α-NM failed to interact. Finally, analysis of neurite outgrowth in retinoic acid-stimulated differentiating NTera2-D1 cells, demonstrates that α-NG but not α-NM treatment reduces neurite length. These results demonstrate that α-NG can interact with Hsp60 in vitro, whereas pathogenetic relevance of this interaction for psychotic symptomatology remains to be clarified.

Increased l1 retrotransposition in the neuronal genome in schizophrenia

Recent studies indicate that long interspersed nuclear element-1 (L1) are mobilized in the genome of human neural progenitor cells and enhanced in Rett syndrome and ataxia telangiectasia. However, whether aberrant L1 retrotransposition occurs in mental disorders is unknown. Here, we report high L1 copy number in schizophrenia. Increased L1 was demonstrated in neurons from prefrontal cortex of patients and in induced pluripotent stem (iPS) cell-derived neurons containing 22q11 deletions. Whole-genome sequencing revealed brain-specific L1 insertion in patients localized preferentially to synapse- and schizophrenia-related genes. To study the mechanism of L1 transposition, we examined perinatal environmental risk factors for schizophrenia in animal models and observed an increased L1 copy number after immune activation by poly-I:C or epidermal growth factor. These findings suggest that hyperactive retrotransposition of L1 in neurons triggered by environmental and/or genetic risk factors may contribute to the susceptibility and pathophysiology of schizophrenia.

Systematic review and collaborative recalculation of 133,693 incident cases of schizophrenia

BACKGROUND

This systematic review and collaborative recalculation was set up to recalculate schizophrenia incidence rates from previously published studies by age and sex.

METHOD

PubMed, EMBASE and PsycINFO databases were searched (January 1950 to December 2009) for schizophrenia incidence studies. Numerator and population data were extracted by age, sex and, if possible, study period. Original data were requested from the authors to calculate age- and sex-specific incidence rates. Incidence rate ratios (IRRs) with their 95% confidence intervals (CIs) were computed by age and sex from negative binomial regression models.

RESULTS

Forty-three independent samples met inclusion criteria, yielding 133 693 incident cases of schizophrenia for analysis. Men had a 1.15-fold (95% CI 1.00-1.31) greater risk of schizophrenia than women. In men, incidence peaked at age 20-29 years (median rate 4.15/10,000 person-years, IRR 2.61, 95% CI 1.74-3.92). In women, incidence peaked at age 20-29 (median rate 1.71/10,000 person-years, IRR 2.34, 95% CI 1.66-3.28) and 30-39 years (median rate 1.24/10,000 person-years, IRR 2.25, 95% CI 1.55-3.28). This peak was followed by an age-incidence decline up to age 60 years that was stronger in men than in women (χ² = 57.90, p < 0.001). The relative risk of schizophrenia was greater in men up to age 39 years and this reversed to a greater relative risk in women over the age groups 50-70 years. No evidence for a second incidence peak in middle-aged women was found.

CONCLUSIONS

Robust sex differences exist in the distribution of schizophrenia risk across the age span, suggesting differential susceptibility to schizophrenia for men and women at different stages of life.

Neural ECM in addiction, schizophrenia, and mood disorder

The extracellular matrix (ECM) has a prominent role in brain development, maturation of neural circuits, and adult neuroplasticity. This multifactorial role of the ECM suggests that processes that affect composition or turnover of ECM in the brain could lead to altered brain function, possibly underlying conditions of impaired mental health, such as neuropsychiatric or neurodegenerative disease. In support of this, in the last two decades, clinical and preclinical research provided evidence of correlations and to some degree causal links, between aberrant ECM function and neuropsychiatric disorders, the most prominent being addiction and schizophrenia. Based on these initial observations of involvement of different classes of ECM molecules (laminin, reelin, and their integrin receptors, as well as tenascins and chondroitin sulfate proteoglycans), ECM targets have been suggested as a novel entry point in the treatment of neuropsychiatric disorders. Hence, understanding how ECM molecules contribute to proper neuronal functioning and how this is dysregulated in conditions of mental illness is of pivotal importance. In this chapter, we will review available literature that implicates the different classes of brain ECM molecules in psychiatric disorders, with a primary focus on addiction (opiates, psychostimulants, and alcohol), and we will compare these ECM adaptations with those implicated in schizophrenia and mood disorders.

Distinct molecular phenotypes in male and female schizophrenia patients

BACKGROUND

In schizophrenia, sex specific dimorphisms related to age of onset, course of illness and response to antipsychotic treatment may be mirrored by sex-related differences in the underlying molecular pathways.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we have carried out multiplex immunoassay profiling of sera from 4 independent cohorts of first episode antipsychotic naive schizophrenia patients (n = 133) and controls (n = 133) to identify such sex-specific illness processes in the periphery. The concentrations of 16 molecules associated with hormonal, inflammation and growth factor pathways showed significant sex differences in schizophrenia patients compared with controls. In female patients, the inflammation-related analytes alpha-1-antitrypsin, B lymphocyte chemoattractant BLC and interleukin-15 showed negative associations with positive and negative syndrome scale (PANSS) scores. In male patients, the hormones prolactin and testosterone were negatively associated with PANSS ratings. In addition, we investigated molecular changes in a subset of 33 patients before and after 6 weeks of treatment with antipsychotics and found that treatment induced sex-specific changes in the levels of testosterone, serum glutamic oxaloacetic transaminase, follicle stimulating hormone, interleukin-13 and macrophage-derived chemokine. Finally, we evaluated overlapping and distinct biomarkers in the sex-specific molecular signatures in schizophrenia, major depressive disorder and bipolar disorder.

CONCLUSIONS/SIGNIFICANCE

We propose that future studies should investigate the common and sex-specific aetiologies of schizophrenia, as the current findings suggest that different therapeutic strategies may be required for male and female patients.

Antibodies directed to Neisseria gonorrhoeae impair nerve growth factor-dependent neurite outgrowth in Rat PC12 cells

In children born from mothers with prenatal infections with the Gram-negative bacterium Neisseria gonorrhoeae, schizophrenia risk is increased in later life. Since cortical neuropil formation is frequently impaired during this disease, actions of a rabbit polyclonal antiserum directed to N. gonorrhoeae on neurite outgrowth in nerve growth factor-stimulated PC12 cells were investigated here. It turned out that 10 μg/ml of the antiserum leads indeed to a significant reduction in neurite outgrowth, whereas an antiserum directed to Neisseria meningitidis had no such effect. Furthermore, reduction in neurite outgrowth could be reversed by the neuroleptic drugs haloperidol, clozapine, risperidone, and olanzapine. On the molecular level, the observed effects seem to include the known neuritogenic transcription factors FoxO3a and Stat3, since reduced neurite outgrowth caused by the antiserum was accompanied by a reduced phosphorylation of both factors. In contrast, restitution of neurite outgrowth by neuroleptic drugs revealed no correlation to the phosphorylation state of these factors. The present report gives a first hint that bacterial infections could indeed lead to impaired neuropil formation in vitro; however, the in vivo relevance of this finding for schizophrenia pathogenesis remains to be clarified in the future.

The relationship of early premorbid adjustment with negative symptoms and cognitive functions in first-episode schizophrenia: a prospective three-year follow-up study

Premorbid adjustment is an important prognostic factor of schizophrenia. The relationships between sub-components of premorbid adjustment and outcomes on symptoms and cognition in first-episode schizophrenia were under-studied. In the current study, we prospectively followed up 93 patients aged 18-55 years presenting with first-episode schizophrenia-spectrum disorder. Psychopathological and cognitive assessments were conducted at baseline, clinical stabilization, 12, 24 and 36 months. Premorbid adjustment was sub-divided into discrete functional domains, developmental stages and premorbid-course types based on ratings of the Premorbid Adjustment Scale (PAS). The study focused on early developmental stages to minimize contamination by prodromal symptoms. Results indicated that gender differences in premorbid functioning were primarily related to early-adolescence adjustment and academic domain. Social domain was more strongly related to negative symptoms, while academic domain was more consistently linked to cognitive outcome (Wisconsin Card Sorting test and verbal fluency). Patients with stable-poor premorbid course had more severe negative symptoms and cognitive impairment. In conclusion, in a Chinese cohort of first-episode schizophrenia-spectrum disorder, sub-components of early premorbid adjustment were shown to be differentially related to clinical and cognitive measures. The results highlighted the importance of applying a more refined delineation of premorbid functioning in studying illness outcome.

Cognitive profiles of three clusters of patients with a first-episode psychosis

OBJECTIVE

The primary objective was to identify specific groups of patients with a first-episode psychosis based on family history, obstetric complications, neurological soft signs, and premorbid functioning. The secondary objective was to relate these groups with cognitive variables.

METHOD

A total of 62 first-episode psychoses were recruited from adult and child and adolescent mental health services. The inclusion criteria were patients between 7 and 65 years old (real range of the samples was 13-35 years old), two or more psychotic symptoms and less than one year from the onset of the symptoms. Premorbid functioning (PAS), soft signs (NES), obstetric complications and a neuropsychological battery (CPT, TMTA/TMTB, TAVEC/TAVECI, Stroop, specific subtest of WAIS-III/WISC-IV) were administered.

RESULTS

We found three clusters: 1) higher neurodevelopment contribution (N=14), 2) higher genetic contribution (N=30), and 3) lower neurodevelopment contribution (N=18). Statistical differences were found between groups in TMTB, learning curve of the TAVEC, digits of the WAIS and premorbid estimated IQ, the cluster 1 being the most impaired.

CONCLUSIONS

A cluster approach could differentiate several groups of patients with different cognitive performance. Neuropsychological interventions, as cognitive remediation, should be addressed specifically to patients with more impaired results.

Neonatal MK-801 treatment differentially alters the effect of adolescent or adult MK-801 challenge on locomotion and PPI in male and female rats

Schizophrenia is a neurodevelopmental disorder and is typically "triggered" by subsequent insults in life. The N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) induces locomotor hyperactivity and prepulse inhibition (PPI) deficits, which can mimic the schizophrenia phenotype. In this experiment, we assessed whether neonatal exposure to MK-801 (postnatal days 5-14) could induce sensitization to both hyperactivity and PPI deficit caused by later-life acute MK-801 treatment during adolescence or adulthood. Our results showed that the hyperactivity induced by an acute MK-801 challenge was enhanced in male and female rats after neonatal MK-801 treatment. Notably, in the PPI test, adult female rats neonatally exposed to MK-801 exhibited a significantly greater reduction in PPI in response to acute MK-801 administration, whereas male rats receiving neonatal MK-801 treatment expressed attenuated PPI disruption in adulthood. Our data indicate that a combination of neonatal and later-life NMDA receptor blockades could induce sensitization in the locomotor activity of both sexes in adolescence and adulthood. In addition, a sex difference was observed in the effects of this treatment regime on PPI.

Neurodevelopment in schizophrenia: the role of the wnt pathways

OBJECTIVES

To review the role of Wnt pathways in the neurodevelopment of schizophrenia.

METHODS

SYSTEMATIC PUBMED SEARCH, USING AS KEYWORDS ALL THE TERMS RELATED TO THE WNT PATHWAYS AND CROSSING THEM WITH EACH OF THE FOLLOWING AREAS: normal neurodevelopment and physiology, neurodevelopmental theory of schizophrenia, schizophrenia, and antipsychotic drug action.

RESULTS

Neurodevelopmental, behavioural, genetic, and psychopharmacological data point to the possible involvement of Wnt systems, especially the canonical pathway, in the pathophysiology of schizophrenia and in the mechanism of antipsychotic drug action. The molecules most consistently found to be associated with abnormalities or in antipsychotic drug action are Akt1, glycogen synthase kinase3beta, and beta-catenin. However, the extent to which they contribute to the pathophysiology of schizophrenia or to antipsychotic action remains to be established.

CONCLUSIONS

The study of the involvement of Wnt pathway abnormalities in schizophrenia may help in understanding this multifaceted clinical entity; the development of Wnt-related pharmacological targets must await the collection of more data.

Prevalence and score of minor physical anomalies in patients with schizophrenia and their first degree relatives: a Tunisian study

Minor physical anomalies (MPAs) have been consistently reported to be more frequent in schizophrenia subjects. Limited research has been conducted on these anomalies among biological relatives of patients with schizophrenia. The aims of this study were to investigate the MPAs in a Tunisian population: subjects with schizophrenia, their healthy siblings and control subjects. This study hypothesized that the mean MPAs score would be greater in patients than controls and that siblings would have intermediate scores. Furthermore, it was hypothesized that MPAs scores would be associated with negative and disorganised symptoms of schizophrenia.

METHODS

We assessed 93 subjects with schizophrenia, 59 of their healthy siblings and 71 healthy controls, matched on gender and age. MPAs were assessed through use of a standardized scale derived from the Waldrop Scale [D. Gourion, G. Viot, C. Goldberger, M. Cartier, M.C. Bourdel, M.F. Poirier, J.P. Olié, H. Lôo, M.O. Krebs, 2001. French validation of a Minor Morphologic Anomalies Scale in schizophrenic patients and their parents. Encephale 27, 143-147]. The schizophrenia psychopathology was evaluated by the Positive and Negative Syndrome Scale (PANSS), Global Assessment of Functioning (GAF) and the Clinical Global Impression-Severity (CGI-S).

RESULTS

Subjects with schizophrenia showed significantly higher MPAs score than siblings (4.6 ± 2.8 vs. 3.0 ± 2.1, p<0.0001) and controls groups: 1.9 ± 1.5 (p<0.0001). Siblings had significantly higher score than control subjects (p=0.02). MPAs were correlated negatively with age of onset of the disease, and age of first hospitalisation, and positively with number of hospitalisations. Positive correlations were found between MPAs and PANSS total score, PANSS negative sub-score and CGI-S score.

COMMENTS

Results of this study showed that MPAs are more frequent in subjects with schizophrenia and their siblings compared to control subjects. Positive correlations were found between MPAs, age of onset, severity of illness, and negative symptoms of schizophrenia, suggesting that those anomalies are correlated to severe form of schizophrenia.

Prediction of acute clinical response following a first episode of non affective psychosis: results of a cohort of 375 patients from the Spanish PAFIP study

OBJECTIVE

Predicting response to antipsychotic treatment might optimize treatment strategies in early phases of schizophrenia. We aimed to investigate sociodemographic, premorbid and clinical predictors of response to antipsychotic treatment after a first episode of non-affective psychosis.

METHOD

375 (216 males) patients with a diagnosis of non affective psychosis entered the study. The main outcome measure was clinical response at 6 weeks and variables at baseline were evaluated as predictors of response. ANOVA for continuous and chi-square for categorical data were used to compare responders and non-responders. Multivariate logistic regression was used to establish a prediction model.

RESULTS

53.3% of study subjects responded to antipsychotic treatment. The following variables were associated with an unfavorable response: 1.--lower severity of symptoms at baseline; 2.--diagnosis of schizophrenia; 3.--longer DUI and DUP; 4.--poorer premorbid adjustment during adolescence and adulthood; 5.--family history of psychosis, and 6.--hospitalization. Patients with a family history of psychosis, longer DUP, poor premorbid functioning and lower severity of psychotic symptoms at intake have a reduced likelihood of responding to antipsychotic treatment.

CONCLUSION

Helping clinicians to identify those first episode patients with a lower probability of having a favorable clinical response is meant as a first step to achieve a successful initial treatment.

Child literacy and psychotic experiences in early adolescence: findings from the ALSPAC study

The aim of this study was to use prospective data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to examine the differences in literacy skills in children who later completed the psychotic like symptoms (PLIKS) interview at 12 years of age. We further examined the association between literacy skills over time in relation to the likelihood of reporting psychotic experiences (PEs). This study examined data from n=6790 children from the ALSPAC cohort who participated in the PLIKS semi-structured interview. Literacy skills such as spelling, basic real and non-real word reading, and reading skills and comprehension were assessed by an ALSPAC spelling task, Wechsler Objective Reading Dimension, and the revised Neale Analysis of Reading Ability (NARA II) respectively. Relative to the group unaffected by PEs, we found a lower performance in all measurements of child literacy skills in those with suspected or definite PEs. The majority of these differences persisted after adjusting for a range of covariates. In addition, both a consistently low pattern of performance and a decline were associated with suspected or definite PEs. Implications for preventative intervention models focussed on children at risk of developing psychotic disorders are discussed within the context of speech and language development.

Aripiprazole for drug-naive or antipsychotic-short-exposure subjects with ultra-high risk state and first-episode psychosis: an open-label study

INTRODUCTION

This study aimed to observe treatment response using aripiprazole for subjects with ultra-high risk (UHR) state of psychosis or at their first-episode psychosis (FEP) who were drug-naive or only have received antipsychotic therapy temporarily.

METHODS

All patients received aripiprazole 3.75 mg/d initially to test tolerability and increased to 7.5 mg during the first 2 weeks. A flexible dosing strategy based on clinical improvement and tolerability with a target dose 15 mg/d by the end of the fourth week. Clinical severity was assessed by a Mandarin version of the positive and negative syndrome scale for schizophrenia at baseline, the end of the second and the fourth week. Adverse reactions were recorded by a log, and concomitant medications were allowed.

RESULTS

A total of 20 FEP and 11 UHR patients, including 18 drug-naive (11 FEP and 7 UHR) and 13 antipsychotic-short-exposure patients (9 FEP and 4 UHR), participated in and 29 completed the study. Most of them received aripiprazole no more than 7.5 mg/d at end point with favorable response, although many of them reported adverse events. Both UHR and FEP patients got significant decrease of positive symptom scores in a similar pattern. Both groups did not show significant changes in negative symptom scores.

CONCLUSION

The treatment response of UHR patients is likely a continuum from that of the FEP patients. Low-dose aripiprazole revealed potential efficacy for patients with less severe psychopathology, at putative prodromal or early state of psychosis, yet still was accompanied by adverse events while treating this mostly drug-naive population.

Social cognition in patients with schizophrenia, their unaffected first degree relatives and healthy controls. Comparison between groups and analysis of associated clinical and sociodemographic variables

AIM

To evaluate and compare the social cognition in patients with schizophrenia, healthy first-degree relatives and controls, by studying the relationship between social cognition and nonsocial cognition, psychopathology, and other clinical and sociodemographic variables.

METHOD

The total sample was comprised of patients diagnosed with paranoid schizophrenia (N = 29), healthy first-degree relatives (N = 21) and controls (N = 28). All groups were assessed with an ad hoc questionnaire and a Social Cognition Scale, which assessed the domains: emotional processing, social perception and attributional style in a Spanish population. The patient group was also assessed with the Scale for the Positive and Negative Syndrome Scale and the Mini-mental state examination. Statistical analyses were performed with SPSS version 15.0.

RESULTS

Patients scored significantly worse in all domains of social cognition assessed, compared with controls, and mastery attributional style, compared with relatives. The type of psychopathology correlated negatively and statistically significantly with different domains of social cognition: negative symptoms with emotional processing and attributional style, and positive symptoms with social perception. Basic cognition scores correlated positively and statistically significantly with the domains social perception and attributional style.

CONCLUSION

Social cognition has become an interesting object of study, especially in how it relates to non-social cognition, psychopathology and global functioning of patients, bringing new elements to be considered in the early detection, comprehensive treatment and psychosocial rehabilitation of patients. Its conceptualization as trait variable, the consideration of the existence of a continuum between patients and relatives are plausible hypotheses that require further research.

Deficient Suppression of Default Mode Regions during Working Memory in Individuals with Early Psychosis and at Clinical High-Risk for Psychosis

BACKGROUND

The default mode network (DMN) is a set of brain regions typically activated at rest and suppressed during extrinsic cognition. Schizophrenia has been associated with deficient DMN suppression, though the extent to which DMN dysfunction predates psychosis onset is unclear. This study examined DMN suppression during working memory (WM) performance in youth at clinical high-risk (CHR) for psychosis, early schizophrenia (ESZ) patients, and healthy controls (HC). We hypothesized that the DMN would show load-dependent suppression during WM retrieval in HC but not in ESZ, with CHR participants showing an intermediate pattern.

METHODS

fMRI data were collected from CHR (n = 32), ESZ (n = 22), and HC (n = 54) participants, ages 12-30. DMN regions were defined via seed-based connectivity analysis of resting-state fMRI data from an independent HC sample. Load-dependent deactivations of these DMN regions in response to WM probes were interrogated.

RESULTS

Healthy controls showed linear load-dependent increases in DMN deactivation. Significant Group-by-Load interactions were observed in DMN regions including medial prefrontal and lateral posterior parietal cortices. Group-by-Load effects in posterior DMN nodes resulted from less suppression at higher WM loads in ESZ relative to HC, with CHR differing from neither group. In medial prefrontal cortex, suppression of activity at higher WM loads was significantly diminished in both CHR and ESZ groups, relative to HC. In addition, investigation of dorsolateral prefrontal cortex (DLPFC) activations revealed that ESZ activated right DLPFC significantly more than HC, with CHR differing from neither group.

CONCLUSION

While HC showed WM load-dependent modulation of DMN suppression, CHR individuals had deficient higher-load DMN suppression that was similar to, but less pronounced than, the distributed suppression deficits evident in ESZ patients. These results suggest that DMN dysregulation associated with schizophrenia predates psychosis onset.

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.

Cognitive functioning and age at onset in non-affective psychotic disorder

OBJECTIVE

Age at psychosis onset has been related to variability in cognitive functioning, but its effect may be mediated by demographic and clinical factors. The aim of the current study was to study the contribution of age at onset, as well as demographic and illness characteristics, to variation in cognitive functioning in patients with schizophrenia spectrum disorder.

METHOD

Patients (n = 1053) and healthy controls (n = 631) underwent comprehensive neuropsychological and clinical assessments. The effect of age at onset on age-standardized cognitive test scores was assessed with multiple linear regression analyses. Mediation by illness and demographic factors was tested using a multiple mediation Sobel test.

RESULTS

A diagnosis of schizophrenia, higher antipsychotic dose, and more negative symptoms were associated with earlier onset of illness, while female sex and a more chronic course were associated with later illness onset. Furthermore, earlier onset was associated with worse performance on immediate recall and sustained attention. However, male sex, more negative symptoms, and higher antipsychotic dose mediated the effect of age at onset on memory, while negative symptoms explained its association with attention/vigilance.

CONCLUSION

Greater impairment in memory and attention in early-onset psychosis may be explained by features indicative of underlying neurodevelopmental vulnerability.

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.

Pituitary volume, stress reactivity and genetic risk for psychotic disorder

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, associated with increased pituitary volume, may mediate observed alterations in stress reactivity in patients with psychotic disorder. We examined the association between pituitary volume, real-life stress reactivity and genetic liability for psychotic disorder.

METHOD

Pituitary volumes were derived from magnetic resonance imaging (MRI) scans of 20 patients with psychotic disorder, 37 non-psychotic siblings of these patients, and 32 controls. The Experience Sampling Method (ESM) was used to measure emotional stress reactivity [changes in negative affect (NA) associated with daily life stress] in the three groups, and biological stress reactivity (changes in cortisol associated with daily life stress) in siblings and controls. Interactions between group, stress and pituitary volume in models of NA and cortisol were examined.

RESULTS

Groups did not differ in pituitary volume. Patients showed significantly higher emotional stress reactivity than siblings and controls. In addition, emotional stress reactivity increased with increasing pituitary volume to a greater degree in patients than in controls and siblings. Siblings had higher cortisol levels than controls but did not show increased cortisol reactivity to stress. There was no interaction between pituitary volume, stress and group in the model of cortisol.

CONCLUSIONS

Higher pituitary volume was associated with increased emotional stress reactivity in patients with psychotic disorder, siblings and controls. The association was significantly stronger in the patient group, suggesting a process of progressive sensitization mediating clinical outcome.

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.

Differential patterns of premorbid social and academic deterioration in deficit and nondeficit schizophrenia

Numerous studies indicate that social dysfunction is associated with negative symptoms of schizophrenia during the chronic phase of illness. However, it is unclear whether social abnormalities exist during the premorbid phase in people who later develop schizophrenia with prominent negative symptoms, or whether social functioning becomes progressively worse in these individuals from childhood to late adolescence. The current study examined differences in academic and social premorbid functioning in people with schizophrenia meeting criteria for deficit (i.e., primary and enduring negative symptoms) (DS: n = 74) and non-deficit forms of schizophrenia (ND: n = 271). Premorbid social and academic functioning was assessed for childhood, early adolescence, and late adolescence developmental periods on the Premorbid Adjustment Scale (PAS). Results indicated that both DS and ND participants showed deterioration in social and academic functioning from childhood to late adolescence. However, while ND schizophrenia demonstrated greater deterioration of academic compared to social premorbid functioning from childhood to late adolescence, the DS group exhibited comparable deterioration across both premorbid domains, with more severe social deterioration than the ND group. Findings suggest that people with DS show poorer social premorbid adjustment than those with ND as early as childhood, and are particularly susceptible to accelerated deterioration as the onset of schizophrenia becomes imminent. Thus, poor premorbid social adjustment and significant social deterioration from childhood to adolescence may be a hallmark feature of people who later go on to develop prominent negative symptoms and a unique marker for the DS subtype of schizophrenia.

How genes and environmental factors determine the different neurodevelopmental trajectories of schizophrenia and bipolar disorder

The debate endures as to whether schizophrenia and bipolar disorder are separate entities or different manifestations of a single underlying pathological process. Here, we argue that this sterile argument obscures the fact that the truth lies somewhere in between. Thus, recent studies support a model whereby, on a background of some shared genetic liability for both disorders, patients with schizophrenia have been subject to additional genetic and/or environmental factors that impair neurodevelopment; for example, copy number variants and obstetric complications are associated with schizophrenia but not with bipolar disorder. As a result, children destined to develop schizophrenia show an excess of neuromotor delays and cognitive difficulties while those who later develop bipolar disorder perform at least as well as the general population. In keeping with this model, cognitive impairments and brain structural abnormalities are present at first onset of schizophrenia but not in the early stages of bipolar disorder. However, with repeated episodes of illness, cognitive and brain structural abnormalities accumulate in both schizophrenia and bipolar disorder, thus clouding the picture.

Inflammation during fetal and neonatal life: implications for neurologic and neuropsychiatric disease in children and adults

Inflammation is increasingly recognized as being of both physiological and pathological importance in the immature brain. The rationale of this review is to present an update on this topic with focus on long-term consequences of inflammation during childhood and in adults. The immature brain can be exposed to inflammation in connection with viral or bacterial infection during pregnancy or as a result of sterile central nervous system (CNS) insults. Through efficient anti-inflammatory and reparative processes, inflammation may resolve without any harmful effects on the brain. Alternatively, inflammation contributes to injury or enhances CNS vulnerability. Acute inflammation can also be shifted to a chronic inflammatory state and/or adversely affect brain development. Hypothetically, microglia are the main immunocompetent cells in the immature CNS, and depending on the stimulus, molecular context, and timing, these cells will acquire various phenotypes, which will be critical regarding the CNS consequences of inflammation. Inflammation has long-term consequences and could speculatively modify the risk of a variety of neurological disorders, including cerebral palsy, autism spectrum disorders, schizophrenia, multiple sclerosis, cognitive impairment, and Parkinson disease. So far, the picture is incomplete, and data mostly experimental. Further studies are required to strengthen the associations in humans and to determine whether novel therapeutic interventions during the perinatal period can influence the occurrence of neurological disease later in life.

Neurodevelopmental liability to schizophrenia: the complex mediating role of age at onset and premorbid adjustment

Large individual variation in the clinical presentation of schizophrenia-spectrum disorders raises key questions regarding their aetiological underpinnings. In this respect, age at onset of the disorder is a particularly interesting marker of liability, as it has been reported to be associated with other signs of developmental compromise, such as male gender, increased presence of familial history of psychosis and poor premorbid adjustment, as well as a more severe clinical outcome in terms of cognition and symptomatology. The association between these variables has encouraged a neurodevelopmental perspective of the aetiological mechanisms involved in the pathophysiology of schizophrenia. However, the complex relationships within neurobiological liability markers, and between these markers and clinical outcome, remain to be understood. In the present study, we used a path-analytic approach to explore: i) the fit of the model to observed data; and both ii) direct and iii) indirect associations between the variables. In a sample of 106 patients with schizophrenia-spectrum disorders, we found a good fit of the model to the observed data, providing further evidence that supports a neurodevelopmental pathway to the disease in a subgroup of patients. However, the most parsimonious model showed complex relationships, where age at onset and premorbid functioning acted as mediators between gender, familial history of psychosis and clinical outcome. These findings refine earlier explanations of the neurobiological basis of schizophrenia, with potential applications in genetic studies based on more homogeneous forms of the disease. We further discuss the putative implications of our results in clinical practice and prevention policies.

A brief review on recent developments in animal models of schizophrenia

Number of patients suffering from schizophrenia is increasing daily, subsequently, increasing the need of proper medication to treat the symptoms and eventually improve the patients' condition. However, all the progress for designing or discovering medication comes to a standstill, as the symptomatic treatment can only be done in the patients, but performing clinical trials with all the possible candidate drugs in human beings and patients is unethical. Thus, the need arises for proper animal and non-human primate animal models of the disease, which would not only serve the purpose of understanding the disease in a better physiological setting, but also would allow the scientists to focus on developing a therapeutically effective and potent medication for treating this hazardous disease. This brief review article focuses on a few animal models which are generally used for carrying out studies on schizophrenic symptoms in research labs and industry worldwide. The paper also tries to validate the pre-clinically available models based on certain specified criteria like the predictive constructive and face validity. Thus, the paper gives guidance toward the mechanistic and traditional models of schizophrenia applying some of the newer principles and helps researchers in deciding a particular relevant model for their own purpose.

A quantitative meta-analysis of population-based studies of premorbid intelligence and schizophrenia

OBJECTIVE

A premorbid IQ deficit supports a developmental dimension to schizophrenia and its cognitive aspects that are crucial to functional outcome. Better characterisation of the association between premorbid IQ and the disorder may provide further insight into its origin and etiology. We aimed to quantify premorbid cognitive function in schizophrenia through systematic review and meta-analysis of longitudinal, population-based studies, and to characterize the risk of schizophrenia across the entire range of premorbid IQ.

METHOD

Electronic and manual searches identified general population-based cohort or nested case-control studies that measured intelligence before onset of schizophrenic psychosis using standard psychometric tests, and that defined cases using contemporaneous ICD or DSM. Meta-analyses explored dose-response relationships between premorbid cognitive deficit (using full-scale, verbal and performance IQ) and risk of schizophrenia. Meta-regression analyses explored relationships with age of illness onset, change in premorbid intelligence over time and gender differences.

RESULTS

Meta-analysis of 4396 cases and over 745000 controls from 12 independent studies confirmed significant decrements in premorbid IQ (effect size -0.43) among future cases. Risk of schizophrenia operated as a consistent dose-response effect, increasing by 3.7% for every point decrease in IQ (p<0.0001). Verbal and nonverbal measures were equally affected. Greater premorbid IQ decrement was associated with earlier illness onset (p<0.0001). There was no evidence of a progressively increasing deficit during the premorbid period toward illness onset.

CONCLUSIONS

Strong associations between premorbid IQ and risk for schizophrenia, and age of illness onset argue for a widespread neurodevelopmental contribution to schizophrenia that operates across the entire range of intellectual ability. This also suggests higher IQ may be protective in schizophrenia, perhaps by increasing active cognitive reserve.

Patient subgroups of schizophrenia based on the Positive and Negative Syndrome Scale: composition and transition between acute and subsided disease states

The present study focuses on schizophrenia patient subgroups with specific symptom pattern using the Positive and Negative Syndrome Scale (PANSS). In this report, we intend to (1) provide a more appropriate analytic method for exploring the subgroups based on PANSS data, (2) validate identified subgroups with external variables, and (3) estimate probabilities of subgroup changes between 2 disease states. The analyzed data include 219 acute-state patients who had completed the PANSS within 1 week of index admission and 225 subsided-state patients who were living in the community and under family care. Regression extension of latent class analysis was performed. We found that acute schizophrenia can be classified into 4 subgroups--whole syndrome, whole syndrome without hostility, partial syndrome with negative symptoms, and partial syndrome with pure reality distortion--and that subsided schizophrenia can be classified into 3 subgroups--florid symptom, marked negative, and remitted. Patients of the whole syndrome, whole syndrome without hostility, partial syndrome with negative symptoms, and partial syndrome with pure reality distortion subgroups at the acute state were most likely to transit to the florid symptom (61%), florid symptom (48%), marked negative (42%), and remitted (56%) subgroups at the subsided state, respectively. Significant relationships of obtained subgroups with sociodemographic variables and neurocognitive variables were identified. These results of different subgroups will provide the background for facilitating current molecular, genetic, and neurobiological studies of schizophrenia.

A systematic review and meta-analysis of neurological soft signs in relatives of people with schizophrenia

BACKGROUND

Neurological soft signs are subtle but observable impairments in motor and sensory functions that are not localized to a specific area of the brain. Neurological soft signs are common in schizophrenia. It has been established that soft signs meet two of five criteria for an endophenotype, namely: association with the illness, and state independence. This review investigated whether soft signs met a further criterion for an endophenotype, namely familial association. It was hypothesized that if familial association were present then neurological soft signs would be: (a) more common in first-degree relatives of people with schizophrenia than in controls; and (b) more common in people with schizophrenia than in their first-degree relatives.

METHOD

A systematic search identified potentially eligible studies in the EMBASE (1980-2011), OVID - MEDLINE (1950-2011) and PsycINFO (1806-2011) databases. Studies were included if they carried out a three-way comparison of levels of soft signs between people with schizophrenia, their first-degree relatives, and normal controls. Data were extracted independently by two reviewers and cross-checked by double entry.

RESULTS

After screening 8678 abstracts, seven studies with 1553 participants were identified. Neurological soft signs were significantly more common in first-degree relatives of people with schizophrenia than in controls (pooled standardised mean difference (SMD) 1.24, 95% confidence interval (c.i) 0.59-1.89). Neurological soft signs were also significantly more common in people with schizophrenia than in their first-degree relatives (SMD 0.92, 95% c.i 0.64-1.20). Sensitivity analyses examining the effects of age and group blinding did not significantly alter the main findings.

CONCLUSIONS

Both hypotheses were confirmed, suggesting that the distribution of neurological soft signs in people with schizophrenia and their first-degree relatives is consistent with the endophenotype criterion of familial association.

Working memory and attention deficits in adolescent offspring of schizophrenia or bipolar patients: comparing vulnerability markers

BACKGROUND

Working memory deficits abound in schizophrenia and attention deficits have been documented in schizophrenia and bipolar disorder. Adolescent offspring of patients may inherit vulnerabilities in brain circuits that subserve these cognitive domains. Here we assess impairments in offspring of schizophrenia (SCZ-Offspring) or bipolar (BP-Offspring) patients compared to controls (HC) with no family history of mood or psychotic disorders to the second degree.

METHODS

Three groups (n=100 subjects; range: 10-20 yrs) of HC, SCZ-Offspring and BP-Offspring gave informed consent. Working memory was assessed using a delayed spatial memory paradigm with two levels of delay (2s & 12s); sustained attention processing was assessed using the Continuous Performance Task-Identical Pairs version.

RESULTS

SCZ-Offspring (but not BP-Offspring) showed impairments in working memory (relative to HC) at the longer memory delay indicating a unique deficit. Both groups showed reduced sensitivity during attention but only BP-Offspring significantly differed from controls.

CONCLUSIONS

These results suggest unique (working memory/dorsal frontal cortex) and potentially overlapping (attention/fronto-striatal cortex) vulnerability pathways in adolescent offspring of patients with schizophrenia and bipolar disorder. Working memory and attention assessments in these offspring may assist in the clinical characterization of the adolescents vulnerable to SCZ or BP.

Young offspring at genetic risk of adult psychoses: the form of the trajectory of IQ or memory may orient to the right dysfunction at the right time

Objective

Neurocognitive dysfunctions analogous to those of adult patients have been detected in children at risk of schizophrenia and bipolar disorder. This led to the following developmental question: Do IQ and memory impairments exhibit different developmental courses from childhood to young adulthood in terms of stability or fluctuations?

Methods

In a high risk sample, we used a step by step sampling approach to narrow-down the early disease mechanisms. Upstream, we started with a 20-year follow-up of 48 densely affected multigenerational kindreds, including 1500 clinically characterized adult members. We then identified 400 adult members affected by a DSM-IV schizophrenia or bipolar disorder. Downstream, we finally focused on 65 offspring (of an affected parent) aged 7 to 22, who were administered a neuropsychological battery. We then constructed cross-sectional trajectories that were compared to those of controls.

Results

The childhood IQ deficit displayed a stability until young adulthood. The delay in visual memory exhibited a non-linear two-stage trajectory: a lagging period during childhood followed by a recuperation period from adolescence until adulthood, as supported by a significant Group x Age Periods interaction. No data suggested deterioration between 7 and 22.

Conclusion

In these offspring at genetic risk, the developmental trajectory of global IQ impairment may not apply to specific domains of cognition such as episodic memory. Different cognitive dysfunctions would mark different developmental courses. The shape of the trajectories might itself have a meaning and provide empirical leads for targeting the right dysfunction at the right time in future prevention research.

To poly(I:C) or not to poly(I:C): advancing preclinical schizophrenia research through the use of prenatal immune activation models

The neurodevelopmental hypothesis of schizophrenia has been highly influential in shaping our current thinking about modeling the disease in animals. Based on the findings provided by human epidemiological studies, a great deal of recent interest has been centered upon the establishment of neurodevelopmental rodent models in which the basic experimental manipulation takes the form of prenatal exposure to infection and/or immune activation. One such model is based on prenatal treatment with the inflammatory agent poly(I:C) (=polyriboinosinic-polyribocytidilic acid), a synthetic analog of double-stranded RNA. Since its initial establishment and application to basic schizophrenia research, the poly(I:C) model has made a great impact on researchers concentrating on the neurodevelopmental and neuroimmunological basis of complex human brain disorders such as schizophrenia, and as a consequence, the model now enjoys wide recognition in the international scientific community. The present article emphasizes that the poly(I:C) model has gained such impact because it successfully accounts for several aspects of schizophrenia epidemiology, pathophysiology, symptomatology, and treatment. The numerous features of this experimental system make the poly(I:C) model a very powerful neurodevelopmental animal model of schizophrenia-relevant brain disease which is expected to be capable of critically advancing our knowledge of how the brain, following an (immune-associated) triggering event in early life, can develop into a "schizophrenia-like brain" over time. Furthermore, the poly(I:C) model seems highly suitable for the exploration of novel pharmacological and neuro-immunomodulatory strategies for both symptomatic and preventive treatments against psychotic disease, as well as for the identification of neurobiological mechanisms underlying gene-environment and environment-environment interactions presumably involved in the etiology of schizophrenia and related disorders.

Diffusion tensor imaging in the early phase of schizophrenia: what have we learned?

The dysconnectivity model suggests that disturbed integration of neural communication is central to schizophrenia. The integrity of macro-structural brain circuits can be examined with diffusion tensor imaging (DTI), an MRI application sensitive to microstructural abnormalities of brain white matter. DTI studies in first-episode schizophrenia patients and individuals at high-risk of psychosis can provide insight into the role of structural dysconnectivity in the liability, onset and early course of psychosis. This review discusses (i) views on the role of white matter abnormalities in schizophrenia, (ii) DTI and its application in schizophrenia, (iii) DTI findings in first-episode patients and subjects at high-risk of psychosis; their timing, anatomical location and early course, (iv) the hypothesized underlying pathological substrate and possible causes of DTI white matter alterations, including effects of adolescent cannabis use, and (v) some methodological issues and future recommendations. In summary, there is evidence that DTI abnormalities convey a liability for psychosis and additional abnormalities occur around onset of psychosis. However, findings in first-episode patients are less robust than in chronic patients, and progression of disturbances may occur in the early course of poor-outcome patients. In addition, acceleration of the normal aging process may occur. Adolescent cannabis use has specific effects on DTI measures. An unresolved issue is the underlying pathology of DTI abnormalities, and combining DTI with other MRI indices can provide more insight. More research is needed on which genetic and environmental factors play a role in the variability of current results.

A Hybrid Machine Learning Method for Fusing fMRI and Genetic Data: Combining both Improves Classification of Schizophrenia

We demonstrate a hybrid machine learning method to classify schizophrenia patients and healthy controls, using functional magnetic resonance imaging (fMRI) and single nucleotide polymorphism (SNP) data. The method consists of four stages: (1) SNPs with the most discriminating information between the healthy controls and schizophrenia patients are selected to construct a support vector machine ensemble (SNP-SVME). (2) Voxels in the fMRI map contributing to classification are selected to build another SVME (Voxel-SVME). (3) Components of fMRI activation obtained with independent component analysis (ICA) are used to construct a single SVM classifier (ICA-SVMC). (4) The above three models are combined into a single module using a majority voting approach to make a final decision (Combined SNP-fMRI). The method was evaluated by a fully validated leave-one-out method using 40 subjects (20 patients and 20 controls). The classification accuracy was: 0.74 for SNP-SVME, 0.82 for Voxel-SVME, 0.83 for ICA-SVMC, and 0.87 for Combined SNP-fMRI. Experimental results show that better classification accuracy was achieved by combining genetic and fMRI data than using either alone, indicating that genetic and brain function representing different, but partially complementary aspects, of schizophrenia etiopathology. This study suggests an effective way to reassess biological classification of individuals with schizophrenia, which is also potentially useful for identifying diagnostically important markers for the disorder.

Neurodevelopmental animal models of schizophrenia: role in novel drug discovery and development

Schizophrenia is a devastating mental illness that is associated with a lifetime of disability. For patients to successfully function in society, the amelioration of disease symptoms is imperative. The recently published results of two large antipsychotic clinical trials (e.g., CATIE, CUtLASS) clearly exemplified the limitations of currently available treatment options for schizophrenia, and further highlighted the critical need for novel drug discovery and development in this field. One of the biggest challenges in schizophrenia-related drug discovery is to find an appropriate animal model of the illness so that novel hypotheses can be tested at the basic science level. A number of pharmacological, genetic, and neurodevelopmental models have been introduced; however, none of these models has been rigorously evaluated for translational relevance or to satisfy requirements of "face," "construct" and "predictive" validity. Given the apparent polygenic nature of schizophrenia and the limited translational significance of pharmacological models, neurodevelopmental models may offer the best chance of success. The purpose of this review is to provide a general overview of the various neurodevelopmental models of schizophrenia that have been introduced to date, and to summarize their behavioral and neurochemical phenotypes that may be useful from a drug discovery and development standpoint. While it may be that, in the final analysis, no single animal model will satisfy all the requirements necessary for drug discovery purposes, several of the models may be useful for modeling various phenomenological and pathophysiological components of schizophrenia that could be targeted independently with separate molecules or multi-target drugs.

Changes in gene expression after phencyclidine administration in developing rats: a potential animal model for schizophrenia

Repeated administration of phencyclidine (PCP), an N-methyl-d-aspartate (NMDA) receptor antagonist, during development, may result in neuronal damage that leads to behavioral deficits in adulthood. The present study examined the potential neurotoxic effects of PCP exposure (10mg/kg) in rats on postnatal days (PNDs) 7, 9 and 11 and the possible underlying mechanism(s) for neurotoxicity. Brain tissue was harvested for RNA extraction and morphological assessments. RNA was collected from the frontal cortex for DNA microarray analysis and quantitative RT-PCR. Gene expression profiling was determined using Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Based on criteria of a fold-change greater than 1.4 and a P-value less than 0.05, 19 genes including NMDAR1 (N-methyl-d-aspartate receptor) and four pro-apoptotic genes were up-regulated, and 25 genes including four anti-apoptotic genes were down-regulated, in the PCP-treated group. In addition, the schizophrenia-relevant genes, Bdnf (Brain-derived neurotrophic factor) and Bhlhb2 (basic helix-loop-helix domain containing, class B, 2), were significantly different between the PCP and the control groups. Quantitative RT-PCR confirmed the microarray results. Elevated neuronal cell death was further confirmed using Fluoro-Jade C staining. These findings support the hypothesis that neurodegeneration caused by PCP occurs, at least in part, through the up-regulation of NMDA receptors, which makes neurons possessing these receptors more vulnerable to endogenous glutamate. The changes in schizophrenia-relevant genes after repeated PCP exposure during development may provide important information concerning the validation of an animal model for this disorder.

White matter neuron alterations in schizophrenia and related disorders

Increased density and altered spatial distribution of subcortical white matter neurons (WMNs) represents one of the more well replicated cellular alterations found in schizophrenia and related disease. In many of the affected cases, the underlying genetic risk architecture for these WMN abnormalities remains unknown. Increased density of neurons immunoreactive for Microtubule-Associated Protein 2 (MAP2) and Neuronal Nuclear Antigen (NeuN) have been reported by independent studies, though there are negative reports as well; additionally, group differences in some of the studies appear to be driven by a small subset of cases. Alterations in markers for inhibitory (GABAergic) neurons have also been described. For example, downregulation of neuropeptide Y (NPY) and nitric oxide synthase (NOS1) in inhibitory WMN positioned at the gray/white matter border, as well as altered spatial distribution, have been reported. While increased density of WMN has been suggested to reflect disturbance of neurodevelopmental processes, including neuronal migration, neurogenesis, and cell death, alternative hypotheses--such as an adaptive response to microglial activation in mature CNS, as has been described in multiple sclerosis--should also be considered. We argue that larger scale studies involving hundreds of postmortem specimens will be necessary in order to clearly establish the subset of subjects affected. Additionally, these larger cohorts could make it feasible to connect the cellular pathology to environmental and genetic factors implicated in schizophrenia, bipolar disorder, and autism. These could include the 22q11 deletion (Velocardiofacial/DiGeorge) syndrome, which in some cases is associated with neuronal ectopias in white matter.

Genetic modelling of childhood social development and personality in twins and siblings with schizophrenia

BACKGROUND

Abnormalities in early social development and personality are present in patients with schizophrenia and their unaffected relatives. This study aimed to establish the degree to which these childhood and adolescent developmental abnormalities are genetically determined.

METHOD

We used a combined twin and family study design (n=531) to assess childhood and adolescent social adjustment and schizotypal personality traits in 98 twin pairs (n=196) varying in their zygosity and concordance for schizophrenia and 156 sibling clusters (n=335) varying in their concordance for schizophrenia.

RESULTS

Schizophrenia was significantly associated with childhood and adolescent deficits in social adjustment and personality, with additive genetic effects being the main source of these phenotypic correlations.

CONCLUSIONS

Abnormalities of social adjustment and personality are present in children and adolescents who later develop schizophrenia, reflecting the influence of common genetic risk.